plc外文文献译文

plc外文文献译文plc外文文献译文PAGE9plc外文文献译文ProgrammablelogiccontrollerAprogrammablelogiccontroller(PLC）isahttp：///wiki/Automation"automationofelectromechanicalprocesses，suchascontrolofmachineryonfactoryHYPERLINK”/wiki/Assembly_line"assemblylines,amusementrides，orlightingfixtures。PLCisusedinmanyindustriesandmachines.1。HistoryThePLCwasinventedinresponsetotheneedsoftheAmericanautomotivemanufacturingindustry.BeforethePLC，control，sequencing，andsafetyinterlocklogicformanufacturingautomobileswasaccomplishedusinghundredsorthousandsofrelays，camtimers,andHYPERLINK”http：///wiki/Drum_sequencer"drumsequencersanddedicatedclosed-loopcontrollers。In1968GMHydramaticissuedarequestforproposalforanelectronicreplacementforhard—wiredrelaysystems。ThefirstPLC,designatedthe084becauseitwasBedfordAssociates’eighty—fourthproject，wastheresult.BedfordAssociatesstartedanewcompanydedicatedtodeveloping,manufacturing,selling，andservicingthisnewproduct:Modicon,whichstoodforMOdularDIgitalCONtroller。TheModiconbrandwassoldin1977toHYPERLINK”/wiki/Gould_Electronics”GouldElectronics，andlateracquiredbyGermanCompanyHYPERLINK”/wiki/AEG"AEGandthenbyFrenchSchneiderElectric，thecurrentowner。Oneoftheveryfirst084modelsthatwaspresentedtoModiconbyHYPERLINK”/wiki/General_Motors"GM，whentheunitwasretiredafternearlytwentyyearsofuninterruptedservice.Modiconusedthe84monikerattheendofitsproductrangeuntilthe984madeitsappearance。2。DevelopmentEarlyPLCsweredesignedtoreplacerelaylogicsystems。ThesePLCswereprogrammedin"HYPERLINK”http：///wiki/Ladder_logic”ladderlogic”,whichstronglyresemblesaschematicdiagramofrelaylogic.OtherearlyPLCsusedaformofHYPERLINK”http：///wiki/Instruction_list”instructionlistprogramming，basedonastack—basedlogicsolver.ModernPLCscanbeprogrammedinavarietyofways,fromladderlogictomoretraditionalprogramminglanguagessuchasBASICandC.Anothermethodis/wiki/Very_high-level_programming_language”veryhigh—levelprogramminglanguagedesignedtoprogramPLCsbasedonHYPERLINK”http：///wiki/State_diagram”statetransitiondiagrams.3.FunctionalityThefunctionalityofthePLChavesequentialrelaycontrol，motioncontrol，HYPERLINK”/wiki/Process_control”processcontrol,/wiki/Computer_network”networking.Regardingthepracticalityofthesedesktopcomputerbasedlogiccontrollers,itisimportanttonotethattheyhavenotbeengenerallyacceptedinheavyindustrybecausethedesktopcomputersrunonlessstableoperatingsystemsthandoPLCs,andbecausethedesktopcomputerhardwareistypicallynotdesignedtothesamelevelsoftolerancetotemperature,Inmorerecentyears，smallproductscalledPLRs(programmablelogicrelays),areusedinlightindustrywhereonlyafewpointsofI/O（i。e.afewsignalscominginfromtherealworldandafewgoingout）areinvolved，andlowcostisdesired。