关于PLC的毕业设计外文翻译

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。

毕业设计论文外文文献翻译基于PLC双电源开关设计外文翻译中英文对照英文题目 Based on PLC dual power switch design 中文题目基于PLC双电源开关设计系 (院) 自动化系专业电气自动化技术滨州学院专科毕业设计(外文翻译)Intelligent double power1 Intelligent dual power supply switching technologyIn this paper, the double load - dual power automatic switching of PLC control, PLC control program to replace relay logic control circuits, it has the three-phase power supply phase detection and protection switching function, power returned to normal after the automatic reverse switch, when a fault and restore normal respectively sends out two difference clear alarm and prompt sound. Double load - dual power automatic switching control of PLC, the open-phase protection mainly adopts the technical proposal that : setting the three-phase open-phase detection signal circuit, the three-phase open-phase detection signal circuit directly from the main circuit of three-phase power supply, namely the intermediate relay KA1-KA3 and KA4-KA6, respectively connected to power supply main loop U1 and U2 A, B and C single phase circuit, KA1-KA3 and KA4-KA6 normally open contacts respectively as PLCinput signal, namely as the preparation of PLC U1 and U2 three-phase open-phase detection logic control program input conditions. With short phase protection double load - dual power automatic switching control, not only has the open-phase protection, but also has a short circuit and overload protection, under-voltage protection function; automatic phase lack detection, three-phase current display, a road power supply circuit can automatically switch to another power source to load power supply, light and sound alarm; in the power supply return to normal after automatic reverse switch; in the event of a failure and return to normal when respectively sends out two difference obvious alarm and prompt sound effects. It overcomes the shortcomings of low double power supply switching control system without phase protection, can automatically reverse switch, as well as fault and return to normal when using asingle audio prompts defects. The control system has perfect function, reliable performance, simple circuit structure, low manufacturing cost etc...2 Intelligent dual power supplies switching main circuit controlWith short phase protection double load - dual power automatic switching control circuit. It includes a main circuit and three-phase short signal detecting sampling circuit. The main circuit of the input power supply power supply U1 and U2, its output has two2滨州学院专科毕业设计(外文翻译)loads W1 and W2. Power main circuit of AC contactor U1 through KM1 main contacts and a load of W1 connected; power supply U2 main circuit through the AC contactor KM2 main contacts and a load of W2 connected; under the control of a control circuit, a power failure occurs, the AC contactor lost the first electrically disconnected, so that the load of detachment faults power supply circuit, the AC contactor KM3 main contact closing conduction contact loop, will be connected to the fault loop load switch automatically to another normal power supply continues to supply. Power supply U1 and U2 main circuit input end of the automatic switch in QF1 and QF2 is the primary role of overload protection and short-circuit protection; two phase power supply main loop in each phase are current meter to indicate the phase current status, with the control circuit of phase lack detection. The three-phase open-phase detection signal sampling circuit, the phase detection signal directly from the main circuit of three-phase power supply, namely the intermediate relay KA1 ~ KA3KA4 ~ KA6 are respectively connected to the power supply main loop U1 and U2 A, B phase and C phase of the single-phase circuit, KA1 ~ KA3 and KA4 ~ KA6 normally open contact as U1 and U2 three-phase open-phase detection switch sampling signal, to the PLC input terminal. Considering the PLC relay output point load capacity, through the contactor KM01 ~ KM03 to drive high current contactor KM1 ~ KM3.For three-phase power U1 A, B phase and C phase lack detection, the use of an intermediate relay KA1, KA2 and KA3, respectively connected topower the U1 main circuit A, B phase and C phase and zero line N constitute a single-phase circuit, the formation of A1, B1 and C1 phase detection circuit. The normally open contact of KA1 ~ KA3 as U1 three-phase.Phase lack detection switch sampling signal, to the PLC input terminal, used in the preparation of PLC U1 three-phase open-phase detection logic control program input conditions; similarly, the three-phase power supply U2 A, B phase and C phase lack detection, but also the use of an intermediate relay KA4, KA5 and KA6, respectively connected to power the U2 main circuit A2, B2 phase and C2 phase and zero line N constitute a single-phase circuit, the formation of A2, B2 and C2 three-phase open-phase detection circuit. KA4 ~ KA6 normally open contacts respectively as U2 three-phase open-phase detection switch sampling signal, to the PLC input terminal, used in the3滨州学院专科毕业设计(外文翻译)preparation of PLC U2 three-phase open-phase detection logic control program input conditions.3 With PLC intelligent dual power controlThe three-phase open-phase detection signal sampling circuit, as U1 and U2 three-phase open-phase detection switch sampling signals of KA1-KA3 and KA4-KA6, the normally open contacts respectively for the input of the PLC X0-X2, X3-X5. In the PLC ladder diagram program, auxiliary relay R1 as the three-phase power supply of U1 three-phase open-phasedetection, which is normally open input conditions for X0, X1 and X2" and" logic; similarly, internal intermediate relay R2 as the three-phase power supply of U2 three-phase open-phase detection, it’s on conditions for the normally open input X3, X4 and X5" and" logic.In automatic switching control process, PLC ladder diagram procedure of auxiliary relay R1 and R2 respectively controlled AC contactor KM1 ( Y0 ) and KM2 ( Y1 ) coil and electric state, directly reflects two three-phase power supply U1 and U2 respectively the total phase condition, namely, either U1 or U2 three-phase power supply phase, KM1 ( Y0 ) or KM2 ( Y1 ) will immediately loses electricity, the normally closed contact of the alternating current contactor closed KM3 ( Y2 ) control coil gets electricity to attract, through the KM3 main contacts closed conduction contact loop, will be connected to the fault circuit load W1 or W2 automatically switches to a normal power supply U2 or U1 to power supply, so as to realize open-phase protection automatic switching. In automatic switching control process, auxiliary relay R1 and R2 main function is: when troubleshooting, three-phase power U1 orU2 recover the normal power supply, R1 (or R2) have electricity, the normally closed contact action, R3 reset, cut KM3 (Y2), then KM1 (Y0) or KM1 (Y1) complex have electricity, thereby automatically reverse switching back to the power supply to load W1 U1, U2 W2 power supply to load the normal power supply state.The control circuit adopts electric whistle (or buzzer) as an alarm sound (at) the same time with the red signal (at the same time with thered signal lamp), and returned to normal when the bell HA as prompt sound. Can produce two distinct alarms and prompt sound effects.4滨州学院专科毕业设计(外文翻译)智能双电源1 智能双电源切换的技术方案本文所述的双负载—双电源自动切换的PLC控制,用PLC控制程序取代继电器逻辑控制电路,其具有对三相供电电源的缺相检测及保护切换功能,在电源恢复正常后能自动进行反切换,当发生故障和恢复正常时能分别发出两种区别明显的报警和提双负载—双电源自动切换的PLC控制,其缺相保护主要采取的技术方案是:示音响。

