PLC控制电梯外文翻译

(文档含英文原文和中文翻译)中英文对照外文翻译文献Application of PLC in the Elevator Control System ofIntelligence BuildingAbstract: The paper mainly discusses one subsystem of intelligence building system: the elevator control system. The PLC strong ability in interference and so on makes the elevator industry one after another to apply the PLC to the elevator control system in order to replace the relay being used in traditional elevator control system. The Application of PLC in the Elevator control system reduces the breakdown rate and efficiently improves the operating reliability of the elevator with safety .The structureof system is also simple and tightly packed.The working principle of the elevator control system is: The spot control information is send into the ＰＬＣfrom the customer input devices firstly, then the PLC control cabinet is required to send out the control signal to drive the equipments according to the system demands. The elevator can then proceed the homologous action according to the control request .The paper selectsＯＭＲＯＮcompany’s Ｃ200HE series PLC, introducing parts of signal hookup of the elevator control system and explaining the function of the control cabinet. Lastly the automation programming is introduced. Simulated experiments enunciates that the design method is viable. It can make the personnel of the industry management center to long-distance monitor and control the elevator in control center, to connect the elevator control system with intelligence building industry management system by Ethernet or special-purpose network such as Lon Works.The elevator working state can also be timely watched.These not only can realize scientific centralized management of the elevator, but also can lower the elevator maintenance cost etc. It is one of the developing direction of intelligence building elevator control system.Keywords: PLC; intelligence building; elevator control system; working principle; program designⅠ. IntroductionIn 1980s The first intelligence mansion had been completed in America, then intelligence building has been abroadly taken attentions by the whole world.The concept of intelligence building has been put different meanings along with the development of society. The early stage intelligence building had been thought that it is equal to the intelligent mansion, but now the intelligence building not only includes the intelligence mansions but also involves intelligence residential districts. This paper mainly discusses one subsystem of intelligence building system: the elevator control system.In intelligence residential districts the enterprise’s information managing system mainly takes charge of the things which related to the daily life, for examplesupervising the district equipments, managing vehicles, disposing critical situations and so on.The elevator supervising and control system is also necessary to the intelligence residential districts.How to make people feel safe ,stable and comfortable and how to save energy resources and protect environments and so on are the basic requirements to the elevator control system.PLC is a common industry control device.It is a special industry control computer which has the perfect function and simple frame. The PLC strong ability in interference and so on makes the elevator industry one after another to apply the PLC to the elevator control system, in order to replace the relay being used in traditional elevator control system. The Application of PLC in the elevator control system reduces the breakdown rate and efficiently improves the operating reliability of the elevator with safety. This paper mainly discusses the elevator control system’s working principles, the system’s software and hardware realization methods and so on.Ⅱ. The Working Principle of Elevator Control System In Fig. 1 the Hardware Structure Graph of Elevator Control System is presented.Fig. 1 The Hardware Structure Graph of Elevator Control SystemThe Working Principles of Elevator Control System are stated as follows: The spot control information is send into the PLC from the customer input devices firstly, then the PLC control cabinet is required to send out the control signal to drive the equipments according to the system demands. The elevator can then perform thehomologous action according to the control request. There are velocity feedback devices in system, which adopt measure velocity generators to provide the elevator velocities and generally are installed in the tail of tow motors .So this is a feedback control system, which can improve the system’s control precision.Ⅲ. The Hardware Configuration of Control System It is not necessary to do interface circuit in the elevator’s PLC control system.What we should do is to send the signals to PLC digital input terminals.The signals include inside and outside calling signals ,floor location inspecting signals , limiting location signals ,opening and shutdown the elevator door signals etc. The DC power which is provided to PLC can be used as indicator light power. The PLC output points can be directly used to control transduce rs for the purpose of electrical motor’s positive turn and reverse ,stop and control each segment velocity and so on .ＯＭＲＯＮcompany’s Ｃ200HE series PLC has been selected as major control configuration according to the input/output points and the length of user’s program. On the other hand we also consider that the system’s function can be expanded in the future .Ｃ200HE series PLC ,whose perfect function and strong reliability, can meet these demands at present.Moreover, input and output devices are needed in elevator control system, besides the PLC, system’s major control device.Part of signal hookups of the elevator electric control system is shown in Fig.2.The control cabinet is the control center, from which we can send out various control commands. The control cabinet often was installed in the elevator room .The electric devices and signal systems, for example the contactors, relays, capacitances, resistors, rectifiers and transformers etc., are centralized in the control cabinet. The Power of the control cabinet was imported from the chief power of the elevator room. This power was also introduced into control panel by soft cables and was linked with each control buttons. The power lines which was derived from control cabinet was delivered to tow electric motors. Others control lines and signal lines were separately sent to each floor junctionⅣ. Program designThe design includes two parts: hardware and software.The hardware design is the base of software. Considering that the control demands are relatively complex, we design the programs separately according to the control function. Furthermore, we follow the principle as follows: When the elevator is ascending, the ascending demands are prior to other demands; When the elevator is descending, the descending demands are prior to other demands. The Sequential Function Chart (SFC) is adopted during the boxes to form elevator’s executive circuitry design. It is a method specially used in industrial sequential control. The SFC method can describe the system’s working procedure in great detail. For example there is a three layers intelligence building. A subprogram, the calling from the third floor as elevator in the first floor, is shown in Fig. 3 with SFC.When all SFC are drawn and I/O address lists are presented, we can convert the SFC to Ladder Diagram (LD).Considering the strict demands for time and for locked each other ,we introduce working bits to remember working steps. We should write out the working bits control program, which can link together each step and make the previous step as the next step restriction condition. Thus the actual outputs are the logic combination of these working steps.Ⅴ. ConclusionThe system program has been debugged completely at present. Simulated experiment enunciates that the design method is viable. Application of PLC in the elevator control system is an effective method. It can make the personnel of the industry management center to long-distance monitor and control the elevator in control center, to connect the elevator control system with intelligence building industry management system by Ethernet or special-purpose network such as Lon Works. The elevator working state can also be timely watched. These not only can realize scientific centralized management of the elevator, but also can lower the elevator maintenance costs etc. It is one of the developing direction of intelligence building elevator control system.References[1]Liang jianqi , Duan zhengang,and He wei .CommunicationImplementation of PLC-Based Elevator Remote Monitoring System (in Chinese)[J] Journal of Beijing Technology and Business University 2003,21(2):18-21[2]Ma Hongqian ,Zhang Xin .Application of PLC in Higher Building Elevator Control System (in Chinese)[J]Journal of Liaoning Higher V ocational Technical Institute 2002,4(5): 86-88.[3]Cui Guangyuan. The Application of PLC to Elevator Control. (in Chinese)[J]Journal of Dongbei Electrical Power Technology 2003,(7): 50-52.Author BiographiesThe first author is currently working as a teacher in Taiyuan University of Technology. Her current research interests include signal processing, intelligence control etc.The second author is currently working as a teacher in Taiyuan University of science and Technology. Her current research interests include telecommunication, intelligence control etc.附录B 外文翻译PLC在智能建筑电梯控制系统中的应用摘要：本文主要讨论了智能建筑系统的一个子系统：电梯控制系统。

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。

双控电梯 PLC控制外文翻译AbstractMicroelectronic technology's development, elevator's dragging way and the control method has had the very big change, the exchange velocity modulation is the current elevator dragging main development direction. At present the lift control system mainly has three control modes: Following electric circuit control system (“early installment elevator many black-white control system), PLC control system, microcomputer control system. Because the black-white control system the failure rate is high, the reliability is bad, control mode not nimble as well as consumed power big and so on shortcomings, at present has been eliminated gradually. Although the microcomputer control system has the strong function in the intelligent control aspect, but also has the interference rejection to be bad, the system design is complex, generally the servicemen master flaws with difficulty and so on its service technology. But PLC control system, because moves the reliability to be high, the use service is convenient, anti-jamming, the design and the debugging cycle is short and so on merits, time is taken seriously the people and so on merits, have become present use most control modes in the lift control system, at present also widely use in the tradition black-white control system's technological transformations.The origin and development of the elevatorElevator in the Chinese dictionary explanation: building electricity powered lift, instead of walking up and down the stairs.When it comes to lift from the origin of the 2600 BC Egyptians built in Pyramid using the original lifting system to start, but this kind of crane energy are human. By 1203, two French monastery installed a crane, the difference is just the machine is the use of donkey as power, load by around a large drum rope for hoisting. This method has been used to modern until Watt invented the steam engine, in about1800, mine owners can use the crane to mine in coal transportation.For hundreds of years, people made various types of elevators, they all have a common defect: as long as the lifting rope snaps, lifting ladder he rapidly hit bottom layer. 1854 Otis design a brake: in the lift platform mounted on top of a truck with a spring and a brake lever and Lift Wells Road on bothsides of the guide rail is connected with the lifting rope, wagon springs, this is only the lifting platform weight is sufficient to pull spring, avoid contact with the brake lever. If the rope breaks, truck spring will pull the ends of vertical weakened, and the brake lever occlusal, can be firmly fixed without in situ platform continues to fall. " Safe lifting ladder" invention success! For a time, Otis has become the center of attention. The first lift not Otis invented, but he was the first" safe" lift the inventor. " Security" this concept not only create lift industry, but also for those who want to build more tall buildings to add more available space design are open thoroughfare.However it can be called the elevator ( electric energy to drive the elevator ) of the product should be at the beginning of the twentieth Century emerged.Elevator technology development trend(1): green environmental protection concept is the development trend of elevator. Have expert prophecy" who first introduced green products and market of race to control, who will grasp the market competition initiative". Development trend to basically have : the continuous improvement of product design, production of environmental protection type low power consumption, low noise, no leakage, no water leakage, no electromagnetic interference, no oil pollution of the elevator hoistway guide. Elevator traction with nylon synthetic fiber rope, steel belt without lubricating oil pollution traction mode. Elevator decoration will use no (little ) environmental pollution material. Elevator no-load rise and full of descending motor power regeneration recycling technology. The installation of lifts will be installed without scaffolding. Elevator parts in the production and use of the process has no effect on the environment ( such as brake pads must not use asbestos ) and materials can be recycled. (2) the application of Bluetooth technology in elevator. Installation of elevators knows line, on line is time-consuming, laborious, easy wrong job. If the control screen and calling system through the Bluetooth wireless call will be connected to the elevator control another revolution at the same time bring us enormous benefits. A installation period will be reduced by more than 30%, the direct benefits of reduced installation costs, customers from booking to use lift cycle cost reduce the ladder and improve cash flow rate. B on the elevator using Bluetooth technology will make the elevator control system using a large amount of the latest and fastest computer, which will further improve the elevator machine reliability, fault rate is greatly reduced, the control precision is further increased, theresult is the elevator more comfortable, more accurate flat layer. C is a good solution to the elevator control and peripherals compatible and contact. In particular can take the elevator and escalator induction to the building management system or intelligent management district system.Elevator System Based on PLCComposed by the order of relay control system is a realization of the first elevator control method. However, to enter the nineties, with the development of science and technology and the widespread application of computer technology, the safety of elevators, reliability of the increasingly high demand on the relay control weaknesses are becoming evident.Elevator control system relays the failure rate high, greatly reduces the reliability and safety of elevators, and escalators stopped often to take with the staff about the inconvenience and fear. And the event rather than taking the lift or squat at the end of the lift will not only cause damage to mechanical components, but also personal accident may occur.Programmable Logic Controller (PLC) is the first order logic control in accordance with the needs of developed specifically for industrial environment applications to operate the electronic digital computing device. Given its advantages, at present, the relay control the lift has been gradually replaced by PLC control. At the same time, AC variable frequency motor speed control technology, the way the lift drag speed has been a gradual transition form DC to AC frequency converter. Thus, PLC control technology increases VVVF Elevator modern technology has become a hot industry.1. PLC elevator control advantages:(1) Used in elevator control PLC, with so ware for automatic control of lift operation, reliability greatly increased.