PLC及变频器技术论文中英文资料对照外文翻译文献综述

(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。

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。

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

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中英文资料对照外文翻译中英文对照外文翻译The development and future of PLCPart 1 PLC overviewProgrammable controller is the first in the late 1960s in the United States, then called PLC programmable logic controller (Programmable Logic Controller) is used to replace relays. For the implementation of the logical judgment, timing, sequence number, and other control functions. The concept is presented PLC General Motors Corporation. PLC and the basic design is the computer functional improvements, flexible, generic and other advantages and relay control system simple and easy to operate, such as the advantages of cheap prices combined controller hardware is standard and overall. According to the practical application of target software in order to control the content of the user procedures memory controller, the controller and connecting the accused convenient target.In the mid-1970s, the PLC has been widely used as a central processing unit microprocessor, import export module and the external circuits are used, large-scale integrated circuits even when the PLC is no longer the only logical (IC) judgment functions also have data processing, PID conditioning and data communications functions. International Electro technical Commission (IEC) standards promulgated programmable controller for programmable controller draft made the following definition : programmable controller is a digital electronic computers operating system, specifically for applications in the industrial design environment. It used programmable memory, used to implement logic in their internal storage operations, sequence control, timing, counting and arithmetic operations, such as operating instructions, and through digital and analog input and output, the control of various types of machinery or production processes. Programmable controller and related peripherals, and industrial control systems easily linked to form a whole, to expand its functional design. Programmable controller for the user, is a non-contact equipment, the procedures can be changed to change productionprocesses. The programmable controller has become a powerful tool for factory automation, widely popular replication. Programmable controller is user-oriented industries dedicated control computer, with many distinctive features.Part 2 History of PLCProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic or so-called relay ladder logic (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days [Moody and Morley, 1999].Although PC based control has started to come into place, PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability in harsh environments. Moreover, according to a study on the PLC market of Frost and Sullivan [1995], an increase of the annual sales volume to 15 million PLCs per year with the hardware value of more than 8 billion US dollars has been predicted, though the prices of computing hardware is steadily dropping. The inventor of the PLC, Richard E Morley, fairly considers the PLC market as a 5-billion industry at the present time.Though PLCs are widely used in industrial practice, the programming of PLC based control systems is still very much relying on trial-and-error. Alike software engineering, PLC software design is facing the software dilemma or crisis in a similar way. Morley himself emphasized this aspect most forcefully by indicating`If houses were built like software projects, a single woodpecker could destroy civilization.”Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old ladder logic programs. Though the hardware costs of PLCs are dropping continuously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLCs can be used.In general, the productivity in generating PLC is far behind compared to other domains, for instance, VLSI design, where efficient computer aided design tools are inpractice. Existent software engineering methodologies are not necessarily applicable to the PLC based software design because PLC-programming requires a simultaneous consideration of hardware and software. The software design becomes, thereby, more and more the major cost driver. In many industrial design projects, more than of the manpower allocated for the control system design and installation is scheduled for testing and debugging PLC programs.In addition, current PLC based control systems are not properly designed to support the growing demand for flexibility and reconfigurability of manufacturing systems. A further problem, impelling the need for a systematic design methodology, is the increasing software complexity in large-scale projects.The objective of this thesis is to develop a systematic software design methodology for PLC operated automation systems. The design methodology involves high-level description based on state transition models that treat automation control systems as discrete event systems, a stepwise design process, and set of design rules providing guidance and measurements to achieve a successful design. The tangible outcome of this research is to find a way to reduce the uncertainty in managing the control software development process, that is, reducing programming and debugging time and their variation, increasing flexibility of 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 developer.Part 3 Now of PLCFrom the structure is divided into fixed PLC and Module PLC, the two kinds of PLC including CPU board, I/O board, display panel, memory block, power, these elements into a do not remove overall. Module type PLC including CPU module, I/O modules, memory, the power modules, bottom or a frame, these modules can be according to certain rules combination configuration.In the user view, a detailed analysis of the CPU's internal unnecessary, but working mechanism of every part of the circuit. The CPU