Programmable logic controllerA programmable logic controller (PLC) or programmable controller is a digital computer used for automation of electromechanical processes,such as control of machinery on factory assembly lines, amusement rides, or lighting fixtures. PLCs are used in many industries and machines. Unlike general-purpose computers, the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in battery-backed or non-volatile memory. A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time, otherwise unintended operation will result.1.HistoryThe PLC was invented in response to the needs of the American automotive manufacturing industry. Programmable logic controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed.Before the PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays, cam timers, and drum sequencers and dedicated closed-loop controllers. The process for updating such facilities for the yearly model change-over was very time consuming and expensive, as electricians needed to individually rewire each and every relay.In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems. The winning proposal came from Bedford Associates of Bedford, Massachusetts. The first PLC, designated the 084 because it was Bedford Associates' eighty-fourth project, was the result. Bedford Associates started a new company dedicated to developing, manufacturing, selling, and servicing this new product: Modicon, which stood for MOdular DIgital CONtroller. One of the people who worked on that project was Dick Morley, who is considered to be the "father" of the PLC. The Modicon brand was sold in 1977 to Gould Electronics, and later acquired by German Company AEG and then by French Schneider Electric, the current owner.One of the very first 084 models built is now on display at Modicon's headquarters in North Andover, Massachusetts. It was presented to Modicon by GM, when the unit was retired after nearly twenty years of uninterrupted service. Modicon used the 84 moniker at the end of its product range until the 984 made its appearance.The automotive industry is still one of the largest users of PLCs.2.DevelopmentEarly PLCs were designed to replace relay logic systems. These PLCs were programmed in "ladder logic", which strongly resembles a schematic diagram of relay logic. This program notation was chosen to reduce training demands for the existing technicians. Other early PLCs used a form of instruction list programming, based on a stack-based logic solver.Modern PLCs can be programmed in a variety of ways, from ladder logic to more traditional programming languages such as BASIC and C. Another method is State Logic, a very high-level programming language designed to program PLCs based on state transition diagrams.Many early PLCs did not have accompanying programming terminals that were capable of graphical representation of the logic, and so the logic was instead represented as a series of logic expressions in some version of Boolean format, similar to Boolean algebra. As programming terminals evolved, it became more common for ladder logic to be used, for the aforementioned reasons. Newer formats such as State Logic and Function Block (which is similar to the way logic is depicted when using digital integrated logic circuits) exist, but they are still not as popular as ladder logic. A primary reason for this is that PLCs solve the logic in a predictable and repeating sequence, and ladder logic allows the programmer (the person writing the logic) to see any issues with the timing of the logic sequence more easily than would be possible in other formats.2.1ProgrammingEarly PLCs, up to the mid-1980s, were programmed using proprietary programming panels or special-purpose programming terminals, which often had dedicated function keys representing the various logical elements of PLC programs. Programs were stored on cassette tape cartridges. Facilities for printing and documentation were very minimal due to lack of memory capacity. The very oldest PLCs used non-volatile magnetic core memory.More recently, PLCs are programmed using application software on personal computers. The computer is connected to the PLC through Ethernet, RS-232, RS-485 or RS-422 cabling. The programming software allows entry and editing of the ladderstyle logic. Generally the software provides functions for debugging and troubleshooting the PLC software, for example, by highlighting portions of the logic to show current status during operation or via simulation. The software will upload and download the PLC program, for backup and restoration purposes. In some models of programmable controller, the program is transferred from a personal computer to the PLC though a programming board which writes the program into a removable chip such as an EEPROM or EPROM.3.FunctionalityThe functionality of the PLC has evolved over the years to include sequential relay control, motion control, process control, distributed control systems and networking. The data handling, storage, processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers. PLC-like programming combined with remote I/O hardware, allow a general-purpose desktop computer to overlap some PLCs in certain applications. Regarding the practicality of these desktop computer based logic controllers, it is important to note that they have not been generally accepted in heavy industry because the desktop computers run on less stable operating systems than do PLCs, and because the desktop computer hardware is typically not designed to the same levels of tolerance to temperature, humidity, vibration, and longevity as the processors used in PLCs. In addition to the hardware limitations of desktop based logic, operating systems such as Windows do not lend themselves to deterministic logic execution, with the result that the logic may not always respond to changes in logic state or input status with the extreme consistency in timing as is expected from PLCs. Still, such desktop logic applications find use in less critical situations, such as laboratory automation and use in small facilities where the application is less demanding and critical, because they are generally much less expensive than PLCs.In more recent years, small products called PLRs (programmable logic relays), and also by similar names, have become more common and accepted. These are very much like PLCs, and are used in light industry where only a few points of I/O (i.e. a few signals coming in from the real world and a few going out) are involved, and low cost is desired. These small devices are typically made in a common physical size and shape by several manufacturers, and branded by the makers of larger PLCs to fill out their low end product range. Popular names include PICO Controller, NANO PLC, and other names implying very small controllers. Most of these have between 8 and 12 digital inputs, 4 and 8 digital outputs, and up to 2 analog inputs. Size is usually about 4" wide, 3" high, and 3" deep. Most such devices include a tiny postage stamp sized LCD screen for viewing simplified ladder logic (only a very small portion of the program being visible at a given time) and status of I/O points, and typically these screens are accompanied by a 4-way rocker push-button plus four more separate pushbuttons, similar to the key buttons on a VCR remote control, and used to navigate and edit the logic. Most have a small plug for connecting via RS-232 or RS-485 to a personal computer so that programmers can use simple Windows applications for programming instead of being forced to use the tiny LCD and push-button set for this purpose. Unlike regular PLCs that are usuallymodular and greatly expandable, the PLRs are usually not modular or expandable, but their price can be two orders of magnitude less than a PLC and they still offer robust design and deterministic execution of the logic.4.PLC Topics4.1.FeaturesThe main difference from other computers is that PLCs are armored for severe conditions (such as dust, moisture, heat, cold) and have the facility for extensive input/output (I/O) arrangements.These connect the PLC to sensors and actuators. PLCs read limit switches, analog process variables (such as temperature and pressure), and the positions of complex positioning systems. Some use machine vision. On the actuator side, PLCs operate electric motors, pneumatic or hydraulic cylinders, magnetic relays, solenoids, or analog outputs. The input/output arrangements may be built into a simple PLC, or the PLC may have external I/O modules attached to a computer network that plugs into the PLC.4.2System scaleA small PLC will have a fixed number of connections built in for inputs and outputs. Typically, expansions are available if the base model has insufficient I/O. Modular PLCs have a chassis (also called a rack) into which are placed modules with different functions. The processor and selection of I/O modules is customised for the particular application. Several racks can be administered by a single processor, and may have thousands of inputs and outputs. A special high speed serial I/O link is used so that racks can be distributed away from the processor, reducing the wiring costs for large plants.4.3User interfacePLCs may need to interact with people for the purpose of configuration, alarm reporting or everyday control.A simple system may use buttons and lights to interact with the user. Text displays are available as well as graphical touch screens. More complex systems use a programming and monitoring software installed on a computer, with the PLC connected via a communication interface.4.4CommunicationsPLCs have built in communications ports, usually 9-pin RS-232, but optionally EIA-485 or Ethernet. Modbus, BACnet or DF1 is usually included as one of the communications protocols. Other options include various fieldbuses such as DeviceNet or Profibus. Other communications protocols that may be used are listed in the List of automation protocols.Most modern PLCs can communicate over a network to some other system, such as acomputer running a SCADA (Supervisory Control And Data Acquisition) system or web browser.PLCs used in larger I/O systems may have peer-to-peer (P2P) communication between processors. This allows separate parts of a complex process to have individual control while allowing the subsystems to co-ordinate over the communication link. These communication links are also often used for HMI devices such as keypads or PC-type workstations.4.5ProgrammingPLC programs are typically written in a special application on a personal computer, then downloaded by a direct-connection cable or over a network to the PLC. The program is stored in the PLC either in battery-backed-up RAM or some other nonvolatile flash memory. Often, a single PLC can be programmed to replace thousands of relays.Under the IEC 61131-3 standard, PLCs can be programmed using standards-based programming languages. A graphical programming notation called Sequential Function Charts is available on certain programmable controllers. Initially most PLCs utilized Ladder Logic Diagram Programming, a model which emulated electromechanical control panel devices (such as the contact and coils of relays) which PLCs replaced. This model remains common today.IEC 61131-3 currently defines five programming languages for programmable control systems: FBD (Function block diagram), LD (Ladder diagram), ST (Structured text, similar to the Pascal programming language), IL (Instruction list, similar to assembly language) and SFC (Sequential function chart). These techniques emphasize logical organization of operations.While the fundamental concepts of PLC programming are common to all manufacturers, differences in I/O addressing, memory organization and instruction sets mean that PLC programs are never perfectly interchangeable between different makers. Even within the same product line of a single manufacturer, different models may not be directly compatible.5.PLC compared with other control systemsPLCs are well-adapted to a range of automation tasks. These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation, and where changesto the system would be expected during its operational life. PLCs contain input and output devices compatible with industrial pilot devices and controls; little electrical design is required, and the design problem centers on expressing the desired sequence of operations. PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design. On the other hand, in thecase of mass-produced goods, customized control systems are economic due to the lower cost of the components, which can be optimally chosen instead of a "generic" solution, and where the non-recurring engineering charges are spread over thousands or millions of units.For high volume or very simple fixed automation tasks, different techniques are used. For example, a consumer dishwasher would be controlled by an electromechanical cam timer costing only a few dollars in production quantities.A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies, input/output hardware and necessary testing and certification) can be spread over many sales, and where the end-user would not need to alter the control. Automotive applications are an example; millions of units are built each year, and very few endusers alter the programming of these controllers. However, some specialty vehicles such as transit busseseconomically use PLCs instead of custom-designedcontrols, because the volumes are low and the development cost would be uneconomic.Very complex process control, such as used in the chemical industry, may require algorithms and performance beyond the capability of even high-performance PLCs. Very high-speed or precision controls may also require customized solutions; forexample, aircraft flight controls.Programmable controllers are widely used in motion control, positioning control and torque control. Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements.PLCs may include logic for single-variable feedback analog control loop, a "proportional, integral, derivative" or "PID controller". A PID loop could be used to control the temperature of a manufacturing process, for example. Historically PLCs were usually configured with only a few analog control loops; where processes required hundreds or thousands of loops, a distributed control system (DCS) would instead be used. As PLCs have become more powerful, the boundary between DCS and PLC applications has become less distinct.PLCs have similar functionality as Remote Terminal Units. An RTU, however, usually does not support control algorithms or control loops. As hardware rapidly becomes more powerful and cheaper, RTUs, PLCs and DCSs are increasingly beginning to overlap in responsibilities, and many vendors sell RTUs with PLC-like features and vice versa. The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTUs and PLCs, although nearly all vendors also offer proprietary alternatives and associated development environments.6.Digital and analog signalsDigital or discrete signals behave as binary switches, yielding simply an On or Off signal (1 or 0, True or False, respectively). Push buttons, limit switches, and photoelectric sensors are examples of devices providing a discrete signal. Discrete signals are sent using either voltage or current, where a specific range is designated as On and another as Off. For example, a PLC might use 24 V DC I/O, with values above 22 V DC representing On, values below 2VDC representing Off, and intermediate values undefined. Initially, PLCs had only discrete I/O.Analog signals are like volume controls, with a range of values between zero and full-scale. These are typically interpreted as integer values (counts) by the PLC, with various ranges of accuracy depending on the device and the number of bits available to store the data. As PLCs typically use 16-bit signed binary processors, the integer values are limited between -32,768 and +32,767. Pressure, temperature, flow, and weight are often representedby analog signals. Analog signals can use voltage or current with a magnitude proportional to the value of the process signal. For example, an analog 0 - 10 V input or 4-20 mA would be converted into an integer value of 0 - 32767.。