(2) Layer was removed and majority of the relay, the control system structure is simple, simplify the external circuit.(3) PLC can be a variety of complex control system, easy to add or change control functions.(4) PLC can be automated fault detection and alarm display to improve the operation of security and ease of maintenance.(5) For the group control the allocation and management, and improve the efficiency of elevator operation.(6)Do not need to change the control scheme changes when the hardware connection.2. VVVF elevator control characteristics.With the power electronics, microelectronics and computer technology to control the rapid development of technology, communication technology VVVF also a very rapid rate. AC variable frequency motor speed control technology is the power to improve the process in order to improve product quality and improving the environment and promoting technological progress as a primary means. Frequency of its excellent performance and the speed brake from a smooth performance, high efficiency, high power factor and power-saving of a broad scope of application and many other advantages of being at home and abroad recognized as the most promising approach speed.Exchange characteristics of VVVF Elevator:(1) low energy consumption.(2) low load circuit, the re emergency power supply device of small.In the acceleration stage, the required start-up current of less than 2.5 times the rated current. Peak starting current and time is short. Since the starting current is drastically reduced, so power consumption and power supply cable diameter can be reduced a lot. Required for emergency power supply devices are also relatively small size.(3) high reliability and long service life.(4) good comfort.Elevator operation is best to follow the speed curve of a given operation. Their characteristics can be adapted to human feelings, and to ensure that noise operation, smooth brake Ping layer and high precision.(5) stable noise-free.(6) In the car, the engine room and adjacent areas to ensure that noise. Because their systems use a high clock frequency. Always produce a true sine wave power supply current yet. Motor torque ripple does not appear. Therefore, to eliminate vibration and noise.3. Elevator control technology.The so-called elevator control technology refers to the elevator drive system and electrical control system of automatic control. 70 as the 20th century in China’s elevator were marked by the exchange of two-speed elevator. Its speed is used to change the elevator traction motor of the very few, two or mute-level approach to the number of windings, very few of them as high-speed winding of the winding, a very few number of windings as the low-speed winding. Windings for high-speed elevator-speed start-up and running, low-speed windings for braking and the maintenance of elevators.The early 80s, VVVF inverter controlled variable lift system available. It uses AC motor drivers, are able to reach the level of DC motor, control the speed of the current has reached 6 m/sec. Its small size, light weight, high efficiency, energy saving, inc1uding the past almost all the advantages of the lift. Is the latest elevator drive systemOperation in vertical lift, there is also the starting point of the terminus station. For more than three-story elevator buildings, the starting point of the terminal stations and stops between the had not, the starting point for these stations at the first floor of the terminal located at the highest floor. Starting point in the first floor of the station known as base stations, known as the starting point at both ends of the terminal stations and stations at both ends of intermediate stops between stations.Outside the station has a call box, box set are used by staff for elevator call button or touch the call button, the general ends of the lift stations in the call box on the Settings button or touch of a button. 1iddle layer of the station set up the call box button or touch button 2. No drivers for the control of elevators, at various stations are set up calls me on a button or touch button. Elevator car and the internal settings (except for debris elevator) to manipulate me. Control box switch on the handle or set up stations and the corresponding layer of buttons or touch-button control box on the touch-control button or command button or touch the city button. Outside the command button or touch-button issue as the signal outside the command signal, within the command button or touch-button issue within the signal as a command signal. 80 In the mid-20th century, the touch button has been replaced by micro-button.As the elevator call box outside the base station, in addition to set up a call button or touch button, but a1so set a key switch in order to work the elevator clearance. Drivers or management staff to open the elevator to the base station can wriggle through a dedicated key to the key switch. Close the elevator in place to autocratically cut off the elevator control power supply or power supply.4. PLC Control Elevator Design.With the continuous development of urban construction, the increasing high-rise buildings, elevators and life in the national economy has a broad application. Elevator high-rise buildings as a means of transport in the vertical run of daily life have been inextricably linked with people. In fact the lift is based on external call control signals, as well as the laws of their own, such as running, and the cal1 is random, the lift is actually a man-machineinteractive control system, simple to use control or logic control order can not meet the control requirement, and therefore, elevator control system uses a random control logic. Elevator control is current1y generally used in two ways, first, the use of computer as a signal control unit, the completion of the lift signal acquisition, operation and function of the se, to achieve the lift and set the autocratic scheduling function to run the election, drag the control from inverter to complete; the second control mode with programmable logic controller (PLC) to replace the computer control signal sets the election. From the control and performance, these two types of methods and there is no significant difference. Most of the domestic manufacturers to choose the second approach, because the smaller scale of production there design and manufacture of high cost of computer control devices; and PLC high reliabi1ity, convenient and flexible program design, anti-interference ability, stable and reliable operation of the characteristics of Therefore, the elevator control system is now widely used to realize programmable control.5. Lift control system.Lift control system is used to manipulate each control process by managing such commands as running direction, car call, landing call, load signal, landing indication, safety protection.Lifts in different applications have different load, speed and drive / control modes. Lifts in same application may also have different control mode. Whatever control mode is adopted, the objective is the same, to be specific, according to car call and landing call, lift control system will execute automatic logic judgment to determine which lift will receive signal, which direction lift will run towards and complete programmed control objective through electrical automatic system based on command.Types of lift control system.Control system development chronicle indicates that there has appeared many control modes, such as such as relay control, PLC, single computer control, multiple-computer control. Prevailing in different era, these control modes are still employed in lifts now due to massive integrated circuit and computer technology development.PLC control system.As abbreviation of programmable logic controller, PLC is an electronic system featuring digital computation. It adopts programmable EPROM to execute logic computation, order control, timing, number counting, arithmetic computation, besides, it can input and output through digital or analogy modes.The mechanism of PLC control is as follows: input of PLC includes such command signals, as power key to home landing, car call, landing call, various safety switches, position signal, while output of PLC includes contactor, relay, indicators of car / landings and communication unitary, indicators inside car and switch, position signal, are input to PC, while other executing com.Programming principle is determined by lift control mode. Programming can either be made according to relay logic control circuit or individually in different phases according to lift control functions after completely separating from relay control circuit. Based on the ready made control circuit, the former is simple and easy to master, while the latter involves less programs by integrating programs of small function.Used in lift control system, PLC has such advantages, as high reliability, stability, easy programming, user-friendliness, convenient maintenance & inspection.Nowadays, there is a wide range and series of programmable logic controllers. Input / output points range from 30 to 8000 or above, so as to meet lift control requirements with different landing number.。

In the article has analyzed the elevator loadcharacteristics, elaborated uses the trapezoid acceleration curve theelevator ideal velocity curve, unifies the frequency changer and thePLC performance, elaborated the elevator control system constitutionand the operational factor. Elaborated the elevator speed curveproduces the method, has induced the characteristic which designs byPLC constitution control system software.Key word: Load characteristics ideal velocity curve control systemsoftware design1. OutlineAlong with the urban construction unceasing development, thehigh-rise construction unceasingly increases, the elevator has thewidespread application in the national economy and the life. Theelevator took in the high-rise construction the vertical movementtransportation vehicle already and people's daily life is inseparable.In fact the elevator is according to exterior movement and so oncalling signal as well as own control rule, but calls is stochastic,the elevator is a person machine interactive control system in fact,purely is cannot satisfy the control request with the sequentialcontrol or the logical control, Therefore, the elevator control system uses the stochastic logical waycontrol. At present the elevator control generally has selected twomethods, one is uses the microcomputer to take the signal controlunit, completes the elevator signal gathering, the running status andthe function hypothesis, realizes the elevator automatic dispatch andthe collection chooses the movement function, drives the control tocomplete by the frequency changer; The second control mode (PLC)substitutes for the microcomputer realization signal collection withthe programmable controller to choose the control. Said from the control mode and the performance, these two methodscertainly not too big difference. The domestic factory mostly choosesthe second way, its reason lies in the production scale slightly, owndesign and the manufacture microcomputer control device cost ishigher; But PLC reliability high, programming convenience nimble, theantijamming ability strong, the movement stable is reliable and so onthe characteristic, therefore the present elevator control systemwidely uses the programmable controller to realize.2. Elevator ideal performance diagramIndicated according to the massive research and the experiment, theperson may accept the maximum acceleration is am <= 1.5m/s2,acceleration rate of change rho m <= the 3m/s3, elevator idealperformance diagram may divide according to the acceleration is thetriangle, the trapezoid and the sine profile, As a result of sine profile acceleration curve realization moredifficult, but the triangle curve maximum acceleration and is startingand applies the brake the section turning point acceleration rate ofchange to be bigger than the trapezoidal curve, namely + rho m jumpsto - rho m or jumps from - rho m to + rho the m acceleration rate ofchange, therefore very little uses, because the trapezoidal curve iseasy to realize and has the good acceleration rate of change frequenttarget, therefore is widely used, uses the trapezoidal accelerationcurve elevator ideal performance diagram like chart 1 to show: The intelligent frequency changer is for the elevator special-purposefrequency changer request and so on elevator nimble velocitymodulation, control and high accuracy even level which but speciallydesigns, may use for parts the general three-phase asynchronous motor,and has function and so on intellectualized software, standardconnection, menu prompt, input elevator curve and other essentialparameter. It has the debugging convenience quickly, moreover can automaticallyrealize the single multilayered function, and has the automaticoptimization deceleration curve the function, is composed the velocitymodulation system crawling time by it few, the even level distance isshort, no matter is the double winding electric motor, or electric motor suitable, its highest design speed may reach 4m/s, itsunique computer monitoring software, may choose the serial interfacerealization input/output signal the non- electronic contact control. The frequency changer constitutes elevator system, when the frequencychanger receives the controller to send out shouts the ladderdirection signal, the frequency changer basis hypothesis speed and theacceleration value, the