PLC毕业设计的外文文献(及翻译)

关于PLC外文文献翻译外文文献翻译2014年6月designate a person responsible for periodically repaired, if significant quality problems, whether it's design or construction reasons, are required at the first meeting to study and propose solutions; 5) post through re-examination on the basis to resolve all remaining issues, well prepared for formal acceptance. 9, officially accepted: 1) the letter of acceptance issued by the Chief Engineer, project manager, and submitted it to the construction completion data; 2) by the employer organization design, supervision and quality supervision stations, construction and other construction units work together to check the quality and acceptance of views put forward, assessed quality rating; 3) Unit checked and confirmed after the completion of works comply with the standards and requirements, issue a certificate of completion to the construction unit, construction and design, quality supervision station, the engineer, civil engineering and other units to sign the certificates of completion; 4) signed a final acceptance certificate and construction unit, and according to the contract provisions of settlement procedures, unless indicated in the contract by the contractor of the warranty work, economic and legal responsibilities of each party are able to remove; 5) get the files transfer and project procedures. 10 quality tracking, maintenance plan is an important partof our quality assurance system, the company sold products and installation works are carried out by the after-sales service obligations. In particular, we developed a departmental duties and quality guarantee measures, as follows: 1) visited customers and product usage information. 2) collect customer feedback, product information, customer reports, complaints. 3) based on customer comments and respond promptly to complaints, to the site to identify the cause analysis, engineering quality problems and fill in the data form. 4) record type, the location, cause, and complete solutions. 5) identify reasons to propose solutions and,Understanding the Basics of S7-200 Network Communications Selecting the Communication Interface for Your NetworkThe S7-200 is designed to solve your communications and networking needs by supporting not only the simplest of networks but also supporting more complex networks. The S7-200 also provides tools that allow you to communicate with other devices, such as printers and weigh scales which use their owncommunications protocols.The S7-200 supports many different types of communication networks. The selection of a network isperformed within the Set PG/PC Interface property dialog. A selected network is referred to as an Interface. The different types of interfaces available to access these communication networks are:1. PPI Multi-Master cables2. CP communication cards3. Ethernet communication cardsTo select the communication interface for STEP 7--Micro/WIN, you perform the following steps. See Figure 7-1.1. Double-click the icon in the Communications Setup window.2. Select the interface parameter fo12Figure 7-1 STEP 7--Micro/WINCommunications Interface第 0 页共 2 页PPI Multi-Master CablesThe S7-200 supports communication through two different types of PPI Multi-Master cables. These cable types permit communication through either an RS-232 or a USB interface.As shown in Figure 7-2, selecting the PPI Multi-Master cable type is simple. You perform the following steps:1. Click the Properties button on the Set PG/PC Interface property page.2. Click the Local Connection tab on the Properties page.3. Select the USB or the desired COM port123Figure 7-2 PPI Multi-Master Cable SelectionTipPlease note that only one USB cable can be used at a time.TipExamples in this manual use the RS-232/PPI Multi-Master cable. TheRS-232/PPI Multi-Master cable replaces the previous PC/PPI cable. AUSB/PPI Multi-Master cable is also available. Refer to Appendix E for order numbers. Using Master and Slave Devices on a PROFIBUS Network The S7-200 supports a master-slave network and can function aseither a master or a slave in a PROFIBUS network, while STEP 7--Micro/WIN is always a master.第 1 页共 3 页MastersA device that is a master on a network can initiate a request to another device on the network. A master can also respond to requestsfrom other masters on the network. Typical master devices include STEP7--Micro/WIN, human-machine interface devices such as a TD 200, and S7-300 or S7-400 PLCs. The S7-200 functions as a master when it isrequesting information from another S7-200 (peer-to-peer communications).TipA TP070 will not work on a network with another master device.SlavesA device that is configured as a slave can only respond to requests from a master device; a slave never initiates a request. For most networks, the S7-200 functions as a slave. As a slave device, the S7-200responds to requests from a network master device, such as an operator panel or STEP 7--Micro/WIN.Setting the Baud Rate and Network AddressThe speed that data is transmitted across the network is the baud rate, which is typically measured in units of kilobaud (kbaud) or megabaud (Mbaud). The baud rate measures how much data can betransmitted within a given amount of time. For example, a baud rate of 19.2 kbaud describes a transmission rate of 19,200 bits per second.Every device that communicates over a given network must beconfigured to transmit data at the same baud rate. Therefore, thefastest baud rate for the network is determined by the slowest device connected to the network.Table 7-1 lists the baud rates supported by the S7-200.Table 7-1 Baud Rates Supported by the S7-200Network Baud RateStandard Network 9.6 kbaud to 187.5 kbauddesignate a person responsible for periodically repaired, if significant quality problems, whether it's design or construction reasons, are required at the first meeting to study and propose solutions; 5) post through re-examination on the basis to resolve all remaining issues, well prepared for formal acceptance. 9, officially accepted: 1) the letter of acceptance issued by the Chief Engineer, project manager, and submitted it to the construction completion data; 2) by the employer organization design, supervision and quality supervisionstations, construction and other construction units work together to check the quality and acceptance of views put forward, assessed quality rating; 3) Unit checked and confirmed after the completion of works comply with the standards and requirements, issue a certificate of completion to the construction unit, construction and design, quality supervision station, the engineer, civil engineering and other units to sign the certificates of completion; 4) signed a final acceptance certificate and construction unit, and according to the contract provisions of settlement procedures, unless indicated in the contract by the contractor of the warranty work, economic and legal responsibilities of each party are able to remove; 5) get the files transfer and project procedures. 10 quality tracking, maintenance plan is an important part of our quality assurance system, the company sold products and installation works are carried out by the after-sales service obligations. In particular, we developed a departmental duties and quality guarantee measures, as follows: 1) visited customers and product usage information. 2) collect customer feedback, product information, customer reports, complaints. 3) based on customer comments and respond promptly to complaints, to the site to identify the cause analysis, engineering quality problems and fill in the data form. 4) record type, the location, cause, and complete solutions. 5) identify reasons to propose solutions and,Using an EM 277 9.6 kbaud to 12 MbaudFreeport Mode 1200 baud to 115.2 kbaudThe network address is a unique number that you assign to each device on the network. The unique network address ensures that the data is transferred to or retrieved from the correct device. The S7-200 supports network addresses from 0 to 126. For an S7-200 with two ports, each port has a network address. Table 7-2 lists the default (factory) settings for the S7-200 devices.Table 7-2 Default Addresses for S7-200 DevicesS7-200 Device Default AddressSTEP 7--Micro/WIN 0HMI (TD 200, TP, or OP) 1S7-200 CPU 2Setting the Baud Rate and Network Address for STEP7--Micro/WINYou must configure the baud rate and network address for STEP 7--Micro/WIN. The baud rate must be the same as the other devices on the network, and the network address must be unique.Typically, you do not change the network address (0) for STEP 7--Micro/WIN. If your network includes another programming package, you might need to change the network address for STEP 7--Micro/WIN.As shown in Figure 7-3, configuring the baud rate and network address for STEP 7--Micro/WIN is simple. After you click the Communications icon in the Navigation bar, you perform the following steps:第 3 页共 5 页\ 1234Figure 7-3 Configuring STEP 7--Micro/WINFigure 7-3 Configuring STEP 7--Micro/WIN1. Double-click the icon in the Communications Setup window.2. Click the Properties button on the Set PG/PC Interface dialog box.3. Select the network address for STEP 7--Micro/WIN.4. Select the baud rate for STEP 7--Micro/WIN.Setting the Baud Rate and Network Address for the S7-200You must also configure the baud rate and network address for theS7-200. The system block of the S7-200 stores the baud rate and network address. After you select the parameters for the S7-200, you must download the system block to the S7-200.The default baud rate for each S7-200 port is 9.6 kbaud, and thedefault network address is 2.As shown in Figure 7-4, use STEP 7--Micro/WIN to set the baud rateand network address for the S7-200. After you select the System Blockicon in the Navigation bar or select the View > Component > System Block menu command, you perform the following steps:1. Select the network address for the S7-200.2. Select the baud rate for the S7-200.designate a person responsible for periodically repaired, ifsignificant quality problems, whether it's design or construction reasons, are required at the first meeting to study and proposesolutions; 5) post through re-examination on the basis to resolve all remaining issues, well prepared for formal acceptance. 9, officiallyaccepted: 1) the letter of acceptance issued by the Chief Engineer, project manager, and submitted it to the construction completion data; 2) by the employer organization design, supervision and quality supervision stations, construction and other construction units work together to check the quality and acceptance of views put forward, assessed quality rating; 3) Unit checked and confirmed after the completion of works comply with the standards and requirements, issue a certificate of completion to the construction unit, construction and design, quality supervision station, the engineer, civil engineering and other units to sign the certificates of completion; 4) signed a final acceptance certificate and construction unit, and according to the contract provisions of settlement procedures, unless indicated in the contract by the contractor of the warranty work, economic and legal responsibilities of each party are able to remove; 5) get the files transfer and project procedures. 10 quality tracking, maintenance plan is an important partof our quality assurance system, the company sold products andinstallation works are carried out by the after-sales service obligations. In particular, we developed a departmental duties andquality guarantee measures, as follows: 1) visited customers and product usage information. 2) collect customer feedback, product information, customer reports, complaints. 3) based on customer comments and respond promptly to complaints, to the site to identify the cause analysis, engineering quality problems and fill in the data form. 4) record type,the location, cause, and complete solutions. 5) identify reasons to propose solutions and,3. Download the system block to the S7-200.12Figure 7-4 Configuring the S7-200 CPUTipSelection of all baud rate options is permitted. STEP 7--Micro/WIN validates this selection during the download of the System Block. Baud rate selections that would prevent STEP 7--Micro/WIN from communicating with the S7-200 are prevented from being downloaded.Setting the Remote AddressBefore you can download the updated settings to the S7-200, you must set both the communications (COM) port of STEP 7--Micro/WIN (local) and the address of the S7-200 (remote) to match the current setting of the remote S7-200. See Figure 7-5.After you download the updated settings, you may need to reconfigure the PG/PC Interface baud rate setting (if different from the setting used when downloading to the remote S7-200). Refer to Figure 7-3 to configure the baud rate.第 5 页共 7 页Figure 7-5 Configuring STEP 7--Micro/WINSearching for the S7-200 CPUs on a NetworkYou can search for and identify the S7-200 CPUs that are attached to your network. You can also search the network at a specific baud rate or at all baud rates when looking for S7-200s.Only PPI Multi-Master cables permit searching of all baud rates.This feature is not available if communicating through a CP card. The search starts at the baud rate that is currently selected.1. Open the Communications dialog box and double-click the Refresh icon to start the search.2. To search all baud rates, select the Search All Baud Rates check box. 2.Selecting the Communications Protocol for Your NetworkThe following information is an overview of the protocols supportedby the S7-200 CPUs.1. Point-to-Point Interface (PPI)2. Multi-Point Interface (MPI)3. PROFIBUSFigure 7-6 Searching for CPUs on a Networkdesignate a person responsible for periodically repaired, if significant quality problems, whether it's design or construction reasons, are required at the first meeting to study and propose solutions; 5) post through re-examination on the basis to resolve all remaining issues, well prepared for formal acceptance. 9, officially accepted: 1) the letter of acceptance issued by the Chief Engineer, project manager, and submitted it to the construction completion data; 2) by the employer organization design, supervision and quality supervision stations, construction and other construction units work together to check the quality and acceptance of views put forward, assessed qualityrating; 3) Unit checked and confirmed after the completion of works comply with the standards and requirements, issue a certificate of completion to the construction unit, construction and design, quality supervision station, the engineer, civil engineering and other units to sign the certificates of completion; 4) signed a final acceptance certificate and construction unit, and according to the contract provisions of settlement procedures, unless indicated in the contract by the contractor of the warranty work, economic and legal responsibilities of each party are able to remove; 5) get the files transfer and project procedures. 10 quality tracking, maintenance plan is an important part of our quality assurance system, the company sold products and installation works are carried out by the after-sales service obligations. In particular, we developed a departmental duties and quality guarantee measures, as follows: 1) visited customers and product usage information. 2) collect customer feedback, product information, customer reports, complaints. 3) based on customer comments and respond promptly to complaints, to the site to identify the cause analysis, engineering quality problems and fill in the data form. 4) record type, the location, cause, and complete solutions. 5) identify reasons to propose solutions and,Based on the Open System Interconnection (OSI) seven-layer model of communications architecture, these protocols are implemented on a token ring network which conforms to the PROFIBUS standard as defined in the European Standard EN 50170. These protocols are asynchronous, character-based protocols with one start bit, eight data bits, even parity, and one stop bit. Communications frames depend upon special start and stop characters, source and destination station addresses, frame length, and a checksum for data integrity. The protocols can run on a network simultaneously without interfering with each other, as long as the baud rate is the same for each protocol.Ethernet is also available for the S7-200 CPU with expansion modules CP243--1 and CP243--1 IT.PPI ProtocolPPI is a master-slave protocol: the master devices send requests to the slave devices, and the slave devices respond. See Figure 7-7. Slave devices do not initiate messages, but wait until a master sends them a request or polls them for a response.Masters communicate to slaves by means of a shared connection which is managed by the PPI protocol. PPI does not limit the number of masters that can communicate with any one slave; however, you cannot install more than 32 masters on the network.Figure 7-7 PPI NetworkS7-200 CPUs can act as master devices while they are in RUN mode, if you enable PPI master mode in the user program. (See the description of SMB30 in Appendix D.) After enabling PPI master mode, you can use the Network Read or the Network Write instructions to read from or write to other S7-200s.While the S7-200 is acting as a PPI master, it still responds as a slave to requests from other masters.第 7 页共 9 页PPI Advanced allows network devices to establish a logical connection between the devices. With PPI Advanced, there are a limited number of connections supplied by each device. See Table 7-3 for the number of connections supported by the S7-200.All S7-200 CPUs support both PPI and PPI Advanced protocols, while PPI Advanced is the only PPI protocol supported by the EM 277 module.Table 7-3 Number of Connections for the S7-200 CPU and EM 277 ModulesModule Baud Rate ConnectionsS7-200 CPU Port 0 9.6 kbaud, 19.2 kbaud, or 187.5 kbaud 4Port 1 9.6 kbaud, 19.2 kbaud, or 187.5 kbaud 4EM 277 Module 9.6 kbaud to 12 Mbaud 6 per moduleMPI ProtocolMPI allows both master-master and master-slave communications. See Figure 7-8. To communicate with an S7-200 CPU, STEP 7--Micro/WINestablishes a master--slave connection. MPI protocol does not communicate with an S7-200 CPU operating as a master.Network devices communicate by means of separate connections (managed by the MPI protocol) between any two devices. Communication between devices is limited to the number of connections supported by the S7-200 CPU or EM 277 modules. See Table 7-3 for the number of connections supported by the S7-200.For MPI protocol, the S7-300 and S7-400 PLCs use the XGET and XPUT instructions to read and write data to the S7-200 CPU. For information about these instructions, refer to your S7-300 or S7-400 programming manual.Figure 7-8 MPI Networkdesignate a person responsible for periodically repaired, if significant quality problems, whether it's design or construction reasons, are required at the first meeting to study and propose solutions; 5) post through re-examination on the basis to resolve all remaining issues, well prepared for formal acceptance. 9, officiallyaccepted: 1) the letter of acceptance issued by the Chief Engineer, project manager, and submitted it to the construction completion data; 2) by the employer organization design, supervision and quality supervision stations, construction and other construction units work together to check the quality and acceptance of views put forward, assessed quality rating; 3) Unit checked and confirmed after the completion of works comply with the standards and requirements, issue a certificate of completion to the construction unit, construction and design, quality supervision station, the engineer, civil engineering and other units to sign the certificates of completion; 4) signed a final acceptance certificate and construction unit, and according to the contract provisions of settlement procedures, unless indicated in the contract by the contractor of the warranty work, economic and legal responsibilities of each party are able to remove; 5) get the files transfer and project procedures. 10 quality tracking, maintenance plan is an important partof our quality assurance system, the company sold products andinstallation works are carried out by the after-sales service obligations. In particular, we developed a departmental duties andquality guarantee measures, as follows: 1) visited customers and product usage information. 2) collect customer feedback, product information, customer reports, complaints. 3) based on customer comments and respond promptly to complaints, to the site to identify the cause analysis, engineering quality problems and fill in the data form. 4) record type,the location, cause, and complete solutions. 5) identify reasons to propose solutions and,PROFIBUS ProtocolThe PROFIBUS protocol is designed for high-speed communications with distributed I/O devices (remote I/O). There are many PROFIBUS devices available from a variety of manufacturers. These devices range from simple input or output modules to motor controllers and PLCs.PROFIBUS networks typically have one master and several slave I/O devices. See Figure 7-9. The master device is configured to know what types of I/O slaves are connected and at what addresses. The master initializes the network and verifies that the slave devices on the network match the configuration. The master continuously writes output data to the slaves and reads input data from them.Figure 7-9 PROFIBUS NetworkWhen a DP master configures a slave device successfully, it then owns that slave device. If there is a second master device on thenetwork, it has very limited access to the slaves owned by the first master.TCP/IP ProtocolThe S7-200 can support TCP/IP Ethernet communication through the use of an Ethernet (CP 243--1) orInternet (CP 243--1 IT) expansion module. Table 7-4 shows the baud rate and number of connections supported by these modules. Table 7-4 Number of Connections for the Ethernet (CP 243--1) and the Internet (CP 243--1 IT)ModulesModule Baud Rate ConnectionsEthernet (CP 243--1) Module 10 to 100 Mbaud 8 general purpose connections第 9 页共 11 页1 STEP 7--Micro/WINInternet (CP 243--1 IT) ModuleconnectionRefer to the CP 243--1 Communications Processor for Industrial EthernetManual or the CP 243--1 IT Communications Processor for Industrial Ethernet andInformation Technology Manual for additional information.designate a person responsible for periodically repaired, if significant quality problems, whether it's design or construction reasons, are required at the first meeting to study and proposesolutions; 5) post through re-examination on the basis to resolve all remaining issues, well prepared for formal acceptance. 9, officially accepted: 1) the letter of acceptance issued by the Chief Engineer, project manager, and submitted it to the construction completion data; 2) by the employer organization design, supervision and quality supervision stations, construction and other construction units work together to check the quality and acceptance of views put forward, assessed quality rating; 3) Unit checked and confirmed after the completion of works comply with the standards and requirements, issue a certificate of completion to the construction unit, construction and design, quality supervision station, the engineer, civil engineering and other units to sign the certificates of completion; 4) signed a final acceptance certificate and construction unit, and according to the contract provisions of settlement procedures, unless indicated in the contract by the contractor of the warranty work, economic and legal responsibilities of each party are able to remove; 5) get the files transfer and project procedures. 10 quality tracking, maintenance plan is an important partof our quality assurance system, the company sold products andinstallation works are carried out by the after-sales service obligations. In particular, we developed a departmental duties andquality guarantee measures, as follows: 1) visited customers and product usage information. 2) collect customer feedback, product information, customer reports, complaints. 3) based on customer comments and respond promptly to complaints, to the site to identify the cause analysis,engineering quality problems and fill in the data form. 4) record type, the location, cause, and complete solutions. 5) identify reasons to propose solutions and,中文翻译理解S7--200网络通讯的基本概念为网络选择通讯接口S7--200可以满足您的通讯和网络需求，它不仅支持简单的网络，而且支持比较复杂的网络。