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。

外文翻译：The monolithic In order to prevent without authorization the visit or the copy monolithic integrated circuit machine in the procedure, the majority of monolithic integrated circuits all has the encryption to lock the localization or the encryption byte, by protects the internal procedure. If in programming time encrypts locks the localization to enable (locking), is unable with the ordinary programming directly reading in the monolithic integrated circuit the procedure, this is the so-called copy protection or says the fixed function. In fact, such protective measures are very frail, is very easily explained. The monolithic integrated circuit aggressor with the aid of the special purpose equipment or the self-made equipment, using the monolithic integrated circuit chip design in loophole or the software flaw, through the many kinds of technical method, may withdraw the essential information from the chip, gains in the monolithic integrated circuit the procedure. Therefore, has the newest technology extremely as electronic products project engineer which the essential understanding current monolithic integrated circuit attacks, achieves knows oneself and the other side, knows fairly well, can effectively prevent oneself spends the product which the massive moneys and the time laboriously designs the matter occurrence which is counterfeited by a others night between.monolithic integrated circuits attacks technology：At present, attacks the monolithic integrated circuit mainly to have four kind of technologies, respectively is:This technical usual use processor correspondence connection and in the use agreement, the encryption algorithm or these algorithm security loophole carries on the attack. The software attack obtains the success a case in point is to early A T M E L A the T 89 C series monolithic integrated circuit attack. The aggressor has used in this series monolithic integrated circuit cleaning operation succession design loophole, uses from arranges the procedure to lock the localization after the cleaning encryption, stops the next step of cleaning internal program memory data the operation, thus makes to add the dense monolithic integrated circuit not to turn the encryption monolithic integrated circuit, then use programming read-out internal procedure.This technology usually monitors the processor by the high time resolution when the normal operation all power sources and the connection connection simulation characteristic, and through monitors its electromagnetic radiation characteristic to implement the attack. Because the monolithic integrated circuit is an active electronic device, when it carries out the different instruction, the corresponding mains input consumption also correspondingly changes. Like this analyzes and examines these changes through the use special electronic surveying instrument and mathematics statistical method, then gains in the monolithic integrated circuit the specific essential information.the mistake has the technology This technical use exceptionally working condition causes the processor to make a mistake, then provides the extra visit to carry on the attack. Uses the most widespread mistake to have the attack method including the voltage impact and the clock impact. The low voltage and the high voltage attack may usefor to forbid the protection circuit work or to fortected the information. The power source and the clock transient state jump may affect the single scroll instruction in certain processors the decoding and the ece the processor to carry out the misoperation. Perhaps the clock transient state jump can reposition the protection circuit but not to be able to destroy is proxecution.This technology is the direct exposed chip interior segment, then the observation, holds controls, disturbs the monolithic integrated circuit by to achieve the attack goal.In order to facilitate in order to, the people divide into above four kind of attacks technology two kinds, a kind is the invasion attack (physical attack), this kind of attack needs to destroy the seal, then with the aid of the semiconductor test facility, the microscope and the micro locator, several hours even several week time can complete on the special laboratory flower. All micro probes technology all belongs to the invasion attack. Moreover three methods belong to the non- invasion attack, the monolithic integrated circuit which attacks cannot by the physical damage. In certain situation non- invasion attacks is specially dangerous, this is because the non- invasion attack needs the equipment usually to be possible the self-restraint and the promotion, therefore is extremely inexpensive.The majority of non- invasions attack needs the aggressor to have the good processor knowledge and the software knowledge. Is opposite with it, the invasion probe attack then does not need too many initial knowledge,moreover usually may use the one whole set similar technology to cope with the width scope the product. Therefore, the attack often starts to the monolithic integrated circuit from the invasion reverse engineering, the accumulation experience is helpful to the development more inexpensive and the fast non- invasion attack technology.Last step will be seeks the protection melt silk the position and protects the melt silk to expose under the ultraviolet ray. With enlargement factor at least 100 time of microscopes, inputs the foot from the programming voltage the segment to track generally, seeks the protection melt silk.This technical use exceptionally working condition causes the processor to make a mistake, then provides the extra visit to carry on the attack. Uses the most widespread mistake to have the attack method including the voltage impact and the clock impact. The low voltage and the high voltage attack may use for to forbid the protection circuit work or to force the processor to carry out the misoperation. Perhaps the clock transient state jump can reposition the protection circuit but not to be able to destroy is protected the information. The power source and the clock transient state jump may affect the single scroll instruction in certain processors the decoding and the execution.(4) probe technologyThis technology is the direct exposed chip interior segment, then the observation, holds controls, disturbs the monolithic integrated circuit by to achieve the attack goal.In order to facilitate in order to, the people divide into above four kindof attacks technology two kinds, a kind is the invasion attack (physical attack), this kind of attack needs to destroy the seal, then with the aid of the semiconductor test facility, the microscope and the micro locator, several hours even several week time can complete on the special laboratory flower. All micro probes technology all belongs to the invasion attack. Moreover three methods belong to the non- invasion attack, the monolithic integrated circuit which attacks cannot by the physical damage. In certain situation non- invasion attacks is specially dangerous, this is because the non- invasion attack needs the equipment usually to be possible the self-restraint and the promotion, therefore is extremely inexpensive.The majority of non- invasions attack needs the aggressor to have the good processor knowledge and the software knowledge. Is opposite with it, the invasion probe attack then does not need too many initial knowledge,moreover usually may use the one whole set similar technology to cope with the width scope the product. Therefore, the attack often starts to the monolithic integrated circuit from the invasion reverse engineering, the accumulation experience is helpful to the development more inexpensive and the fast non- invasion attack technology.3 invasions attacks general process：The invasion attack first step uncovers the chip seal. Some two methods may achieve this goal: The first kind is dissolves the chip seal completely, the exposed metal segment. The second kind is only moves above the silicon nucleus plastic seal. The first method needs the chip to tests on the jig, with the aid of Taiwan to operate. The second method except needs to have the aggressor certain knowledge and Wants outside skill, but also needs individual wisdom and the patience, but operates relatively quite is convenient.Above the chip plastic may use the knife to open, around the chip epoxy resin may use the aqua fortis perish. The hot aqua fortis can dissolve the chip seal but not to be able to affect the chip and the segment. This process carries on generally under the extremely dry condition, because the water existence possibly can corrode already the aluminum wire connection which exposes.Then first uses the acetone in the supersonic pond to clean this chip by except the remaining nitric acid, then cleans with the clear water by and is dry except the salinity. Not the supersonic pond, jumps over generally this step. In this kind of situation, the chip surface can a little dirty, but not too affects the ultraviolet ray to the chip operation effect.Last step will be seeks the protection melt silk the position and protects the melt silk to expose under the ultraviolet ray. With enlargement factor at least 100 time of microscopes, inputs the foot from the programming voltage the segment to track generally, seeks the protection melt silk.If does not have the microscope, then uses the chip different partially exposes to the ultraviolet ray under and the observed result way carries on the simple search. When operation applies not the opaque slip of paper cover chipby to protect the program memory not by the ultraviolet ray cleaning. Will protect the melt silk to expose in the ultraviolet ray next 5 ~ 10 minutes can broken the protection position protective function, afterwards, will use the simple programming to be possible the direct readout program memory content.Regarding used the protective layer to protect E E P R O the M unit the monolithic integrated circuit to say that, the use ultraviolet ray repositioned the protection circuit is not feasible. Regarding this kind of type monolithic integrated circuit, uses the micro probe technology reading the memory content generally. Opens after the chip seal, puts in the chip under the microscope to be able very easy finding中文翻译单片机为了防止未经授权访问或拷贝单片机的机内程序，大部分单片机都带有加密锁定位或者加密字节，以保护片内程序。