starting motor, after achieved the maximumspeed, the uniform speed moves, when arrives the goal leveldecelerates, the controller sends out shuts off the high velocitysignal, reduces the speed which the frequency changer establishes themaximum speed to reduce to the crawling speed, In decelerates in the movement process, the frequency changer can theautomatic computation decelerate to the even level spot betweendistance, and calculates the optimized curve, thus canaccording tothe optimized curve movement, cause the low speed crawling time toreduce to 0.3s, the frequency changer through adjusts leveling thespeed in the elevator even level process or applies the brake thepitch to adjust leveling the precision. Namely when the elevator stops too early, the frequency changerincreases the low speed value or the reduction applies the brake thepitch value, otherwise reduces the low speed value or increasesapplies the brake the pitch value, when the elevator to leaves evenlevel position 4 - 10cm, has the even level switch automaticseparation low speed signal, the system according to the optimizedcurve realization high accuracy even level, thus achieved the evenlevel accurate is reliable.3. Elevator speed curveElevator movement comfortableness is decided in its movementprocess acceleration a and the acceleration rate of change p size, theoversized acceleration or the acceleration rate of change can createpassenger's ill feeling. At the same time, for guaranteed the elevatorthe operating efficiency, a, the p value not suitable excessively issmall. Can guarantee a, the p best value elevator performance diagramis called the elevator the ideal performance diagram. The elevatormovement ideal curve should be the parabola - straight linecomprehensive velocity curve, namely elevator Canada, reduces theprocess constitutes by the parabola and the straight line. Theelevator assigns the curve is whether ideal, direct influence actualperformance diagram.3.1 velocity curves have the methodUses FX2-64MR PLC, and a consideration input output requestincreased FX-8EYT, FX-16EYR, the FX-8EYR three expansions modules andthe FX2-40AW twisted pair line correspondence adapter, FX2-40AW usesin the system serial communication. Using PLC the expansion functionmodule D/A module realization speed ideal curve output, whenbeforehand the digitized ideal velocity curve stores the PLC register,the procedure movement, through looks up the table way to read in D/A,transforms the simulation quantity after D/A the speed ideal curveoutput.3.2 Acceleration assign the curve the production8 D/A outputs 0 ~ 5V/0 ~ 10V, the corresponding numerical valueis 16 enters system several 00 ~ FF, altogether 255 levels. Ifelevator rise time between 2.5 ~ 3seconds. According to theconservative value computation, in the elevator acceleration processeach time Zha Biao time-gap not suitably surpasses 10ms.As a result of elevator logic control section procedure biggest, butthe PLC movement uses the cyclical scanning mechanism, thus usuallyuses looks up the table method, Zha Biao instruction time-gapexcessively is each time long, cannot satisfiedly assign the curve theprecision request. In the PLC movement process, its CPU with variousequipment between exchange of information, user program execution,signal gathering, control quantity operation and so on output all isdefers to the fixed order to circulate the scanning way to carry on,each circulation all must carry on the inquiry, the judgement and theoperation to all functions. This kind of order and the form capableperson are not the change. The usual scanning cycle, is basic mustcomplete six steps the work, including movement surveillance, andprogramming exchange information, and digital processor exchangeinformation, and communication processor exchange information,execution user program and input output connection service and so on.In a cycle, CPU only carries out to the entire user program. This kindof mechanism has its convenient one side, but timeliness is bad. Theexcessively long scanning time, directly affects the system to thesignal response effect, in under the guarantee control functionpremise, maximum limit reduces CPU the cyclical scanning time is avery complex question. Generally only can short adopt the method fromthe user program execution time. The elevator logic control sectionprocedure scanning time has surpassed 10ms, although has adopted somereduced procedure scanning time means, but still will be unable toscan the time to fall to 10ms below. At the same time, applies thebrake the section curve to use according to is away from theprinciple, each section of distances arrive the response time notsuitably surpasses 10ms. In order to satisfy the system the timelyrequest, in the velocity curve production way, uses the severancemethod, thus effectively has overcome the PLC scanning mechanismlimit.The starting acceleration movement by decides the cycle interruptservice isr to complete. This kind of severance cannot carry on theswitch by the procedure, once establishes, continuously presses thehypothesis time-gap circulation severance,therefore, the startingmovement condition must put in the interrupt service isr, when doesnot satisfy the movement condition, the severance namely returns.3.2 Decelerates applies the brake the curve productionIn order to guarantee applies the brake process completing,must carry on in the master routine applies the brake the condition tojudge and to decelerate a determination. In decelerates before adetermination, the elevator continuously is in the acceleration or thesteady fast movement process. The acceleration process completes bythe fixed cyclical severance, accelerates after the correspondingpattern maximum value, the acceleration procedure movement conditionno longer satisfies, after each time severs, no longer carries out theacceleration procedure, directly returns from the severance. Theelevator corresponds the pattern the maximum value movement,decelerates in this pattern to after, has the high-speed countingseverance, the execution decelerates the service routine. Revises thecounter in this interrupt service isr to suppose the definite valuethe condition, guaranteed the next time will sever the execution. In the PLC internal register, deceleration curve table value from big to small , each time severs all carries out time "theindicator needle to add 1" the operation, then the next severance willlook up the table number is smaller than this severance to look up the table numbers. Thegate area peaceful level area judgement produces by exterior signal,guarantees the moderating process the reliability.4. Elevator control system4.1 Elevators control system characteristicIs relates the elevator movement comfortable feeling target in theelevator performance diagram start section the key link, but thecomfortable feeling with the acceleration direct correlation,according to controls the theory, must cause some quantity accordingto prearrange the rule change to have to carry on the positivegoverning to it, said regarding the elevator control system, mustcause the acceleration to have to use the acceleration feedbackaccording to the ideal curve change, according to electric motormoment of force equation: M - MZ= Delta M=J (dn/dt), obviously theacceleration rate of change had reflected the system dynamic extensionis apart from the change, the control acceleration is apart from DeltaM=M - MZ on the control system dynamic extension. Therefore uses theacceleration in thissection the timing control principle, when thestart ascent portion speed achieved when stable state value 90%,systematically will cut the speed control from the accelerationcontrol, because in the steady fast section, the speed will besmaller for the permanent value control undulation, the accelerationchange will not be big, also will use the speed closed-loop controlto be allowed to cause the stable state speed hold certain precision,will be applies the brake the section precise even level to create thecondition. Uses the PI regulator control in the system speed ascentportion and steady fast Duan Suidu, but two section of PI parameter isdifferent, enhances the system the dynamic response target.Applies the brake the section in the system, namely must to reduce thespeed to carry on the essential control, guarantees the comfortablefeeling, also must strictly controls according to the elevatormovement speed and the distance relations, guarantees the even levelthe precision. In system’s rotational speed reduces to 120r/min in front of, in orderto enable two to obtain the proper attention to both, adopts by theacceleration to the timing control primarily, simultaneously actsaccording to on each as soon as the stopping distance the actualrotational speed and the theory rotational speed deviation revises theacceleration to assign the curve the method. For example in is awayfrom the even level spot some as soon as to be away from L place, thespeed should reduce to Vm/s, but the actual rotational speed is highis V ' m/s, then explained adds the system turns is apart frominsufficiently, after therefore calculates the here to assign reducesspeed value -ag, causes it to add on a negative deviation againepsilon, even if the here reduces the speed given value to revise for- (ag+ epsilon) causes to assign reduces the speed and the true speednegative deviation enlarges, thus enlarged the system to turn thedistance, caused the speed very quickly to fall to the standard value,when electric motor’s rotational speed reduces to 120r/min after, this time thetheater box above the level only had several centimeters, The elevatorrunning rate is very low, for did not prevent phenomenon appearancewhich stops to the even level area, enables the elevator comparativelyquickly to enter the even level area, uses the proportional control inthis section, and uses the time optimization control, guaranteed theelevator accurately promptly enters the even level area, achieves theaccurate reliable even level.4.2 elevators controls constitutionBecause the elevator movement is according to the floor and the theater box calling signal, the travelling schedule signalcarries on the control, but the floor and the theater box call isstochastic, therefore, the systems control uses the stochastic logicalcontrol. Namely in realizes in the elevator basic control requestfoundation by the smooth logic control, according to stochastic inputsignal, as well as elevator corresponding condition at the rightmoment control elevator movement. Moreover, the theater boxposition is determined by the pulse encoder pulse number that, anddelivers PLC the counter to carry on the control. At the same time,each building establishes to approach the switch to use in to examinethe system the floor signal. In order to be advantageous for the observation, is at the floor tothe elevator movement direction as well as the elevator to carry onthe demonstration, uses LED and the photo tube demonstrated, but tothe floor and the theater box calling signal to the indicating lampdemonstrated (on switch has indicating lamp).In order to enhance the elevator the operating efficiency peacefullevel precision, the system requests PLC to be able to theater boxCanada, to decelerate as well as to apply the brake to carry on theeffective control. Realizes according to the theater box physicallocation as well as the exchange velocity modulation system controlalgorithm. For the elevator movement security, the system shouldestablish the reliable fail safe and the corresponding es the PLC realization the elevator control system to constitute byfollowing several main parts.4.2.1 PLC control circuit; PLC receives shouts the ladder from thepanel board and each level to summon the signal, the theater boxand the gate system function signal as well as the well and thefrequency changer condition signal, realizes the elevator collectionafter the procedure judgement and the operation to choose the control.PLC during the output demonstration and supervisory signal, sends outthe movement direction, the start, Canada to the frequencychanger/decelerates moves and applies the brake to stop the ladderequisignal.4.2.2 electric currents, speed double closed loops electric circuit;Frequency changer itself is equipped with the electric currentdetector set, from this constitution electric current closed loop;Through revolves the encoder with the electricalmachinery coaxialjoint, produces a, the b two pulses enters the frequency changer,during confirmation direction, counts the constitution speed closedloop using the pulse.4.2.3 displacements control circuit; The elevator took one kindcarries the person tool, reigns under the potential state of loading,besides request safe reliable, but also requests the movement to besteady, rides comfortably, anchors accurately. Uses the frequencyconversion to modulate velocity Shuanghuan to control may basicallyanswer the purpose, the use existing revolves the encoder toconstitute the speed ring at the same time, moves the proportionthrough the frequency changer PG card output and the electricalmachinery speed and the elevator the pulse number, introduces it PLChigh-speed counting to input the port, through the accumulation pulsenumber, (1) calculates the pulse equivalent after the type, from thisdefinite elevator position. Elevator displacement H=SI In the formula I - accumulation pulse number; S - pulse equivalent; S = plD/(pr) (1) L – Proportion of decelerates ; D - tows the wheel diameter; P - revolves the encoder every time to transfer corresponding thepulse number; R - PG card frequency division ratio.4.2.4 ends stations protection; When in elevator direction detectionline, on the good directional relay, the express train assistancecontact device, the express train movement contact device, the doorlock relay, on the good contact device electricity attracts gathers, mechanical floodgate opens, on elevator line. When the theater box bumps intoforces speed changeing the switch, the PLC internal lock saves the relay toresult in the electricity to attract gathers, timer Tim10, Tim11 startfixed time, it fixed time time length visible end station leveldistance with ladder fast hypothesis. After on forces speed changing theswitch movement, the elevator transfers the slow train movement by theexpress train movement, in the normal condition, the previous line ofeven strata time elevator should stop. If the theater box has notstopped continues the line, when Tim10 supposes the definite value toreduce the zero hour, it the separation, the slow traincontact device and on the good contact device loses the electricity,the elevator stops moving. Bumps into after the arrogant theater boxon forces speed changing the switch, because certain reason elevators have notbeen able to transfer the slow train movement, and the express trainmovement contactdevice has not been able to release, when