control works, by it reads CPU instruction, interprets the instruction and executes instructions. But the pace of work by shock signal control.Unit work under the controller command used in a digital or logic operation.In computing and storage register of computation result, it is also among the controller command and work. CPU speed and memory capacity is the important parameters for PLC , its determines the PLC speed of work, IO PLC number and software capacity, so limits to control size.Central Processing Unit (CPU) is the brain of a PLC controller. CPU itself is usually one of the microcontrollers. Aforetime these were 8-bit microcontrollers such as 8051, and now these are 16-and 32-bit microcontrollers. Unspoken rule is that you’ll find mostly Hitachi and Fujicu microcontrollers in PLC controllers by Japanese makers, Siemens in European controllers, and Motorola microcontrollers in American ones. CPU also takes care of communication, interconnectedness among other parts of PLC controllers, program execution, memory operation, overseeing input and setting up of an output.System memory (today mostly implemented in FLASH technology) is used by a PLC for a process control system. Aside form. this operating system it also contains a user program translated forma ladder diagram to a binary form. FLASH memory contents can be changed only in case where user program is being changed. PLC controllers were used earlier instead of PLASH memory and have had EPROM memory instead of FLASH memory which had to be erased with UV lamp and programmed on programmers. With the use of FLASH technology this process was greatly shortened. Reprogramming a program memory is done through a serial cable in a program for application development.User memory is divided into blocks having special functions. Some parts of a memory are used for storing input and output status. The real status of an input is stored either as “1”or as “0”in a specific memory bit/ each input or output has one corresponding bit in memory. Other parts of memory are used to store variable contents for variables used in used program. For example, time value, or counter value would be stored in this part of the memory.PLC controller can be reprogrammed through a computer (usual way), but also through manual programmers (consoles). This practically means that each PLC controller can programmed through a computer if you have the software needed for programming. Today’s transmission computers are ideal for reprogramming a PLC controller in factory itself. This is of great importance to industry. Once the system is corrected, it is also important to read the right program into a PLC again. It is also good to check from time totime whether program in a PLC has not changed. This helps to avoid hazardous situations in factory rooms (some automakers have established communication networks which regularly check programs in PLC controllers to ensure execution only of good programs).Almost every program for programming a PLC controller possesses various useful options such as: forced switching on and off of the system input/outputs (I/O lines), program follow up in real time as well as documenting a diagram. This documenting is necessary to understand and define failures and malfunctions. Programmer can add remarks, names of input or output devices, and comments that can be useful when finding errors, or with system maintenance. Adding comments and remarks enables any technician (and not just a person who developed the system) to understand a ladder diagram right away. Comments and remarks can even quote precisely part numbers if replacements would be needed. This would speed up a repair of any problems that come up due to bad parts. The old way was such that a person who developed a system had protection on the program, so nobody aside from this person could understand how it was done. Correctly documented ladder diagram allows any technician to understand thoroughly how system functions.Electrical supply is used in bringing electrical energy to central processing unit. Most PLC controllers work either at 24 VDC or 220 V AC. On some PLC controllers you’ll find electrical supply as a separate module. Those are usually bigger PLC controllers, while small and medium series already contain the supply module. User has to determine how much current to take from I/O module to ensure that electrical supply provides appropriate amount of current. Different types of modules use different amounts of electrical current.This electrical supply is usually not used to start external input or output. User has to provide separate supplies in starting PLC controller inputs because then you can ensure so called “pure” supply for the PLC controller. With pure supply we mean supply where industrial environment can not affect it damagingly. Some of the smaller PLC controllers supply their inputs with voltage from a small supply source already incorporated into a PLC.Part 4 PLC design criteriaA systematic approach to designing PLC software can overcome deficiencies in thetraditional way of programming manufacturing control systems, and can have wide ramifications in several industrial applications. Automation control systems are modeled by formal languages or, equivalently, by state machines. Formal representations provide a high-level description of the behavior of the system to be controlled. State machines can be analytically evaluated as to whether or not they meet the desired goals. Secondly, a state machine description provides a structured representation to convey the logical requirements and constraints such as detailed safety rules. Thirdly, well-defined control systems design outcomes are conducive to automatic code generation- An ability to produce control software executable on commercial distinct logic controllers can reduce programming lead-time and labor cost. In particular, the thesis is relevant with respect to the following aspects.In modern manufacturing, systems are