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。

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。

The PLC : New Technology,Greater Data SharingⅠ Introduction to Programmable ControllersIt's always good to get an overview of where designs have been and were they are going. To do this it's essential to get a bird's eye view of the concepts and processes that make the PLC so valuable in industrial control. Pitting PLCs against other control types will also serve to show the pros and cons for different applications.⒈ Definition of a PLC1.1 What is a PLC?A Programmable Logic Controller, or PLC for short, is simply a special computer device used for industrial control systems. They are used in many industries such as oil refineries, manufacturing lines, conveyor systems and so on. Where ever there is a need to control devices the PLC provides a flexible way to "softwire" the components together.Concretely speaking, Programmable Logic Controllers (PLC) continue to evolve as new technologies are added to their capabilities. The PLC started out as a replacement for banks of relays. Gradually, various math and logic manipulation functions were added. Today they are the brains of the vast majority of automation, processes and special machines. PLCs now incorporate smaller cases, faster CPUs, networking and various internet technologies.The basic units have a CPU (a computer processor) that is dedicated to run one program that monitors a series of different inputs and logically manipulates the outputs for the desired control. They are meant to be very flexible in how they can be programmed while also providing the advantages of high reliability (no program crashes or mechanical failures), compact and economical over traditional control systems.You can think of PLC technology as a small industrialized computer that has been highly specialized for reliability in the factory environment. At its core, a PLC looks at digital and analog sensors and switches (inputs), reads its control program, makes mathematical calculations and as a result controls various hardware (outputs) such as valves, lights, relays, servo motors, etc. in a time frame of milliseconds.While PLCs were very good at quickly controlling automation, they did not share data easily. At best, PLCs would exchange information with operator interfaces (HMI) and Supervisory Control and Data Acquisition (SCADA) software packages on the factory floor. Any data exchange with the Business Level of the company (information services, scheduling, accounting and analysis systems) had to be collected, converted and relayed through a SCADA package.Typical of most PLCs, the communication networks were unique to the brand and limited in speed. With the acceptance of Ethernet, communication network speeds have increased but are still sometimes using proprietary protocols.1.2 A Simple ExampleConsider something as simple as a switch that turns on a light. In this system with a flick of the switch the light would turn on or off. Beyond that though there is no more control. If your boss came along and said I want that light to turn on thirty seconds after the switch has been flipped, then you would need to buy a timer and do some rewiring. So it is time, labor and money for any little change.1.3 A PLC Saves the DayNow consider the same device with a PLC in the middle. The switch is fed as an input into the PLC and the light is controlled by a PLC output. Implementing a delay in this system is easy since all that needs to be changed is the program in the PLC to use a delay timer.This is a rather simple example but in a larger system with many switchs and lights (and a host of other devices) all interacting with each other this kind of flexibility is not only nice but imperitive. Hopefully a light bulb has now turned on over your head.⒉ The Birth of the PLC2.1 The Original ChallengeThe early history of the PLC is fascinating. Imagine if you will a fifty foot long cabinet filled with relays whose function in life is to control a machine. Wires run in and out of the system as the relays click and clack to the logic. Now imagine there is a problem or a small design change and you have to figure it all out on paper and then shut down the machine, move some wires, add some relays, debug and do it all over again. Imagine the labor involved in the simplest of changes. This is the problem that faced the engineers at the Hydra-matic division of GM motors in the late 1960's. Fortunately for them the prospect of computer control was rapidly becoming a reality for large corporations as themselves. So in 1968 the GM engineers developed a design criteria for a "standard machine controller". This early model simply had to replace relays but it also had to be: ∙ A solid-state system that was flexible like a computer but priced competitively with a like kind relay logic system.∙Easily maintained and programmed in line with the all ready accepted relay ladder logic way of doing things.∙It had to work in an industrial environment with all it's dirt, moisture, electromagnetism and vibration.∙It had to be modular in form to allow for easy exchange of components and expandability.2.2 The Race is OnThis was a tall order in 1968 but four companies took on the challenge.∙Information Instruments, Inc. (fully owned by Allen-Bradley a year later).∙Digital Equipment Corp. (DEC)∙Century Detroit∙Bedford AssociatesBedford Associates, run by Richard Morley, won the contract and quickly formed a new company around the technology called MODICON after Modular Digital Control. By June of 1969 they were selling the first viable Programmable Controller the "084" (their 84th project) which sold over one thousand units. These early experiences gave birth to their next model the "184" in 1973 which set Modicon as the early leader in programmable controllers.Not to be outdone, the powerhouse Allen-Bradley (all ready known for it's rheostats, relays and motor controls) purchased Information Instruments in 1969 and began development on this new technology. The early models (PDQ-II and PMC) were deemed to be too large and complex. By 1971 Odo Struger and Ernst Dummermuth had begun to develop a new concept known as the Bulletin 1774 PLC which would make them successful for years to come. Allen-Bradley termed their new device the "Programmable Logic Controller" (patent #3,942,158) over the then accepted term "Programmable Controller". The PLC terminology became the industry standard especially when PC became associated with personal computers.Ⅱ Number Systems and CodesAt the heart of any computer system are the numbering systems and digital codes used for instructions and memory storage. Besides the ones and zeros it is important to understand how these bits are packaged into codes like BCD and Gray codes. Understanding these concepts enables the programmer to manipulate the PLC at it's most basic level. Don't you want to feel the power at your fingertips!? Now for the most part these types of concepts will be transparent when programming but there will be occasions when you'll be glad you read this.When the cavemen first started counting they sat around looking at their fingers and stopped at ten. It took man a little longer to figure out the concept of zero but nobody is perfect. So we've ended up with a common way of counting by 10's which in tech jargon is refered to as base-10 or radix-10. Base or radix refers to the number of symbols you have available to count. We'll see that computers make it more difficult for us lazy humans because they like to count by base-2 (binary). In a compromise with computers us humans have developed the base-8 (octal) or base-16 (hexadecimal) systems.⒈ Binary People: Learning your 1's and 0's1.1 Introduce"There are 10 types of people in the world: Those who understand binary, and those who don't."If you don't get this joke then hopefully by the end of the chapter you'll get a chuckle out of it. You see, in the binary number system 10 = 2. How? Consider if you had no choice but to count with only a zero or a one. Pretend that the evil goblin of number snatchers had taken every number from two to nine. How would you count anything? You'd have to do it like 0, 1, 10, 11, 100, 101, 110, 111 and so on. You get the point? Therefore, if you had three apples then the third apple would be designated as 10 when in reality you only have three apples to eat.When it comes to computers and therefore PLCs they can only store in memory a 0 or a 1. That's the beauty of our digital age, it's either "on" or it's "off". Those memory chips in computers are actually made of rows upon rows of circuits that are either on at some voltage or off at some voltage. Therefore a computer at it's very basic level can only count using a 0 (off) or a 1 (on).That's why it's called binary because there are only two numbers like there are only two wheels on a bicycle. The number system we are used to using is called decimal (dec = 10) and therefore we get to use ten numbers from 0 to 9. When you think about it, it's truly arbitrary how we count. You could also use an octal system (by 8) or hexidecimal (by 16) numbering system which we'll talk about a little later.1.2 Base 10: An Old Familiar FriendLet's start off by looking closer at our all too familiar base 10 decimal system and then compare it to binary. Decimal, like all these other number systems, is based on place-value system. This means that the value of a digit depends both on the digit