学校名称外文翻译专业：班级学号：学生姓名：指导教师：二〇一一年六月学校名称本科生毕业设计原文1：Programmable logic controllers 译文1：可编程逻辑控制器原文2：Foundation of PLC译文2：PLC基础专业班级：学生姓名：指导教师：学院：2011年6月原文1：Programmable logic controllersProgrammable logic controller(PLC) is eight 10- Year on behalf new generation industry that develop the control equip, and is an automatic control, calculator with the thing that the correspondence technique combine together, and is a the spot equipments for exclusively used foring the industry production line controling. Make the PLC there is characteristics of obvious oneself on the design with the long- term and continuous that circulate because of the special of the complexity, usage environment of the control object: The dependable is high, and the adaptability is wide, and have to correspond by letter the function, and weave the the convenience, construction mold piece . Gather the the control in the modern in the system, the PLC have already become a kind of importance of basic control unit, control the realm the inside in the industry applied the foreground is very and extensive.A programmable logic controller(PLC) is a solid-state devide used to control machine motion or process operation by means of a stored program. The PLC sends output control signals and receives input signals through input/output (I/O) devices.A PLC controls outputs in response to stimuli at the inputs according to the logic prescribed by the stored program.The inputs are made up of limit switches,pushbuttons,thumbwheels, switches,pulses,analog signals,ASCII serial data,and binary or BCD data from absolute position encoders.The outputs are voltage or current levers to drive end devices such as lolenids,motor staters,relays,lights,and so on.Other output devices such include analog devices,digital BCD displays,ASCII compatible devices,servo variable-speed drives,and even computers.Programmable controllers were developed(circa in 1968) when General Motors Corp,and other automobile manufacturers were experimenting to see if there might be an alterantive to scrapping all their hardwired control panels of machine tools and other production equipment during a model changeover.This annual tradition was necessary because rewiring of the panels was more expensive than buying new oens.The automotive companies approached a number of control equipment manufacturers and asked them to develop a control system that would have a longer productive life without major rewiring,but would still be understandable to and repairable by plant personnel.The new product wa namd a“programmable controller”．The processor part of the PLC contains a central processing unit and memory.The central proce ssing unit(CPU) is the“trafficdirector”of the processor,the memory stores ing into the processor are the electrical signals from the input devices，as conditioned by the input module to voltage levels acceptable to processor logic．The processor scans the state of I／O and updates outputs based on instructions stored in the memory of the PLC．For example，the processor may be programmed so that if an input connected to a limit switch is true(1imit switch closed),then a corresponding output wired to an output module is to be energized．This output might be asolenoid for example．The processor remembers this command through its memory and compares on each scan to see if that limit is, in fact ,closed. If it is closed, the processor energizes the solenoid by turning on the output module.The output device, such as a solenoid or motor stater,is wired to an output mofule’s terminal,and itreceives its shift signal from the processor, in effect the peocessor is performing a long and complicated series of logic decisions. The PLC performs such decisions sequentially and in accordance with the stored program.similarly, analog I/O allows the processor to make decisions based on the magnitude of a signal, rather than just if is on or off.For example,the processor may be programmes toencrease or decrease the steam flow to a boiler(analog output) based on a comparison of the actual temperature in the boiler(analog input) to the desired temperature. this is often performed by utilizing the built-in PID(proportional,integral,derivative) capabilities of the processor.Proper power to the programmable controller is critical. Today’s systems are available in a wide variety of electrical configurations. Virtually all are designed for use in single-phase power systems, and most are now beginning to be offered with the optional ability to operate in a DC supply environment. AC designs are offered in either single voltage supplies, such as 115 or 230V AC; while some can be configured as either through a selection made on the power supply. Proper grounding of the power supply connection is required for a safe installation. Some programmable controller designs have individual grounding connections from rack to face- plates and other system components, so care must be taken to follow well electrical practice in system grounding during electricalinstallation. In certain applications, a 24 or 120 V DC power supply is required. This is common for installations that axe made where no AC power is available, such as remote electrical generation stations. It is also found where AC power is unreliable and where loss of control is considered an unacceptable situationEven the best of today' s well-designed and manufactured programmable controllers require occasional preventative maintenance and repair. This section looks at some of the tools provided by the manufacturer and techniques for general maintenance.Most of the medium- and large-sized programmable controller systems available today are designed to be maintained by individuals with a wide variety of skills, without the benefit of in-depth formal training of this piece of equipment. This is accomplished in the design by providing individual modules of functionality installed in a chassis serviced from the front (all module types including power supplies). Front access is critical to proper maintenance. This allows easy inspection and replacement of the suspected bad module. Module health is determined by inspecting the LED indicators normally provided on the front of each module. Typical indicators will be on or off depending on the design and individual condition of the module in question. Various CPU and I/O modules will have indicators showing I/O control communications status, memory integrity, power supply tolerance check, scan integrity, and others. On future controller designs, and even today on a few systems, it is likely that English language messages will be displayed on the controller advising the user or maintenance personnel that a particular failure has occurred and recommended actions to take.The modular design and diagnostic indicators are, of course, important, but would be quite useless without well designed documentation provided by the manufacturer for the programmable controller system in question. Proper documentation will have sections dedicated to each major subsystem including CPU, I/O, and programming device. Each should explain in depth the stop-by-stop inspection of the system. All possible combinations of failure mode should be listed, along with suggested actions for repair. This will most often involve only the substitution of a re- placement board for the suspected failed unit. The user is urged to purchase a set of spare modules for the system in question as recommended by the manufacturer. This is normally, at a minimum, a single replacement module for each CPU and programming device serviceable module, and spare I/O modules equal to 10% of the number in the system.Because a PLC is “software based”,its control logic functions can be changed byreprogramming its memory. Keyboard programming devices facilitate entry of the revised program, which can be designed to cause an existing machine or process to operate in a different sequence or to respond to different levels of, or combinations of stimuli .Hardware modifications are needed only if additional, changed, or relocated input/output devices are involved.Programmable controller memory is formatted into bits, bytes, and words of memory.A bit is a single storage element for either a zero or a one. A byte consists of eight bits, and a word (normally) consists of 16 bits, or two bytes. Some systems still use a word length of eight bits, but most have adopted a 16 bit word, even though they may use an 8 bit microprocessor.Depending on the specific design of the programmable controller, it will have a stated memory capacity. This is an indication, although not the only one, of the capability and power of the system. Medium and large controllers are normally expandable from one memory size to their maximum size. Small controllers are normally fixed in their memory size. Size of the memory capacity must be examined relative to the word size ( 8 bit or 16 bit) and utilization. While it is clear that twice the information can be stored in a 16 bit word than in an 8 bit word, it may not be immediately clear that some controllers utilize memory more efficiently than others. For example, a normally open contact and its associated reference address (e.g. Input 1), may use in 8 bit byte each for storage. Combined, they consume one 16 bit word. Some controllers may use more memory than this for these instructions or others. In a large program, these inefficiencies can build on each other to cause a poor utilization of the system memory. A careful analysis of the various programmable controller models is required to assess utilization efficiency. Normal practice calls for an additional 20% - 40% of memory size to be specified to allow for modifications and later expansion. This analysis, combined with knowledge of the application needs, will allow for an intelligent choice of programmable controller.In fine, PLC conduct and actions the spot control equipments, can dependable，accurately complete the control the operation, and can pass with upper grade work machine correspondence, constitute the distribute type the system to complete to control the industry equip. system control request, is a modern industry control the inside compare forerunner’s control project, and apply the foreground to is extensive.译文1：可编程逻辑控制器可编程逻辑控制器（PLC）是八十年代发展起来的新一代工业控制装置，是自动控制、计算机和通信技术相结合的产物，是一种专门用于工业生产过程控制的现场设备。

毕业设计(论文)外文资料翻译学院：机械电子工程学院专业：机械设计制造及其自动化姓名：孙明明学号： 070501504外文出处： The advantages of PLC control,filed under PLC Articles附件： 1.外文资料翻译译文；2.外文原文。

(用外文写)附件1：外文资料翻译译文PLC的控制优势任何控制系统从概念到进入工厂工作都要经历四个阶段。

PLC系统在每一个阶段都有优势。

第一阶段是设计，对工厂的需要进行研究和制定控制策略，传统的运行平台的设计和制造必须在设计进行前完成。

PLC系统仅仅需要的是一个模糊的关于机器的可能大小的想法和I/O数量的要求（多少输入和输出接口）。

在这个阶段输入和输出芯片十分便宜，所以可以内置一个很健全的备用容量，它允许用来补充遗漏项目和为未来的扩充做准备。

其次是设计。

传统的方案是，每一项工作都是“一次成型”这不可避免的造成了工程拖延和增加成本。

一个的PLC系统使用最简单的标准件螺栓连接在一起。

在这样的连接下开始编写 PLC程序（或者至少是写入详细的程序规范）。

下一阶段是安装，安装是一种繁琐和昂贵的工作，例如安装传感器、执行器、限制开关系统和主机的连接。

分布式PLC系统使用串行链路式的预编译，测试界面可以简化安装它带来了巨大的成本优势。

PLC的程序多数在这个阶段完成。

最后是调试，而这正是PLC真正的优势被发掘的部分。

没有任何设备在第一次就正常工作。

人性就是这样，总会有一些疏漏。

与传统的系统变动情况的耗时和昂贵相比，PLC的设计师提供了系的内置备用内存容量、备用I/O和一些备用多芯电缆线，多数的变动能迅速和相对便宜的完成。

另外一个好处是，所有的变化PLC都有记录，程序的调试和修改不会因为没有被记录而遗失，这是一个经常发生在常规系统中的问题。

还有一个额外的第五阶段，维护，一旦启动工作，并移交生产就产生了维护的问题。

所有设备都有缺点，大多数设备在错误的模式中度过了它们的大部分的时间。

1、外文原文A: Fundamentals of Single-chip MicrocomputerTh e si ng le -c hi p m ic ro co mp ut er i s t he c ul mi na ti on of both t h e de ve lo pm en t of the dig it al com pu te r an d th e in te gr at ed c i rc ui t arg ua bl y t h e tow m os t s ig ni f ic an t i nv en ti on s o f t he 20th c e nt ur y [1].Th es e tow type s of arch it ec tu re are foun d in sin g le -ch i p m i cr oc om pu te r. Som e empl oy the spli t prog ra m/da ta me mo ry of the H a rv ar d ar ch it ect u re , sh ow n in Fig.3-5A -1, oth ers fo ll ow the p h il os op hy , wi del y ada pt ed for gen er al -p ur po se com pu te rs and m i cr op ro ce ss o r s, o f ma ki ng no log i ca l di st in ct ion be tw ee n p r og ra m and dat a me mo ry as in the Pr in ce to n arch ite c tu re , show n i n Fig.3-5A-2.In gen er al ter ms a sin gl e -chi p mic ro co mp ut er i sc h ar ac te ri zed b y t he i nc or po ra ti on of a ll t he un it s of a co mp uter i n to a sin gl e d ev i ce , as sho wn inFi g3-5A -3.Fig.3-5A-1 A Harvard typeFig.3-5A-2. A conventional Princeton computerFig3-5A-3. Principal features of a microcomputerRead only memory (ROM.R OM is usua ll y for the pe rm an ent,n o n-vo la ti le stor a ge of an app lic a ti on s pr og ra m .M an ym i cr oc om pu te rs and m are inte nd e d for high -v ol um e ap pl ic at ions a n d he nc e t h e eco n om ic al man uf act u re of th e de vic e s re qu ir es t h at t he cont en t s o f t he prog ra m me m or y be co mm it t ed perm a ne ntly d u ri ng the man ufa c tu re of ch ip s .Cl ea rl y, thi s im pl ie s a r i go ro us app ro ach to ROM cod e deve l op me nt sin ce cha ng es can not b e mad e afte r manu f a c tu re .Th is dev e lo pm en t proc ess may invo lv e e m ul at io n us in g aso ph is ti ca te d de ve lo pm en t sy ste m wit h a h a rd wa re emu la tio n cap ab il it y as w el l as the use o f po we rf ul s o ft wa re too ls.So me man uf act u re rs pro vi de add it io na l RO M opt i on s by i n cl ud in g in their ra n ge dev ic es wit h (or int en de d fo r use wit h u s er pro gr am ma ble me mo ry. Th e sim p le st of th es e is usu al ly d e vi ce whi ch can op er at e in a micro p ro ce ssor mod e by usi ng som e o f the inp ut /outp u t li ne s as an ad dr es s an d da ta b us fora c ce ss in g ex te rna l mem or y. Thi s t y pe of de vi ce can beh av ef u nc ti on al ly as th e sing le chip mi cr oc om pu te r from whi ch it is d e ri ve d al be it wit h re st ri ct ed I/O and a mod if ied ex te rn al c i rc ui t. The use of thes e d ev ic es is com mo n eve n in prod uc ti on c i rc ui ts wher e t he vo lu me does no tj us ti f y t h e d ev el o pm en t c osts o f c us to m o n -ch i p R OM [2];t he re c a n s ti ll bea s ignif i ca nt saving i n I /O and o th er c h ip s com pa re d to a conv en ti on al mi c ro pr oc es sor b a se d ci rc ui t. Mor e ex ac t re pl ace m en t fo r RO M dev i ce s ca n be o b ta in ed in th e fo rm of va ri an ts w it h 'p ig gy -b ack 'E P RO M(Er as ab le pro gr am ma bl e ROM s oc ke ts or dev ic e s with EPROM i n st ea d o f RO M 。