Tim11supposes the definite value to reduce the zero hour, it N.C. contactthe separation, the express train movement contact device and on thegood contact device loses the electricity, the elevator stops moving.Therefore, no matter is the slow train movement or the express trainmovement, so long as on forces speed changing the switch to send out thesignal, no matter the end stands other protection switches whetheract, can cause the elevator with the aid of Tim10 and Tim11 to stopmoving, thus causes the elevator end station protection to be morereliable.Under when the elevator needs the line, so long as had has chosen theladder instruction, got down the good directional relay to result inelectricity its Chang Kaidian closed, the lock saved the relay toreposition, Tim10 and Tim11 lost the electricity, it N.C. contactclosed for the elevator normal under line has prepared for. The lowerextremity stands the protection principle and the upper extremestation protection similar no longer duplicates.4.2.5 floors count; The floor counts uses relatively counts the way.Before the movement through from the study way, determines thecorresponding floor highly pulse number, corresponds 17 elevatorsseparately to store 16 memories units DM06 ~ DM21. The floor counter(CNT46) is a bidirectional counter, when arrives each level the floorcounts, according to moves the direction to carry on adds 1 or reduces1 to count. In the movement, the high speed counter tiredly estimates the valuereal-time counts the point correspondence pulse number with the floorto carry on the comparison, is equal when sends out the floor to countthe signal, the previous line of Canada 1, the next line reduces 1. Inorder to prevent the counter in counts the pulse high level periodrepetition to count, uses the floor to count on the signal along totrigger the floor counter.4.2.6 is fast speed changing; When the high speed counter value and the fastspeed changing point correspondence pulse number is equal, if the elevator isin the quick operating also this level has chooses the level signal,sends the fast speed changing signal. If the elevator medium speed movement oralthough the quick operating but this not chooses the level signal,then does not send speed changing the signal.4.2.7 areas signals; When high speed counter CNT47 value correspondsin the pulse number scope when the gate area, sends the gate areasignal.4.2.8 pulses signals failure detection; Pulse signal accurategathering and the transmission appears in the system especiallyimportantly, revolves the encoder for the examination and the pulsetransmission circuit breakdown, whether there is has designed thepulse signal and the errors and omissions pulse examination electriccircuit, guarantees the system normal operation through the real-timeexamination. In order to eliminate the pulse to count the accumulativeerror, in base station the establishment reset switch, turns on PLC highspeed counter CNT47 the replacement end.5. Software design characteristic5.1 uses the priority formationPosition and movement direction locates which according to theelevator, in the programming, has used four priorities formations,namely on good priority formation, on line of inferior priorityformation, under good priority formation, next line of inferiorpriority formation. When among them, on good priority formation forelevator upward movement, locates the upward movement calling signalin the elevator which above the position the floor sends out, thearray which should call which the signal cabin correspondence thefloor to have the pulse number depositing register constitutes. Whenprevious line of inferior priority formation for elevator upwardmovement, locates the upward movement calling signal in the elevatorwhich below the position the floor sends out, the formation whichshould call which the signal cabin correspondence the floor to havethe pulse number depositing register constitutes. Control system inelevator movement real-time arrangement four priorities exhibition,has provided the foundation for the realization stochastic logiccontrol.5.2 uses advanced first leaves the formationAccording to elevator movement direction, with to the priorityformation's in non-vanishing unit (has when call this unit is 70units, does not have when call then this unit for zero) (advancedsends in the register formation first to leave formation FIFO), theuse advanced first leaves the read-out instruction SFRDP instruction,sends in the FIFO first unit in data compares the register.5.3 uses the stochastic logical controlWhen the elevator approaches by some movement direction somefloor decelerates the position, distinguished whether this floor doeshave with to the calling signal (on a line of call symbolizedregister, next line of call symbolized when register, has callrequest, corresponding register is l, otherwise is 0), if has, thecorresponding register pulse number and the comparison register willcarry on the comparison, if will be same, then will decelerate in thisfloor stops: If is not same, then sends in this register data comparesthe register, and the original comparison register data preservation,carries out this floor to decelerate stops. After this movementfinished, the data which will preserve reis sent in compares theregister, will realize the stochastic logical control.5.4 uses the software demonstration The system use travelling schedule judgement floor, andtransforms the BCD code output, through hardware connection electriccircuit by LED demonstration.5.5 pair of frequency changers control PLC acts according to the stochastic logical control therequest, may send out to the frequency changer to the movement, thereverse movement, is decelerating as well as applies the brake thesignal, again controls the electrical machinery by the frequencychanger basis certain control rule and the control algorithm. At thesame time, when the system appears the breakdown, PLC to the frequencychanger sends out the signal.6. Concluding remark Uses elevator control system which the MIC340 elevatorspecial-purpose frequency changer constitutes, may realize theintellectualization which the elevator controls, but because theperiod of five days ladder and the elevator in person arrives eachlevel the population is the intelligent elevator is unable todetermine, even if uses the AITP artificial intelligence system, thetransmission transportation passenger flow information also is fuzzy,for solves the elevator this vertical transportation control systemtwo to be big cannot know the factor, will need us to go to theunceasing research and the exploration in the next work.译文:文中分析了电梯的负载特性，阐述了采用梯形加速曲线的电梯理想速度曲线，结合变频器和PLC的性能，论述了电梯控制系统的构成和工作特性。

PLC控制系统外文翻译附录Abstract: Programmable controller in the field of industrial control applications, and PLC in the application process, to ensure normal operation should be noted that a series of questions, and give some reasonable suggestions.Key words: PLC Industrial Control Interference Wiring Ground Proposal DescriptionOver the years, programmable logic controller (hereinafter referred to as PLC) from its production to the present, to achieve a connection to the storage logical leap of logic; its function from weak to strong, to achieve a logic control to digital control of progress; its applications from small to large, simple controls to achieve a single device to qualified motion control, process control and distributed control across the various tasks. PLC today in dealing with analog, digital computing, human-machine interface and the network have been a substantial increase in the capacity to become the mainstream of the field of control of industrial control equipment, in all walks of life playing an increasingly important role.ⅡPLC application areasCurrently, PLC has been widely used in domestic and foreign steel, petroleum, chemical, power, building materials, machinery manufacturing, automobile, textile, transportation, environmental and cultural entertainment and other industries, the use of mainly divided into the following categories:1. Binary logic controlReplace traditional relay circuit, logic control, sequential control, can be used to control a single device can also be usedfor multi-cluster control and automation lines. Such as injection molding machine, printing machine, stapler machine, lathe, grinding machines, packaging lines, plating lines and so on.2. Industrial Process ControlIn the industrial production process, there are some, such as temperature, pressure, flow, level and speed, the amount of continuous change (ie, analog), PLC using the appropriate A / D and D / A converter module, and a variety of control algorithm program to handle analog, complete closed-loop control. PID closed loop control system adjustment is generally used as a conditioning method was more. Process control in metallurgy, chemical industry, heat treatment, boiler control and so forth have a very wide range of applications3. Motion ControlPLC can be used in a circular motion or linear motion control. Generally use a dedicated motion control module, for example a stepper motor or servo motor driven single-axis or multi-axis position control module, used in a variety of machinery, machine tools, robots, elevators and other occasions.4. Data ProcessingPLC with mathematics (including matrix operations, functions, operation, logic operation), data transfer, data conversion, sorting, look-up table, bit manipulation functions, you can complete the data collection, analysis and processing.Dataprocessing is generally used, such as paper making, metallurgy, food industry, some of the major control system5. Communications and networkingPLC communication with the communication between PLC and the PLC and other communications between intelligentdevices. Along with the development of factory automation network, the PLC now has communication interface, communication is very convenient.ⅢApplication features of PLC1. High reliability, strong anti-interferenceHigh reliability is the key to performance of electrical control equipment. PLC as the use of modern large scale integrated circuit technology, using the strict production process, the internal circuits to the advanced anti-jamming technology, with high reliability. Constitute a control system using PLC, and the same size compared to relay contactor system, electrical wiring and switch contacts have been reduced to hundreds or even thousands of times, fault also greatly reduced. In addition, PLC hardware failure with self-detection, failure alarm timely information. In the application software, application are also incorporated into the peripheral device fault diagnosis procedure, the system is in addition to PLC circuits and devices other than the access protection fault diagnosis. In this way, the whole system extremely high reliability.2. Fully furnished, fully functional, applicabilityPLC to today, has formed a series products of various sizes, can be used for occasions of all sizes of industrial control. In addition to processing other than logic, PLC data, most of computing power has improved, can be used for a variety of digital control in the field. A wide variety of functional units in large numbers, so that penetration to the position of PLC control, temperature control, CNC and other industrial control. Enhanced communication capabilities with PLC and human-machine interface technology, using the PLC control system composed of a variety of very easily.3. Easy to learn, well engineering and technical personnel welcomePLC is facing the industrial and mining enterprises in the industrial equipment. It interfaces easily, programming language easily acceptable for engineering and technical personnel. Ladder language, graphic symbols and expressions and relay circuit very close to are not familiar with electronic circuits, computer principles and assembly language do not understand people who engage in industrial control to open the door.4. System design, the workload is small, easy maintenance, easy to transformPLC logic with memory logic instead of wiring, greatly reducing the control equipment external wiring, make the control system design and construction of the much shorter period, while routine maintenance is also easier up, even more important is to change the procedures of the same equipment has been changed production process possible. This is particularly suitable for many varieties, small batch production situations.(1)Installation and wiring● Power lines, control lines and power lines and PLC I / O lines should be split wiring, isolation transformer and PLC and I / O should be used between the cable connection Shuangjiao. The PLC's IO lines and power lines go separate lines, such as to be in the same groove, the separation of bundled communication lines, DC lines, if conditions allow, the best sub-groove alignment, not only will it have the greatest possible distance and can reduce the noise to a minimum.● PLC should stay away from strong interference sources such as welding, high-power silicon rectifier devices and large power equipment, not with the high-voltage electrical switchinstalled in the same cabinet. PLC in the cabinet should stay away from power lines (the distance between the two should be more than 200mm). And PLC cabinets installed within the same inductive load, such as large power relay, contactor coil, arc should be parallel RC circuit.● PLC input and output separately from the best alignment, switch and analog should be laid separately. The transmission of analog signals should be shielded cable, one end or both ends of the shield should be grounding resistance should be less than the shielding layer 1 / 10.● AC output line and DC output lines do n ot use the same cable, the output line should be far from power lines and power lines, to avoid parallel.(2)I / O wiring terminalInput Connection● Input wiring generally not too long. But if the environment interfere with small, small voltage drop, the input terminal can be properly longer.●Input / output lines can not be used with a cable, input / output lines should be separated.● The extent possible, normally open contact form to connect to the input in the establishment of the ladder and relay the same schematic, easy to read。