characterized by product and process innovation, become customer-driven and thus have to respond quickly to changing system requirements. A major challenge is therefore to provide enabling technologies that can economically reconfigure automation control systems in response to changing needs and new opportunities. Design and operational knowledge can be reused in real-time, therefore, giving a significant competitive edge in industrial practice.Studies have shown that programming methodologies in automation systems have not been able to match rapid increase in use of computing resources. For instance, the programming of PLCs still relies on a conventional programming style with ladder logic diagrams. As a result, the delays and resources in programming are a major stumbling stone for the progress of manufacturing industry. Testing and debugging may consume over 50% of the manpower allocated for the PLC program design. Standards [IEC 60848, 1999; IEC-61131-3, 1993; IEC 61499, 1998; ISO 15745-1, 1999] have been formed to fix and disseminate state-of-the-art design methods, but they normally cannot participate in advancing the knowledge of efficient program and system design.A systematic approach will increase the level of design automation through reusing existing software components, and will provide methods to make large-scale system design manageable. Likewise, it will improve software quality and reliability and will be relevant to systems high security standards, especially those having hazardous impact on the environment such as airport control, and public railroads.The software industry is regarded as a performance destructor and complexity generator. Steadily shrinking hardware prices spoils the need for software performance interms of code optimization and efficiency. The result is that massive and less efficient software code on one hand outpaces the gains in hardware performance on the other hand. Secondly, software proliferates into complexity of unmanageable dimensions; software redesign and maintenance-essential in modern automation systems-becomes nearly impossible. Particularly, PLC programs have evolved from a couple lines of code 25 years ago to thousands of lines of code with a similar number of 1/O points. Increased safety, for instance new policies on fire protection, and the flexibility of modern automation systems add complexity to the program design process. Consequently, the life-cycle cost of software is a permanently growing fraction of the total cost. 80-90% of these costs are going into software maintenance, debugging, adaptation and expansion to meet changing needs.Today, the primary focus of most design research is based on mechanical or electrical products. One of the by-products of this proposed research is to enhance our fundamental understanding of design theory and methodology by extending it to the field of engineering systems design. A system design theory for large-scale and complex system is not yet fully developed. Particularly, the question of how to simplify a complicated or complex design task has not been tackled in a scientific way. Furthermore, building a bridge between design theory and the latest epistemological outcomes of formal representations in computer sciences and operations research, such as discrete event system modeling, can advance future development in engineering design.From a logical perspective, PLC software design is similar to the hardware design of integrated circuits. Modern VLSI designs are extremely complex with several million parts and a product development time of 3 years [Whitney, 1996]. The design process is normally separated into a component design and a system design stage. At component design stage, single functions are designed and verified. At system design stage, components are aggregated and the whole system behavior and functionality is tested through simulation. In general, a complete verification is impossible. Hence, a systematic approach as exemplified for the PLC program design may impact the logical hardware design.Part 5 AK 1703 ACPFollowing the principle of our product development, AK 1703 ACP has highfunctionality and flexibility, through the implementation of innovative and reliable technologies, on the stable basis of a reliable product platform.For this, the system concept ACP (Automation, Control and Protection) creates the technological preconditions. Balanced functionality permits the flexible combination of automation, telecontrol and communication tasks. Complemented with the scalable performance and various redundancy configurations, an optimal adaptation to the respective requirements of the process is achieved.AK 1703 ACP is thus perfectly suitable for automation with integrated telecontrol technology as:• Telecontrol substation or central device• Automation unit with autonom ous functional groups• Data node, station control device, front-end or gateway• With local or remote peripherals• For rear panel installation or 19 inch assembly• Branch-neutral product, therefore versatile fields of application and high product stability• Versatile communication• Easy engineering• Plug & play for spare parts• Open system architecture• Scalable redundancy• The intelligent terminal - TM 1703The Base Unit AK 1703 ACP with Peripheral Elements has one basic system element CP-2010/CPC25 (Master control element) and CP-2012/PCCE25 (Processing and communication element) ,one bus line with max. 16 peripheral elements can be connected.CP-2010/CPC25 Features and FunctionsSystem Functions:• Central element,coordinating all system servicesCentral hub function for all connected basic system elements• Time managementCentral clock of the automation unitSetting and keeping the own clock`s time with a resolution of 10msSynchronization via serid communication via LAN or local• RedundancyV oting and change-over for redundant processing and communication elements of the own automation unitSupports voting and change-over by an external SCA-RS