毕业设计中英文翻译院系专业班级姓名学号指导教师20**年 4 月Programmable Logic Controllers (PLC)1、MotivationProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic or so-called relay ladder logic (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days [Moody and Morley, 1999].Although PC based control has started to come into place, PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability in harsh environments. Moreover, according to a study on the PLC market of Frost and Sullivan [1995], an increase of the annual sales volume to 15 million PLCs per year with the hardware value of more than 8 billion US dollars has been predicted, though the prices of computing hardware is steadily dropping. The inventor of the PLC, Richard E Morley, fairly considers the PLC market as a 5-billion industry at the present time.Though PLCs are widely used in industrial practice, the programming of PLC based control systems is still very much relying on trial-and-error. Alike software engineering, PLC software design is facing the software dilemma or crisis in a similar way. Morley himself emphasized this aspect most forcefully by indicating [Moody and Morley, 1999, p. 110]:`If houses were built like software projects, a single woodpecker could destroy civilization.”Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old ladder logic programs. Though the hardware costs of PLCs are dropping continuously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLCs can be used.In general, the productivity in generating PLC is far behind compared to other domains, for instance, VLSI design, where efficient computer aided design tools are in practice. Existent software engineering methodologies are not necessarily applicable to the PLC basedsoftware design because PLC-programming requires a simultaneous consideration of hardware and software. The software design becomes, thereby, more and more the major cost driver. In many industrial design projects, more than SO0/a of the manpower allocated for the control system design and installation is scheduled for testing and debugging PLC programs [Rockwell, 1999].In addition, current PLC based control systems are not properly designed to support the growing demand for flexibility and reconfigurability of manufacturing systems. A further problem, impelling the need for a systematic design methodology, is the increasing software complexity in large-scale projects.PLCs (programmable logic controllers) are the control hubs for a wide variety of automated systems and processes. They contain multiple inputs and outputs that use transistors and other circuitry to simulate switches and relays to control equipment. They are programmable via software interfaced via standard computer interfaces and proprietary languages and network options.Programmable logic controllers I/O channel specifications include total number of points, number of inputs and outputs, ability to expand, and maximum number of channels. Number of points is the sum of the inputs and the outputs. PLCs may be specified by any possible combination of these values. Expandable units may be stacked or linked together to increase total control capacity. Maximum number of channels refers to the maximum total number of input and output channels in an expanded system. PLC system specifications to consider include scan time, number of instructions, data memory, and program memory. Scan time is the time required by the PLC to check the states of its inputs and outputs. Instructions are standard operations (such as math functions) available to PLC software. Data memory is the capacity for data storage. Program memory is the capacity for control software.Available inputs for programmable logic controllers include DC, AC, analog, thermocouple, RTD, frequency or pulse, transistor, and interrupt inputs. Outputs for PLCs include DC, AC, relay, analog, frequency or pulse, transistor, and triac. Programming options for PLCs include front panel, hand held, and computer.Programmable logic controllers use a variety of software programming languages for control. These include IEC 61131-3, sequential function chart (SFC), function block diagram (FBD), ladder diagram (LD), structured text (ST), instruction list (IL), relay ladder logic (RLL), flow chart, C, and Basic. The IEC 61131-3 programming environment provides support for five languages specified by the global standard: Sequential Function Chart,Function Block Diagram, Ladder Diagram, Structured Text, and Instruction List. This allows for multi-vendor compatibility and multi-language programming. SFC is a graphical language that provides coordination of program sequences, supporting alternative sequence selections and parallel sequences. FBD uses a broad function library to build complex procedures in a graphical format. Standard math and logic functions may be coordinated with customizable communication and interface functions. LD is a graphic language for discrete control and interlocking logic. It is completely compatible with FBD for discrete function control. ST is a text language used for complex mathematical procedures and calculations less well suited to graphical languages. IL is a low-level language similar to assembly code. It is used in relatively simple logic instructions. Relay Ladder Logic (RLL), or ladder diagrams, is the primary programming language for programmable logic controllers (PLCs). Ladder logic programming is a graphical representation of the program designed to look like relay logic. Flow Chart is a graphical language that describes sequential operations in a controller sequence or application. It is used to build modular, reusable function libraries. C is a high level programming language suited to handle the most complex computation, sequential, and data logging tasks. It is typically developed and debugged on a PC. BASIC is a high level language used to handle mathematical, sequential, data capturing and interface functions.Programmable logic controllers can also be specified with a number of computer interface options, network specifications and features. PLC power options, mounting options and environmental operating conditions are all also important to consider.2、ResumeA PLC (programmable Logic Controller) is a device that was invented to replace the necessary sequential relay circuits for control.The PLC works by looking at its input and depending upon their state, turning on/off its outputs. The user enters a program, usually via software or programmer, which gives the desired results.PLC is used in many "real world" applications. If there is industry present, chance are good that there is a PLC present. If you are involved in machining, packing, material handling, automated assembly or countless other industries, you are probably already using them. If you are not, you are wasting money and time. Almost any application that needs some type of electrical control has a need for a PLC.For example, let's assume that when a switch turns on we want to turn a solenoid on for 5second and then turn it off regardless of how long the switch is on for. We can do this with a simple external timer. But what if the process included 10 switches and solenoids? We should need 10 external times. What if the process also needed to count how many times the switch individually turned on? We need a lot of external counters.As you can see the bigger the process the more of a need we have for a PLC. We can simply program the PLC to count its input and turn the solenoids on for the specified time.We will take a look at what is considered to be the "top 20" PLC instructions. It can be safely estimated that with a firm understanding of these instructions one can solve more than 80% of the applications in existence.Of course we will learn more than just these instruction to help you solve almost ALL potential PLC applications.The PLC mainly consists of a CPU, memory areas, and appropriate circuits to receive input/output data. We can actually consider the PLC to be a box full of hundreds or thousands of separate relay, counters, times and data storage locations,Do these counters,timers, etc. really exist? No,they don't "physically" exist but rather they simulated and be considered software counters, timers, etc. . These internal relays are simulated through bit locations in registers.What does each part do? Let me tell you.Input RelaysThese are connected to the outside world.They physically exsit and receive signals from switches,sensors,ect..Typically they are not relays but rather they are transistors.Internal Utility RelaysThese do not receive signals from the outside world nor do they physically exist.they are simulated relays and are what enables a PLC to eliminate external relays.There are also some special relays that are dedicated to performing only one task.Some are always on while some are always off.Some are on only once during power-on and are typically used for initializing data that was stored.CountersThese again do not physically exist. They are simulated counters and they can be programmed to count pulses.Typically these counters can count up,down or both up anddown.Since they are simulated,they are limited in their counting speed.Some manufacturers also include high-speed counters that are hardware based.We think of these as physically existing.Most times these counters can count up,down or up and down.TimersThese also do not physically exist.They come in many varieties and increments.The most common type is an on-delay type.Others include off-delays and both retentive and non-retentive types.Increments vary from 1ms through 1s.Output RelaysThere are connected to the outside world.They physically exist and send on/off signals to solenoids,lights,etc..They can be transistors,relays,or triacs depending upon the model chosen Data StorageTypically there are registers assigned to simply store data.They are usually used as temporary storage for math or data manipulation.They can also typically be used to store data when power is removed form the PLC.Upon power-up they will still have the same contents as before power was moved.Very convenient and necessary!A PLC works by continually scanning a program.We can think of this scan cycle as consisting of 3 important steps.There are typically more than 3 but we can focus on the important parts and not worry about the others,Typically the others are checking the system and updating the current internal counter and timer values,Step 1 is to check input status,First the PLC takes a look at each input to determine if it is on off.In other words,is the sensor connected to the first input on?How about the third...It records this data into its memory to be used during the next step.Step 2 is to execute program.Next the PLC executes your program one instruction at a time.Maybe your program said that if the first input was on then it should turn on the first output.Since it already knows which inputs are on/off from the previous step,it will be able to decide whether the first output should be turned on based on the state of the first input.It will store the execution results for use later during the next step.Step 3 is to update output status.Finally the PLC updates the status the outputs.It updates the outputs based on which inputs were on during the first step and the results executing your program during the second step.Based on the example in step 2 it would now turn on the firstoutput because the first input was on and your program said to turn on the first output when this condition is true.After the third step the PLC goes back to step one repeats the steps continuously.One scan time is defined as the time it takes to execute the 3 steps continuously.One scan time is defined as the time it takes to execute the 3 steps listed above.Thus a practical system is controlled to perform specified operations as desired.3、PLC StatusThe lack of keyboard, and other input-output devices is very noticeable on a PLC. On the front of the PLC there are normally limited status lights. Common lights indicate;power on - this will be on whenever the PLC has powerprogram running - this will often indicate if a program is running, or if no program is runningfault - this will indicate when the PLC has experienced a major hardware or software problemThese lights are normally used for debugging. Limited buttons will also be provided for PLC hardware. The most common will be a run/program switch that will be switched to program when maintenance is being conducted, and back to run when in production. This switch normally requires a key to keep unauthorized personnel from altering the PLC program or stopping execution. A PLC will almost never have an on-off switch or reset button on the front. This needs to be designed into the remainder of the system.The status of the PLC can be detected by ladder logic also. It is common for programs to check to see if they are being executed for the first time, as shown in Figure 1. The ’first scan’ input will be true on the very first time the ladder logic is scanned, but false on every other scan. In this case the address for ’first scan’ in a PLC-5 is ’S2:1/14’. With the logic in the example the first scan will seal on ’light’, until ’clear’ is turned on. So the light will turn on after the PLC has been turned on, but it will turn off and stay off after ’clear’ is turned on. The ’first scan’ bit is also referred to at the ’first pass’ bit.Figure 1 An program that checks for the first scan of the PLC4、Memory TypesThere are a few basic types of computer memory that are in use today.RAM (Random Access Memory) - this memory is fast, but it will lose its contents when power is lost, this is known as volatile memory. Every PLC uses this memory for the central CPU when running the PLC.ROM (Read Only Memory) - this memory is permanent and cannot be erased. It is often used for storing the operating system for the PLC.EPROM (Erasable Programmable Read Only Memory) - this is memory that can be programmed to behave like ROM, but it can be erased with ultraviolet light and reprogrammed.EEPROM (Electronically Erasable Programmable Read Only Memory) – This memory can store programs like ROM. It can be programmed and erased using a voltage, so it is becoming more popular than EPROMs.All PLCs use RAM for the CPU and ROM to store the basic operating system for the PLC. When the power is on the contents of the RAM will be kept, but the issue is what happens when power to the memory is lost. Originally PLC vendors used RAM with a battery so that the memory contents would not be lost if the power was lost. This method is still in use, but is losing favor. EPROMs have also been a popular choice for programming PLCs. The EPROM is programmed out of the PLC, and then placed in the PLC. When the PLC is turned on the ladder logic program on the EPROM is loaded into the PLC and run. This method can be very reliable, but the erasing and programming technique can be time consuming. EEPROM memories are a permanent part of the PLC, and programs can be stored in them like EPROM. Memory costs continue to drop, and newer types (such as flash memory) are becoming available, and these changes will continue to impact PLCs.5、Objective and Significance of the ThesisThe objective of this thesis is to develop a systematic software design methodology for PLC operated automation systems. The design methodology involves high-level description based on state transition models that treat automation control systems as discrete event systems, a stepwise design process, and set of design rules providing guidance and measurements to achieve a successful design. The tangible outcome of this research is to find a way to reduce the uncertainty in managing the control software development process, that is, reducing programming and debugging time and their variation, increasing flexibility of theautomation systems, and enabling software reusability through modularity. The goal is to overcome shortcomings of current programming strategies that are based on the experience of the individual software developer.A systematic approach to designing PLC software can overcome deficiencies in the traditional way of programming manufacturing control systems, and can have wide ramifications in several industrial applications. Automation control systems are modeled by formal languages or, equivalently, by state machines. Formal representations provide a high-level description of the behavior of the system to be controlled. State machines can be analytically evaluated as to whether or not they meet the desired goals. Secondly, a state machine description provides a structured representation to convey the logical requirements and constraints such as detailed safety rules. Thirdly, well-defined control systems design outcomes are conducive to automatic code generation- An ability to produce control software executable on commercial distinct logic controllers can reduce programming lead-time and labor cost. In particular, the thesis is relevant with respect to the following aspect Customer-Driven ManufacturingIn modern manufacturing, systems are characterized by product and process innovation, become customer-driven and thus have to respond quickly to changing system requirements.A major challenge is therefore to provide enabling technologies that can economically reconfigure automation control systems in response to changing needs and new opportunities. Design and operational knowledge can be reused in real-time, therefore, giving a significant competitive edge in industrial practice.Higher Degree of Design Automation and Software QualityStudies have shown that programming methodologies in automation systems have not been able to match rapid increase in use of computing resources. For instance, the programming of PLCs still relies on a conventional programming style with ladder logic diagrams. As a result, the delays and resources in programming are a major stumbling stone for the progress of manufacturing industry. Testing and debugging may consume over 50% of the manpower allocated for the PLC program design. Standards [IEC 60848, 1999; IEC-61131-3, 1993; IEC 61499, 1998; ISO 15745-1, 1999] have been formed to fix and disseminate state-of-the-art design methods, but they normally cannot participate in advancingthe knowledge of efficient program and system design.A systematic approach will increase the level of design automation through reusing existing software components, and will provide methods to make large-scale system design manageable. Likewise, it will improve software quality and reliability and will be relevant to systems high security standards, especially those having hazardous impact on the environment such as airport control, and public railroads.System ComplexityThe software industry is regarded as a performance destructor and complexity generator. Steadily shrinking hardware prices spoils the need for software performance in terms of code optimization and efficiency. The result is that massive and less efficient software code on one hand outpaces the gains in hardware performance on the other hand. Secondly, software proliferates into complexity of unmanageable dimensions; software redesign and maintenance-essential in modern automation systems-becomes nearly impossible. Particularly, PLC programs have evolved from a couple lines of code 25 years ago to thousands of lines of code with a similar number of 1/O points. Increased safety, for instance new policies on fire protection, and the flexibility of modern automation systems add complexity to the program design process. Consequently, the life-cycle cost of software is a permanently growing fraction of the total cost. 80-90% of these costs are going into software maintenance, debugging, adaptation and expansion to meet changing needs [Simmons et al., 1998].Design Theory DevelopmentToday, the primary focus of most design research is based on mechanical or electrical products. One of the by-products of this proposed research is to enhance our fundamental understanding of design theory and methodology by extending it to the field of engineering systems design. A system design theory for large-scale and complex system is not yet fully developed. Particularly, the question of how to simplify a complicated or complex design task has not been tackled in a scientific way. Furthermore, building a bridge between design theory and the latest epistemological outcomes of formal representations in computer sciences and operations research, such as discrete event system modeling, can advance future development in engineering design.Application in Logical Hardware DesignFrom a logical perspective, PLC software design is similar to the hardware design of integrated circuits. Modern VLSI designs are extremely complex with several million parts and a product development time of 3 years [Whitney, 1996]. The design process is normally separated into a component design and a system design stage. At component design stage, single functions are designed and verified. At system design stage, components are aggregated and the whole system behavior and functionality is tested through simulation. In general, a complete verification is impossible. Hence, a systematic approach as exemplified for the PLC program design may impact the logical hardware design.可编程控制器1、前言可编程序的逻辑控制器（PLC），是由Richard E.Morley 于1968年发明的，如今已经被广泛的应用于生产、运输、化学等工业中。

1、外文原文（复印件）A: Fundamentals of Single-chip MicrocomputerTh e si ng le-ch i p mi cr oc om pu ter is t he c ul mi nat i on o f bo th t h e d ev el op me nt o f th e d ig it al com p ut er an d t he int e gr at ed ci rc ui ta r gu ab ly th e t ow m os t s i gn if ic ant i nv en ti on s o f t h e 20t h c en tu ry[1].Th es e to w typ e s of a rc hi te ctu r e ar e fo un d i n s in gl e-ch ip m i cr oc om pu te r. So m e em pl oy t he sp l it p ro gr am/d ata me mo ry o f th e H a rv ar d ar ch it ect u re, sh ow n i n -5A, ot he rs fo ll ow th e ph i lo so ph y, w i de ly a da pt ed fo r g en er al-p ur pos e c om pu te rs an d m i cr op ro ce ss or s, o f m a ki ng no lo gi c al di st in ct io n b e tw ee n p ro gr am a n d da t a m em ory a s i n th e Pr in cet o n ar ch it ec tu re,sh ow n in-5A.In g en er al te r ms a s in gl e-chi p m ic ro co mp ut er i sc h ar ac te ri zed b y the i nc or po ra tio n of al l t he uni t s o f a co mp ut er i n to a s in gl e dev i ce, as s ho wn in Fi g3-5A-3.-5A-1 A Harvard type-5A. A conventional Princeton computerFig3-5A-3. Principal features of a microcomputerRead only memory (ROM).R OM i s u su al ly f or th e p er ma ne nt, n o n-vo la ti le s tor a ge o f an a pp lic a ti on s pr og ra m .M an ym i cr oc om pu te rs an d mi cr oc on tr ol le r s a re in t en de d fo r h ig h-v ol ume a p pl ic at io ns a nd h en ce t he e co nom i ca l ma nu fa ct ure of t he d ev ic es r e qu ir es t ha t the co nt en ts o f the pr og ra m me mo ry b e co mm it te dp e rm an en tl y d ur in g th e m an uf ac tu re o f c hi ps . Cl ear l y, th is im pl ie sa ri g or ou s a pp roa c h t o R OM co de d e ve lo pm en t s in ce c ha ng es ca nn otb e m ad e af te r man u fa ct ur e .T hi s d e ve lo pm en t pr oce s s ma y in vo lv e e m ul at io n us in g a s op hi st ic at ed deve lo pm en t sy st em w i th a ha rd wa re e m ul at io n ca pa bil i ty a s we ll a s th e u se of po we rf ul so ft wa re t oo ls.So me m an uf act u re rs p ro vi de ad d it io na l RO M opt i on s byi n cl ud in g i n th ei r ra ng e de vi ce s wi th (or i nt en de d fo r us e wi th) u s er pr og ra mm ab le m em or y. Th e s im p le st of th es e i s us ua ll y d ev ice w h ic h ca n op er ate in a m ic ro pr oce s so r mo de b y usi n g so me o f th e i n pu t/ou tp ut li ne s as a n ad dr es s an d da ta b us f or acc e ss in g e xt er na l m e mo ry. T hi s t ype o f d ev ic e c an b e ha ve fu nc ti on al l y a s t he si ng le c h ip mi cr oc om pu te r fr om wh ic h i t i s de ri ve d a lb eit w it h r es tr ic ted I/O an d a mo di fie d e xt er na l ci rcu i t. T he u se o f t h es e RO Ml es sd e vi ce s is c om mo n e ve n in p ro du ct io n c ir cu it s wh er e t he v ol um e do es n o t ju st if y th e d e ve lo pm en t co sts of c us to m on-ch i p RO M[2];t he re c a n st il l b e a si g ni fi ca nt s a vi ng in I/O a nd ot he r c hi ps co mp ar ed t o a c on ve nt io nal mi cr op ro ce ss or b as ed c ir cu it. M o re e xa ctr e pl ac em en t fo r RO M d ev ic es c an b e o bt ai ne d in t he f o rm o f va ri an ts w i th 'pi gg y-ba ck'EP RO M(Er as ab le p ro gr am ma bl e ROM)s oc ke ts o rd e vi ce s w it h EP ROM i ns te ad o f R OM 。