The Programmable Logic ControllerJohn R. Hackworth, Frederick D. Hackworth, Jr.Programmable Logic Controllers: Programming Methods and Applications.2.5~2.8,The Programmable Logic Controller,John R. Hackworth, Frederick D. Hackworth, Jr.First Edition. London: Prentice Hall,2003.35~501.1 System Block DiagramA Programmable Controller is a specialized computer. Since it is a computer, it has all the basic component parts that any other computer has; a Central Processing Unit, Memory, Input Interfacing and Output Interfacing. A typical programmable controller block diagram is shown in Figure 2.5.Figure 2.5 Programmable Controller Block DiagramThe Central Processing Unit (CPU) is the control portion of the PLC. It interprets the program commands retrieved from memory and acts on those commands. In present day PLC's this unit is a microprocessor based system. The CPU is housed in the processor module of modularized systems.Memory in the system is generally of two types; ROM and RAM. The ROM memorycontains the program information that allows the CPU to interpret and act on the Ladder Logic program stored in the RAM memory. RAM memory is generally kept alive with an on-board battery so that ladder programming is not lost when the system power is removed.This battery can be a standard dry cell or rechargeable nickel-cadmium type. Newer PLC units are now available with Electrically Erasable Programmable Read Only Memory (EEPROM) which does not require a battery. Memory is also housed in the processor module in modular systems.Input units can be any of several different types depending on input signals expected as described above. The input section can accept discrete or analog signals of various voltage and current levels. Present day controllers offer discrete signal inputs of both AC and DC voltages from TTL to 250 VDC and from 5 to 250 VAC. Analog input units can accept input levels such as ±10 VDC, ±5 VDC and 4-20 ma. current loop values. Discrete input units present each input to the CPU as a single 1 or 0 while analog input units contain analog to digital conversion circuitry and present the input voltage to the CPU as binary number normalized to the maximum count available from the unit. The number of bits representing the input voltage or current depends upon the resolution of the unit. This number generally contains a defined number of magnitude bits and a sign bit. Register input units present the word input to the CPU as it is received (Binaryor BCD).Output units operate much the same as the input units with the exception that the unit is either sinking (supplying a ground) or sourcing (providing a voltage) discrete voltages or sourcing analog voltage or current. These output signals are presented as directed by theCPU. The output circuit of discrete units can be transistors for TTL and higher DC voltage or Triacs for AC voltage outputs. For higher current applications and situations where a physical contact closure is required, mechanical relay contacts are available. These higher currents, however, are generally limited to about 2-3 amperes. The analog output units have internal circuitry which performs the digital to analog conversion and generates the variable voltage or current output.1.2 Update - Solve the Ladder - UpdateWhen power is applied to a programmable logic controller, the PLC’s operation consists of two steps: (1) update inputs and outputs and (2) solve the ladder. This may seem like a very simplistic approach to something that has to be more complicated but there truly are only these two steps.If these two steps are thoroughly understood, writing and modifying programs and getting the most from the device is much easier to accomplish. With this understanding, the things that can be undertaken are then up to the imagination of the programmer.You will notice that the “update - solve the ladder” sequence begins after startup. The actual startup sequence includes some operations transparent to the user or programmer that occur before actual PLC operation on the user program begins. During this startup there may be extensive diagnostic checks performed by the processor on things like memory, I/O devices, communication with other devices (if present) and program integrity. In sophisticated modular systems, the processor is able to identify the various module types, their location in the system and address. This type of system analysis and testing generally occurs during startup before actual program execution.1.3 UpdateThe first thing the PLC does when it begins to function is update I/O. This means that all discrete input states are recorded from the input unit and all discrete states to be output are transferred to the output unit. Register data generally has specific addresses associated with it for both input and output data referred to as input and output registers. These registers are available to the input and output modules requiring them and are updated with the discrete data. Since this is input/output updating, it is referred to as I/O Update. The updating of discrete input and output information is accomplished with the use of input and output image registers set aside in the PLC memory. Each discrete input point has associated with it one bit of an input image register. Likewise, each discrete output point has one bit of an output image register associated with it. When I/O updating occurs, each input point that is ON at that time will cause a 1 to be set at the bit address associated with that particular input. If the input is off, a 0 will be set into the bit address. Memory in today's PLC's is generally configured in 16 bit words. This means that one word of memory can store the states of 16 discrete input points.Therefore, there may be a number of words of memory set aside as the input and output image registers. At I/O update, the status of the input image register is set according to the state of all discrete inputs and the status of the output image register is transferred to the output unit.This transfer of information typically only occurs at I/O update. It may be forced to occur at other times in PLC's which have an Immediate I/O Update command. This command will force the PLC to update the I/O at other times although this would be a special case.One major item of concern about the first output update is the initial state of outputs.This is a concern because their may be outputs that if initially turned on could create a safety hazard, particularly in a system which is controlling heavy mechanical devices capable of causing bodily harm to operators. In some systems, all outputs may need to be initially set to their off state to insure the safety of the system. However, there may be systems that require outputs to initially be set up in a specific way, some on and some off. This could take the form of a predetermined setup or could be a requirement that the outputs remain in the state immediately before power-down. More recent systems have provisions for both setup options and even a combination of the two. This is a prime concern of the engineer and programmer and must be defined as the system is being developed to insure the safety of personnel that operate and maintain the equipment. Safety as related to system and program development will be discussed in a later chapter.1.4 Solve the LadderAfter the I/O update has been accomplished, the PLC begins executing the commands programmed into it. These commands are typically referred to as the ladder diagram. The ladder diagram is basically a representation of the program steps using relay contacts and coils. The ladder is drawn with contacts to the left side of the sheet and coils to the right.This is a holdover from the time when control systems were relay based.This type of diagram was used for the electrical schematic of those systems.A sample ladder diagram is shown in Figure 2-6.Figure 2-6 Sample Ladder DiagramThe symbols used in Figure 2.6 may be foreign at this point, so a short explana ---tion will be necessary. The symbols at the right of the ladder diagram labeled CR1, CR2, CR3 and CR4 and are circular in shape are the software coils of the relays. The symbols at the left which look like capacitors, some with diagonal lines through them , are the contacts associated with the coils. The symbols that look like capacitors with --out the diagonal lines through them are normally open contacts. These are analogous to a switch that is normally off. When the switch is turned on, the contact closes. The contact symbols at the left that look like capacitors with diagonal lines through them are normally closed contacts. A normally closed contact is equivalent to a switch that is normally turned on. It will turn off when the switch is actuated.As can be seen in Figure 2.6, contact and coil position is as described above. Also, one can see the reason for the term ladder diagram if the rungs of a stepladder are visualized. In fact, each complete line of the diagram is referred to as one rung of logic. The actual interpretation of the diagram will also be discussed later although some explanationis required here.The contact configuration on the left side of each rung can be visualized as switches and the coils on the right as lights.If the switches are turned on and off in the proper configuration, the light to the right will illuminate.The PLC executes this program from left to right and top to bottom, in that order.It first looks at the switch (contact) configuration to determine if current can be passed to the light (coil).The data for this decision comes from the output and input image registers.If current can be passed, the light (coil) will then be turned on.If not, the light (coil) will be turned off.This is recorded in the output image register Once the PLC has looked at the left side of therung it ignores the left side of the rung until the next time it solves that particular rung. Once the light (coil) has been either turned on or off it will remain in that state until the next time the PLC solves that particular rung.After solving a rung, the PLC moves on to solve the next rung in the same manner and so forth until the entire ladder has been executed and solved.One rule that is different from general electrical operation is the direction of current flow in the rung.In a ladder logic, rung current can only flow from left to right and up and down; never from right to left.As an example, in the ladder shown in Figure 2.7, coil CR1 will energize if any of thefollowing conditions exist:Figure 2.7 Illustration of allowed current flow in ladder rung1. CR7 is off, CR6 is on.2. CR7 is off, CR2 is on, CR5 is on.3. CR7 is off, CR2 is on, CR3 is on.4. CR1 is on, CR4 is on, CR3 is on.5. CR1 is on, CR4 is on, CR5 is on.You will notice that the current flow in the circuit in each of the cases listed above is from left to right and up and down. CR1 will not energize in the case listed below: CR1 is on, CR4 is on, CR2 is on, CR6 is on, CR5 is off, CR3 is off, CR7 is on.This is because current would have to flow from right to left through the CR2 contact. This is not allowed in ladder logic even though current could flow in this direction if we were to build it with real relays.Remember, we are working in the software world not the hardware world.To review, after the I/O update, the PLC moves to the first rung of ladder logic.It solves the contact configuration to determine if the coil is to be energized or de-energized.It then energizes or de-energizes the coil.After this is accomplished, it moves to the left side of the next rung and repeats the procedure.This continues until all rungs have been solved. When this procedure is complete with all rungs solved and all coils in the ladder set up according to the solution of each rung, the PLC proceeds to the next step of it's sequence, the I/O update.At I/O update, the states of all coils which are designated as outputs are transferred from the output image register to the output unit and the states of all inputs are transferred to the input image register.Note that any input changes that occur during the solution of the ladder are ignored because they are only recorded at I/O update time.The state of each coil is recorded to the output image register as each rung is solved. However, these states are not transferred to the output unit until I/O update time.Figure2.8 Scan CycleThis procedure of I/O update and solving the ladder diagram and I/O update is referred to as scanning and is represented in Figure 2.8. The period between one I/O update and the next is referred to as one Scan.The amount of time it takes the PLC to get from one I/O update to the next is referred to as Scan Time.Scan time is typically measured in milliseconds and is related to the speed of the CPU and the length of the ladder diagram that has to be solved .The slower the processor or the longer the ladder diagram, the longer the scan time of the system.The speed at which a PLC scans memory is referred to as Scan Rate.Scan rate units are usually listed in msec/K of memory being utilized for the program.As an example, if a particular PLC has a rated scan rate of 8 msec/K and the program occupies 6K of memory, it will take the PLC 48 msec to complete one scan of the program.1.5.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 thehardwired logic with soft-wired logic or so-called relay ladder logic (RLL), aprogramming 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 perfor- mance, 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 thePLC, Richard E Morley, fairly considers the PLC market as a5-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 soft ware 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 based software design because PLC-programming requires a simultaneous consideration ofhardware 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 projects1.6.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, hat is, reducing programming and debugging time and their variation, increasing flexibility of the automation 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 developerDesign 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 engineeringsystems 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 designApplication 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 designPLCPLC （programmable logical controller ）face ever more complex challenge these days. Where once they quietly relays and gave an occasional report to a corporate mainframe, they are now grounded into cells, give new jobs and new languages, and are forced to compete against a growing array of control products. For this year ’s annual PLC technology update, we queried PLC makers on these topics and moreProgramming languagesHigher level PLC programming languages have been around for some time, but latelytheir popularity has been mushrooming. As Raymond Lavelle, vice president and general manager, Siemens Energy and Automation. Inc, Programmable Controls Division, points out : ” As programmable controls are being used for more and more sophisticated operations, languages other than ladder logic become more practical, efficient, and powerful. For example, it's very difficult to write a trigonometric function using ladder logic. ” Languages gaining acceptance include Boolean, control system flowcharting, and such function chart languages as Graphtec and its variations. And these’s increasing interest in languages like C and BASIC.PLCs in process control Thus far, PLCs have not been used extensively for continuous process control. Will this continue? ”The feeling that I ’ve gotten, ” says Ken Jeannette, manager, product planning, Series One and Series Six products, at GE Frame North America, "is that PLCs will be used in the process industry but not necessarily for process control.”Several vendors-obviously betting that the opposite will happen-have introduced PLCs optimized for process applications. Rich Ryan ,manager, commercial marketing, Allen-Bradley Programmable Controls Div, cites PLCs ’ increasing use in such industries as food, chemicals,and petroleum. Ryan feel there are two types of applications in which they’re appropriate.”One,"he says, "is where the size of the process control system that's being automated doesn’t justify DCS[distributed control systems].With the starting price tags of those products being relatively high, a programmable controller makes sense for small, low loop count applications. The seconds where you have to integrate the loop closely with the sequential logic. Batch controller sere prime examples, where the sequence and maintaining the process variable are intertwined so closely that the benefits of having a programmable controller to do the sequential logic outweighs someof the disadvantages of not having a distributed control system.”Bill Barkovtz, president of Triconex, predicts that "all future controllers that come out in the process control system business will embrace a lot more PLC technology and a lot more PLC functionality than they ever did before.”中文翻译可编程逻辑控制器约翰R Hackworth，弗雷德里克 D Hackworth.可编程逻辑控制器：编程方法及应用.2.5~2.8，可编程逻辑控制器，约翰R Hackworth，弗雷德里克 D Hackworth第一版. 伦敦:普伦蒂斯霍尔出版社,2003,35~50一系统框图可编程控制器是一种专用的计算机。