redundancy switchSupports applicational voting and change-over by an external system,e.g.a control system• SAT TOLLBOX|| connectionStoring firmware and parameters on a Flash CardCommunication:• Communication via installable protocol elements to any superior or subordinate automation unit• Automatic data flow routing• Priority based data transmission (priority control)• Own circular buffer and process image for each connected station(data keeping)• Redundant communication routesCommunication with redundant remote stations• Special application specific functions for dial-up trafficTest if stations are reachableProcess Peripherals:• T ransmission of spontaneous information objects from and to peripheral elements, via the serial Ax 1703 peripheral busFunctions for Automation:• Open-/closed-loop control function for the execution of freely definable user programs which are created with CAEX plus according to IEC 61131-3,ing function diagram technology512KB for user programApprox 50.000 variables and signals,2.000 of them retainedCycle of 10ms or a multiple thereofOnline testLoadable without service interruption• Redundant open-/closed-loop control functionsSynchronization via redundancy linkTransmission of periodic process information between the open-/closed-loop control function and the peripheral elements,via the serial Ax 1703 peripheral bus.PLC的发展和未来一、PLC概述可编程控制器是60年代末在美国首先出现的，当时叫可编程逻辑控制器PLC （Programmable Logic Controller），目的是用来取代继电器。

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

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

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。

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

外文文献PLC technique discussion and future developmentProgrammable Controller (Programmable Logic Controller, customarily referred to as PLC) is a microprocessor as the core of the general industrial automation devices. Is in the late 1960 s in the relay control system developed on the basis of, it will traditional relay control technology combined with computer technology and communication technology, has a simple structure, superior performance, high reliability, flexible, general and convenient use, easy to programming. In particular, the characteristics of the PLC is shown as the followingAspects: (1) the high reliability of hardware. PLC is specialized in industrial environment under the conditions of application and design. Can be placed in a well designed PLC has a very high voltage noise, electromagnetic interference and mechanical vibration, extreme temperature, and humidity environment. Is in the aspect of hardware design, first of all with high quality components, and adopt reasonable system structure, strengthening, simplify installation, makes it easy to anti vibration shock, to the printed circuit board design, machining and welding process are taken very strict measures, and on the circuit, the structure and process had taken some unique ways. Because the PLC itself has very high reliability, so in the event of a failure parts mostly focused on the input/output parts and such as sensors, limit switches, photoelectric switch, electromagnetic valve, motor, etc. programming and easy to use. Automatic control by microcomputer, commonly used assembly language programming, difficult to grasp, requires the user has a certain level of knowledge of computer hardware and software. PLC used for process control, problem oriented programming method, compared with the currently used assembly language microcomputer control, while inside the PLC increases the interpretation procedure, to increase the program's execution time, but for most of the mechanical and electrical control equipment, this loss is negligible. (3) Wiring is simple, high universality. In the case of electrical matching, PLC connection just put the input signal of the device (button, switch, etc.) connected to the input terminal of PLC, will accept the output signal of executive control tasks (contactor, solenoid valves), executive components connected to the PLC output terminals. Wiring is simple, leaves out the conventional relay control system wiring and removing the trouble. PLC programming logic provides can change according to the requirements of logical relationship, so that production line automation process can change at will. This performance makes the PLC has the very high economic benefits. Used to connect field devices of the hardware interface design has actually become a part of PLC, since the diagnosis of modular interface circuit can point to the fault, and easy to troubleshooting and replacement of fault parts, so that the software and hardware design of the site electrical personnel and technical personnel to use. (4) can be connected tocontrol network system. PLC can be connected to become powerful network system. General PLC network can be divided into two kinds: one kind is a low-speed network, USES the master-slave mode communication, transfer rate from the potter thousands and thousands of potter to the transmission distance is 500 ~ 2500 m; Another kind of high-speed network, USES the token passing mode communication, communication rate of 1 m to 10 MBPS, transmission distance is 500 ~ 1000 m, 1024 online nodes. These two types of networks are linked together, can be compatible with different types of programmable controller and computer, forming control range a lot of local network. 