PopularnamesincludePICOController，NANOPLC，andothernamesimplyingverysmallcontrollers.thePLRsareusuallynotmodularorexpandable,buttheirpricecanbetwoHYPERLINK”http：///wiki/Orders_of_magnitude"ordersofmagnitudelessthanaPLCandtheystillofferrobustdesignanddeterministicexecutionofthelogic。4。PLCcomparedwithothercontrolsystemsPLCsarewell-adaptedtoarangeofHYPERLINK”http：///wiki/Automation"automationtasks.Thesearetypicallyindustrialprocessesinmanufacturingwherethecostofdevelopingandmaintainingtheautomationsystemishighrelativetothetotalcostoftheautomation，andwherechangestothesystemwouldbeexpectedduringitsoperationallife。PLCscontaininputandoutputdevicescompatiblewithindustrialpilotdevicesandcontrols;littleelectricaldesignisrequired,andthedesignproblemcentersonexpressingthedesiredsequenceofoperations。PLCapplicationsaretypicallyhighlycustomizedsystemssothecostofapackagedPLCislowcomparedtothecostofaspecificcustom-builtcontrollerdesign.Ontheotherhand,inthecaseofmass—producedgoods,customizedcontrolsystemsareeconomicduetothelowercostofthecomponents，whichcanbeoptimallychoseninsteadofa"generic"solution,andwherethenon—recurringengineeringchargesarespreadoverthousandsormillionsofunits。AHYPERLINK”/wiki/Microcontroller"microcontroller—baseddesignwouldbeappropriatewherehundredsorthousandsofunitswillbeproducedandsothedevelopmentcost(designofpowersupplies，input/outputhardwareandnecessarytestingandcertification）canbespreadovermanysales,andwheretheend-userwouldnotneedtoalterthecontrol.Automotiveapplicationsareanexample;millionsofunitsarebuilteachyear,andveryfewend—usersaltertheprogrammingofthesecontrollers。However,somespecialtyvehiclessuchastransitbusseseconomicallyusePLCsinsteadofcustom-designedcontrols,becausethevolumesarelowandthedevelopmentcostwouldbeuneconomic。Programmablecontrollersarewidelyusedinmotioncontrol,positioningcontrolandtorquecontrol.SomemanufacturersproducemotioncontrolunitstobeintegratedwithPLCsothat/wiki/CNC”CNCmachine)canbeusedtoinstructmachinemovements。PLCsmayincludelogicforsingle-variablefeedbackanalogcontrolloop，a"proportional，integral，derivative”or"HYPERLINK”http：///wiki/PID_controller"PIDcontroller"。APIDloopcouldbeusedtocontrolthetemperatureofamanufacturingprocess，forexample.HistoricallyPLCswereusuallyconfiguredwithonlyafewanalogcontrolloops;whereprocessesrequiredhundredsorthousandsofloops，ahttp：///wiki/Remote_Terminal_Unit”RTUs，PLCsandDCSsareincreasinglybeginningtooverlapinresponsibilities,andmanyvendorssellRTUswithPLC—likefeaturesandviceversa。TheindustryhasstandardizedontheHYPERLINK”/wiki/IEC_61131—3"IEC61131—3functionalblocklanguageforcreatingprogramstorunonRTUsandPLCs,althoughnearlyallvendorsalsoofferproprietaryalternativesandassociateddevelopmentenvironments.5。