itself and it's position within the number. The following figure shows the weights of a decimal number broken down into columns.That much is obvious right? So with a number like 9876 we add it up like this:The value of the number is computed by multiplying each digit by the weight of its position and adding up the results.Remember that for a base 10 system the weights are 1, 10, 100, 1000 and so on. For a binary system the weights are 1, 2, 4, 8, 16, 32, 64, etcTo figure out the value of a binary system we do the same as with the decimal but withdifferent weights.1.3 Now for BinaryThe base of the number is usually expressed in a subscript so that in our examples 111112 = 3110 and 101012= 2110. It sure is a little cumbersome to count in binary but at least it's easier then Roman numerals.1.4 Word, Byte and BitWhat do you call a group of binary digits? The geeks who first thought this stuff up decided to call a binary digit a bit (b-inary dig-it). This is not to be confused with Tim-bits. After some time they decided that it would be good to call a group of 8 bits a byte. Funny bunch of geeks that they were the term nibble became used for 4 bits being a subset of byte. Finally, a group of 16 bits are referred to as a word. Here's a picture to drive home the point.Unless you're a glutton for punishment a standard scientific calculator switches between the different number formats with ease. In fact there's one built into the Windows operating system that typically lives under the Start button | All Programs | Accessories. Pull down the View menu and select "Scientific". I've highlighted the area below where you can switch between hexadecimal, decimal, octal and binary. Very handy even for doing math and logical functions (i.e. AND, OR, etc.).⒉ Octal? What the Hex?"Do not worry about your problems with mathematics, I assure you mine are far greater." --- Albert EinsteinYou're throbbing head is probably all ready telling you that binary numbers are not easy to read. As a compromise between humans and computers the octal (base 8) and hexadecimal (base 16) are used.2.1 OctalWhile octal is not as common as it's cousin hexadecimal it is still used in various PLCs so it's important to grasp the concept. For instance, when programming an AutomationDirect PLC the memory addresses are in octal. Octal, like an octopus' eight legs, means eight and therefore there are eight numbers to use from zero to seven. The column weights are 1, 8, 64, 512, etc. The weights are derived by taking the base number to the power of the column, 80=1, 81=8, 82=64, 83=512, etc. Now we can do the same exercise as in the last chapter to convert an octal number to decimal.I know this isn't helpful so far. Where it really comes in handy is coverting from binary to octal because all you have to do is break down the binary number into chunks of three. This is because 8 is 23.Most programmable controllers have inputs and output cards grouped in 8 or 16 (and high density of 32 and 64). The reason for this is the way computers like to have things in powers of 2, 4, 8, 16 and so on. So if it is not in octal it is typically in hexadecimal.2.2 HexadecimalHexadecimal is a little more tricky because it is base 16 and therefore we need something beyond 0 through 9 for symbols and this is done by using the letters 'A' through 'F'. Hexadecimal is used for the same reasons as octal so that we can represent binary in a condensed form and make it easier for conversion. Where octal used 3 bits the hexadecimal system used 4 bits to represent one number.If you're going to be programming something like a Mitsubishi PLC then you better get used to hexadecimal.2.3 Conclusionand so on and so on . . .⒊ When Being Negative is a ComplementLet's delve deeper into PLC programming by considering again our common word made of 16 bits. If it was all filled up with one's then the decimal value would be 65535. So a range from 0 to 65535 could be represented. Adding binary numbers together would be very similar to addition in d e c i m a l.F o r e x a m p l e0+1=1a n d1+1=10(c a r r y t h e o n e).The problem comes when you need to subtract. How do you represent a negative number when you can't just put a minus sign in front of it and say it's good? Remember that the computer can only do a 0 or a 1. To our rescue comes a concept called taking the plement's are a pretty cool trick and you can learn more about them at Wikipedia. We'll keep it simple here and talk about two's complement which is the most common in computers and PLCs.Signed binary numbers are achieved by stealing the 16th bit in a word (the most significant bit) a n d u s i n g t h a t a s a s i g n b i t w h e r e0i s p o s i t i v e a n d1i s n e g a t i v e.By doing this we have shifted the range of values from 0 to 65535 to -32767 to +32767. So the high end of our value is decreased but we've made it a whole lot easier to indicate a negative number and do subtraction. Here's how it works. Let's take a number like 30 and perform thetwo's complement to get -30.Maybe not what you would expect? The beauty of this is that now all the processor has to worry about is adding the two numbers to get the correct value. See how this magically works in the table below (I'm just going to use 8 bits now to simplify things but it works just the same with however many bits you want).For the most part this will all work seamlessly in the background while you program away. It's just that every once in a while you'll need this knowledge to overcome any limitations in the system. Dealing with negative numbers can be pretty tricky but with complements like this you better not let it go to your head.⒋ ASCII ... and ye shall receiveASCII is an acronym for American Standard Code for Information Interchange. You can see now why they shortened it down to ASCII which is pronounced as 'askey' by us geeks. This is the most common code for the exchange of letters and control characters between computers and their peripheral devices like printers. It is a standard that provides an easy way for the letters on our monitors to get into a binary format that a computer can understand. Thus it also finds its way into our everyday PLC lives in form of serial transmission to a display or printer.All the assigned ASCII codes can be represented with 7 bits. Remember from our binary chapter that 7 bits of binary represent 128 in decimal. Typical PLCs though have 8 bits of data and therefore the left over bit is used for parity checking just to make sure everything is transmitting correctly. The following chart shows all the assigned letters, numbers and control characters with the computer number on the left and the symbol on the right. Some of these look weird because this stuff goes way back to the days when you had to control teletypes and phone lines. These days I'm typically only concerned with 10 (line feed), 13 (carriage return) and 32 through 126.ASCII Chart in Word format available for download4.1 International CodesIn a lot of ways ASCII is very restrictive because the A stands for American and so it basically serves only English. Until recently the computer world has been trying to catch up to the many different languages in the world and the need for computers to be able to use them all. Thus there are many different character sets for other languages. The Alphabet Soup is a great resource to locate a language and it's corresponding character set. The real advance though has come with the advent of Unicode which is one standard representing all the languages of the world. Unicode has and will continue to supersede all these other types of alphanumeric codes because it simplifies the use of multiple languages. The list of possibilities is endless so if you ever need to program in Ugaritic then you got it.ⅢThe introduction for the Siemens’s PLCBenefits∙The S7-400F/FH largely consists of standard components and is an integral part of Totally Integrated Automation (TIA)；∙The S7-400F/FH is an integral part of Safety Integrated, the Siemens safety program for industrial.∙Applications∙The S7-400F/FH has a TÜV approval (TÜV = German Technical Inspectorate) and fulfils all relevant. StandardsHardware and engineering costs are reduced due to the fact that the fail-safe S7-400F/FH is largely built from standard components:∙There is no need for an additional F-CPU and the cabling to it；∙Engineering costs are lower because a standard CPU can be programmed normally instead of using an additional F-CPU；Programs from safety-related systems can also be adopted.CommunicationBoth safety-related and standard communication between the central controller and the safety-related and standard modules of the ET 200M go through PROFIBUS-DP. To achieve a fail-safe communication between each component, the PROFISafe profile is used. The PROFISafe profile is characterized by the fact that additional safety information is added to a standard data frame. This safety information is exchanged between the S7-400F/FH and the I/O only. No additional hardware components are required. This means that standard communications and safety-related communications use the same basic hardware - automation and fail-safety are getting closer together all the time!We hope eagerly that the essay is helpful to you, and we are able to provide more information about PLC and other industrial control equipment. We can promise that we will try our best to help you if you need us.可编程控制器：高新科技，强大数据共享一、可编程控制器的简介开展一项新的研究是要纵观其设计趋向于发展方向。