5. Easy to install, easy to maintain. PLC installation is simple and powerful functions, its relatively small size allows them to install the relay control box usually required for half of the space. In the large PLC system installation, remote I/o in the optimal location. Remote I/O station through double axis of coaxial cable, or even to the CPU, which greatly reduces the material and labor, remote subsystem method means from different parts of the system can be installed in field. Because almost all of the components are modular, only need to change when maintaining module level plug-in components, fault detection circuit diagnosis indicator will be embedded in each part, can indicate the device is working correctly, the resistance in programming is visible input/output devices ON or OFF, still can write programming instructions to report failures. In addition, PLC automation technology, computer technology and communication technology together, and you can also complete the following functions: logic control, timing control, counting control, stepper control, A/D and D/A conversion, data processing, communication network and monitoring on the control system. In general, the application of PLC have boom in the world, the PLC development direction mainly toward miniaturization, deflationary force, standardization, standardization, intelligence, high speed, large capacity, network development, this will make the PLC function is stronger, higher reliability, more convenient use, wide application and moreThe PLC biggest characteristics lie in: The electrical engineering teacher already no longer electric hardware up too many calculations of cost, as long as order the importation that the button switch or the importation of the sensors order to link the PLC up can solve problem, pass to output to order the conjunction contact machine or control the start equipments of the big power after the electric appliances, but the exportation equipments direct conjunction of the small power can.PLC internal containment have the CPU of the CPU, and take to have an I/ O for expand of exterior to connect a people's address and saving machine three big pieces to constitute, CPU core is from an or many is tired to add the machine to constitute, mathematics that they have the logic operation ability, and can read the procedure save the contents of the machine to drive the homologous saving machine and I/ Os to connect after pass the calculation; The I/ O add inner part is tired the input and output system of the machine and exterior link, and deposit the related data into the procedure saving machine or data saving machine; The saving machine can deposit the data that the I/ O input in the saving machine, and in work adjusting to become tired to add themachine and I/ Os to connect, saving machine separately saving machine RAM of the procedure saving machine ROM and dates, the ROM can do deposit of the data permanence in the saving machine, but RAM only for the CPU computes the temporary calculation usage of hour of buffer space.The PLC anti- interference is very and excellent, our root need not concern its service life and the work situation bad, these all problems have already no longer become the topic that we fail, but stay to our is a concern to come to internal resources of make use of the PLC to strengthen the control ability of the equipments for us, make our equipments more gentle.PLC language is not we imagine of edit collected materials the language or language of Cs to carry on weaving the distance, but the trapezoid diagram that the adoption is original after the electric appliances to control, make the electrical engineering teacher while weaving to write the procedure very easy comprehended the PLC language, and a lot of non- electricity professional also very quickly know and go deep into to the PLC.Is PLC one of the advantage above and only, this is also one part that the people comprehend more and easily, in a lot of equipments, the people have already no longer hoped to see too many control buttons, they damage not only and easily and produce the artificial error easiest, small is not a main error perhaps you can still accept; But lead even is a fatal error greatly is what we can't is tolerant of. New technique always for bringing more safe and convenient operation for us, make we a lot of problems for face on sweep but light, do you understand the HMI? Says the HMI here you basically not clear what it is, also have no interest understanding, change one inside text explains it into the touch to hold or man-machine interface you knew, and it combines with the PLC to our larger space.HMI the control not only is reduced the control press button, increase the vivid of the control, more main of it is can sequence of, and at can the change data input to output the feedback with data, control in the temperature curve of imitate but also can keep the manifestation of view to come out. And can write the function help procedure through a plait to provide the help of various what lies in one's power, the one who make operate reduces the otiose error. Currently the HMI factory is also more and more, the function is also more and more strong, the price is also more and more low, and the noodles of the usage are wide more and more. The HMI foreground can say that think ° to be good very.At a lot of situations, the list is a smooth movement that can't guarantee the equipments by the control of the single machine, but pass the information exchanges of the equipments and equipments to attain the result that we want. For example fore pack and the examination of the empress work preface, we will arrive wrapping information feedback to examine the place, and examine the information of the place to also want the feedback to packing. Pass the information share thus to make both the chain connect, becoming a total body, the match of your that thus make is more close, at each other attain to reflect the result that mutually flick.The PLC correspondence has already come more body now its value, at the PLC and correspondence between PLC, can pass the communication of the information and the share of the dates to guarantee that of the equipments moderates mutually, the result that arrive already to repair with each other. Data conversion the adoption RS232 between PLC connect to come to the transmission data, but the RS232 pick up a people and can guarantee 10 meters only of deliver the distance, if in the distance of 1000 meters we can pass the RS485 to carry on the correspondence, the longer distance can pass the MODEL