Programmable logic controllerA programmable logic controller (PLC) is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusementrides, or lighting fixtures. PLC is used in many industries and machines.The PLC was invented in response to the needs of the American automotive manufacturing industry. 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. In 1968 GM Hydramatic issued a request for proposal for an electronic replacement for hard-wired relay 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. 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 of the very first 084 models that 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.Early PLCs were designed to replace relay logic systems.These PLCs were programmed in "ladder logic", which strongly resembles a schematic diagram of relay logic. 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 ladderlogic 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.The functionality of the PLChave sequential relay control, motion control, process control, distributed control systems and 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,In more recent years, small products called PLRs (programmable logic relays), are used in light industry where only a few points of I/O . a few signals coming in from the real world and a few going out) are involved, and low cost is desired. Popular names include PICO Controller, NANO PLC, and other namesimplying very small controllers. the PLRsare usually not modular or expandable, buttheir price can be two orders of magnitude less than a PLC and they still offer robust design and deterministic execution of the logic.compared with other control systemsPLCsare well-adapted to a range of automation tasks. These are typically industrial processes in manufacturing where thecost 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 systemsso the cost of a packaged PLCis 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.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 manysales, 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.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 CNCmachine) can be used to instruct machine movements.PLCsmayinclude logic for single-variable feedback analogcontrol loop, a "proportional, integral, derivative" or "PID controller". A PID loop could be used to control the temperatureof a manufacturing process, for example. Historically PLCswere 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 becomesmore 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 proprietaryalternatives and associated development environments.prospects for PLC.The 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. PLCs read limit switches, analog process variables (such as temperature and pressure), and the positions of complex positioning systems. Someuse machine vision. Onthe 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.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 PLCshave 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/Olink is used so that racks can be distributed away from the processor, reducing the wiring costs for large plants.interfacePLCs may need to interact with people for the purpose ofconfiguration, 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.PLCs have built in communications ports, usually 9-pin RS-232, but optionally EIA-485 or Ethernet. Modbus, BACnet or DF1is 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 mayhave 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.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、游乐设施或照明的装置。

In the article has analyzed the elevator loadcharacteristics, elaborated uses the trapezoid acceleration curve theelevator ideal velocity curve, unifies the frequency changer and thePLC performance, elaborated the elevator control system constitutionand the operational factor. Elaborated the elevator speed curveproduces the method, has induced the characteristic which designs byPLC constitution control system software.Key word: Load characteristics ideal velocity curve control systemsoftware design1. OutlineAlong with the urban construction unceasing development, thehigh-rise construction unceasingly increases, the elevator has thewidespread application in the national economy and the life. Theelevator took in the high-rise construction the vertical movementtransportation vehicle already and people's daily life is inseparable.In fact the elevator is according to exterior movement and so oncalling signal as well as own control rule, but calls is stochastic,the elevator is a person machine interactive control system in fact,purely is cannot satisfy the control request with the sequentialcontrol or the logical control, Therefore, the elevator control system uses the stochastic logical waycontrol. At present the elevator control generally has selected twomethods, one is uses the microcomputer to take the signal controlunit, completes the elevator signal gathering, the running status andthe function hypothesis, realizes the elevator automatic dispatch andthe collection chooses the movement function, drives the control tocomplete by the frequency changer; The second control mode (PLC)substitutes for the microcomputer realization signal collection withthe programmable controller to choose the control. Said from the control mode and the performance, these two methodscertainly not too big difference. The domestic factory mostly choosesthe second way, its reason lies in the production scale slightly, owndesign and the manufacture microcomputer control device cost ishigher; But PLC reliability high, programming convenience nimble, theantijamming ability strong, the movement stable is reliable and so onthe characteristic, therefore the present elevator control systemwidely uses the programmable controller to realize.2. Elevator ideal performance diagramIndicated according to the massive research and the experiment, theperson may accept the maximum acceleration is am <= 1.5m/s2,acceleration rate of change rho m <= the 3m/s3, elevator idealperformance diagram may divide according to the acceleration is thetriangle, the trapezoid and the sine profile, As a result of sine profile acceleration curve realization moredifficult, but the triangle curve maximum acceleration and is startingand applies the brake the section turning point acceleration rate ofchange to be bigger than the trapezoidal curve, namely + rho m jumpsto - rho m or jumps from - rho m to + rho the m acceleration rate ofchange, therefore very little uses, because the trapezoidal curve iseasy to realize and has the good acceleration rate of change frequenttarget, therefore is widely used, uses the trapezoidal accelerationcurve elevator ideal performance diagram like chart 1 to show: The intelligent frequency changer is for the elevator special-purposefrequency changer request and so on elevator nimble velocitymodulation, control and high accuracy even level which but speciallydesigns, may use for parts the general three-phase asynchronous motor,and has function and so on intellectualized software, standardconnection, menu prompt, input elevator curve and other essentialparameter. It has the debugging convenience quickly, moreover can automaticallyrealize the single multilayered function, and has the automaticoptimization deceleration curve the function, is composed the velocitymodulation system crawling time by it few, the even level distance isshort, no matter is the double winding electric motor, or electric motor suitable, its highest design speed may reach 4m/s, itsunique computer monitoring software, may choose the serial interfacerealization input/output signal the non- electronic contact control. The frequency changer constitutes elevator system, when the frequencychanger receives the controller to send out shouts the ladderdirection signal, the frequency changer basis hypothesis speed and theacceleration value, the starting motor, after achieved the maximumspeed, the uniform speed moves, when arrives the goal leveldecelerates, the controller sends out shuts off the high velocitysignal, reduces the speed which the frequency changer establishes themaximum speed to reduce to the crawling speed, In decelerates in the movement process, the frequency changer can theautomatic computation decelerate to the even level spot betweendistance, and calculates the optimized curve, thus canaccording tothe optimized curve movement, cause the low speed crawling time toreduce to 0.3s, the frequency changer through adjusts leveling thespeed in the elevator even level process or applies the brake thepitch to adjust leveling the precision. Namely when the elevator stops too early, the frequency changerincreases the low speed value or the reduction applies the brake thepitch value, otherwise reduces the low speed value or increasesapplies the brake the pitch value, when the elevator to leaves evenlevel position 4 - 10cm, has the even level switch automaticseparation low speed signal, the system according to the optimizedcurve realization high accuracy even level, thus achieved the evenlevel accurate is reliable.3. Elevator speed curveElevator movement comfortableness is decided in its movementprocess acceleration a and the acceleration rate of change p size, theoversized acceleration or the acceleration rate of change can createpassenger's ill feeling. At the same time, for guaranteed the elevatorthe operating efficiency, a, the p value not suitable excessively issmall. Can guarantee a, the p best value elevator performance diagramis called the elevator the ideal performance diagram. The elevatormovement ideal curve should be the parabola - straight linecomprehensive velocity curve, namely elevator Canada, reduces theprocess constitutes by the parabola and the straight line. Theelevator assigns the curve is whether ideal, direct influence actualperformance diagram.3.1 velocity curves have the methodUses FX2-64MR PLC, and a consideration input output requestincreased FX-8EYT, FX-16EYR, the FX-8EYR three expansions modules andthe FX2-40AW twisted pair line correspondence adapter, FX2-40AW usesin the system serial communication. Using PLC the expansion functionmodule D/A module realization speed ideal curve output, whenbeforehand the digitized ideal velocity curve stores the PLC register,the procedure movement, through looks up the table way to read in D/A,transforms the simulation quantity after D/A the speed ideal curveoutput.3.2 Acceleration assign the curve the production8 D/A outputs 0 ~ 5V/0 ~ 10V, the corresponding numerical valueis 16 enters system several 00 ~ FF, altogether 255 levels. Ifelevator rise time between 2.5 ~ 3seconds. According to theconservative value computation, in the elevator acceleration processeach time Zha Biao time-gap not suitably surpasses 10ms.As a result of elevator logic control section procedure biggest, butthe PLC movement uses the cyclical scanning mechanism, thus usuallyuses looks up the table method, Zha Biao instruction time-gapexcessively is each time long, cannot satisfiedly assign the curve theprecision request. In the PLC movement process, its CPU with variousequipment between exchange of information, user program execution,signal gathering, control quantity operation and so on output all isdefers to the fixed order to circulate the scanning way to carry on,each circulation all must carry on the inquiry, the judgement and theoperation to all functions. This kind of order and the form capableperson are not the change. The usual scanning cycle, is basic mustcomplete six steps the work, including movement surveillance, andprogramming exchange information, and digital processor exchangeinformation, and communication processor exchange information,execution user program and input output connection service and so on.In a cycle, CPU only carries out to the entire user program. This kindof mechanism has its convenient one side, but timeliness is bad. Theexcessively long scanning time, directly affects the system to thesignal response effect, in under the guarantee control functionpremise, maximum limit reduces CPU the cyclical scanning time is avery complex question. Generally only can short adopt the method fromthe user program execution time. The elevator logic control sectionprocedure scanning time has surpassed 10ms, although has adopted somereduced procedure scanning time means, but still will be unable toscan the time to fall to 10ms below. At the same time, applies thebrake the section curve to use according to is away from theprinciple, each section of distances arrive the response time notsuitably surpasses 10ms. In order to satisfy the system the timelyrequest, in the velocity curve production way, uses the severancemethod, thus effectively has overcome the PLC scanning mechanismlimit.The starting acceleration movement by decides the cycle interruptservice isr to complete. This kind of severance cannot carry on theswitch by the procedure, once establishes, continuously presses thehypothesis time-gap circulation severance,therefore, the startingmovement condition must put in the interrupt service isr, when doesnot satisfy the movement condition, the severance namely returns.3.2 Decelerates applies the brake the curve productionIn order to guarantee applies the brake process completing,must carry on in the master