1、外文原文（复印件)A: Fundamentals of Single-chip MicrocomputerTh e si ng le-ch i p mi cr oc om pu ter is t he c ul mi nat i on o f bo th t h e d ev el op me nt o f th e d ig it al com p ut er an d t he int e gr at ed ci rc ui ta r gu ab ly th e t ow m os t s i gn if ic ant i nv en ti on s o f t h e 20t h c en tu ry[1].Th es e to w t ype s o f a rc hi te ct ur e a re fo un d i n s i ng le—ch ip m i cr oc om pu te r。

S o me em pl oy th e s p li t p ro gr am/d at a me mo ry of t he H a rv ar d ar ch it ect u re, sh ow n in Fi g.3-5A—1，ot he r s fo ll ow t hep h il os op hy, wi del y a da pt ed f or ge n er al—pu rp os e c o mp ut er s an dm i cr op ro ce ss or s, of ma ki ng no lo gi c al di st in ct io n be tw ee n p ro gr am a n d da ta m em or y a s i n th e Pr in cet o n ar ch it ec tu re,sh ow n in F ig。

3-5A-2.In g en er al te r ms a s in gl e—ch i p mi cr oc om pu ter isc h ar ac te ri zed b y the i nc or po ra tio n of al l t he uni t s o f a co mp ut er i n to a s in gl e de v i ce，as s ho wn i n F ig3—5A—3。

可编程控制器本科毕业论文中英文翻译材料关于PLC外文翻译中文翻译可编程控制器技术可编程序控制器(Programmable Logic Controller，习惯上简称为PLC)是以微处理器为核心的通用工业自动化装置。

是20世纪60年代末在继电器控制系统的基础上开发出来的，它将传统的继电器控制技术与计算机技术和通信技术融为一体，具有结构简单、性能优越、可靠性高、灵活通用、易于编程、使用方便等优点。

具体来说，PLC的特点表现为以下几个方面:?硬件的可靠性高。

PLC专业在工业环境的恶劣条件下应用而设计。

一个设计良好的PLC能置于有很强电噪声、电磁干扰、机械振动、极端温度和湿度很大的环境中。

在硬件设计方面，首先是选用优质器件，再就是采用合理的系统结构，加固、简化安装，使它易于抗振冲击，对印刷电路板的设计、加工和焊接都采取了极为严格的工艺措施，而在电路、结构及工艺上采取了一些独特的方式。

由于PLC 本身具有很高的可靠性，所以在发生故障的部位大多集中在输入/输出的部位以及如传感器件、限位开关、光电开关、电磁阀、电机等外围装置上。

?编程简单，使用方便。

用微机实现自动控制，常使用汇编语言编程，难于掌握，要求使用者具有一定水平的计算机硬件和软件知识。

PLC采用面向控制过程、面向问题的编程方式，与目前微机控制常用的汇编语言相比，虽然在PLC内部增加了解释程序，增加了程序的执行时间，但对大多数的机电控制设备来说，这种损耗是微不足道的。

?接线简单，通用性好。

在电信号匹配的情况下，PLC的接线只需将输入信号的设备(按钮、开关等)与PLC输入端子连接，将接受输出信号执行控制任务的执行元件(接触器、电磁阀)与PLC输出端子连接。

接线简单、工作量少，省去了传统的继电器控制系统的接线和拆线的麻烦。

PLC的编程逻辑提供了能随要求而改变的逻辑关系，这样生产线的自动化过程就能随意改变。

这种性能使PLC具有很高的经济效益。

用于连接现场设备的硬件接口实际上已经设计成为PLC的组成部分，模块化的自诊断接口电路能指出故障，并易于排除故障与替换故障部件，这样的软硬件设计就使现场电气人员与技术人员易于使用。

翻译对应文章Programmable Logic Controllers可编程序逻辑控制器1.1动力1968年，Richard E. Morley创造出了新一代工业控制装置可编程逻辑控制器(PLC),现在，PLC已经被广泛应用于工业领域，包括机械制造也、运输系统、化学过程设备、等许多其他领域。

初期可编程控制器只是用一种类似于语言的软件逻辑于代替继电器硬件逻辑，并且使开发时间由6个月缩短到6天。

虽然计算机控制技术已经产生，但是PLC控制因为它的高性能、成本低、并且对恶劣的环境有很强的适应能力而在工业控制的广泛应用中保持优势。

而且，尽管硬件的价格在逐渐下跌，据估计，根据Frost和Sullivan对PLC市场的调查研究表明，每年销售硬件的价格要比销售PLC的价格（一千五百万）至少多出八十亿美元。

PLC的创造者Richard E. Morley十分肯定的认为目前PLC市场是一个价值五十亿的工业虽然PLC广泛应用于工业控制中，PLC控制系统的程序依然和语法有关。

和软件过程一样，PLC的软件设计也以同样的方式会遇到软件错误或危机。

Morley在演讲中着重强调了这个方面。

如果房子建造的像软件过程一样，那么仅仅一只啄木鸟就可以摧毁文明。

特别的，PLC程序要解决的实际问题是消除软件错误和减少老式梯形逻辑语言的花费。

尽管PLC的硬件成本在继续下降，但是在工业控制上减少梯形逻辑的扫描时间仍然是一个问题，以至于可以用到低耗时的PLC。

一般来说，和其他领域相比生产PLC的周期要短很多。

例如，在实践中，VISI设计是一种有效的计算机辅助设计。

PLC不需要使用目前的以软件设计为基础软件工程方法论，因为PLC程序要求对软件和硬件搜都要考虑到。

因此，软件设计越来越成为花费动力。

在许多的工业设计工程中，超过的人力分配给了控制系统设计和安装，并且他们要对。

PLC程序测试和排除错误，再者，PLC控制系统不适合设计对适应性和重构有越来越多要求的生产系统。

PLCs --Past, Present and FutureEveryone knows there's only one constant in the technology world, and that's change. This is especially evident in the evolution of Programmable Logic Controllers (PLC) and their varied applications. From their introduction more than 30 years ago, PLCs have become the cornerstone of hundreds of thousands of control systems in a wide range of industries.At heart, the PLC is an industrialized computer programmed with highly specialized languages, and it continues to benefit from technological advances in the computer and information technology worlds. The most prominent of which is miniaturization and communications.The Shrinking PLCWhen the PLC was first introduced, its size was a major improvement - relative to the hundreds of hard-wired relays and timers it replaced. A typical unit housing a CPU and I/O was roughly the size of a 19 television set. Through the 1980s and early 1990s, modular PLCs continued to shrink in footprint while increasing in capabilities and performance (see Diagram 1 for typical modular PLC configuration).In recent years, smaller PLCs have been introduced in the nano and micro classes that offer features previously found only in larger PLCs. This has made specifying a larger PLC just for additional features or performance, and not increased I/O count, unnecessary, as even those in the nano class are capable of Ethernet communication, motion control, on-board PID with autotune, remote connectivity and more.PLCs are also now well-equipped to replace stand-alone process controllers in many applications, due to their ability to perform functions of motion control, data acquisition, RTU (remote telemetry unit) and even some integrated HMI (human machine interface) functions. Previously, these functions often required their own purpose-built controllers and software, plus a separate PLC for the discrete control and interlocking.The Great CommunicatorPossibly the most significant change in recent years lies in the communications arena. In the 1970s Modicon introduction of Modbus communications protocol allowed PLCs to communicate over standard cabling. This translates to an ability to place PLCs in closer proximity to real world devices and communicate back to other system controls in a main panel.In the past 30 years we have seen literally hundreds of proprietary and standard protocols developed, each with their own unique advantages.Today's PLCs have to bedata compilers and information gateways. They have to interface with bar code scanners and printers, as well as temperature and analog sensors. They need multiple protocol support to be able to connect with other devices in the process. And furthermore, they need all these capabilities while remaining cost-effective and simple to program.Another primary development that has literally revolutionized the way PLCs are programmed, communicate with each other and interface with PCs for HMI, SCADA or DCS applications, came from the computing world.Use of Ethernet communications on the plant floor has doubled in the past five years. While serial communications remain popular and reliable, Ethernet is fast becoming the communications media of choice with advantages that simply can't be ignored, such as: * Network speed. * Ease of use when it comes to the setup and wiring. * Availability of off-the-shelf networking components. * Built-in communications setups.Integrated Motion ControlAnother responsibility the PLC has been tasked with is motion control. From simple open-loop to multi-axis applications, the trend has been to integrate this feature into PLC hardware and software.There are many applications that require accurate control at a fast pace, but not exact precision at blazing speeds. These are applications where the stand-alone PLC works well. Many nano and micro PLCs are available with high-speed counting capabilities and high-frequency pulse outputs built into the controller, making them a viable solution for open-loop control.The one caveat is that the controller does not know the position of the output device during the control sequence. On the other hand, its main advantage is cost. Even simple motion control had previously required an expensive option module, and at times was restricted to more sophisticated control platforms in order to meet system requirements.More sophisticated motion applications require higher-precision positioning hardware and software, and many PLCs offer high-speed option modules that interface with servo drives. Most drives today can accept traditional commands from host (PLC or PC) controls, or provide their own internal motion control. The trend here is to integrate the motion control configuration into the logic controller programming software package.Programming LanguagesA facet of the PLC that reflects both the past and the future is programming language. The IEC 61131-3 standard deals with programming languages and defines two graphical and two textual PLC programming language standards: * Ladder logic (graphical). * Function block diagram (graphical). * Structured text(textual).Instruction list (textual).This standard also defines graphical and textual sequential function chart elements to organize programs for sequential and parallel control processing. Based on the standard, many manufacturers offer at least two of these languages as options for programming their PLCs. Ironically, approximately 96 percent of PLC users recently still use ladder diagrams to construct their PLC code. It seems that ladder logic continues to be a top choice given it's performed so well for so long.Hardware PlatformsThe modern PLC has incorporated many types of Commercial off the Shelf (COTS) technology in its CPU. This latest technology gives the PLC a faster, more powerful processor with more memory at less cost. These advances have also allowed the PLC to expand its portfolio and take on new tasks like communications, data manipulation and high-speed motion without giving up the rugged and reliable performance expected from industrial control equipment.New technology has also created a category of controllers called Programmable Automation Controllers, or PACs. PACs differ from traditional PLCs in that they typically utilize open, modular architectures for both hardware and software, using de facto standards for network interfaces, languages and protocols. They could be viewed as a PC in an industrial PLC-like package.The FutureA 2005 PLC Product Focus Study from Reed Research Group pointed out factors increasingly important to users, machine builders and those making the purchasing decisions. The top picks for features of importance were.* The ability to network, and do so easily. Ethernet communications is leading the charge in this realm. Not only are new protocols surfacing, but many of the industry de facto standard serial protocols that have been used for many years are being ported to Ethernet platforms. These include Modbus (ModbusTCP), DeviceNet (Ethernet/IP) and Profibus (Profinet). Ethernet communication modules for PLCs are readily available with high-speed performance and flexible protocols. Also, many PLC CPUs are now available with Ethernet ports on board, saving I/O slot space. PLCs will continue to develop more sophisticated connectivity to report information to other PLCs, system control systems, data acquisition (SCADA) systems and enterprise resource planning (ERP) systems. Additionally, wireless communications will continue to gain popularity.* The ability to network PLC I/O connections with a PC. The same trends that have benefited PLC networking have migrated to the I/O level. Many PLC manufacturers are supporting the most accepted fieldbus networks, allowing PLC I/O to be distributed over large physical distances, or located where it was previously considered nearly impossible. This has opened the door for personal computers to interface with standard PLC I/O subsystems by using interface cards, typically supplied by the PLC manufacturer or a third party developer. Now these challenging locations can be monitored with today a PC. Where industrial-grade control engines are not required, the user can take advantage of more advanced software packages and hardware flexibility at a lower cost.* The ability to use universal programming software for multipletargets/platforms. In the past it was expected that an intelligent controller would be complex to program. That is no longer the case. Users are no longer just trained programmers, such as design engineers or systems integrators, but end-users who expect easier-to-use software in more familiar formats. The Windows-based look and feel that users are familiar with on their personal computers have become the most accepted graphical user interface. What began as simple relay logic emulation for programming PLCs has evolved into languages that use higher level function blocks that are much more intuitive to configure. PLC manufacturers are also beginning to integrate the programming of diverse functions that allow you to learn only one package in configuring logic, HMI, motion control and other specialized capabilities. Possibly the ultimate wish of the end-user would be for a software package that could seamlessly program many manufacturers PLCs and sub-systems. After all, Microsoft Windows operating system and applications work similarly whether installed on a Dell, HP or IBM computer, which makes it easier for the user.Overall, PLC users are satisfied with the products currently available, while keeping their eye on new trends and implementing them where the benefits are obvious. Typically, new installations take advantage of advancing technologies, helping them become more accepted in the industrial world.PLC的过去、现在与未来众所周知，科技世界里只有一个永恒真理，那就是变化。