only to carry on deliver.The PLC data transmission is just to be called a form to it in a piece of and continuous address that the data of the inner part delivers the other party, we, the PLC of the other party passes to read data in the watch to carry on the operation. If the data that data in the watch is a to establish generally, that is just the general data transmission, for example today of oil price rise, I want to deliver the price of the oil price to lose the oil ally on board, that is the share of the data; But take data in the watch for an instruction procedure that controls the PLC, that had the difficulty very much, for example you have to control one pedestal robot to press the action work that you imagine, you will draw up for it the form that a procedure combine with the data sends out to pass by.The form that information transport contain single work, the half a work and the difference of a workers .The meaning of the single work also is to say both, a can send out only, but a can receive only, for example a spy he can receive the designation of the superior only, but can't give the superior reply; A work of half is also 2 and can send out similar to accept the data, but can't send out and accept at the same time, for example when you make a phone call is to can't answer the phone, the other party also; But whole pair works is both can send out and accept the data, and can send out and accept at the same time. Be like the Internet is a typical example.The process that information transport also has synchronous and different step cent: The data line and the clock lines are synchronous when synchronous meaning lie in sending out the data, is also the data signal and the clock signals to be carry on by the CPU to send out at the same time, this needs to all want the specialized clock signal each other to carry on the transmission and connect to send, and is constrained, the characteristics of this kind of method lies in its speed very quick, but correspond work time of take up the CPU and also want to be long oppositely, at the same time the technique difficulty also very big. Its request lies in canting have an error margins in a dates deliver, otherwise the whole piece according to compare the occurrence mistake, this on the hardware is a bigger difficulty. Applied more and more extensive in some appropriative equipments, be like the appropriative medical treatment equipments, the numerical signal equipments...etc., in compare the one data deliver, its result is very good.And the different step is an application the most extensive, this receive benefit in it of technique difficulty is opposite and want to be small, at the same time not need to prepare the specialized clock signal, its characteristics to lie in, its data is partition, the long-lost send out andaccept, be the CPU is too busy of time can grind to a stop sex to work, also reduced the difficulty on the hardware, the data throw to lose at the same time opposite want to be little, we can pass the examination of the data to observe whether the data that we send out has the mistake or not, be like strange accidentally the method, tired addition and eight efficacies method etc., can use to helps whether the data that we examine to send out have or not the mistake occurrence, pass the feedback to carry on the discriminator.A line of transmission of the information contains a string of and combine the cent of: The usual PLC is 8 machines, certainly also having 16 machines. We can be an at the time of sending out the data a send out to the other party, also can be 88 send out the data to the other party, an and 8 differentiations are also the as that we say to send out the data and combine sends out the data. A speed is more and slowly, but as long as 2 or three lines can solve problem, and can use the telephone line to carry on the long range control. But combine the ocular transmission speed is very quick of, it is a string of ocular of 25600%, occupy the advantage in the short distance, the in view of the fact TTL electricity is even, being limited by the scope of one meter generally, it combine unwell used for the data transmission of the long pull, thus the cost is too expensive.Under a lot of circumstances we are total to like to adopt the string to combine the conversion chip to carry on deliver, under this kind of circumstance not need us to carry on to deposited the machine to establish too and complicatedly, but carry on the data exchanges through the data transmission instruction directly, but is not a very viable way in the correspondence, because the PLC of the other party must has been wait for your data exportation at the time of sending out the data, it can't do other works.When you are reading the book, you hear someone knock on door, you stop to start up of affair, open the door and combine to continue with the one who knock on door a dialogue, the telephone of this time rang, you signal hint to connect a telephone, after connecting the telephone through, return overdo come together knock on door to have a conversation, after dialogue complete, you continue again to see your book, this kind of circumstance we are called the interruption to it, it has the authority, also having sex of have the initiative, the PLC had such function .Its characteristics lie in us and may meet the urgently abrupt affairs in the operation process of the equipments, we want to stop to start immediately up of work, the whereabouts manages the more important affair, this kind of circumstance is we usually meet of, PLC while carry out urgent mission, total will keep the current appearance first, for example the address of the procedure, CPU of tired add the machine data etc., be like to stick down which the book that we see is when we open the door the page or simply make a mark, because we treat and would still need to continue immediately after book of see the behind. The CPU always does the affair that should do according to our will, but