Programmable logic controllerA programmable logic controller (PLC) or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides， or lighting fixtures. PLCs are used in many industries and machines。

Unlike general—purpose computers，the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in battery—backed or non-volatile memory. A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time， otherwise unintended operation will result。

1。

HistoryThe PLC was invented in response to the needs of the American automotive manufacturing industry。

2012届毕业设计说明书外文文献院、部：电气与信息工程学院学生姓名：XX指导教师：XX 职称讲师专业：自动化班级：XX完成时间：XXProgrammable logic controllerA programmable logic controller (PLC) or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or lighting fixtures. PLCs are used in many industries and machines. Unlike general-purpose computers, the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in battery-backed or non-volatile memory. A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time, otherwise unintended operation will result.1 HistoryThe PLC was invented in response to the needs of the American automotive manufacturing industry. Programmable logic controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed.Before the PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays, cam timers, and drum sequencers and dedicated closed-loop controllers. The process for updating such facilities for the yearly model change-over was very time consuming and expensive, as electricians needed to individually rewire each and every relay.In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems. The winning proposal came from Bedford Associates of Bedford, Massachusetts. The first PLC, designated the 084 because it was Bedford Associates' eighty-fourth project, was the result. Bedford Associates started a new company dedicated to developing, manufacturing, selling, and servicing this new product: Modicon, which stood for MOdular DIgital CONtroller. One of the people who worked on that project was Dick Morley, who is considered to be the "father" of the PLC. The Modicon brand was sold in 1977 to Gould Electronics, and later acquiredby German Company AEG and then by French Schneider Electric, the current owner.One of the very first 084 models built is now on display at Modicon's headquarters in North Andover, Massachusetts. It was presented to Modicon by GM, when the unit was retired after nearly twenty years of uninterrupted service. Modicon used the 84 moniker at the end of its product range until the 984 made its appearance.The automotive industry is still one of the largest users of PLCs.2 DevelopmentEarly PLCs were designed to replace relay logic systems. These PLCs were programmed in "ladder logic", which strongly resembles a schematic diagram of relay logic. This program notation was chosen to reduce training demands for the existing technicians. Other early PLCs used a form of instruction list programming, based on a stack-based logic solver.Modern PLCs can be programmed in a variety of ways, from ladder logic to more traditional programming languages such as BASIC and C. Another method is State Logic, a very high-level programming language designed to program PLCs based on state transition diagrams.Many early PLCs did not have accompanying programming terminals that were capable of graphical representation of the logic, and so the logic was instead represented as a series of logic expressions in some version of Boolean format, similar to Boolean algebra. As programming terminals evolved, it became more common for ladder logic to be used, for the aforementioned reasons. Newer formats such as State Logic and Function Block (which is similar to the way logic is depicted when using digital integrated logic circuits) exist, but they are still not as popular as ladder logic.A primary reason for this is that PLCs solve the logic in a predictable and repeating sequence, and ladder logic allows the programmer (the person writing the logic) to see any issues with the timing of the logic sequence more easily than would be possible in other formats.2.1ProgrammingEarly PLCs, up to the mid-1980s, were programmed using proprietary programming panels or special-purpose programming terminals, which often had dedicated function keys representing the various logical elements of PLC programs. Programs were stored on cassette tape cartridges. Facilities for printing and documentation were very minimal due to lack of memory capacity. The very oldestPLCs used non-volatile magnetic core memory.More recently, PLCs are programmed using application software on personal computers. The computer is connected to the PLC through Ethernet, RS-232, RS-485 or RS-422 cabling. The programming software allows entry and editing of the ladder-style logic. Generally the software provides functions for debugging and troubleshooting the PLC software, for example, by highlighting portions of the logic to show current status during operation or via simulation. The software will upload and download the PLC program, for backup and restoration purposes. In some models of programmable controller, the program is transferred from a personal computer to the PLC though a programming board which writes the program into a removable chip such as an EEPROM or EPROM.3 FunctionalityThe functionality of the PLC has evolved over the years to include sequential relay control, motion control, process control, distributed control systems and networking. The data handling, storage, processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers. PLC-like programming combined with remote I/O hardware, allow a general-purpose desktop computer to overlap some PLCs in certain applications. Regarding the practicality of these desktop computer based logic controllers, it is important to note that they have not been generally accepted in heavy industry because the desktop computers run on less stable operating systems than do PLCs, and because the desktop computer hardware is typically not designed to the same levels of tolerance to temperature, humidity, vibration, and longevity as the processors used in PLCs. In addition to the hardware limitations of desktop based logic, operating systems such as Windows do not lend themselves to deterministic logic execution, with the result that the logic may not always respond to changes in logic state or input status with the extreme consistency in timing as is expected from PLCs. Still, such desktop logic applications find use in less critical situations, such as laboratory automation and use in small facilities where the application is less demanding and critical, because they are generally much less expensive than PLCs.In more recent years, small products called PLRs (programmable logic relays), and also by similar names, have become more common and accepted. These are very much like PLCs, and are used in light industry where only a few points of I/O (i.e. afew signals coming in from the real world and a few going out) are involved, and low cost is desired. These small devices are typically made in a common physical size and shape by several manufacturers, and branded by the makers of larger PLCs to fill out their low end product range. Popular names include PICO Controller, NANO PLC, and other names implying very small controllers. Most of these have between 8 and 12 digital inputs, 4 and 8 digital outputs, and up to 2 analog inputs. Size is usually about 4" wide, 3" high, and 3" deep. Most such devices include a tiny postage stamp sized LCD screen for viewing simplified ladder logic (only a very small portion of the program being visible at a given time) and status of I/O points, and typically these screens are accompanied by a 4-way rocker push-button plus four more separate push-buttons, similar to the key buttons on a VCR remote control, and used to navigate and edit the logic. Most have a small plug for connecting via RS-232 or RS-485 to a personal computer so that programmers can use simple Windows applications for programming instead of being forced to use the tiny LCD and push-button set for this purpose. Unlike regular PLCs that are usually modular and greatly expandable, the PLRs are usually not modular or expandable, but their price can be two orders of magnitude less than a PLC and they still offer robust design and deterministic execution of the logic.4 PLC Topics4.1 FeaturesThe main difference from other computers is that PLCs are armored for severe conditions (such as dust, moisture, heat, cold) and have the facility for extensive input/output (I/O) arrangements. These connect the PLC to sensors and actuators. PLCs read limit switches, analog process variables (such as temperature and pressure), and the positions of complex positioning systems. Some use machine vision. On the actuator side, PLCs operate electric motors, pneumatic or hydraulic cylinders, magnetic relays, solenoids, or analog outputs. The input/output arrangements may be built into a simple PLC, or the PLC may have external I/O modules attached to a computer network that plugs into the PLC.4.2 System scaleA small PLC will have a fixed number of connections built in for inputs and outputs. Typically, expansions are available if the base model has insufficient I/O.Modular PLCs have a chassis (also called a rack) into which are placed modules with different functions. The processor and selection of I/O modules is customised for the particular application. Several racks can be administered by a single processor, and may have thousands of inputs and outputs. A special high speed serial I/O link is used so that racks can be distributed away from the processor, reducing the wiring costs for large plants.4.3 User interfacePLCs may need to interact with people for the purpose of configuration, alarm reporting or everyday control.A simple system may use buttons and lights to interact with the user. Text displays are available as well as graphical touch screens. More complex systems use a programming and monitoring software installed on a computer, with the PLC connected via a communication interface.4.4 CommunicationsPLCs have built in communications ports, usually 9-pin RS-232, but optionally EIA-485 or Ethernet. Modbus, BACnet or DF1 is usually included as one of the communications protocols. Other options include various fieldbuses such as DeviceNet or Profibus. Other communications protocols that may be used are listed in the List of automation protocols.Most modern PLCs can communicate over a network to some other system, such as a computer running a SCADA (Supervisory Control And Data Acquisition) system or web browser.PLCs used in larger I/O systems may have peer-to-peer (P2P) communication between processors. This allows separate parts of a complex process to have individual control while allowing the subsystems to co-ordinate over the communication link. These communication links are also often used for HMI devices such as keypads or PC-type workstations.4.5ProgrammingPLC programs are typically written in a special application on a personal computer, then downloaded by a direct-connection cable or over a network to the PLC. The program is stored in the PLC either in battery-backed-up RAM or some othernon-volatile flash memory. Often, a single PLC can be programmed to replace thousands of relays.Under the IEC 61131-3 standard, PLCs can be programmed using standards-based programming languages. A graphical programming notation called Sequential Function Charts is available on certain programmable controllers. Initially most PLCs utilized Ladder Logic Diagram Programming, a model which emulated electromechanical control panel devices (such as the contact and coils of relays) which PLCs replaced. This model remains common today.IEC 61131-3 currently defines five programming languages for programmable control systems: FBD (Function block diagram), LD (Ladder diagram), ST (Structured text, similar to the Pascal programming language), IL (Instruction list, similar to assembly language) and SFC (Sequential function chart). These techniques emphasize logical organization of operations.While the fundamental concepts of PLC programming are common to all manufacturers, differences in I/O addressing, memory organization and instruction sets mean that PLC programs are never perfectly interchangeable between different makers. Even within the same product line of a single manufacturer, different models may not be directly compatible.5 PLC compared with other control systemsPLCs are well-adapted to a range of automation tasks. These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation, and where changes to the system would be expected during its operational life. PLCs contain input and output devices compatible with industrial pilot devices and controls; little electrical design is required, and the design problem centers on expressing the desired sequence of operations. PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design. On the other hand, in the case of mass-produced goods, customized control systems are economic due to the lower cost of the components, which can be optimally chosen instead of a "generic" solution, and where the non-recurring engineering charges are spread over thousands or millions of units.For high volume or very simple fixed automation tasks, different techniques are used. For example, a consumer dishwasher would be controlled by anelectromechanical cam timer costing only a few dollars in production quantities.A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies, input/output hardware and necessary testing and certification) can be spread over many sales, and where the end-user would not need to alter the control. Automotive applications are an example; millions of units are built each year, and very few end-users alter the programming of these controllers. However, some specialty vehicles such as transit busses economically use PLCs instead of custom-designed controls, because the volumes are low and the development cost would be uneconomic.Very complex process control, such as used in the chemical industry, may require algorithms and performance beyond the capability of even high-performance PLCs. Very high-speed or precision controls may also require customized solutions; for example, aircraft flight controls.Programmable controllers are widely used in motion control, positioning control and torque control. Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements.PLCs may include logic for single-variable feedback analog control loop, a "proportional, integral, derivative" or "PID controller". A PID loop could be used to control the temperature of a manufacturing process, for example. Historically PLCs were usually configured with only a few analog control loops; where processes required hundreds or thousands of loops, a distributed control system (DCS) would instead be used. As PLCs have become more powerful, the boundary between DCS and PLC applications has become less distinct.PLCs have similar functionality as Remote Terminal Units. An RTU, however, usually does not support control algorithms or control loops. As hardware rapidly becomes more powerful and cheaper, RTUs, PLCs and DCSs are increasingly beginning to overlap in responsibilities, and many vendors sell RTUs with PLC-like features and vice versa. The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTUs and PLCs, although nearly all vendors also offer proprietary alternatives and associated development environments.6 Digital and analog signalsDigital or discrete signals behave as binary switches, yielding simply an On or Off signal (1 or 0, True or False, respectively). Push buttons, limit switches, and photoelectric sensors are examples of devices providing a discrete signal. Discrete signals are sent using either voltage or current, where a specific range is designated as On and another as Off. For example, a PLC might use 24 V DC I/O, with values above 22 V DC representing On, values below 2VDC representing Off, and intermediate values undefined. Initially, PLCs had only discrete I/O.Analog signals are like volume controls, with a range of values between zero and full-scale. These are typically interpreted as integer values (counts) by the PLC, with various ranges of accuracy depending on the device and the number of bits available to store the data. As PLCs typically use 16-bit signed binary processors, the integer values are limited between -32,768 and +32,767. Pressure, temperature, flow, and weight are often represented by analog signals. Analog signals can use voltage or current with a magnitude proportional to the value of the process signal. For example, an analog 0 - 10 V input or 4-20 mA would be converted into an integer value of 0 - 32767.可编程逻辑控制器可编程逻辑控制器（PLC）或可编程序控制器是用于机电过程自动化的数字计算机，例如控制机械厂生产线、游乐设施或照明装置。