PLC technique discussion and future developmentT.J.byersElectronic Test Equipment-principles and ApplicationsPrinceton University .AmericaAlong with the development of the ages, the technique that is nowadays is also gradually perfect, the competition plays more strong; the operation that list depends the artificial has already can't satisfied with the current manufacturing industry foreground, also can't guarantee the request of the higher quantity and high new the image of the technique business enterprise.The people see in produce practice, automate brought the tremendous convenience and the product quantities for people up of assurance, also eased the personnel's labor strength, reduce the establishment on the personnel. The target control of the hard realization in many complicated production lines, whole and excellent turn, the best decision etc, well-trained operation work, technical personnel or expert, governor but can judge and operate easily, can acquire the satisfied result. The research target of the artificial intelligence makes use of the calculator exactly to carry out, imitate these intelligences behavior, moderating the work through person's brain and calculators, with the mode that person's machine combine, for resolve the very complicated problem to look for the best path.We come in sight of the control that links after the electric appliances in various situation, that is already the that time generation past, now of after use in the mold a perhaps simple equipments of grass-roots control that the electric appliances can do for the low level only; And the PLC emergence also became the epoch-making topic, adding the vivid software control through a very and stable hardware, making the automation head for the new high tide.The PLC biggest characteristics lie in: The electrical engineering teacher already no longer electric hardware up too many calculations of cost, as long as order the importation that the button switch or the importation of the sensors order to link the PLC up can solve problem, pass to output to order the conjunction contact machine or control the start equipments of the big power after the electric appliances, but the exportation equipmentsdirect conjunction of the small power can.PLC internal containment have the CPU of the CPU, and take to have an I/ O for expand of exterior to connect a people's address and saving machine three big pieces to constitute, CPU core is from an or many is tired to add the machine to constitute, mathematics that they have the logic operation ability, and can read the procedure save the contents of the machine to drive the homologous saving machine and I/ Os to connect after pass the calculation; The I/ O add inner part is tired the input and output system of the machine and exterior link, and deposit the related data into the procedure saving machine or data saving machine; The saving machine can deposit the data that the I/ O input in the saving machine, and in work adjusting to become tired to add the machine and I/ Os to connect, saving machine separately saving machine RAM of the procedure saving machine ROM and dates, the ROM can do deposit of the data permanence in the saving machine, but RAM only for the CPU computes the temporary calculation usage of hour of buffer space.The PLC anti- interference is very and excellent, our root need not concern its service life and the work situation bad, these all problems have already no longer become the topic that we fail, but stay to our is a concern to come to internal resources of make use of the PLC to strengthen the control ability of the equipments for us, make our equipments more gentle.PLC language is not we imagine of edit collected materials the language or language of Cs to carry on weaving the distance, but the trapezoid diagram that the adoption is original after the electric appliances to control, make the electrical engineering teacher while weaving to write the procedure very easy comprehended the PLC language, and a lot of non- electricity professional also very quickly know and go deep into to the PLC.Is PLC one of the advantage above and only, this is also one part that the people comprehend more and easily, in a lot of equipments, the people have already no longer hoped to see too many control buttons, they damage not only and easily and produce the artificial error easiest, small is not a main error perhaps you can still accept; But lead even is a fatal error greatly is what we can't is tolerant of. New technique always for bringing more safe and convenient operation for us, make we a lot of problems for face on sweep but light, do you understand the HMI? Says the HMI here you basically not clear what it is, also have no interest understanding, change one inside text explains it into the touch to hold orman-machine interface you knew, it combines with the PLC to our larger space.HMI the control not only is reduced the control press button, increase the vivid of the control, more main of it is can sequence of, and at can the change data input to output the feedback with data, control in the temperature curve of imitate but also can keep the manifestation of view to come out. And can write the function help procedure through a plait to provide the help of various what lies in one's power, the one who make operate reduces the otiose error. Currently the HMI factory is also more and more, the function is also more and more strong, the price is also more and more low, and the noodles of the usage are wide more and more. The HMI foreground can say that think to be good.At a lot of situations, the list is a smooth movement that can't guarantee the equipments by the control of the single machine, but pass the information exchanges of the equipments and equipments to attain the result that we want. For example fore pack and the examination of the empress work preface, we will arrive wrapping information feedback to examine the place, and examine the information of the place to also want the feedback to packing. Pass the information share thus to make both the chain connect, becoming a total body, the match of your that thus make is more close, at each other attain to reflect the result that mutually flick.The PLC correspondence has already come more body now its value, at the PLC and correspondence between Places, can pass the communication of the information and the share of the data’s to guarantee that of the equipments moderates mutually, the result that arrive already to repair with each other. Data conversion the adoption RS232 between PLC connect to come to the transmission data, but the RS232 pick up a people and can guarantee 10 meters only of deliver the distance, if in the distance of 1000 meters we can pass the RS485 to carry on the correspondence, the longer distance can pass the MODEL only to carry on deliver.The PLC data transmission is just to be called a form to it in a piece of and continuous address that the data of the inner part delivers the other party, we, the PLC of the other party passes to read data in the watch to carry on the operation. If the data that data in the watch is a to establish generally, that is just the general data transmission, for example today of oil price rise, I want to deliver the price of the oil price to lose the oil ally on board, that is the share of the data; But take data in the watch for an instruction procedure that controls the PLC, that had the difficulty very much, for example you have to control one pedestal robot to pressthe action work that you imagine, you will draw up for it the form that a procedure combine with the data sends out to pass by.The form that information transport contain single work, the half a work and the difference of a workers .The meaning of the single work also is to say both, a can send out only, but a can receive only, for example a spy he can receive the designation of the superior only, but can't give the superior reply; A work of half is also 2 and can send out similar to accept the data, but can't send out and accept at the same time, for example when you make a phone call is to can't answer the phone, the other party also; But whole pair works is both can send out and accept the data, and can send out and accept at the same time. Be like the Internet is a typical example.The process that information transport also has synchronous and different step cent: The data line and the clock lines are synchronous when synchronous meaning lie in sending out the data, is also the data signal and the clock signals to be carry on by the CPU to send out at the same time, this needs to all want the specialized clock signal each other to carry on the transmission and connect to send, and is constrained, the characteristics of this kind of method lies in its speed very quick, but correspond work time of take up the CPU and also want to be long oppositely, at the same time the technique difficulty also very big. Its request lies in canting have an error margins in a dates deliver, otherwise the whole piece according to compare the occurrence mistake, this on the hardware is a bigger difficulty. Applied more and more extensive in some appropriative equipments, be like the appropriative medical treatment equipments, the numerical signal equipments...etc., in compare the one data deliver, its result is very good.And the different step is an application the most extensive, this receive benefit in it of technique difficulty is opposite and want to be small, at the same time not need to prepare the specialized clock signal, its characteristics to lie in, its data is partition, the long-lost send out and accept, be the CPU is too busy of time can grind to a stop sex to work, also reduced the difficulty on the hardware, the data throw to lose at the same time opposite want to be little, we can pass the examination of the data to observe whether the data that we send out has the mistake or not, be like strange accidentally the method, tired addition and eight efficacies method etc, can use to helps whether the data that we examine to send out have or not themistake occurrence, pass the feedback to carry on the discriminator.A line of transmission of the information contains a string of and combines the cent of: The usual PLC is 8 machines, certainly also having 16 machines. We can be at the time of sending out the data a send out to the other party, also can be 88 send out the data to the other party, and 8 differentiations are also the as that we say to send out the data and combine sends out the data. A speed is more and slowly, but as long as 2 or three lines can solve problem, and can use the telephone line to carry on the long range control. But combine the ocular transmission speed is very quick of, it is a string of ocular of 25600%, occupy the advantage in the short distance, the in view of the fact TTL electricity is even, being limited by the scope of one meter generally, it combine unwell used for the data transmission of the long pull, thus the cost is too expensive.Under a lot of circumstances we are total to like to adopt the string to combine the conversion chip to carry on deliver, under this kind of circumstance not need us to carry on to deposited the machine to establish too and complicatedly, but carry on the data exchanges through the data transmission instruction directly, but is not a very viable way in the correspondence, because the PLC of the other party must has been wait for your data exportation at the time of sending out the data, it can't do other works.When you are reading the book, you hear someone knock on door, you stop to start up of affair, open the door and combine to continue with the one who knock on door a dialogue, the telephone of this time rang, you signal hint to connect a telephone, after connecting the telephone through, return overdo come together knock on door to have a conversation, after dialogue complete, you continue again to see your book, this kind of circumstance we are called the interruption to it, it has the authority, also having sex of have the initiative, the PLC had such function .Its characteristics lie in us and may meet the urgently abrupt affairs in the operation process of the equipments, we want to stop to start immediately up of work, the whereabouts manages the more important affair, this kind of circumstance is we usually meet of, PLC while carry out urgent mission, total will keep the current appearance first, for example the address of the procedure, CPU of tired add the machine data etc., be like to stick down which the book that we see is when we open the door the page or simply make a mark, because we treat and would still need to continue immediately after book of see the behind.The CPU always does the affair that should do according to our will, but your mistake of give it an affair, it also would be same to do, this we must notice.The interruption is not only a, sometimes existing jointly with the hour several inside break, break off to have the preferred Class, they will carry out the interruption of the higher Class according to person's request. This kind of breaks off the medium interruption to also became to break off the set. The Class that certainly breaks off is relevant according to various resources of CPU with internal PLC; also following a heap of capacity size of also relevant fasten.The contents that break off has a lot of kinds, for example the exterior break off, correspondence in of send out and accept the interruption and settle and the clock that count break off, still have the WDT to reset the interruption etc., they enriched the CPU to respond to the category while handle various business. Speak thus perhaps you can't comprehend the internal structure and operation orders of the interruption completely also, we do a very small example to explain.Each equipment always will not forget a button, it also is at we meet the urgent circumstance use of that is nasty to stop the button. When we meet the Human body trouble and surprised circumstances we as long as press it, the machine stops all operations immediately, and wait for processing the over surprised empress recover the operation again. Nasty stop the internal I/ O of the internal CPU of the button conjunction PLC to connect up, be to press button an exterior to trigger signal for CPU, the CPU carries on to the I/ O to examine again, being to confirm to have the exterior to trigger the signal, CPU protection the spot breaks off procedure counts the machine turn the homologous exterior I/ O automatically in the procedure to go to also, be exterior interruption procedure processing complete, the procedure counts the machine to return the main procedure to continue to work. Have 1:00 can what to explain is we generally would nasty stop the button of exterior break off to rise to the tallest Class, thus guarantee the safety.When we are work a work piece, giving the PLC a signal, counting PLC inner part the machine add 1 to compute us for a day of workload, a count the machine and can solve problem in brief, certainly they also can keep the data under the condition of dropping the electricity, urging the data not to throw to lose, this is also what we hope earnestly.The PLC still has the function that the high class counts the machine, being us while accept some dates of high speed, the high speed that here say is the data of the in all aspects tiny second class, for example the bar code scanner is scanning the data continuously, calculating high-speed signal of the data processor DSP etc., we will adopt the high class to count the machine to help we carry on count. It at the PLC carries out the procedure once discover that the high class counts the machine to should of interruption, will let go of the work on the hand immediately. The trapezoid diagram procedure that passes by to weave the distance again explains the high class for us to carry out procedure to count machine would automatic performance to should of work, thus rise the Class that the high class counts the machine to high one Class.You heard too many this phrases perhaps:" crash", the meaning that is mostly is a workload of CPU to lead greatly, the internal resources shortage etc. the circumstance can't result in procedure circulate. The PLC also has the similar circumstance, there is a watchdog WDT in the inner part of PLC, we can establish time that a procedure of WDT circulate, being to appear the procedure to jump to turn the mistake in the procedure movement process or the procedure is busy, movement time of the procedure exceeds WDT constitution time, the CPU turn but the WDT reset the appearance. The procedure restarts the movement, but will not carry on the breakage to the interruption.The PLC development has already entered for network ages of correspondence from the mode of the one, and together other works control the net plank and I/ O card planks to carry on the share easily. A state software can pass all se hardwires link, more animation picture of keep the view to carries on the control, and cans pass the Internet to carry on the control in the foreign land, the blast-off that is like the absolute being boat No.5 is to adopt this kind of way to make airship go up the sky.The development of the higher layer needs our continuous effort to obtain. The PLC emergence has already affected a few persons fully, we also obtained more knowledge and precepts from the top one experience of the generation, coming to the continuous development PLC technique, push it toward higher wave tide.可编程控制器技术讨论与未来发展T.J.拜尔斯（电子测试设备原理及应用普林斯顿大学）随着时代的发展，当今的技术也日趋完善、竞争愈演愈烈；单靠人工的操作已不能满足于目前的制造业前景，也无法保证更高质量的要求和高新技术企业的形象。

PLC及变频器技术中英文资料对照外文翻译文献综述PLC and inverter technology trends1. The development trend of the programmable controller“PLC is one kind specially for the digital operation operation electronic installation which applies under the industry environment designs. It uses may the coding memory, uses for in its internal memory operation and so on actuating logic operation, sequence operation, time, counting and arithmetic operation instructions, and can through digital or the simulation-like input and the output, controls each type the machinery or the production process. PLC and the related auxiliary equipment should according to form a whole easy with the industrial control system, easy to expand its function the principle to design.”In the 21st century, PLC will have a bigger development. Technologically speaking, computer technology's new achievement more will apply in the programmable controller's design and the manufacture, will have the operating speed to be quicker, the storage capacity to be bigger, an intelligent stronger variety to appear; Looked from the product scale that further develops to subminiature and the ultra-large direction; Looked from the product overcoatability that the product variety will be richer, the specification to be more complete, the perfect man-machine contact surface, the complete communication facility will adapt each industrial control situation demand well; Looked from the market that various countries will produce the multi-variety product the situation to break respectively along with the international competition aggravating, will present the minority several brand monopoly international market the aspect, will present the international general programming language; Looking from the network state of play, the programmable controller and other industrial control computer networkconstitution large-scale control system is the programmable controller technology development direction. Present computer collection and distribution control system DCS (Distributed Control System) had the massive programmable controller application. Is following computer network's development, the programmable controller takes the automation directed net and the international universal network important component, outside industry and industry numerous domain display more and more major function.2. Inverter technology development trendsInverter into the practical phase of more than 1 / 4 century during this period, the frequency converter technology as the basis of power electronics technology and microelectronics technology manager of a leap in the development, as the new power electronic devices and high-performance microprocessor The application of control technology and the development of increasingly high cost performance of the inverter, more and more small size, but manufacturers are still in constant frequency converter to achieve the further miniaturization and doing new efforts. From a technical point of view, with the frequency converter to further expand the market of the future, with the converter and inverter technology will be on the development of technologies in the following areas further development:(1) large capacity and small size;(2) high-performance and multi-function;(3) enhance the ease-of-use;(4) increase in life expectancy and reliability;(5) of pollution-free.Large capacity and small size of the power semiconductor devices will be with the development of continuous development. In recent years, driven by a voltage power semiconductor devices IGBT (Isolated Gate Bipolar Transistor, isolation gate bipolar transistors) has developed very rapidly and quickly into the traditional use of BJT (bipolar power transistor) and power MOSFET (FET) The various fields. In addition, the IGBT switching device for the IPM (Intelligent Power Module, IPM) and Monolithic Power IC chip will power switching devices and driving circuit, such as the protection of integrated circuits in the same package, with high performance andreliability The merits, with their high current and high pressure of the development of small and medium-sized converter will certainly be more widely used.With micro-electronics technology and semiconductor technology development, for Inverter CPU and semiconductor devices and a variety of sensors of getting higher and higher. With the frequency converter technology and the development of the growing maturity of the exchange governor, modern control theory are constantly new applications. These have further improved the performance of inverter provided the conditions. In addition, with the frequency converter to further promote the use and support are also constantly made new demands, the frequency converter manufacturers to continuously improve the performance and frequency converter functions in Inverter new efforts to meet user And the need for the fierce competition in the market in an invincible position.With the frequency converter market continues to expand, how to further enhance the ease-of-use inverter, so that the technical staff and even ordinary non-technical staff can quickly master the use of frequency converter technology has become manufacturers must consider the issue. Because only easy-to-use products can continue to acquire new customers and further expand the market, so the future of the new converter will be more easy to operate.With the development of semiconductor technology and the development of power electronics technology, the frequency converter used in the various components of the life and reliability are constantly improving, they will make their own life and the frequency converter to further increase reliability.In recent years, people have attached great importance to environmental issues, and thus a "green products" name. Therefore, the inverter, must also consider its impact on the surrounding environment.Promote the use of the frequency converter in the early stages of the noise problem was once a big problem. With the low-noise converter IGBT the emergence of this issue has basically been resolved. However, with the noise problem to solve, people's looks and a converter to the surrounding environment and the impact of other continuously explore new solutions. For example, the use of a diode-voltage converter and PWMinverter circuit converter, the frequency converter itself the high harmonics will bring supply voltage and current distortion, and at the same power to affect the other equipment. However, through the use of the frequency converter Rectifier circuit PWM, we can basically solve the problem. Although because of price and control technology and other aspects of the reasons for the current PWM converter has not been promoting the inverter, but, with the frequency converter technology development and the people of the importance of environmental issues.PLC及变频器技术的发展趋势1．可编程控制器的发展趋势可编程控制器是一种数字运算操作的电子系统，专为在工业环境下应用而设计。

1、外文原文A: Fundamentals of Single-chip MicrocomputerTh e si ng le -c hi p mic ro co mput er i s t he c ul mi na ti on of both t h e de ve lo pmen t o f t he d ig it al co m pu te r an d th e i n te gr at ed c i rc ui t a rg ua bl y t h e to w mos t s ig ni f ic an t i nv en ti on s of t he 20th c e nt ur y [1].Th es e t ow ty pe s of ar ch it ec tu re a re fo un d i n s in gle -ch i p m i cr oc ompu te r. So me em pl oy t he spl i t pr og ra m/da ta memory o f th e Ha rv ar d ar ch it ect ure , sh own in Fi g.3-5A-1, o th ers fo ll ow t he ph il os op hy , wi del y a da pt ed f or ge ner al -pur po se co m pu te rs a nd m i cr op ro ce ss or s, o f maki ng n o log i ca l di st in ct ion be tw ee n pr og ra m an d d at a memory a s i n t he P r in ce to n ar ch ite c tu re , sh own i n F ig.3-5A-2.In g en er al te r ms a s in gl e -chi p m ic ro co mput er i sc h ar ac te ri zed by t he i nc or po ra ti on of a ll t he un it s of a co mputer i n to a s in gl e d ev i ce , as s ho wn in Fi g3-5A-3.Fig.3-5A-1 A Harvard typeProgrammemory DatamemoryCPU Input&Outputunitmemory CPU Input&OutputunitFig.3-5A-2. A conventional Princeton computerReset Interrupts PowerFig3-5A-3. Principal features of a microcomputerRead only memory (ROM).R OM i s us ua ll y f or th e p erm an ent, no n-vo la ti le s tor age o f an a pp lic ati on s pr og ra m .Man ym i cr oc ompu te rs an d m ar e in te nd e d f or hi gh -v ol ume a ppl ic at ions an d he nc e t he eco nomic al m an uf act ure o f th e de vic es re qu ir es t h at t he co nt en t s of t he pr og ra m mem or y b e co mm it t ed pe rm ane ntly du ri ng t he m an ufa c tu re o f ch ip s .Cl ea rl y, t hi s i mpl ie s a r i go ro us a pp ro ach to R OM c od e de ve l op ment s in ce ch ang es c an not be mad e af te r manu f ac tu re .Th is d ev elo pmen t pr oc ess ma y in vo lv e emul at io n us in g a so ph is ti ca te d d eve lo pmen t sy ste m w it h a ha rd ware e mula tio n c ap ab il it y as wel l as t he u se o f po werf ul s o ft ware t oo ls.Some m an uf act ure rs p ro vi de ad d it io na l ROM opt i on s byi n cl ud in g i n th eir r ange d ev ic es wi t h (or i nt en de d f or u se wit h)us er p ro gr ammable memory. Th e sim ple st o f th es e i s u su al lyde vi ce w hi ch c an o per at e in a mi cro pro ce ss or mod e b y u si ng s ome of t he i np ut /o utp ut li ne s as a n a ddr es s an d da ta b us f or ac ce ss in g ex te rna l m emor y. T hi s t y pe o f de vi ce ca n b eh av eExternalTimingcomponents System clock Timer/ CounterSerial I/OPrarallelI/ORAMROMCPUf u nc ti on al ly a s t he si ng le ch ip mi cr oc ompu te r fro m w hi ch it is de ri ve d al be it wi t h re st ri ct ed I/O a nd a m od if ied ex te rn alc i rc ui t. Th e u se o f th es e dev ic es i s c ommon e ve n i n pr od uc ti on c i rc ui ts wh ere t he vo lu me do es no t j us tif y t h e dev el opmen t costsof c us to m o n-ch i p ROM[2];t he re c a n s ti ll be a s ig nif i ca nt sa vingi n I/O an d o th er c hip s c ompa re d t o a co nv en ti on al mi c ro pr oc es sor ba se d ci rc ui t. Mo r e ex ac t re pl ace m en t fo r RO M dev i ce s ca n be ob ta in ed i n th e f orm o f va ri an ts wit h 'p ig gy-b ack'EPRO M(Er as ab le pr o gr ammabl e RO M )s oc ke ts o r d ev ic e s wi th EP ROM i n st ea d of ROM 。