routine applies the brake the condition tojudge and to decelerate a determination. In decelerates before adetermination, the elevator continuously is in the acceleration or thesteady fast movement process. The acceleration process completes bythe fixed cyclical severance, accelerates after the correspondingpattern maximum value, the acceleration procedure movement conditionno longer satisfies, after each time severs, no longer carries out theacceleration procedure, directly returns from the severance. Theelevator corresponds the pattern the maximum value movement,decelerates in this pattern to after, has the high-speed countingseverance, the execution decelerates the service routine. Revises thecounter in this interrupt service isr to suppose the definite valuethe condition, guaranteed the next time will sever the execution. In the PLC internal register, deceleration curve table value from big to small , each time severs all carries out time "theindicator needle to add 1" the operation, then the next severance willlook up the table number is smaller than this severance to look up the table numbers. Thegate area peaceful level area judgement produces by exterior signal,guarantees the moderating process the reliability.4. Elevator control system4.1 Elevators control system characteristicIs relates the elevator movement comfortable feeling target in theelevator performance diagram start section the key link, but thecomfortable feeling with the acceleration direct correlation,according to controls the theory, must cause some quantity accordingto prearrange the rule change to have to carry on the positivegoverning to it, said regarding the elevator control system, mustcause the acceleration to have to use the acceleration feedbackaccording to the ideal curve change, according to electric motormoment of force equation: M - MZ= Delta M=J (dn/dt), obviously theacceleration rate of change had reflected the system dynamic extensionis apart from the change, the control acceleration is apart from DeltaM=M - MZ on the control system dynamic extension. Therefore uses theacceleration in thissection the timing control principle, when thestart ascent portion speed achieved when stable state value 90%,systematically will cut the speed control from the accelerationcontrol, because in the steady fast section, the speed will besmaller for the permanent value control undulation, the accelerationchange will not be big, also will use the speed closed-loop controlto be allowed to cause the stable state speed hold certain precision,will be applies the brake the section precise even level to create thecondition. Uses the PI regulator control in the system speed ascentportion and steady fast Duan Suidu, but two section of PI parameter isdifferent, enhances the system the dynamic response target.Applies the brake the section in the system, namely must to reduce thespeed to carry on the essential control, guarantees the comfortablefeeling, also must strictly controls according to the elevatormovement speed and the distance relations, guarantees the even levelthe precision. In system’s rotational speed reduces to 120r/min in front of, in orderto enable two to obtain the proper attention to both, adopts by theacceleration to the timing control primarily, simultaneously actsaccording to on each as soon as the stopping distance the actualrotational speed and the theory rotational speed deviation revises theacceleration to assign the curve the method. For example in is awayfrom the even level spot some as soon as to be away from L place, thespeed should reduce to Vm/s, but the actual rotational speed is highis V ' m/s, then explained adds the system turns is apart frominsufficiently, after therefore calculates the here to assign reducesspeed value -ag, causes it to add on a negative deviation againepsilon, even if the here reduces the speed given value to revise for- (ag+ epsilon) causes to assign reduces the speed and the true speednegative deviation enlarges, thus enlarged the system to turn thedistance, caused the speed very quickly to fall to the standard value,when electric motor’s rotational speed reduces to 120r/min after, this time thetheater box above the level only had several centimeters, The elevatorrunning rate is very low, for did not prevent phenomenon appearancewhich stops to the even level area, enables the elevator comparativelyquickly to enter the even level area, uses the proportional control inthis section, and uses the time optimization control, guaranteed theelevator accurately promptly enters the even level area, achieves theaccurate reliable even level.4.2 elevators controls constitutionBecause the elevator movement is according to the floor and the theater box calling signal, the travelling schedule signalcarries on the control, but the floor and the theater box call isstochastic, therefore, the systems control uses the stochastic logicalcontrol. Namely in realizes in the elevator basic control requestfoundation by the smooth logic control, according to stochastic inputsignal, as well as elevator corresponding condition at the rightmoment control elevator movement. Moreover, the theater boxposition is determined by the pulse encoder pulse number that, anddelivers PLC the counter to carry on the control. At the same time,each building establishes to approach the switch to use in to examinethe system the floor signal. In order to be advantageous for the observation, is at the floor tothe elevator movement direction as well as the elevator to carry onthe demonstration, uses LED and the photo tube demonstrated, but tothe floor and the theater box calling signal to the indicating lampdemonstrated (on switch has indicating lamp).In order to enhance the elevator the operating efficiency peacefullevel precision, the system requests PLC to be able to theater boxCanada, to decelerate as well as to apply the brake to carry on theeffective control. Realizes according to the theater box physicallocation as well as the exchange velocity modulation system controlalgorithm. For the elevator movement security, the system shouldestablish the reliable fail safe and the corresponding es the PLC realization the elevator control system to constitute byfollowing several main parts.4.2.1 PLC control circuit; PLC receives shouts the ladder from thepanel board and each level to summon the signal, the theater boxand the gate system function signal as well as the well and thefrequency changer condition signal, realizes the elevator collectionafter the procedure judgement and the operation to choose the control.PLC during the output demonstration and supervisory signal, sends outthe movement direction, the start, Canada to the frequencychanger/decelerates moves and applies the brake to stop the ladderequisignal.4.2.2 electric currents, speed double closed loops electric circuit;Frequency changer itself is equipped with the electric currentdetector set, from this constitution electric current closed loop;Through revolves the encoder with the electricalmachinery coaxialjoint, produces a, the b two pulses enters the frequency changer,during confirmation direction, counts the constitution speed closedloop using the pulse.4.2.3 displacements control circuit; The elevator took one kindcarries the person tool, reigns under the potential state of loading,besides request safe reliable, but also requests the movement to besteady, rides comfortably, anchors accurately. Uses the frequencyconversion to modulate velocity Shuanghuan to control may basicallyanswer the purpose, the use existing revolves the encoder toconstitute the speed ring at the same time, moves the proportionthrough the frequency changer PG card output and the electricalmachinery speed and the elevator the pulse number, introduces it PLChigh-speed counting to input the port, through the accumulation pulsenumber, (1) calculates the pulse equivalent after the type, from thisdefinite elevator position. Elevator displacement H=SI In the formula I - accumulation pulse number; S - pulse equivalent; S = plD/(pr) (1) L – Proportion of decelerates ; D - tows the wheel diameter; P - revolves the encoder every time to transfer corresponding thepulse number; R - PG card frequency division ratio.4.2.4 ends stations protection; When in elevator direction detectionline, on the good directional relay, the express train assistancecontact device, the express train movement contact device, the doorlock relay, on the good contact device electricity attracts gathers, mechanical floodgate opens, on elevator line. When the theater box bumps intoforces speed changeing the switch, the PLC internal lock saves the relay toresult in the electricity to attract gathers, timer Tim10, Tim11 startfixed time, it fixed time time length visible end station leveldistance with ladder fast hypothesis. After on forces speed changing theswitch movement, the elevator transfers the slow train movement by theexpress train movement, in the normal condition, the previous line ofeven strata time elevator should stop. If the theater box has notstopped continues the line, when Tim10 supposes the definite value toreduce the zero hour, it the separation, the slow traincontact device and on the good contact device loses the electricity,the elevator stops moving. Bumps into after the arrogant theater boxon forces speed changing the switch, because certain reason elevators have notbeen able to transfer the slow train movement, and the express trainmovement contactdevice has not been able to release, when Tim11supposes the definite value to reduce the zero hour, it N.C. contactthe separation, the express train movement contact device and on thegood contact device loses the electricity, the elevator stops moving.Therefore, no matter is the slow train movement or the express trainmovement, so long as on forces speed changing the switch to send out thesignal, no matter the end stands other protection switches whetheract, can cause the elevator with the aid of Tim10 and Tim11 to stopmoving, thus causes the elevator end station protection to be morereliable.Under when the elevator needs the line, so long as had has chosen theladder instruction, got down the good directional relay to result inelectricity its Chang Kaidian closed, the lock saved the relay toreposition, Tim10 and Tim11 lost the electricity, it N.C. contactclosed for the elevator normal under line has prepared for. The lowerextremity stands the protection principle and the upper extremestation protection similar no longer duplicates.4.2.5 floors count; The floor counts uses relatively counts the way.Before the movement through from the study way, determines thecorresponding floor highly pulse number, corresponds 17 elevatorsseparately to store 16 memories units DM06 ~ DM21. The floor counter(CNT46) is a bidirectional counter, when arrives each level the floorcounts, according to moves the direction to carry on adds 1 or reduces1 to count. In the movement, the high speed counter tiredly estimates the valuereal-time counts the point correspondence pulse number with the floorto carry on the comparison, is equal when sends out the floor to countthe signal, the previous line of Canada 1, the next line reduces 1. Inorder to prevent the counter in counts the pulse high level periodrepetition to count, uses the floor to count on the signal along totrigger the floor counter.4.2.6 is fast speed changing; When the high speed counter value and the fastspeed changing point correspondence pulse number is equal, if the elevator isin the quick operating also this level has chooses the level signal,sends the fast speed changing signal. If the elevator medium speed movement oralthough the quick operating but this not chooses the level signal,then does not send speed changing the signal.4.2.7 areas signals; When high speed counter CNT47 value correspondsin the pulse number scope when the gate area, sends the gate areasignal.4.2.8 pulses signals failure detection; Pulse signal accurategathering and the transmission appears in the system especiallyimportantly, revolves the encoder for the examination and the pulsetransmission circuit breakdown, whether there is has designed thepulse signal and the errors and omissions pulse examination electriccircuit, guarantees the system normal operation through the real-timeexamination. In order to eliminate the pulse to count the accumulativeerror, in base station the establishment reset switch, turns on PLC highspeed counter CNT47 the replacement end.5. Software design characteristic5.1 uses the priority formationPosition and movement direction locates which according to theelevator, in the programming, has used four priorities formations,namely on good priority formation, on line of inferior priorityformation, under good priority formation, next line of inferiorpriority formation. When among them, on good priority formation forelevator upward movement, locates the upward movement calling signalin the elevator which above the position the floor sends out, thearray which should call which the signal cabin correspondence thefloor to have the pulse number depositing register constitutes. Whenprevious line of inferior priority formation for elevator upwardmovement, locates the upward movement calling signal in the elevatorwhich below the position the floor sends out, the formation whichshould call which the signal cabin correspondence the floor to havethe pulse number depositing register constitutes. Control system inelevator movement real-time arrangement four priorities exhibition,has provided the foundation for the realization stochastic logiccontrol.5.2 uses advanced first leaves the formationAccording to elevator movement direction, with to the priorityformation's in non-vanishing unit (has when call this unit is 70units, does not have when call then this unit for zero) (advancedsends in the register formation first to leave formation FIFO), theuse advanced first leaves the read-out instruction SFRDP instruction,sends in the FIFO first unit in data compares the register.5.3 uses the stochastic logical controlWhen the elevator approaches by some movement direction somefloor decelerates the position, distinguished whether this floor doeshave with to the calling signal (on a line of call symbolizedregister, next line of call symbolized when register, has callrequest, corresponding register is l, otherwise is 0), if has, thecorresponding register pulse number and the comparison register willcarry on the comparison, if will be same, then will decelerate in thisfloor stops: If is not same, then sends in this register data comparesthe register, and the original comparison register data preservation,carries out this floor to decelerate stops. After this movementfinished, the data which will preserve reis sent in compares theregister, will realize the stochastic logical control.5.4 uses the software demonstration The system use travelling schedule judgement floor, andtransforms the BCD code output, through hardware connection electriccircuit by LED demonstration.5.5 pair of frequency changers control PLC acts according to the stochastic logical control therequest, may send out to the frequency changer to the movement, thereverse movement, is decelerating as well as applies the brake thesignal, again controls the electrical machinery by the frequencychanger basis certain control rule and the control algorithm. At thesame time, when the system appears the breakdown, PLC to the frequencychanger sends out the signal.6. Concluding remark Uses elevator control system which the MIC340 elevatorspecial-purpose frequency changer constitutes, may realize theintellectualization which the elevator controls, but because theperiod of five days ladder and the elevator in person arrives eachlevel the population is the intelligent elevator is unable todetermine, even if uses the AITP artificial intelligence system, thetransmission transportation passenger flow information also is fuzzy,for solves the elevator this vertical transportation control systemtwo to be big cannot know the factor, will need us to go to theunceasing research and the exploration in the next work.译文:文中分析了电梯的负载特性，阐述了采用梯形加速曲线的电梯理想速度曲线，结合变频器和PLC的性能，论述了电梯控制系统的构成和工作特性。