TheprospectsforPLC.5.1.FeaturesThemaindifferencefromothercomputersisthatPLCsarearmoredforsevereconditions(suchasdust,moisture,heat,cold)andhavethefacilityforextensiveinput/output（I/O)arrangements.PLCsreadlimitswitches，analogprocessvariables（suchastemperatureandpressure），andthepositionsofcomplexpositioningsystems.Someuse/wiki/Pneumatic"pneumaticorHYPERLINK”/wiki/Hydraulic"hydrauliccylinders，magneticHYPERLINK”/wiki/Relay”relays，http：///wiki/RS-232"RS—232，butoptionallyHYPERLINK”http：///wiki/EIA—485”EIA-485orHYPERLINK”/wiki/Ethernet"Ethernet。HYPERLINK”http：///wiki/Modbus”Modbus,HYPERLINK”/wiki/BACnet”BACnetorHYPERLINK”/w/index。php？title=DF1＆action=edit&redlink=1"DF1isusuallyincludedasoneofthecommunicationsprotocols。OtheroptionsincludevariousfieldbusessuchasHYPERLINK”/wiki/DeviceNet”DeviceNetorhttp：///wiki/List_of_automation_protocols”Listofautomationprotocols.MostmodernPLCscancommunicateoveranetworktosomeothersystem，suchasacomputerrunningaHYPERLINK”/wiki/SCADA”SCADA(SupervisoryControlAndDataAcquisition)systemorwebbrowser.PLCsusedinlargerI/OsystemsmayhaveHYPERLINK”/wiki/Peer—to—peer”peer-to—peer(P2P）communicationbetweenprocessors.Thisallowsseparatepartsofacomplexprocesstohaveindividualcontrolwhileallowingthesubsystemstoco—ordinateoverthecommunicationlink。ThesecommunicationlinksarealsooftenusedforHMIdevicessuchaskeypadsorHYPERLINK”/wiki/Personal_computer”PC—typeworkstations。可编程逻辑控制器可编程逻辑控制器（PLC）或可编程序控制器是用于机电过程自动化的数字计算机，例如控制机械厂生产线、游乐设施或照明的装置。可编程控制器可在许多工业和机器中使用.1。历史PLC发明是针对于美国汽车制造行业的需要。可编程逻辑控制器最初通过了在软件版本更换硬连线的控制板生产模式更改时的汽车工业.在PLC之前，控制、程序化和安全联锁逻辑制造汽车是使用上百或上千的继电器、凸轮计时器、鼓定序仪和专用的闭环控制器来完成的。在1968年GMHydramatic发布通用汽车公司的提议,电子替代布线中继系统.第一个PLC选定084，因为它是贝得福得同事的第八十四个项目.贝得福得同事建立了一家新的公司致力开发、生产、销售,和服务这一新产品：Modicon，代表模块化数字控制器。1977年古尔德电子公司当前所有者收购法国施耐德电气公司同德国公司AEG并售予该品牌为Modicon。这是专门为通用汽车服务的,并且经过了近二十多年的不间断服务。直至984出现，Modicon使用的84名字才在其产品范围中结束。2。发展早期的可编程控制器是设计来取代继电器逻辑系统。这些可编程控制器的“阶梯逻辑”是与继电器逻辑示意图非常类似的。其他早期的可编程控制器使用指令列表编程,基于一个堆栈编程逻辑求解器进行求解。现代可编程控制器在各种各样的方式可以被编程,从梯形逻辑语言到更加传统的编程语言例如BASIC和C语言。另一个方法是状态逻辑，被设计的一种非常高级编程语言根据状态转换图的可编程控制器编程。3.功能PLC的功能包括连续的继电器控制，运动控制，过程控制,分布式控制系统和网络。在重工业中PLC被认为没有这些桌面计算机为主的逻辑控制器的实际性强，因为PLC在台式计算机系统中运行不是很稳定，并且，因为台式计算机硬件没有被设计成耐温度、湿气、振动和耐用作为可编程控制器的处理器。在近些年,小产品称为PLR（可编程逻辑继电器)已经应用于轻工业,它只有少部分的输入/输出（例如一些真实的输入输出信号）参与，低成本,很理想。俗名包括PICO控制器、纳米PLC和其他的小控制器。PLR通常是模块化,大大扩展,控制器通常不会取模块化并且不是可扩展的,但是他们提供稳健设计的确定性和执行逻辑的价值比PLC少.4。PLC相比其它控制系统可编程控制器是可适应一系列自动化任务。这些都是自动化的在制造中通常工业过程开发和维护自动化系统的成本在哪里高，相对于总成本和其寿命期间预计将对系统更改。可编程控制器包含输入和输出设备兼容工业试验设备和管制，小电气的设计问题对预期操作是必要的。PLC应用程序通常是高度定制系统，因此成本包装可编程序控制器（PLC)的费用比一个具体定制设计的小控制器要高.另外一方面在批量生产货物的情况下自定义的控制系统是组成、成本较低的最佳选择，而不是一个非反复出现工程费用“普通”的解决方案.一种基于微控制器的设计是需要成百上千个单位（设计电源供应器，输入/输出硬件和必要的检测和认证)和开发成本可以分散到很多的销售，最终用户不需要更改该控件。汽车应用程序就是一个例子：数以百万计的内置单位每一年需要建造，很少最终用户更改这些控制器的编程。然而，一些其他车辆如交通公共汽车经常定制设计的控制，而不是用PLC，因为数量很低,发展成本会赚不到钱的。可编程序控制器广泛用于运动控制、定位控制和转矩控制.一些制造商生产运动控制单元与PLC集成、G-code(涉及数控机床）可以用于指导机器运作。可编程控制器可能包括一个“比例，积分，微分"的单变量反馈模拟控制循环的逻辑或“控制器"。以PID回路可用于控制温度为例。历史上PLC通常配置只有少数模拟控制回路,通常配置可编程控制器将使