PLC有关的外文英语文件及翻译RelaysThe Programmable Logic ControllerEarly machines were controlled by mechanical means using cams, gears, levers andother basic mechanical devices. As the complexity grew, so did the need for a more sophisticated control system. This system contained wired relay and switch control elements. These elements were wired as required to provide the control logic necessary for the particular type of machine operation. This was acceptable for a machine that never needed to be changed or modified, but as manufacturing techniques improved and plant changeover to new products became more desirable and necessary,a more versatile means of controlling this equipment had to be developed. Hardwired relay and switch logic was cumbersome and time consuming to modify. Wiring had to be removed and replaced to provide for the new control scheme required. This modification was difficult and time consuming to design and install and any small "bug" in the design could be a major problem to correct since that also required rewiring of the system. A new means to modify control circuitry was needed. The development and testing ground for this new means was the U.S. auto industry. The time period was the late 1960's and early 1970's and the result was the programmable logic controller, or PLC. Automotive plants were confronted with a change in manufacturing techniques every time a model changed and, in some cases, for changes on the same model if improvements had to be made during the model year. The PLC provided an easy way to reprogram the wiring rather than actually rewiring the control system.The PLC that was developed during this time was not very easy to program. The language was cumbersome to write and required highly trained programmers. These early devices were merely relay replacements and could do very little else. The PLC has at first gradually, and in recent years rapidly developed into a sophisticated and highly versatile control system component. Units today are capable of performing complex math functions including numerical integration and differentiation and operate at the fast microprocessor speeds now available. Older PLCs were capable of only handling discrete inputs and outputs (that is, on-off type signals), while today's systems can accept and generate analog voltagesPLC有关的外文英语文件及翻译and currents as well as a wide range of voltage levels and pulsed signals. PLCs arealso designed to be rugged. Unlike their personal computer cousin, they can typicallywithstand vibration, shock, elevated temperatures, and electrical noise to whichmanufacturing equipment is exposed.As more manufacturers become involved in PLC production and development, and PLC capabilities expand, the programming language is also expanding. This is necessary to allow the programming of these advanced capabilities. Also, manufacturers tend to develop their own versions of ladder logic language (the language used to program PLCs). This complicates learning to program PLC's in general since one language cannot be learned that is applicable to all types. However, as with other computer languages, once the basics of PLC operation and programming in ladder logic are learned, adapting to the various manufacturers ’ devices is not a complicated process. Most system designers eventually settle on one particular manufacturer that produces a PLC that is personally comfortable to program and has the capabilities suited to his or her area of applications.It should be noted that in usage, a programmable logic controller is generally referred toas a “ PLC” or “ programmable controller ” . Although the term “ programmable contr generally accepted, it is not abbreviated “ PC”becausethe abbreviation “ PC” is usuallyused in reference to a personal computer. As we will see in this chapter, a PLC is by nomeans a personal computer.Programmable controllers (the shortened name used for programmable logic controllers) are much like personal computers in that the user can be overwhelmed by the vast array of options and configurations available. Also, like personal computers, the best teacher of which one to select is experience. As one gains experience with the various options and configurations available, it becomes less confusing to be able to select the unit that will best perform in a particular application.The typical system components for a modularized PLC are:1. Processor.The processor (sometimes call a CPU), as in the self contained units, is generally specified according to memory required for the program to be In the rmodularizeversions,capability can also be a factor. This includes features such as highe math functions, PID control loops and optional programming commands. The processor consists of the microprocessor, system memory, serial communication ports for printer, PLC LAN link and external programming device and, in some cases, the system power supply to power the processor and I/O modules.2. Mounting rack.This is usually a metal framework with a printed circuit board backplane which provides means for mounting the PLC input/output (I/O) modules and processor. Mounting racks are specified according to the number of modules required to implement the system. The mounting rack provides data and power connections to the processor and modules via the backplane. For CPUs that do not contain a power supply, the rack also holds the modular power supply. There are systems in which the processor is mounted separately and connected by cable to the rack. The mounting rack can be available to mount directly to a panel or can be installed in a standard 19" wide equipment cabinet. Mounting racks are cascadable so several may be interconnected to allow a system to accommodate a large number of I/O modules.3. Input and output modules.Input and output (I/O) modules are specified according to the input and output signals associated with the particular application. These modules fall into the categories of discrete, analog, high speed counter or register types.Discrete I/O modules are generally capable of handling 8 or 16 and, in some cases 32, on-off type inputs or outputs per module. Modules are specified as input or output but generally not both although some manufacturers now offer modules that can be configured with both input and output points in the same unit. The module can be specified as AC only, DC only or AC/DC along with the voltage values for which it is designed.Analog input and output modules are available and are specified according to the desired resolution and voltage or current range. As with discrete modules, these are generally input or output; however some manufacturers provide analog input and output in the same module. Analog modules are also available which can directly accept thermocouple inputsfor temperature measurement and monitoring by the PLC.Pulsed inputs to the PLC can be accepted using a high speed countermodule. This module can be capable of measuring the frequency of an inputsignal from a tachometer or other frequency generating device. These modules can also count the incoming pulses if desired. Generally, both frequency and count are available from the same module at the same time if both are required in the application.Register input and output modules transfer 8 or 16 bit words of information to and from the PLC. These words are generally numbers (BCD or Binary) which are generated from thumbwheel switches or encoder systems for input or data to be output to a display device by the PLC.Other types of modules may be available depending upon the manufacturer of thePLC and it's capabilities. These include specialized communication modules to allow for the transfer of information from one controller to another. One new development is an I/O Module which allows the serial transfer of information to remote I/O units that can be as far as 12,000 feet away.4. Power supply.The power supply specified depends upon the manufacturer's PLC being utilized in the application. As stated above, in some cases a power supply capable of delivering all required power for the system is furnished as part of the processor module. If the power supply is a separate module, it must be capable of delivering a current greater than the sum of all the currents needed by the other modules. For systems with the power supply inside the CPU module, there may be some modules in the system which require excessive power not available from the processor either because of voltage or current requirements that can only be achieved through the addition of a second power source. This is generally true if analog or external communication modules are present since these require DC supplies which,± in the case of analog modules, must be well regulated.5. Programming unit.The programming unit allows the engineer or technician to enter and edit the programto be executed. In it's simplest form it can be a hand held device with a keypad for programentry and a display device (LED or LCD) for viewing program steps or functions, as shown. More advanced systems employ a separate personal computer which allows the programmer to write, view, edit and download the program to the PLC. This is accomplished with proprietary software available from the PLC manufacturer. This software also allows the programmer or engineer to monitor the PLC as it is running the program. With this monitoring system, such things as internal coils, registers, timers and other items not visible externally can be monitored to determine proper operation. Also, internal register data can be altered if required to fine tune program operation. This can be advantageous when debugging the program. Communication with the programmable controller with this system is via a cable connected to a special programming port on the controller. Connection to the personal computer can be through a serial port or from a dedicated card installed in the computer.A Programmable Controller is a specialized computer. Since it is a computer, it has all the basic component parts that any other computer has; a Central Processing Unit,Memory, Input Interfacing and Output Interfacing.The Central Processing Unit (CPU) is the control portion of the PLC. It interprets the program commands retrieved from memory and acts on those commands. In present day PLC's this unit is a microprocessor based system. The CPU is housed in the processor module of modularized systems.Memory in the system is generally of two types; ROM and RAM. The ROM memory contains the program information that allows the CPU to interpret and act on the Ladder Logic program stored in the RAM memory. RAM memory is generally kept alive with an on-board battery so that ladder programming is not lost when the system power is removed. This battery can be a standard dry cell or rechargeablenickel-cadmium type. Newer PLC units are now available with Electrically Erasable Programmable Read Only Memory (EEPROM) which does not require a battery. Memory is also housed in the processor module in modular systems.Input units can be any of several different types depending on input signals expected as described above. The input section can accept discrete or analog signals of various voltage and current levels. Present day controllers offer discrete signal inputs of both AC and DCvoltages from TTL to 250 VDC and from 5 to 250 VAC. Analog input units can accept input levels such as ±10 VDC, ±5 VDC and 4-20 ma. current loop values. Discrete input units present each input to the CPU as a single 1 or 0 while analog input units contain analog to digital conversion circuitry and present the input voltage to the CPU as binary number normalized to the maximum count available from the unit. The number of bits representing the input voltage or current depends upon the resolution of the unit. This number generally contains a defined number of magnitude bits and a sign bit. Register input units present the word input to the CPU as it is received (Binary or BCD).Output units operate much the same as the input units with the exception that the unit is either sinking (supplying a ground) or sourcing (providing a voltage) discrete voltages or sourcing analog voltage or current. These output signals are presented as directed by the CPU. The output circuit of discrete units can be transistors for TTL and higher DC voltage or Triacs for AC voltage outputs. For higher current applications and situations where a physical contact closure is required, mechanical relay contacts are available. These higher currents, however, are generally limited to about 2-3 amperes. The analog output units have internal circuitry which performs the digital to analog conversion and generates the variable voltage or current output.The first thing the PLC does when it begins to function is update I/O. This means that all discrete input states are recorded from the input unit and all discrete states to be output are transferred to the output unit. Register data generally has specific addresses associated with it for both input and output data referred to as input and output registers. These registers are available to the input and output modules requiring them and are updated with the discrete data. Since this is input/output updating, it is referred to as I/O Update. The updating of discrete input and output information is accomplished with the use of input and output image registers set aside in the PLC memory. Each discrete input point has associated with it one bit of an input image register. Likewise, each discrete output point has one bit of an output image register associated with it. When I/O updating occurs, each input point that is ON at that time will cause a 1 to be set at the bit address associated with that particular input. If the input is off, a 0 will be set into the bit address. Memory in today's PLC's is generallyconfigured in 16 bit words. This means that one word of memory can store the states of 16 discrete input points. Therefore, there may be a number of words of memory set aside asthe input and output image registers. At I/O update, the status of the input image register isset according to the state of all discrete inputs and the status of the output image register is transferred to the output unit. This transfer of information typically only occurs at I/O update.It may be forced to occur at other times in PLC's which have an Immediate I/O Update command. This command will force the PLC to update the I/O at other times although this would be a special case.Before a study of PLC programming can begin, it is important to gain a fundamental understanding of the various types of PLCs available, the advantages and disadvantagesof each, and the way in which a PLC executes a program. The open frame, shoebox, and modular PLCs are each best suited to specific types of applications based on the environmental conditions, number of inputs and outputs, ease of expansion, and method of entering and monitoring the program. Additionally, programming requires a prior knowledgeof the manner in which a PLC receives input information, executes a program, and sends output information. With this information, we are now prepared to begin a study of PLC programming techniques.When writing programs for PLCs, it is beneficial to have a background in ladder diagramming for machine controls. This is basically the material that was covered in Chapter 1 of this text. The reason for this is that at a fundamental level, ladder logic programs for PLCs are very similar to electrical ladder diagrams. This is no coincidence.The engineers that developed the PLC programming language were sensitive to the fact that most engineers, technicians and electricians who work with electrical machines on a day-to-day basis will be familiar with this method of representing control logic. This would allow someone new to PLCs, but familiar with control diagrams, to be able to adapt very quickly to the programming language. It is likely that PLC programming language is one of the easiest programming languages to learn.可编程序控制器初期的机器用机械的方法采纳凸轮控制、齿轮、杠杆和其余基本机械设施。

摘自《可编程控制器在过程自动化中的应用》PROGRAMMABLE LOGIC CONTROLLERS INPROCESS AUTOMATIONAhti Mikkor, Lembit RoosimölderAbstract: Nowadays, control problems are solved using operating components from a wide variety of technologies: electronics, hydraulics, pneumatics and mechanics. Functio-nality, reliability and price of the controlled system are deter-mined by the quality of the solution made. The paper concentrates on practical use of programmable logic controllers (PLC) that is based on the five years project development experience in this area. Successful solutions and problems are under focus.Specific hardware, controller programming problems, data/signals exchange and human machine interfaces are considered. As a result the method for selecting programmable controllers according to specific needs is developed. Practical suggestions, possible hazards and warnings are proposed that could help to avoid mistakes.Key words: programmable controllers, PLC, automation, automation systems, process automation.1. INTRODUCTIONModern machinery consists of both mechanical and electronic parts. Overall functionality is determined by “balance”between these components. Initial planning and solution selection plays critical role in final result.In control methods the selection has to be made between relay-based circuits, special devices, programmable logic controllers (PLC) and new development electronics. This article is concentrated on PLC-s and experience that has collected over 5-year practical work with PLC-s. Strong and weak sides, positive and negative practices are discussed. Suggestions weather to use programmable controllers or not have been formed to help decision making.The most important decision in planning PLC-based system is selecting processor type. Mistakes mean extra costs for modifications or even need for completely new devices. The most common error is overestimating programming possibilities of small-sized processors. There are several methods for selecting PLC. Unfortunately most of them focus on electrical side of PLC-s and maximum count of signals allowed. They don’t involve analysis to determine possible special needs for user program or communications.Based on several existing methods, practical experience and future trends a new method for selecting PLC was developed. Ahti Mikkor has gainedhis experience by taking part in more than 15 big-scale automation projects. These projects include development of power consumption monitoring system in AS Kunda Nordic Cement factory, renewing testing rig for flowmeters, building Ahtme powerplant turbine safety systems, water treatment plants in towns Rakvere and Põlva, waste water treatment plant in town Jõgeva and development of monitoring system for central heating network in Tartu.2. PROS AND CONS IN USING PROGRAMMABLE LOGIC CONTROLLERS2.1 Positive argumentsThe main advantage that programmable controllers provide is flexibility (Jack, 2003). Behaviour of the system can be easily changed via program without any other alterations. Special devices for example make any changes in control algorithm very hard to implement. Flexibility makes PLC-s well suitable for frequently changed applications, for example in robotics.In PLC-s the relations between inputs and outputs are determined by user program. By using advanced programming technologies it is much easier to implement complex control algorithms than in any hard-wired solutions. It makes PLC-s very competitive for complex tasks, for example in controlling chemical processes.Special modules allow vast amount of different signals to be connected to the PLC system. Use of PLC-s should be considered in applications that require some “special” input or output signals. Typical example would be positioning using reference data from high-speed input.Typically PC visualization software packages are made for PLC-s. Some special devices have also PC software packages. Wide range of communication options between PLC-s makes it possible to gather all information from field devices into one central control point.Communication lines between PLC-s allow using information collected from other parts of the system in local process control. Modern communication technologies enable remote diagnostics and configuration (Jack, 2003). These two significantly reduce overall maintenance costs of the system.2.2 Negative argumentsProgrammable controllers are not equipped with enough memory to store big amounts of data. Although future trends show growth in PLC memory sizes, special devices (recorders) are still better suited for standalone datalogging applications. For networked solutions there is possibility to use visualization software packages together with PLC-s to archive collected data in any database format necessary. If logged data amounts are small or there are also control functions included, it’s reasonable to still use PLC-s. About visualization software packages it’s good to know that in standard versions most of them do not support offline recording so that after communication breakdown it is not possible toacquire data backwards from PLC.Modern communication options for PLC-s include standard protocols for example Ethernet. It is tempting to use existing office networks also as data carrier for automation system communications. Time has shown that it is better practice to keep these two separated if there is a need for constant online communication. Hardly traceable temporal network overloads can cause problems also in automation system communications All PLC-s need be programmed. All programming works include risk for accidental errors in control algorithm. Special devices are well tested and generally free of this kind of problems. If available, it’s economically thoughtful to use special devices.Safety applications that require highest degree of reliability should contain simplest devices and circuits possible. There is a rule that every new link in chain decreases overall reliability.In small applications it’s often cost saving to use relay-based circuits instead of PLC-s.3. FUTURE TRENDSProgress in process automation systems is aiming at so called complete automation when all the human has to do is to enter the parameters of the product wanted and everything else is carried out by machines (Rosin, 2000). Although the destination lies far ahead, trends indicate movement in that direction.Firstly, systems become more and more standardized. Big manufacturers organize their products into families. The aim is to reduce amount of knowledge needed for configuration and maintenance works of different devices from same company. It’s also important that this way built applications are easily expandable.Secondly, importance of communication is rising (Hughes, 2000). There are many reasons, some of more essentials are:• Better collaboration of different parts of the system.•Cutting costs on cabling. Less cabling results fall in fault probability, but also increases severity of ones that occur.• Sensors and actuators can be at longer distances from the processor module than if using conventional methods.• Increased scalability of the systems. New devices can be added at minimal costs.• At some cases it is better to make architecture of many small independent modules and network them. This solution enables system to keep working although some parts have failed.• Communication networks ease fault diagnostics and provide remote management possibilities. Central operating stations can be formed relatively easy.• Possibility to connect devices form different manufacturers (OPCFoundation, 2003).Third important tendency is spreading use of so called software controllers or Soft PLC-s (Siemens AG, 2003). These are PC software-based solutions that relate with field devices via communication networks. There is no need for processor module, resources of PC are used. Some Soft PLC-s are still formed as processor cards for PC (figure 1). Reliable communication networks are essential. Soft PLC-s are well suited for data acquisition applications because of data storage possibilities of PC-s.Figure 1. Siemens Simatic WinAC Slot PLC 412Fourthly, combo-devices (figure 2) that contain both operator panel and medium size processor module gain popularity (Siemens AG, 2002). In this solution possibility of disturbances is low and reuse of some components make whole package cheaper.Figure 2. Combo device Siemens Simatic C7-613Fifthly, processor software takes over properties from PC software. Data collected from production can be easily transferred into office applications (Siemens AG, 2000).4. METHOD FOR SELECTING PROGRAMMABLE CONTROLLERA method for forming an application specific list of required properties for selecting programmable controller was developed. There are nine criterions and the results are presented in Table 1. Selection is made by comparing results table with controller’s technical data. Following is short description of every criteria involved.Nature of solution determines weather it is expanding of old system or completely new development. In first case the architecture of system and hardware requirements are limited by already existing solution. Using hardware from same company makes servicing easier and avoids integration problems that would occur when using products form different manufacturers. For example many hardware producers integrate their own specific communication interfaces directly into processor module and for every universal protocol a special module is needed (Siemens AG, 2003). It is also possible to reduce spare part stock amounts when using same type hardware all over the system.Maximum number of electrical inputs-outputs allowed is classical criteria to determine processor class. If complex control algorithms and non-standard functions are needed, it’s not the most important parameter any more. Generally it is money saving to use one bigger processor module for input-output signals that originate from nearby locations than several smaller ones. In this case there will be no need for communication network and programming will be easier too.Special signals and modules are usually available for medium and large controller families only. Many microcontrollers do not even have possibility to add analogue output (Siemens AG, 2003). In some cases using special modules is the only way, in other ones (positioning) it is just an opportunity to save money.Layouts of sensors and actuators can be very different, sometimes the sensors are located several kilometres away from the actuator (pumping liquids in long pipes). In this case special communication network (Profibus, AS-inteface) might be the only solution. If not, it can at least save costs by reducing cabling works. Not all programmable controllers have interfaces for communication protocols.Properties of processor have important role in complex applications. Most common problem is lack of programming memory, sometimes also data memory. Memory requirements can be estimated by number of input and output signals. But in practice 100 digital input-output points system often has 3 times smaller program than 10 digital input-output points system. The only way to estimate program size exactly is using previous experience.Program specialities include special program functions needed. Different areas of applications have some typically used functions, for example temperature control in building automation. Programming is much simpler if these functions are already built into system software of processor. In process automation 2 digital output (up-down) closed loopPID regulation is quite often used. It might be a surprise but it’s not included in most of the microcontrollers (Siemens AG, 2003) and for average programmer it’s too complicated task to create his own regulator using standard functions. Basically there are 2 solutions: either to avoid this construction or to use applicable controller.Table 1. Table for method resultsCommunication is becoming more important in nowadays automation systems. In some cases non-standardised devices as barcode readers or electronic weights have to be included into the system. Then it’s vital to have functions for protocol programming (freeport programming). Standardised protocols demand existence of specific modules. Working conditions can usually be overcome by using special cabinets, but there are also specific series of programmable controllers that have improved resistance for electromagnetic disturbances, humidity and vibrations. In very dusty environments all cooling ventilators have to be equipped withfilters.5. CONCLUSIONSMain benefits of programmable controllers are:• flexibility• communication possibilities• realisation of complex control algorithms• reliabilityAlternative solutions should be considered if:• system is very simple• special devices are available• data recording is necessaryInitial selection of appropriate solution and hardware has great influence on final result. Mistakes in this step significantly increase overall budget of project as some programs might have to be changed and some hardware replaced.Based on his practical experience the author has formed a method for selecting programmable controller. It has 9 criteria’s: • nature of solution (new or existing)•maximum number of electrical inputs-outputs allowed (digital, analogue, inputs, outputs)• need for special modules (high-speed digital outputs)• layout of sensors and actuators (local or periphery)• properties of processor (program and data memory)• program specialities (special functions)• communication needs (Profibus, ASCII)• working conditions (humidity, temperature, vibration, dust) Method is not guaranteed to always point out the best selection, but using it certainly avoids mistakes.6. REFERENCESHughes, T. A. Programmable Controllers, Third Edition. ISA –The Instrumentation, Systems, and Automation Society, 2000, 334 p.Jack, H. Automating Manufacturing Systems with PLC-s, 828 p.,Available:/~jackh/books/plcs/pdf/plcbook4_2.pdf, Accessed:3.10.2003LOGO! Manual. Siemens AG, 2003, 312 p.OPC Foundation homepage: /, Accessed: 9.11.2003Rosin, A. Programmable Controllers Simatic S7. Tallinn, TTU, 2000, 120 p. [Master Thesis] – in Estonian.Berger, H. Automating with SIMATIC. Siemens AG, 2003, 214 p.SIMATIC Programming with STEP 7 V 5.2: Manual. Siemens AG, 2002, 610 p.SIMATIC S7-200 Programmable Controller System Manual. Siemens AG, 2003, 474 p.SIMATIC HMI WinCC Configuration Manual. Volume 1, 2, 3. Siemens AG 2000, 468 p.参考文献[1] Hughes, T. A. Programmable Controllers, Third Edition. ISA – The Instrumentation, Systems, and Automation Society, 2000, 334 p.[2] Jack, H. Automating Manufacturing Systems with PLC-s, 828 p., Available:[3]/~jackh/books/plcs/pdf/plcbook4_2.pd f,Accessed:3.10.2003[4] LOGO! Manual. Siemens AG, 2003, 312 p.[5] OPC Foundation homepage: /, Accessed: 9.11.2003[6] Rosin, A. Programmable Controllers Simatic S7. Tallinn, TTU, 2000, 120 p. [Master Thesis] – in Estonian.[7] Berger, H. Automating with SIMATIC. Siemens AG, 2003, 214 p.[8] SIMATIC Programming with STEP 7 V 5.2: Manual. Siemens AG, 2002, 610 p.[9] SIMATIC S7-200 Programmable Controller System Manual. Siemens AG, 2003, 474 p.[10] SIMATIC HMI WinCC Configuration Manual. Volume 1, 2, 3. Siemens AG2000, 468 p.翻译：摘自《可编程控制器在过程自动化中的应用》摘要：目前，控制问题解决了各种各样的技术操作部分：电子，液压，气动和机械。