your mistake of give it an affair, it also would be same to do, this we must notice.The interruption is not only a, sometimes existing jointly with the hour several inside break,break off to have the preferred Class, they will carry out the interruption of the higher Class according to person's request. This kind of breaks off the medium interruption to also became to break off the set. The Class that certainly break off is relevant according to various resources of CPU with internal PLC, also following a heap of capacity size of also relevant fasten.The contents that break off has a lot of kinds, for example the exterior break off, correspondence in of send out and accept the interruption and settle and the clock that count break off, still have the WDT to reset the interruption etc., they enriched the CPU to respond to the category while handle various business. Speak thus perhaps you can't comprehend the internal structure and operation orders of the interruption completely also, we do a very small example to explain.Each equipment always will not forget a button, it also is at we meet the urgent circumstance use of, which is nasty to stop the button. When we meet the Human body trouble and surprised circumstances we as long as press it, the machine stops all operations immediately, and wait for processing the over surprised empress recover the operation again. Nasty stop the internal I/ O of the internal CPU of the button conjunction PLC to connect up, be to press button an exterior to trigger signal for CPU, the CPU carries on to the I/ O to examine again, being to confirm to have the exterior to trigger the signal, CPU protection the spot breaks off procedure counts the machine turn the homologous exterior I/ O automatically in the procedure to go to also, be exterior interruption procedure processing complete, the procedure counts the machine to return the main procedure to continue to work. Have 1:00 can what to explain is we generally would nasty stop the button of exterior break off to rise to the tallest Class, thus guarantee the safety.When we are work a work piece, giving the PLC a signal, counting PLC inner part the machine add 1 to compute us for a day of workload, a count the machine and can solve problem in brief, certainly they also can keep the data under the condition of dropping the electricity, urging the data not to throw to lose, this is also what we hope earnestly.The PLC still has the function that the high class counts the machine, being us while accept some dates of high speed, the high speed that here say is the data of the in all aspects tiny second class, for example the bar code scanner is scanning the data continuously, calculating high-speed signal of the data processor DSP etc., we will adopt the high class to count the machine to help we carry on count. It at the PLC carries out the procedure once discover that the high class counts the machine to should of interruption, will let go of the work on the hand immediately. The trapezoid diagram procedure that passes by to weave the distance again explains the high class for us to carry out procedure to count machine would automatic performance to should of work, thus rise the Class that the high class counts the machine to high one Class.You heard too many this phrases perhaps:" crash", the meaning that is mostly is a workload of CPU to lead greatly, the internal resources shortage etc. the circumstance can't result in procedure circulate. The PLC also has the similar circumstance, there is a watchdog WDT in theinner part of PLC, we can establish time that a procedure of WDT circulate, being to appear the procedure to jump to turn the mistake in the procedure movement process or the procedure is busy, movement time of the procedure exceeds WDT constitution time, the CPU turn but the WDT reset the appearance. The procedure restarts the movement, but will not carry on the breakage to the interruption.The PLC development has already entered for network ages of correspondence from the mode of the one, and together other works control the net plank and I/ O card planks to carry on the share easily. A state software can pass all se hardwires link, more animation picture of keep the view to carries on the control, and cans pass the Internet to carry on the control in the foreign land, the blast-off that is like the absolute being boat No.5 is to adopt this kind of way to make airship go up the sky.The development of the higher layer needs our continuous effort to obtain. The PLC emergence has already affected a few persons fully, we also obtained more knowledge and precepts from the top one experience of the generation, coming to the continuous development PLC technique, push it toward higher wave tide.Knowing the available PLC network options and their best applications will ensure an efficient and flexible control system design.The programmable logic controller's (PLC) ability to support a range of communication methods makes it an ideal control and data acquisition device for a wide variety of industrial automation and facility control applications. However, there is some confusion because so many possibilities exist. To help eliminate this confusion, let's list what communications are available and when they would be best applied.To understand the PLC communications versatility, let's first define the terms used in describing the various systems.ASCII: This stands for "American Standard Code for Information Interchange." As shown in Fig. 1, when the letter "A" is transmitted, for instance, it's automatically coded as "65" by the sending equipment. The receiving equipment translates the "65" back to the letter "A." Thus, different devices can communicate with each other as long as both use ASCII code.ASCII module: This intelligent PLC module is used for connecting PLC to other devices also capable of communicating using ASCII code as a vehicle.Bus topology: This is a linear local area network (LAN) arrangement, as shown in Fig. 