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。

S7-200 based modular training facilities opento experimental designPLCPLC (programmable logic controller) is a micro-controller core, the computer technology, automatic control technology; communication network together network technology is an advanced automatic control device. The current PLC has become the three major branch of modern industrial automation Column (PLC, robotics, CAD / CAM), widely used in various fields of automation and control systems, various types of enterprises Industry require a certain amount of practical experience with such talent. Thus, PLC application technology has become the industrial automation technology relevant professional technical personnel and university students to learn important lessons.Siemens SIMATIC S7-200 series are small PLC, its high price in the domestic market large market share, because of its flexible and powerful communication features and other special advanced features are increasingly the more widely used in automatic control systems [1]. Siemens Automation and Drives Group is currently actively cooperate with colleges and universities Siemens to build the establishment of training center for small-scale automation, Qingdao University is one of them. Siemens to provide similar training center S7-200 training-related equipment and software development. Teachers take advantage of this favorable experimental conditions, based on the design of these devices to open .Made a number of pilot projects PLC open, so that school has spare capacity, "enough" to further strengthen the PLC application technology student learning, Understand and operate the most advanced automation equipment, the initial grasp of advanced control technologies of industrial automation and control system design technology patients, improve their practical ability to achieve training objectives applicable talents to meet community needs for such technical personnel requirements.1 Modular S7-200 training equipmentPrinciple and Application of PLC technology tolearn and master the necessary hardware and softwaretest platform to support. Siemens automatic in myschool Group set up jointly with the driver of a smallautomated training centers, equipped with 10 sets oftraining equipment S7-200, diagram at right .Figure(painted on some of the expansion module) below. Thedevice is modular in design, the main module in additionto superior performance, cost-effective .Higher CPU224XP host, but also comes with text display TD400C,with special PT100 temperature transmitter, Heaters, fans,and other physical control object, basic literacy trainingto achieve most of experiments, people could beconducted. Siemens products for the rich functionmodule, consider the cost and other factors, with acertain number of functional modules, including EM231RTD temperature measurement module, EM253 positioncontrol module, EM241 Modem communication module, CP243-1 Ethernet communication module, EM277 Prefabs-DP module, SP series weighing Siwarex MS weighing module sensors and extension of six modules, connected by bus expansion unit to achieve the function of switch-free wiring, training, experiments can be used interchangeably. Also comes with HMI (Human Machine Interface) devices TP177B, OP177B, MP277, etc. A total of 10 touch-screens, hanging in the equipment rack can also be supported by a separate operation. Using the standard package of equipment S7-300 rail card installed, so that reliable and stable module is installed, and when necessary S7-300 modules can be very easy to experiment with the addition of any module S7-300, the S7-200 and S7-300 the installation of a common platform. This experimental equipment for teaching, training and scientific research has provided teachers, good hardware conditions.2 PLC open to experimental designPLC courses each semester due to class a lot, by the laboratory equipment, space and curriculum hours restrictions, generally Principle and Application of PLC programs created in the experiment mainly supporting the basic instruction to practice, sequential control, a simple digital V olume control system design, such as the marquee design, automatic round trip transportation movement control, intersection traffic lights model control, Three-tier model of control of the elevator, the part of the experiment content is based, compulsory. For the S7-200 special high-level utility function Energy-rich extension module and field communication function widely used implementation is rarely involved. Taking into account students Ability to accept differences and experimental conditions, this part of the experiment for the content best suited to open experiment [2] , That is, relative to teachers Laboratory equipment and related information, made experimental mission requirements, prepared by the students to self test program to determine the effective efficiency measurement experiment Ifthe method of thinking so that students have more room to stimulate the students enthusiasm and initiative, ability of students to engineering practice, Ability to innovate, analyze and solve problems Ability of great importance [3] . Therefore, the use of existing experimental design Equipment, and taking into account the students learn to master the knowledge structure, design and development of some pilot projects open.2.1 The main module design based on the opening experimentUse of the main module, in addition to the completion of some basic PLC programming experiment, we can also perform some special functions [4] Experiment, Also practiced Micro / Win programming environment integrated with a variety of programming guide, are:(1) The main module includes TD400C, it is a highly cost-effective dedicated S7-200 PLC's new generation of text Display, is a simple man-machine interface device, no special configuration of HMI software, the use of Micro / WIN V4.0 SP4 to On the version of Chinese language interface in the configuration wizard to TD [5] . The configuration opening in TD400C experiments, show the user through the configuration Menu, the alarm menu, and interact with S7-200 CPU, CPU storage area for data access and editing, enabling small Type of human-computer interaction function with the control system, such as basic experiments with automatic round trip transportation control program can be realized Through the control panel to control the car motion state, and in position to reach both ends of the alarm screen limit, while TD400C modify the car to stay at the ends of time, so that the experimental effect is more rich and vivid, but also to enable students to understand the master Production site using the actual control equipment.(2) High-speed counter, high-speed output, internal and external interrupts and other useful special features, through an open experiment Learn and master, such as the first high-speed output by PTO (pulse train) output, and achieve the high-speed counter High-speed output of the PTO HSC0 count, the interrupt function by repeated HSC0 count, a programming Adjust the PWM (pulse width modulation) high-speed output, the timer interrupt to implement a second counter, and the current count value, PWM output duty cycle and other related content displayed on the TD 400C.(3) The main module with the PT100 temperature transmitter will be converted from 0 to 100 degrees C 0 ~ 10V analog input received as Into the CPU, the heater, fan and other physical control objects connected to the digital output on the CPU can be realized on analog Data transformation, manual PID control programming, using the configuration wizard to complete the PID, PID parameter self-tuning function of the experiment, so that Students deeply understand and master the industrial field of analog PID control knowledge and implementation.(4)Two S7-200 series PLC via RS232 communication cable, you can use the PPI protocol to form a Single master station communication network, can be PPI point to point communication experiment, to achieve data exchange between the two PLC, such as the I0.0 ~ I0.7 master map to the slave state of the Q0.0 ~ Q0.7, from the station I0.0 ~ I0.7 of the state map to the main station Q0.0 ~ Q0.7, the network will allow students to experience the simple wizard to use reading and writing instruction, and extended through the formation of PPI networks can be implemented Control functions are more complex.(5) S7-200 CPU's communications port supports a free-port communication mode; you can use user-defined communication protocol implementation now with the computer or other device with a serial communication interface for communication. Here, simple and easy for students to use Visual Basic (VB) language PC program to realize S7-200 CPU PC with the free port communication mode between the experimental [6], Completed by the PLC field switching, analog control of processing, the host computer realization of the process parameters of the monitoring, analysis, Statistics and revision, to provide a good interface for easy monitoring.2.2 CP243-1 Ethernet module based on the open design of experimentsSiemens SIMATIC NET Industrial Ethernet is an open communication system on top, can manage and control network Integration, and even can be integrated into the Internet, for remote control and provides the conditions for global networking. S7-200 PLC with a CP243-1 Ethernet module or Internet CP243-1 IT module S7-200 can be connected to the Ethernet. In this, select are CP243-1 expansion module some experiments, through the Micro / WIN configuration of the Ethernet Wizard to complete the simple model Block configuration. Computer by installing the Ethernet card and Micro / WIN, can be realized via Ethernet S7-200 CPU Remote programming, configuration and diagnostics. In addition, the two are equipped with CP243-1 module S7-200 PLC, through the software programming and download the configuration program, can be realized through the network cable to connect two S7-200 PLC Ethernet-based data exchange. By This experiment allows students to commonly used industrial site between the S7-200 Ethernet communications have a clear understanding.2.3 touch screen design based on the opening experimentTD400C can only display text information, and requirements of many industrial control systems controlled object has a strong human-machine interface function can, through the meaning and message with a clear picture to the operator and control systems to achieve dialogue and interaction between Uses. Man-machine interface touch screen is the direction of development. Touch-screen devices using existing open experiment designed to allow students to learn as He through the configuration software WinCC Flexible configuration of the touch screen and transfer procedures [7] And the HMI and PLC data Exchange and data structures, such as students in the HMI configuration of traffic light system is running on a monitor screen or inside the elevator car operation For interface, combined with the preparation of the experiment based on the S7-200 signal-controlled crossroads of three elevator control procedures or procedures, Testing procedures can be performed correctly, but also to enable students to operate advanced equipment, and learn its configuration methods. In addition, to learn Students design a running effect of the controlled object interface, such as the movement of car transport materials, machinery and hand movement, etc., can make up for lab Less than the actual controlled object in the defect, this can greatly help students in the ability to innovate, improve and control system features a rich, Stimulate enthusiasm for learning and enthusiasm.Given above, S7-200 using the modular design of the part of the training facilitiesopens to experimental projects. Specialized courses as students learn The deepening of learning, knowledge, and plenty of time to increase reserves under the circumstances, but also in the graduation project will combine multiple modules Together to achieve a relatively complex system, such as the S7-300 CPU access system, with the S7-200 to achieve the Prefabs, MPI communications, the use of EM253 motion control position control module, servo motor and stepper motor control knowledge and understanding And control and so on.3 ConclusionsFull use of existing modular laboratory S7-200 training equipment, a large number of open research and development pilot project to enrich the real Test content, broaden the horizons of students, for students to learn deeply felt PLC interesting, learning PLC useful, while students mastered Industrial field is currently producing more with the typical products and the latest Siemens technology development and application of a comprehensive understanding of PLC control Technology, computer industry configuration control, touch screen control, networking, and automation control systems in real mutual penetration And added that practical ability of students to analyze and solve problems in the comprehensive capabilities have been greatly improved, more confident To face the fierce competition for jobs, it was widely welcomed by students.外文资料翻译基于模块化 S7-200 培训设备的 PLC 开放实验设计PLC（可编程序控制器）是以微控制器为核心，把计算机技术、自动控制技术、通信网络技术融合在一起的一种先进的自动控制装置。

plc类毕业设计范文English Response:Introduction.Programmable logic controllers (PLCs) are industrial computers used for automation control in various industries. PLC systems are designed to handle complex processes efficiently and reliably, making them essential for the smooth operation of modern industrial facilities. This graduation design project aims to develop a PLC-basedcontrol system for a specific industrial process, demonstrating the practical application of PLC technologyin a real-world scenario.System Design.The PLC system design involves selecting appropriate hardware components, configuring the PLC program, and establishing communication interfaces with other devices.The hardware components include a PLC unit, input/output modules, power supply, and necessary wiring. The PLC program is developed using ladder logic or a high-level programming language, defining the control logic fordesired system behavior. Communication interfaces enablethe PLC to exchange data with sensors, actuators, and other equipment via protocols such as Modbus or Ethernet.Process Simulation.To evaluate the effectiveness of the designed PLC system, a process simulation is conducted. This involves creating a virtual representation of the industrial process and connecting it to the PLC. The simulation allows for testing the control logic under various operating conditions, identifying potential issues, and fine-tuning the system's performance. The simulation results provide valuable insights into the system's reliability, efficiency, and response time.System Implementation.Once the design is validated through simulation, the PLC system is implemented in the actual industrial environment. This involves installing the hardware components, wiring the input/output devices, and downloading the PLC program. The system undergoes thorough testing and commissioning to ensure proper operation and compliance with safety standards. Maintenance procedures are established for regular troubleshooting and preventative maintenance tasks.Data Analysis and Optimization.The implemented PLC system generates valuable data that can be used for ongoing monitoring, analysis, and optimization. The collected data is stored in a database and analyzed using statistical techniques to identify patterns, trends, and potential areas for improvement. The analysis results are used to refine the control logic, adjust system parameters, and implement predictive maintenance strategies, maximizing system efficiency and reducing downtime.Conclusion.The PLC-based control system developed in this graduation design project demonstrates the successful application of PLC technology in industrial automation. The system effectively controls the industrial process,ensuring reliable and efficient operation. The simulation, implementation, and data analysis processes provide a comprehensive evaluation and optimization framework, enabling continuous improvement and enhanced system performance. The project showcases the practical skills and knowledge acquired in the PLC domain, providing a solid foundation for a successful career in industrial automation.中文回答：引言。