Programmable logic controllerA programmable logic controller(PLC)is a digital computer used for automation of electromechanical processes,such as control of machinery on factory assembly lines,amusement rides,or lighting fixtures.PLC is used in many industries and machines.1.HistoryThe PLC was invented in response to the needs of the American automotive manufacturing industry.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. In1968GM Hydramatic issued a request for proposal for an electronic replacement for hard-wired relay systems.The first PLC,designated the084because 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.The Modicon brand was sold in1977to Gould Electronics,and later acquired by German Company AEG and then by French Schneider Electric,the current owner.One of the very first084 models that was presented to Modicon by GM,when the unit was retired after nearly twenty years of uninterrupted service.Modicon used the84moniker at the end of its product range until the984made its appearance.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.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.3.FunctionalityThe functionality of the PLC have sequential relay control,motion control, process control,distributed control systems and networking.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 computersrun 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, In more recent years,small products called PLRs(programmable logic relays), 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. Popular names include PICO Controller,NANO PLC,and other names implying very small controllers.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 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.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.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 machinemovements.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 IEC61131-3functional block language for creating programs to run on RTUs and PLCs,although nearly all vendors also offer proprietary alternatives and associated development environments.5.The prospects for PLC.5.1.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.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.5.2System 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.5.3User 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.5.4CommunicationsPLCs have built in communications ports,usually9-pin RS-232,but optionally EIA-485or Ethernet.Modbus,BACnet or DF1is 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.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、游乐设施或照明的装置。

机械专业中英文文献翻译Elevator System Based on PLCComposed by the order of relay control system is a realization of the first elevator control method. However, to enter the nineties, with the development of science and technology and the widespread application of computer technology, the safety of elevators, reliability of the increasingly high demand on the relay control weaknesses are becoming evident.Elevator control system relays the failure rate high, greatly reduces the reliability and safety of elevators, and escalators stopped often to take with the staff about the inconvenience and fear. And the event rather than taking the lift or squat at the end of the lift will not only cause damage to mechanical components, but also personal accident may occur.Programmable Logic Controller (PLC) is the first order logic control in accordance with the needs of developed specifically for industrial environment applications to operate the electronic digital computing device. Given its advantages, at present, the relay control the lift has been gradually replaced by PLC control. At the same time, AC variable frequency motor speed control technology, the way the lift drag speed has been a gradual transition from DC to AC frequency converter. Thus, PLC control technology increases VVVF Elevator modern technology has become a hot industry.1. PLC elevator control advantages(1) used in elevator control PLC, with software for automatic control of liftoperation, reliability greatly increased.(2) layer was removed and a majority of the relay, the control system structure issimple, to simplify the external circuit.(3) PLC can be a variety of complex control system, easy to add or changecontrol functions.(4) PLC can be automated fault detection and alarm display to improve theoperation of security and ease of maintenance.(5) for the group control the allocation and management, and improve theefficiency of elevator operation.(6) do not need to change the control scheme changes when the hardware connection.2. VVVF elevator control characteristicsWith the power electronics, microelectronics and computer technology to control the rapid development of technology, communication technology VVVF also a very rapid rate. AC variable frequency motor speed control technology is the power to improve the process in order to improve product quality and improving the environment and promoting technological progress as a primary means. Frequency of its excellent performance and the speed brake from a smooth performance, high efficiency, high power factor and power-saving effect of a broad scope of application and many other advantages of being at home and abroad recognized as the most promising approach speedExchange characteristics of VVVF Elevator(1)low energy consumption(2) low load circuit, the required emergency power supply device of smallIn the acceleration stage, the required start-up current of less than 2.5 times the rated current. Peak starting current and time is short. Since the starting current is drastically reduced, so power consumption and power supply cable diameter can be reduced a lot. Required for emergency power supply devices are also relatively small size.(3) high reliability and long service life.(4) good comfortElevator operation is best to follow the speed curve of a given operation. Their characteristics can be adapted to human feelings, and to ensure that noise operation, smooth brakePing layer and high precision(5) Stable noise-free(6) In the car, the engine room and adjacent areas to ensure that noise. Because their systems use a high clock frequency. Always produce a true sine wave power supply current yet. Motor torque ripple does not appear. Therefore, to eliminate vibration and noise.3. Elevator control technologyThe so-called elevator control technology refers to the elevator drive system and electrical control system of automatic control. 70 as the 20th century in China's elevator was marked by the exchange of two-speed elevator. Its speed is used to change the elevator traction motor of the very few, two or multi-level approach to the number of windings, very few of them as high-speed winding of the winding, a very few number of windings as the low-speed winding. Windings for high-speedelevator-speed start-up and running, low-speed windings for braking and the maintenance of elevators.The early 80s, VVVF inverter controlled variable lift system available. It uses AC motor drives, are able to reach the level of DC motor, control the speed of the current has reached 6 m / sec. Its small size, light weight, high efficiency, energy saving, including the past almost all the advantages of the lift. Is the latest elevator drive system.Operation in vertical lift, there is also the starting point of the terminus station. For more than three-story elevator buildings, the starting point of the terminal stations and stops between the had not, the starting point for these stations at the first floor of the terminal located at the highest floor. Starting point in the first floor of the station known as base stations, known as the starting point at both ends of the terminal stations and stations at both ends of intermediate stops between stations.Outside the station has a call box, box set are used by staff for elevator call button or touch the call button, the general ends of the lift stations in the call box on the Settings button or touch of a button. Middle layer of the station set up the call box button or touch button 2. No drivers for the control of elevators, at various stations are set up calls me on a button or touch button. Elevator car and the internal settings (except for debris elevator) to manipulate me. Control box switch on the handle or set up stations and the corresponding layer of buttons or touch-button control box on the touch-control button or command button or touch the city button. Outside the command button or touch-button issue as the signal outside the command signal, within the command button or touch-button issue within the signal as a command signal. 80 In the mid-20th century, the touch button has been replaced by micro-button.As the elevator call box outside the base station, in addition to set up a call button or touch button, but also set a key switch in order to work the elevator clearance. Drivers or management staff to open the elevator to the base station can wriggle through a dedicated key to the key switch. Close the elevator in place to automatically cut off the elevator control power supply or power supply.4. PLC Control Elevator DesignWith the continuous development of urban construction, the increasing high-rise buildings, elevators and life in the national economy has a broad application. Elevator high-rise buildings as a means of transport in the vertical run of daily life has beeninextricably linked with people. In fact the lift is based on external call control signals, as well as the laws of their own, such as running, and the call is random, the lift is actually a man-machine interactive control system, simple to use control or logic control order can not meet the control requirements, and therefore , elevator control system uses a random control logic. Elevator control is currently generally used in two ways, first, the use of computer as a signal control unit, the completion of the lift signal acquisition, operation and function of the set, to achieve the lift and set the automatic scheduling function to run the election, drag the control from inverter to complete; the second control mode with programmable logic controller (PLC) to replace the computer control signal sets the election. From the control and performance, these two types of methods and there is no significant difference. Most of the domestic manufacturers to choose the second approach, because the smaller scale of production, their design and manufacture of high cost of computer control devices; and PLC high reliability, convenient and flexible program design, anti-interference ability, stable and reliable operation of the characteristics of Therefore, the elevator control system is now widely used to realize programmable controller.5. Elevator control system characteristicsOperation of the lift curve is above the start to run comfort indicators lift the key features, and comfort are directly related with the acceleration, according to control theory, for a certain amount of change according to the law must be directly controlled, for elevator control system, according to the ideal acceleration curve acceleration feedback to be used, in accordance with the motor torque equation: M-MZ = ΔM = J (dn / dt), can be seen reflected in the rate of change of acceleration of the system of dynamic torque changes on the control system to control the acceleration of the dynamic torque ΔM = M-MZ. Therefore, during this time to control the use of the principle of acceleration, when the start rate of increase in steady-state value above 90%, the acceleration control system by the switch to speed control, as in paragraph steady speed, speed control for the constant fluctuations in the smaller, little change in acceleration, speed and the use of closed-loop control can maintain a steady-state speed accuracy and precision for the braking section to create the conditions ping layer. Is rising at a rate in the system, and although the above-speed PI regulator used to control, but two of the PI parameters are different in order to improve the system dynamic response indicators. The brake in the system,that is, to reduce the speed of control necessary to ensure the comfort, but also strictly in accordance with the operation of the lift of the relationship between speed and distance control to ensure the accuracy of flat layers. To the speed in the system before 120r/min, in order to take into account both be taken to control the acceleration of time-based and at the same time in each braking distance based on actual speed and speed deviations from the theory to fix the acceleration curve of a given method. For example, from a flat layer at the distance L, the speed should be reduced to Vm / s, while the actual high speed V'm / s, is illustrated by the increase in the braking torque is not enough here, therefore to calculate value determined by the speed-ag after it combined with a negative deviation of ε, even here the value given by the speed of amended - (ag + ε) so that a given rate of deceleration and the actual increase of negative bias, which increases braking torque big, so fast down to the standard value, when the motor speed 120r/min down after the car at this time only a dozen or so cm layer anomaly, low speed lift, in order to prevent yet floor parking area on the phenomenon in order to enable faster access to the lift to floor area ratio adjustment used in this paragraph and the use of optimal control of time in order to ensure accurate and timely access to elevator floor area, in order to achieve accurate and reliable level layer.PLC控制下的电梯系统由继电器组成的顺序控制系统是最早的一种实现电梯控制的方法。