2A, in which individual nodes are tapped into a main communications cable at a single point and broadcast messages. These messages travel in both directions on the bus from the point of connection until they are dissipated by terminators at each end of the bus.CPU: This stands for "central processing unit," which actually is that part of a computer, PLC, or other intelligent device where arithmetic and logical operations are performed and instructions are decoded and executed.Daisy chain: This is a description of the connection of individual devices in a PLC network, where, as shown in Fig. 3, each device is connected to the next and communications signals pass from one unit to the next in a sequential fashion.Distributed control: This is an automation concept in which portions of an automated system are controlled by separate controllers, which are located in close proximity to their area of direct control (control is decentralized and spread out over the system).Host computer: This is a computer that's used to transfer data to, or receive data from, a PLC in a PLC/computer network.Intelligent device: This term describes any device equipped with its own CPU.I/O: This stands for "inputs and outputs," which are modules that handle data to the PLC (inputs) or signals from the PLC (outputs) to an external device.Kbps: This stands for "thousand bits per second," which is a rate of measure for electronic data transfer.Mbps: This stands for "million bits per second."Node: This term is applied to any one of the positions or stations in a network. Each node incorporates a device that can communicate with all other devices on the network.Protocol: The definition of how data is arranged and coded for transmission on a network.Ring topology. This is a LAN arrangement, as shown in Fig. 2C, in which each node is connected to two other nodes, resulting in a continuous, closed, circular path or loop for messages to circulate, usually in one direction. Some ring topologies have a special "loop back" feature that allows them to continue functioning even if the main cable is severed.RS232. This is an IEEE standard for serial communications that describes specific wiring connections, voltage levels, and other operating parameters for electronic data communications. There also are several other RS standards defined.Serial: This is an electronic data transfer scheme in which information is transmitted one bit at a time.Serial port: This the communications access point on a device that is set up for serial communications.Star topology. This is a LAN arrangement in which, as shown in Fig. 2B, nodes are connected to one another through a central hub, which can be active or passive. An active hub performs network duties such as message routing and maintenance. A passive central hub simply passes the message along to all the nodes connected to it.Topology: This relates to a specific arrangement of nodes in a LAN in relation to one another.Transparent: This term describes automatic events or processes built into a system that require no special programming or prompting from an operator.Now that we're familiar with these terms, let's see how they are used in describing the available PLC network options.PLC network optionsPLC networks provide you with a variety of networking options to meet specific control and communications requirements. Typical options include remote I/O, peer-to-peer, and host computer communications, as well as LANs. These networks can provide reliable and cost-effective communications between as few as two or as many as several hundred PLC, computers, and other intelligent devices.Many PLC vendors offer proprietary networking systems that are unique and will not communicate with another make of PLC. This is because of the different communications protocols, command sequences, error-checking schemes, and communications media used by each manufacturer.However, it is possible to make different PLC "talk" to one another; what's required is an ASCII interface for the connection(s), along with considerable work with software.Remote I/0 systemsA remote I/O configuration, as shown in Fig. 4A, has the actual inputs and outputs at some distance from the controller and CPU. This type of system, which can be described as a "master-and-slave" configuration, allows many distant digital and analog points to be controlled by a single PLC. Typically, remote I/Os are connected to the CPU via twisted pair or fiber optic cables.Remote I/O configurations can be extremely cost-effective control solutions where only a few I/O points are needed in widely separated areas. In this situation, it's not always necessary, or practical for that matter, to have a controller at each site. Nor is it practical to individually hard wire each I/O point over long distances back to the CPU. For example, remote I/O systems can be used in acquiring data from remote plant or facility locations. Information such as cycle times, counts, duration or events, etc. then can be sent back to the PLC for maintenance and management reporting.In a remote I/O configuration, the master controller polls the slaved I/O for its current I/O status. The remote I/O system responds, and the master PLC then signals the remote I/O to change the state of outputs as dictated by the control program in the PLC memory. This entire cycle occurs hundreds of times per second.Peer-to-peer networksPeer-to-peer networks, as shown in Fig. 4B, enhance reliability by decentralizing the control functions without sacrificing coordinated control. In this type of network, numerous PLC are connected to one another in a daisy-chain fashion, and a common memory table is duplicated in the memory of each. In this way, when any PLC writes data to this memory area, the information is automatically transferred to all other PLCs in the network. They then can use this information in their own operating programs.With peer-to-peer networks, each PLC in the network is responsible for its own control site。