本科毕业设计（论文）外文翻译( 2017 届 )题目：关于xxx的PLC控制系统设计分院:电气工程与自动化学院专业:电气工程及其自动化班级:姓名:学号:指导老师:完成日期:2009年12月原文：Introductions to PLC and Intelligent ControlKatsuhiko OgataA PLC (i.e. Programmable Logic Controller)is a device that was invented to replace the necessary sequential relay circuits for machine control. The PLC works by looking at its inputs and depending upon their state, turning on/off its outputs. The user enters a program, usually via software or programmer, that gives the desired results.PLCs are used in many “real world” applications. If there is industry present, chances are good that there is a PLC present. If you are involved in machining, packaging, 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 wh en a switch turns on we want to turn a solenoid on for 5 seconds 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 would need 10 external timers. 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 inputs 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.That’s right, more than 80%! Of course we’ll learn more than just these instructions to help you solve almost ALL your potential PLC applications.The PLC mainly consists of a CPU, memory areas, and appropriate circuits to receive input/output data, as shown in Fig.1. We can actually consider the PLC to be a box full of hundreds or thousands of separate relays, counters, timers and data storage locations. Do these counters, timers, etc. really exist? No, they don’t “physically” ex ist but rather they are simulated and can be considered software counters, timers, etc. These internal relays are simulated through bit locations in registers.Fig.1 The structure of PLCWhat does each part do?INPUT RELAYS-(contacts) These are connected to the outside world. They physically exist and receive signals from switches, sensors, etc.. Typically they are not relays but rather they are transistors.INTERNAL UTILITY RELAYS-(contacts) These 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.COUNTERS-These 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 and down. Since they are simulated, they are limited in their counting speed. Some manufacturers also include high-speed counters that are hardware based. We can think of these as physically existing. Most times these counters can count up, down or up and down.TIMERS-These also do not physically exist. They come in many varieties and increments.The most common type is an on-delay type. Others include off-delay and both retentive and non-retentive types. Increments vary from 1ms through 1s.OUTPUT RELAYS-(coils) These 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 STORAGE-Typically 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 from the PLC. Upon power-up they will still have the same contents as before power was removed. 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, as shown in Fig.2. There are typically more than 3 but we can focus on the important parts andnot worry about the others. Typically the others are checking the system and updating the current internal counter and timer values.Fig.2 The work process of PLCStep 1-CHECK INPUT STATUS-First the PLC takes a look at each input to determine if it is on or off. In other words, is the sensor connected to the first input on? How about the second input? How about the third… It records this data into its memory to be used during the next step.Step 2-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. [3] It will store the execution results for use later during the next step.Step 3-UPDATE OUTPUT STATUS-Finally the PLC updates the status of the outputs. It updates the outputs based on which inputs were on during the first step and the results of executing your program during the second step. Based on the example in step 2 it would now turn on the first output 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 and repeats the 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.Intelligence and intelligent systems can be characterized in a number of ways and along a number of dimensions. There are certain attributes of intelligent systems, common in many definitions, which are of particular interest to the control community.In the following, several alternative definitions and certain essential characteristics of intelligent systems are first discussed. A brief working definition of intelligent systems that captures their common characteristics is then presented. In more detail, we start with a rather general definition of intelligent systems, we discusslevels of intelligence, and we explain the role of control in intelligent systems and outline several alternative definitions. We then discuss adaptation and learning, autonomy and the necessity for efficient computational structures in intelligent systems, to deal with complexity. We conclude with a brief working characterization of intelligent (control) systems.We start with a general characterization of intelligent systems:An intelligent system has the ability to act appropriately in an uncertain environment, where an appropriate action is that which increases the probability of success, and success is the achievement of behavioral subgoals that support the system’s ultimate goal.In order for a man-made intelligent system to act appropriately, it may emulate functions of living creatures and ultimately human mental faculties. An intelligent system can be characterized along a number of dimensions. There are degrees or levels of intelligence that can be measured along the various dimensions of intelligence. At a minimum, intelligence requires the ability to sense the environment, to make decisions and to control action. Higher levels of intelligence may include the ability to recognize objects and events, to represent knowledge in a world model, and to reason about and plan for the future. In advanced forms, intelligence provides the capacity to perceive and understand, to choose wisely, and to act successfully under a large variety of circumstances so as to survive and prosper in a complex and often hostile environment. Intelligence can be observed to grow and evolve, both through growth in computational power and through accumulation of knowledge of how to sense, decide and act in a complex and changing world.The above characterization of an intelligent system is rather general. According to this, a great number of systems can be considered intelligent. In fact, according to this definition, even a thermostat may be considered to be an intelligent system, although of low level of intelligence. It is common, however, to call a system intelligent when in fact it has a rather high level of intelligence.There exist a number of alternative but related definitions of intelligent systems and in the following we mention several. They provide alternative, but related characterizations of intelligent systems with emphasis on systems with high degrees of intelligence.The following definition emphasizes the fact that the system in question processes information, and it focuses on man-made systems and intelligent machines:A. Machine intelligence is the process of analyzing, organizing and converting data into knowledge; where (machine) knowledge is defined to be the structured information acquired and applied to remove ignorance or uncertainty about a specific task pertaining to the intelligent machine. This definition leads to theprinciple of increasing precision with decreasing intelligence, which claims that: applying machine intelligence to a database generates a flow of knowledge, lending an analytic form to facilitate modeling of the process.Next, an intelligent system is characterized by its ability to dynamically assign subgoals and control actions in an internal or autonomous fashion:B. Many adaptive or learning control systems can be thought of as designing a control law to meet well-defined control objectives. This activity represents the system’s attempt to organize or order its “knowledge” of its own dynamical behavior, so to meet a control objective. The organization of knowledge can be seen as one important attribute of intelligence. If this organization is done autonomously by the system, then intelligence becomes a property of the system, rather than of the system’s designer. This implies that systems which autonomously(self)-organize controllers with respect to an internally realized organizational principle are intelligent control systems. [5]A procedural characterization of intelligent systems is given next:C. Intelligence is a property of the system that emerges when the procedures of focusing attention, combinatorial search, and generalization are applied to the input information in order to produce the output. One can easily deduce that once a string of the above procedures is defined, the other levels of resolution of the structure of intelligence are growing as a result of the recursion. Having only one level structure leads to a rudimentary intelligence that is implicit in the thermostat, or to a variable-structure sliding mode controller.The concepts of intelligence and control are closely related and the term “Intelligent Control” has a unique and distinguishable meaning. An intelligent system must define and use goals. Control is then required to move the system to these goals and to define such goals. Consequently, any intelligent system will be a control system. Conversely, intelligence is necessary to provide desirable functioning of systems under changing conditions, and it is necessary to achieve a high degree of autonomous behavior in a control system. Since control is an essential part of any intelligent system, the term “Intelligent Control Systems” is sometimes used in engineering literature instead of “Intelligent Systems” or “Intelligent Machines”. The term “Intelligent Control System” simply stresses the control aspect of the intelligent system.Below, one more alternative characterization of intelligent (control) systems is included. According to this view, a control system consists of data structures or objects (the plant models and the control goals) and processing units or methods (the control laws) :D. An intelligent control system is designed so that it can autonomously achieve a high level goal, whileits components, control goals, plant models and control laws are not completely defined, either because they were not known at the design time or because they changed unexpectedly.There are several essential properties present in different degrees in intelligent systems. One can perceive them as intelligent system characteristics or dimensions along which different degrees or levels of intelligence can be measured. Below we discuss three such characteristics that appear to be rather fundamental in intelligent control systems.Adaptation and Learning. The ability to adapt to changing conditions is necessary in an intelligent system. Although adaptation does not necessarily require the ability to learn, for systems to be able to adapt to a wide variety of unexpected changes learning is essential. So the ability to learn is an important characteristic of (highly) intelligent systems.Autonomy and Intelligence. Autonomy in setting and achieving goals is an important characteristic of intelligent control systems. When a system has the ability to act appropriately in an uncertain environment for extended periods of time without external intervention, it is considered to be highly autonomous. There are degrees of autonomy; an adaptive control system can be considered as a system of higher autonomy than a control system with fixed controllers, as it can cope with greater uncertainty than a fixed feedback controller. Although for low autonomy no intelligence (or “low” intelligence) is necessary, for high degrees of autonomy, intelligence in the system (or “high” degrees of intelligence) is essential.Structures and Hierarchies. In order to cope with complexity, an intelligent system must have an appropriate functional architecture or structure for efficient analysis and evaluation of control strategies. This structure should be “sparse” a nd it should provide a mechanism to build levels of abstraction (resolution, granularity)or at least some form of partial ordering so to reduce complexity. [7] An approach to study intelligent machines involving entropy emphasizes such efficient computational structures. Hierarchies (that may be approximate, localized or combined in heterarchies)that are able to adapt, may serve as primary vehicles for such structures to cope with complexity. The term “hierarchies” refers to functional hierarchies, or hierarchies of range and resolution along spatial or temporal dimensions, and it does not necessarily imply hierarchical hardware. Some of these structures may be hardwired in part. To cope with changing circumstances, the ability to learn is essential, so these structures can adapt to significant, unanticipated changes.In view of the above, a working characterization of intelligent systems (or of (highly)intelligent (control) systems or machines) that captures the essential characteristics present in any such system is:An intelligent system must be highly adaptable to significant unanticipated changes, and so learning is essential. It must exhibit high degree of autonomy in dealing with changes. It must be able to deal with significant complexity, and this leads to certain sparse types of functional architectures such as hierarchies.Nationality：USASource：Modern Control Engineering .Prentice Hall译文：PLC和智能控制简介尾形克彦PLC(即可编程逻辑控制器)是机械控制中为替代必要的继电器时序电路而发明的一种设备。