Beer filling, Gland machine PLC control system1.IntorductionMalt beer production process is divided into manufacturing, manufacturing wort, before fermentation, after fermentation, filtration sterilization, packaging, and so few procedures. Beer filling, Gland part of a packaging machine processes. The membrane filtration of beer after the pipeline into the rotary Jiugang, then the valve into the bottle of wine, Gland, was bottled beer. Beer filling, Gland machine's efficiency and degree of automation direct impact on the level of beer production. China's beer industry to meet the increasing scale of production and the demand for beer modern high-speed filling machinery filling the requirements of domestic beer manufacturers are actively seeking to transform the unit or the filling of beer production equipment, making it a good use Performance, advanced technology and high production efficiency and operating a safe and secure, low maintenance costs of the modernization of beer filling machine.2. Filling beer, Gland principle and control aircraft partsLiquid filling machine by filling principle can be divided into atmospheric filler,filling machines and vacuum pressure on the filling machine. Beer filling,Gland-filling method used pressure is higher than the atmospheric pressure under the filling, storage of the cylinder pressure than the pressure of the bottle, beer bottle into the liquid on pressure.Technology at home and abroad to achieve the filling line is basically: The Rotary Jiugang the rotating movement, placed in Jiugang slots on the empty bottles through the machinery will be fixed at the upper Jiugang vacuum valve to open, closed Vacuum bottles for good treatment, Bozhuan stem from operating, open the valve of the bottle filling CO2 gases, vacuum convex .Round to open the vacuum valve, the bottle will air mixed with CO2 out of gas, open the valve again, the CO2 gas bottle filling, the filling valve on the pressure valve in the bottle close to back-pressure gas pressure at the open-Jiuye Pingbi into the bottle, through pneumatic or electrical control filling valve to achieve the filling of beer. Today's advanced international beer filling, Gland machine control system mainly by the photoelectric switch position detection part and take the bottles with, Jiugang speed part, dominated by the PLC, touch screen and other components. Filling, Gland of the mechanical structure and PLC programmable control devices, frequency stepless speed regulation, human-computer interface, and other modern means of complete automatic control technology, the combination of a mechanical and electrical integration.3. Controlled part of the programmeMany domestic beer manufacturers are now using the filling, Gland of the control system of uneven degree of automation; button and all the manual switch technology have set up operations in a box on the panel, PLC controller for the majority of Japanese companies or OMRON Mitsubishi's early products, equipment chain of control, less protection settings, plus the beer filling the scene poor environment, humidity, such as contact with the switch contacts serious corrosion, the system's signal detection of the high failure rate, resulting in equipment control system Operation of low reliability, the normal operation of equipment, such asshort-cycle phenomenon.To the actual transformation of the Dandong Yalu River Brewery Co., Ltd. of filling, Gland machine control system as an example, the transformation of methods to clarify the control of such equipment thinking and ideas, according to the scene of the actual process conditions, to prepare the operation of the PLC Procedures. For beer filling, Gland control system of the actual situation and in accordance with the actual process conditions at the scene, re-design of the equipment of the PLC control system. This transformation of the same methods and ideas can be applied to other liquids and the transformation of filling equipment.3.1 system hardware configurationJapan's Mitsubishi Corporation to use the FX2N128MRPLC use the system to replace the original 2-OMRON's C60P PLC, the original system of the PLC is due to old models, and computer on-line communications need to configure special converters, the system need to increase the external I / O input points , The extension of spare parts more difficult to find. FX2N128MRPLC is an integrated 128-point I / O controller of the box, a computing speed, command rich, high-cost performance, on-line programming simple and easy extension of the advantages of the Mitsubishi FX series, features the strongest small controller .(1) by the Mitsubishi 900 series of 970 GOT human-computer touch screen system to replace the original use of the button panel display equipment and monitor the operation of operating parameters. 970GOT HMI for the 16-color high-brightness significantly, through the convergence of connectivity and FX2N128MRPLC directly connected to the CPU, achieving rapid response. Has many maintenance features, such as the list-editing features, ladder monitoring (troubleshooting) function, the systemmonitoring functions to find fault and maintenance of PLC Systems. (2) filling, Gland of the frequency converter in the transformation of no replacement, on-site detection signal means-testing is still used switch, switch for detecting long-term work in the humidity of the great occasions, the choice of capacitive proximity switches, according to PLC I / O terminal of the connection mode, select the type of close PNP switch, the control system of Figure 1.3.2 Systems ProgrammingPLC controller programming focus and the core is around Jiugang the rotation speed control and Jiugang on 60 bottles of detecting the location of the displaced, broken bottles, empty bottles at the location of testing and related displacement filling Such as control valves. The bottles displacement of testing procedures, using a Mitsubishi PLC in the left command.Figure 1 control system structure diagram .Bottles displacement of detection, using the left-PLC command, which commands the whole of one of the core control procedures, the main electrical switch detection and bottles at the bottle simultaneously detect mobile, the main motor to every week, just to the corresponding Jiugang Have a bottle of, PLC unit within the internal correspondence that 60 bottles of the unit for the M500 ~ M559, the number of units by the first letter K is set to K60, with each change in a second letter K is set to K1, M50 Reaction of the empty bottles in the short position, and detect the location of the motor speed to go on the frequency shift in the corresponding unit within the built-in "1" or "0", control valves and the corresponding mixing caps The motor stopped and opened. Continuous detection system in place after the 90 empty bottles, stop stirring caps the motor running, testing the number of bottles in accordance with the user's requirements can be arbitrary.A bottle of detection. Rotary Jiugang through pressure to back pressure with the bottle of liquor in the process of empty bottles in the back-pressure, because the bottle itself may crack and other reasons leading to a sudden burst bottles, which need to detect the location of unexploded bottle bottle, in this bottle - The position opened purge solenoid valves, compressed air out, broken bottles at the bottle-blowing from the position in a row after the purge and several bottles of the electromagnetic valve open jet, a high-pressure spray Shuizhu, in the break Bottle position around a few bottles of spray bottles in a row. Detection of broken bottles and bottle-detection switch simultaneously detect movement of breaking bottles, to the main motor of each week, precisely corresponding Jiugang passed a bottle of, PLC unit within the internal correspondence that 20 broken bottles at the unit for the M600 ~ M619, unit With the number of the first letter K is set to K20, with each change in a second letter K is set to K1, M52 response to the location of the broken bottles and detected the location of the motor speed to the frequency shift continue, In the corresponding unit within the built-in "1" or "0", control and the corresponding jet purge solenoid valve opened and stopped. Continuous Spray and purge solenoid valve open to listen, time stopped in accordance with technological requirements can be arbitrary.System security is to control access to the caps simultaneously tracking, not only accurately detect the electrical switching speed detection, the broken bottles into the bottle and detection switch detection switch three conditions.970GOT human-computer touch-screen terminals operated by the software company's Mitsubishi GT WORKS package, which is a GT Designer with the entire GOT9000 series of graphics software packages. The package is simple, prior to a personal computer simulation on the configurationand debug, after the man-machine operators to download terminals. At the same time, because the man-machine interface and a touch-screen role, will set common switch on the screen to facilitate the operation. And also to increase the number of features, such as setting alarm information.4.After transformation control systemSystem at the normal operation of the machine for automatic control, in accordance with bottles into and out of the bottle for lack or slow pace set by running into the bottle stall bottles, no less than a bottle cap, automatic washing bottles burst, filling automatic back-pressure position , Covered under the system automatically lose covered a stop and safety protection, such as the coordination of action interlock. All the original button after the operation of the touch screen on.5.Detection of the state control system monitoringDetection switch into the bottle and break bottles detection switch bottles of pressure by testing each part of the small metal plates above the location of a photoelectric pulse output, a further PLC acquisition, as each bottle of the pressure above the small metal plates is the location of activities , In the machine running after some time, some pressure above the small bottles of iron tablets and detection switch in the location of displacement, resulting in detection switch mistaken judgement, if not for the judgement of bottles of bottles, bottle explosion Lou Jian, misuse, such as the seizure of output errors So that the PLC have mistaken action, such as a back-pressure, unexploded bottle blowing, washing, stirring cap control system malfunction, such as failure phenomenon.Before the transformation of the daily production process, encountered this phenomenon, the operatives could only switch to thevarious functional or manual control buttons reach the stall so that the equipment work in the absence of monitoring state, the machine lost control function. Caused a lot of production of raw materials such as gas, water, wine waste. Only in the production of intermittent, can be fitter and maintenance electrician in accordance with the detection of small switch on the light-emitting diodes and anti-displacement by adjusting the distance only 5 ~ 8 mm detection switch installation location, and switch to fix detection of small metal plates Gap. This means of detection is very backward, after adjustment reaction to the results, timely response can not be adjusted results.In view of this testing situation, after the transformation of the filling, Gland control system configuration, this part of a new detection and integration in human-computer touch screen, complete bottle of detection.In human-computer touch screen interface on the page display, respectively, at customs, such as electromagnetic motor mixing valve switch state are in different colors to show, very intuitive.Increase the system's functions is to ensure the irrigation of the machine-Gland normal operation of automated control system specifically designed to.6 Concluding remarksAfter the transformation of the control system will greatly simplify the complicated mechanical structure, the running and control of inspection, the degree of automation systems meet the design requirements, greatly reducing the operational strength of the labor so that the shrub-like beer output than in the past Raising more than 30 percent, greatly reduce the failure rate. Embodies the modern equipment of automatic control technology. In the digestion and absorption of today'sindustrial control on the basis of advanced technology innovation, development of domestic technology from the most advanced filling control system.啤酒灌装、压盖机PLC控制系统1. 引言啤酒生产过程分为麦芽制造、麦芽汁制造、前发酵、后发酵、过滤灭菌、包装等几道工序。

