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1、本科毕业设计（论文）外文翻译(2010届)题目：关于xxx的PLC控制系统设计分院:电气工程与自动化学院专业:电气工程及其自动化班级:姓名:学号:指导老师:完成日期:2009年12月1原文：IntroductionstoPLCandIntelligentControlKatsuhikoOgataAPLC(i.e.ProgrammableLogicController)isadevicethatwasinventedtoreplacethenecessarysequentialrelaycircuitsfo
2、rmachinecontrol.ThePLCworksbylookingatitsinputsanddependingupontheirstate,turningon/offitsoutputs.Theuserentersaprogram,usuallyviasoftwareorprogrammer,thatgivesthedesiredresults.PLCsareusedinmany“realworld”applications.Ifthereisindustrypresent,chancesareg
3、oodthatthereisaPLCpresent.Ifyouareinvolvedinmachining,packaging,materialhandling,automatedassemblyorcountlessotherindustries,youareprobablyalreadyusingthem.Ifyouarenot,youarewastingmoneyandtime.Almostanyapplicationthatneedssometypeofelectricalcontrolhasan
4、eedforaPLC.Forexample,let’sassumethatwhenaswitchturnsonwewanttoturnasolenoidonfor5secondsandthenturnitoffregardlessofhowlongtheswitchisonfor.Wecandothiswithasimpleexternaltimer.Butwhatiftheprocessincluded10switchesandsolenoids?Wewouldneed10externaltimers.
5、Whatiftheprocessalsoneededtocounthowmanytimestheswitchindividuallyturnedon?Weneedalotofexternalcounters.Asyoucansee,thebiggertheprocessthemoreofaneedwehaveforaPLC.WecansimplyprogramthePLCtocountitsinputsandturnthesolenoidsonforthespecifiedtime.Wewilltakea
6、lookatwhatisconsideredtobethe“top20”PLCinstructions.Itcanbesafelyestimatedthatwithafirmunderstandingoftheseinstructionsonecansolvemorethan80%oftheapplicationsinexistence.That’sright,morethan80%!Ofcoursewe’lllearnmorethanjusttheseinstructionstohelpyousolve
7、almostALLyourpotentialPLCapplications.ThePLCmainlyconsistsofaCPU,memoryareas,andappropriatecircuitstoreceiveinput/outputdata,asshowninFig.1.WecanactuallyconsiderthePLCtobeaboxfullofhundredsorthousandsofseparaterelays,counters,timersanddatastoragelocations
8、.Dothesecounters,timers,etc.reallyexist?No,theydon’t“physically”existbutrathertheyaresimulatedandcanbeconsideredsoftwarecounters,timers,etc.Theseinternalrelaysaresimulatedthroughbitlocationsinregisters.11Fig.1Thestr