附录外文资料PLC technique discussion and future developmentAlong with the development of the ages, the technique that is nowadays is also gradually perfect, the competition plays more strong; the operation that list depends the artificial has already can't satisfied with the current manufacturing industry foreground, also can't guarantee the request of the higher quantity and high new the image of the technique business enterprise.The people see in produce practice, automate brought the tremendous convenience and the product quantities for people up of assurance, also eased the personnel's labor strength, reduce the establishment on the personnel. The target control of the hard realization in many complicated production lines, whole and excellent turn, the best decision etc., well-trained operation work, technical personnel or expert, governor but can judge and operate easily, can acquire the satisfied result. The research target of the artificial intelligence makes use of the calculator exactly to carry out, imitate these intelligences behavior, moderating the work through person's brain and calculators, with the mode that person's machine combine, for resolve the very complicated problem to look for the best pathWe come in sight of the control that links after the electric appliances in various situation, that is already the that time generation past, now of after use in the mold a perhaps simple equipments of grass-roots control that the electric appliances can do for the low level only; And the PLC emergence also became the epoch-making topic, adding the vivid software control through a very and stable hardware, making the automation head for the new high tide.The PLC biggest characteristics lie in: The electrical engineering teacher already no longer electric hardware up too many calculations of cost, as long as order the importation that the button switch or the importation of the sensors order to link the PLC up can solve problem, pass to output to order the conjunction contact machine or control the start equipments of the big power after the electric appliances, but the exportation equipments direct conjunction of the small power can.PLC internal containment have the CPU of the CPU, and take to have an I/ O for expand of exterior to connect a people's address and saving machine three big pieces to constitute, CPU core is from an or many is tired to add the machine to constitute, mathematics that they have the logic operation ability, and can read the procedure save the contents of the machine to drive the homologous saving machine and I/ Os to connect after pass the calculation; The I/ O add inner part is tired the input and output system of the machine and exterior link, and deposit the related data into the procedure saving machine or data saving machine; The saving machine can deposit the data that the I/ O input in the saving machine, and in work adjusting to becometired to add the machine and I/ Os to connect, saving machine separately saving machine RAM of the procedure saving machine ROM and dates, the ROM can do deposit of the data permanence in the saving machine, but RAM only for the CPU computes the temporary calculation usage of hour of buffer space.The PLC anti- interference is very and excellent, our root need not concern its service life and the work situation bad, these all problems have already no longer become the topic that we fail, but stay to our is a concern to come to internal resources of make use of the PLC to strengthen the control ability of the equipments for us, make our equipments more gentle.PLC language is not we imagine of edit collected materials the language or language of Cs to carry on weaving the distance, but the trapezoid diagram that the adoption is original after the electric appliances to control, make the electrical engineering teacher while weaving to write the procedure very easy comprehended the PLC language, and a lot of non- electricity professional also very quickly know and go deep into to the PLC.Is PLC one of the advantage above and only, this is also one part that the people comprehend more and easily, in a lot of equipments, the people have already no longer hoped to see too many control buttons, they damage not only and easily and produce the artificial error easiest, small is not a main error perhaps you can still accept; But lead even is a fatal error greatly is what we can't is tolerant of. New technique always for bringing more safe and convenient operation for us, make we a lot of problems for face on sweep but light, do you understand the HMI? Says the HMI here you basically not clear what it is, also have no interest understanding, change one inside text explains it into the touch to hold or man-machine interface you knew, and it combines with the PLC to our larger space.HMI the control not only is reduced the control press button, increase the vivid of the control, more main of it is can sequence of, and at can the change data input to output the feedback with data, control in the temperature curve of imitate but also can keep the manifestation of view to come out. And can write the function help procedure through a plait to provide the help of various what lies in one's power, the one who make operate reduces the otiose error. Currently the HMI factory is also more and more, the function is also more and more strong, the price is also more and more low, and the noodles of the usage are wide more and more. The HMI foreground can say that think ° to be good very.At a lot of situations, the list is a smooth movement that can't guarantee the equipments by the control of the single machine, but pass the information exchanges of the equipments and equipments to attain the result that we want. For example fore pack and the examination of the empress work preface, we will arrive wrapping information feedback to examine the place, and examine the information of the place to also want the feedback to packing. Pass the information share thus to make both the chain connect, becoming a total body, the match of your that thus make is more close,at each other attain to reflect the result that mutually flick.The PLC correspondence has already come more body now its value, at the PLC and correspondence between PLCs, can pass the communication of the information and the share of the dates to guarantee that of the equipments moderates mutually, the result that arrive already to repair with each other. Data conversion the adoption RS232 between PLC connect to come to the transmission data, but the RS232 pick up a people and can guarantee 10 meters only of deliver the distance, if in the distance of 1000 meters we can pass the RS485 to carry on the correspondence, the longer distance can pass the MODEL only to carry on deliver.The PLC data transmission is just to be called a form to it in a piece of and continuous address that the data of the inner part delivers the other party, we, the PLC of the other party passes to read data in the watch to carry on the operation. If the data that data in the watch is a to establish generally, that is just the general data transmission, for example today of oil price rise, I want to deliver the price of the oil price to lose the oil ally on board, that is the share of the data; But take data in the watch for an instruction procedure that controls the PLC, that had the difficulty very much, for example you have to control one pedestal robot to press the action work that you imagine, you will draw up for it the form that a procedure combine with the data sends out to pass by.The form that information transport contain single work, the half a work and the difference of a workers .The meaning of the single work also is to say both, a can send out only, but a can receive only, for example a spy he can receive the designation of the superior only, but can't give the superior reply; A work of half is also 2 and can send out similar to accept the data, but can't send out and accept at the same time, for example when you make a phone call is to can't answer the phone, the other party also; But whole pair works is both can send out and accept the data, and can send out and accept at the same time. Be like the Internet is a typical example.The process that information transport also has synchronous and different step cent: The data line and the clock lines are synchronous when synchronous meaning lie in sending out the data, is also the data signal and the clock signals to be carry on by the CPU to send out at the same time, this needs to all want the specialized clock signal each other to carry on the transmission and connect to send, and is constrained, the characteristics of this kind of method lies in its speed very quick, but correspond work time of take up the CPU and also want to be long oppositely, at the same time the technique difficulty also very big. Its request lies in canting have an error margins in a dates deliver, otherwise the whole piece according to compare the occurrence mistake, this on the hardware is a bigger difficulty. Applied more and more extensive in some appropriative equipments, be like the appropriative medical treatment equipments, the numerical signal equipments...etc., in compare the one data deliver, its result is very good.And the different step is an application the most extensive, this receive benefit init of technique difficulty is opposite and want to be small, at the same time not need to prepare the specialized clock signal, its characteristics to lie in, its data is partition, the long-lost send out and accept, be the CPU is too busy of time can grind to a stop sex to work, also reduced the difficulty on the hardware, the data throw to lose at the same time opposite want to be little, we can pass the examination of the data to observe whether the data that we send out has the mistake or not, be like strange accidentally the method, tired addition and eight efficacies method etc., can use to helps whether the data that we examine to send out have or not the mistake occurrence, pass the feedback to carry on the discriminator.A line of transmission of the information contains a string of and combine the cent of: The usual PLC is 8 machines, certainly also having 16 machines. We can be an at the time of sending out the data a send out to the other party, also can be 88 send out the data to the other party, an and 8 differentiations are also the as that we say to send out the data and combine sends out the data. A speed is more and slowly, but as long as 2 or three lines can solve problem, and can use the telephone line to carry on the long range control. But combine the ocular transmission speed is very quick of, it is a string of ocular of 25600%, occupy the advantage in the short distance, the in view of the fact TTL electricity is even, being limited by the scope of one meter generally, it combine unwell used for the data transmission of the long pull, thus the cost is too expensive.Under a lot of circumstances we are total to like to adopt the string to combine the conversion chip to carry on deliver, under this kind of circumstance not need us to carry on to deposited the machine to establish too and complicatedly, but carry on the data exchanges through the data transmission instruction directly, but is not a very viable way in the correspondence, because the PLC of the other party must has been wait for your data exportation at the time of sending out the data, it can't do other works.When you are reading the book, you hear someone knock on door, you stop to start up of affair, open the door and combine to continue with the one who knock on door a dialogue, the telephone of this time rang, you signal hint to connect a telephone, after connecting the telephone through, return overdo come together knock on door to have a conversation, after dialogue complete, you continue again to see your book, this kind of circumstance we are called the interruption to it, it has the authority, also having sex of have the initiative, the PLC had such function .Its characteristics lie in us and may meet the urgently abrupt affairs in the operation process of the equipments, we want to stop to start immediately up of work, the whereabouts manages the more important affair, this kind of circumstance is we usually meet of, PLC while carry out urgent mission, total will keep the current appearance first, for example the address of the procedure, CPU of tired add the machine data etc., be like to stick down which the book that we see is when we open the door the page or simply make a mark, because we treat and would still need to continue immediately after book of see the behind. The CPU always does the affair that should do according to our will, but your mistake of give it an affair, it also would be same to do, this we must notice.The interruption is not only a, sometimes existing jointly with the hour several inside break, break off to have the preferred Class, they will carry out the interruption of the higher Class according to person's request. This kind of breaks off the medium interruption to also became to break off the set. The Class that certainly break off is relevant according to various resources of CPU with internal PLC, also following a heap of capacity size of also relevant fasten.The contents that break off has a lot of kinds, for example the exterior break off, correspondence in of send out and accept the interruption and settle and the clock that count break off, still have the WDT to reset the interruption etc., they enriched the CPU to respond to the category while handle various business. Speak thus perhaps you can't comprehend the internal structure and operation orders of the interruption completely also, we do a very small example to explain.Each equipment always will not forget a button, it also is at we meet the urgent circumstance use of, which is nasty to stop the button. When we meet the Human body trouble and surprised circumstances we as long as press it, the machine stops all operations immediately, and wait for processing the over surprised empress recover the operation again. Nasty stop the internal I/ O of the internal CPU of the button conjunction PLC to connect up, be to press button an exterior to trigger signal for CPU, the CPU carries on to the I/ O to examine again, being to confirm to have the exterior to trigger the signal, CPU protection the spot breaks off procedure counts the machine turn the homologous exterior I/ O automatically in the procedure to go to also, be exterior interruption procedure processing complete, the procedure counts the machine to return the main procedure to continue to work. Have 1:00 can what to explain is we generally would nasty stop the button of exterior break off to rise to the tallest Class, thus guarantee the safety.When we are work a work piece, giving the PLC a signal, counting PLC inner part the machine add 1 to compute us for a day of workload, a count the machine and can solve problem in brief, certainly they also can keep the data under the condition of dropping the electricity, urging the data not to throw to lose, this is also what we hope earnestly.The PLC still has the function that the high class counts the machine, being us while accept some dates of high speed, the high speed that here say is the data of the in all aspects tiny second class, for example the bar code scanner is scanning the data continuously, calculating high-speed signal of the data processor DSP etc., we will adopt the high class to count the machine to help we carry on count. It at the PLC carries out the procedure once discover that the high class counts the machine to should of interruption, will let go of the work on the hand immediately. The trapezoid diagram procedure that passes by to weave the distance again explains the high class for us to carry out procedure to count machine would automatic performance to should of work, thus rise the Class that the high class counts the machine to high one Class.You heard too many this phrases perhaps:" crash", the meaning that is mostly is a workload of CPU to lead greatly, the internal resources shortage etc. the circumstance can't result in procedure circulate. The PLC also has the similar circumstance, there is a watchdog WDT in the inner part of PLC, we can establish time that a procedure of WDT circulate, being to appear the procedure to jump to turn the mistake in the procedure movement process or the procedure is busy, movement time of the procedure exceeds WDT constitution time, the CPU turn but the WDT reset the appearance. The procedure restarts the movement, but will not carry on the breakage to the interruption.The PLC development has already entered for network ages of correspondence from the mode of the one, and together other works control the net plank and I/ O card planks to carry on the share easily. A state software can pass all se hardwires link, more animation picture of keep the view to carries on the control, and cans pass the Internet to carry on the control in the foreign land, the blast-off that is like the absolute being boat No.5 is to adopt this kind of way to make airship go up the sky.The development of the higher layer needs our continuous effort to obtain. The PLC emergence has already affected a few persons fully, we also obtained more knowledge and precepts from the top one experience of the generation, coming to the continuous development PLC technique, push it toward higher wave tide.Knowing the available PLC network options and their best applications will ensure an efficient and flexible control system design.The programmable logic controller's (PLC's) ability to support a range of communication methods makes it an ideal control and data acquisition device for a wide variety of industrial automation and facility control applications. However, there is some confusion because so many possibilities exist. To help eliminate this confusion, let's list what communications are available and when they would be best applied.To understand the PLC's communications versatility, let's first define the terms used in describing the various systems.ASCII: This stands for "American Standard Code for Information Interchange." As shown in Fig. 1, when the letter "A" is transmitted, for instance, it's automatically coded as "65" by the sending equipment. The receiving equipment translates the "65" back to the letter "A." Thus, different devices can communicate with each other as long as both use ASCII code.ASCII module: This intelligent PLC module is used for connecting PLCs to other devices also capable of communicating using ASCII code as a vehicle.Bus topology: This is a linear local area network (LAN) arrangement, as shown in Fig. 2A, in which individual nodes are tapped into a main communications cable at a single point and broadcast messages. These messages travel in both directions on thebus from the point of connection until they are dissipated by terminators at each end of the bus.CPU: This stands for "central processing unit," which actually is that part of a computer, PLC, or other intelligent device where arithmetic and logical operations are performed and instructions are decoded and executed.Daisy chain: This is a description of the connection of individual devices in a PLC network, where, as shown in Fig. 3, each device is connected to the next and communications signals pass from one unit to the next in a sequential fashion.Distributed control: This is an automation concept in which portions of an automated system are controlled by separate controllers, which are located in close proximity to their area of direct control (control is decentralized and spread out over the system).Host computer: This is a computer that's used to transfer data to, or receive data from, a PLC in a PLC/computer network.Intelligent device: This term describes any device equipped with its own CPU.I/O: This stands for "inputs and outputs," which are modules that handle data to the PLC (inputs) or signals from the PLC (outputs) to an external device.Kbps: This stands for "thousand bits per second," which is a rate of measure for electronic data transfer.Mbps: This stands for "million bits per second."Node: This term is applied to any one of the positions or stations in a network. Each node incorporates a device that can communicate with all other devices on the network.Protocol: The definition of how data is arranged and coded for transmission on a network.Ring topology. This is a LAN arrangement, as shown in Fig. 2C, in which each node is connected to two other nodes, resulting in a continuous, closed, circular path or loop for messages to circulate, usually in one direction. Some ring topologies have a special "loop back" feature that allows them to continue functioning even if the main cable is severed.RS232. This is an IEEE standard for serial communications that describes specific wiring connections, voltage levels, and other operating parameters for electronic data communications. There also are several other RS standards defined.Serial: This is an electronic data transfer scheme in which information istransmitted one bit at a time.Serial port: This the communications access point on a device that is set up for serial communications.Star topology. This is a LAN arrangement in which, as shown in Fig. 2B, nodes are connected to one another through a central hub, which can be active or passive. An active hub performs network duties such as message routing and maintenance. A passive central hub simply passes the message along to all the nodes connected to it.Topology: This relates to a specific arrangement of nodes in a LAN in relation to one another.Transparent: This term describes automatic events or processes built into a system that require no special programming or prompting from an operator.Now that we're familiar with these terms, let's see how they are used in describing the available PLC network options.PLC network optionsPLC networks provide you with a variety of networking options to meet specific control and communications requirements. Typical options include remote I/O, peer-to-peer, and host computer communications, as well as LANs. These networks can provide reliable and cost-effective communications between as few as two or as many as several hundred PLCs, computers, and other intelligent devices.Many PLC vendors offer proprietary networking systems that are unique and will not communicate with another make of PLC. This is because of the different communications protocols, command sequences, error-checking schemes, and communications media used by each manufacturer.However, it is possible to make different PLCs "talk" to one another; what's required is an ASCII interface for the connection(s), along with considerable work with software.Remote I/0 systemsA remote I/O configuration, as shown in Fig. 4A, has the actual inputs and outputs at some distance from the controller and CPU. This type of system, which can be described as a "master-and-slave" configuration, allows many distant digital and analog points to be controlled by a single PLC. Typically, remote I/Os are connected to the CPU via twisted pair or fiber optic cables.Remote I/O configurations can be extremely cost-effective control solutions where only a few I/O points are needed in widely separated areas. In this situation, it's not always necessary, or practical for that matter, to have a controller at each site. Noris it practical to individually hard wire each I/O point over long distances back to the CPU. For example, remote I/O systems can be used in acquiring data from remote plant or facility locations. Information such as cycle times, counts, duration or events, etc. then can be sent back to the PLC for maintenance and management reporting.In a remote I/O configuration, the master controller polls the slaved I/O for its current I/O status. The remote I/O system responds, and the master PLC then signals the remote I/O to change the state of outputs as dictated by the control program in the PLC's memory. This entire cycle occurs hundreds of times per second.Peer-to-peer networksPeer-to-peer networks, as shown in Fig. 4B, enhance reliability by decentralizing the control functions without sacrificing coordinated control. In this type of network, numerous PLCs are connected to one another in a daisy-chain fashion, and a common memory table is duplicated in the memory of each. In this way, when any PLC writes data to this memory area, the information is automatically transferred to all other PLCs in the network. They then can use this information in their own operating programs.With peer-to-peer networks, each PLC in the network is responsible for its own control site and only needs to be programmed for its own area of responsibility. This aspect of the network significantly reduces programming and debugging complexity; because all communications occur transparently to the user, communications programming is reduced to simple read-and-write statements.In a peer-to-peer system, there's no master PLC. However, it's possible to designate one of the PLCs as a master for use as a type of group controller. This PLC then can be used to accept input information from an operator input terminal, for example, sending all the necessary parameters to other PLCs and coordinating the sequencing of various events.Host computer linksPLCs also can be connected with computers or other intelligent devices. In fact, most PLCs, from the small to the very large, can be directly connected to a computer or part of a multi drop host computer network via RS232C or RS422 ports. This combination of computer and controller maximizes the capabilities of the PLC, for control and data acquisition, as well as the computer, for data processing, documentation, and operator interface.In a PLC/computer network, as shown in Fig. 4C, all communications are initiated by the host computer, which is connected to all the PLCs in a daisy-chain fashion. This computer individually addresses each of its networked PLCs and asks for specific information. The addressed PLC then sends this information to the computer for storage and further analysis. This cycle occurs hundreds of times per second.Host computers also can aid in programming PLCs; powerful programming and documentation software is available for program development. Programs then can be written on the computer in relay ladder logic and downloaded into the PLC. In this way, you can create, modify, debug, and monitor PLC programs via a computer terminal.In addition to host computers, PLCs often must interface with other devices, such as operator interface terminals for large security and building management systems. Although many intelligent devices can communicate directly with PLCs via conventional RS232C ports and serial ASCII code, some don't have the software ability to interface with individual PLC models. Instead, they typically send and receive data in fixed formats. It's the PLC programmer's responsibility to provide the necessary software interface.The easiest way to provide such an interface to fixed-format intelligent devices is to use an ASCII/BASIC module on the PLC. This module is essentially a small computer that plugs into the bus of the PLC. Equipped with RS232 ports and programmed in BASIC, the module easily can handle ASCII communications with peripheral devices, data acquisition functions, programming sequences, "number crunching," report and display generation, and other requirements.Access, protocol, and modulation functions of LANsBy using standard interfaces and protocols, LANs allow a mix of devices (PLCs, PCs, mainframe computers, operator interface terminals, etc.) from many different vendors to communicate with others on the network.Access: A LAN's access method prevents the occurrence of more than one message on the network at a time. There are two common access methods.Collision detection is where the nodes "listen" to the network and transmit only if there are no other messages on the network. If two nodes transmit simultaneously, the collision is detected and both nodes retransmit until their messages get through properly.Token passing allows each node to transmit only if it's in possession of a special electronic message called a token. The token is passed from node to node, allowing each an opportunity to transmit without interference. Tokens usually have a time limit to prevent a single node from tying up the token for a long period of time.Protocol: Network protocols define the way messages are arranged and coded for transmission on the LAN. The following are two common types.Proprietary protocols are unique message arrangements and coding developed by a specific vendor for use with that vendor's product only.Open protocols are based on industry standards such as TCP/IP or ISO/OSI。