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1、西北工业大学明德学院本科毕业设计论文（本科毕业论文）外文文献及译文题目：Programmablelogiccontroller专业名称:学生姓名:指导老师:毕业时间:2014年6月西北工业大学明德学院本科毕业设计论文外文文献原文：ProgrammablelogiccontrollerByCynthiaCooperFromWikipedia,thefreeencyclopediaAprogrammablelogiccontrollerorsimplyprogrammablecontrollerisadigi
2、talcomputerusedforautomationofindustrialprocesses,suchascontrolofmachineryonfactoryassemblylines.Unlikegeneral-purposecomputers,thePLCisdesignedformultipleinputsandoutputarrangements,extendedtemperatureranges,immunitytoelectricalnoise,andresistancetovibra
3、tionandimpact.Programstocontrolmachineoperationaretypicallystoredinbattery-backedornon-volatilememory.APLCisanexampleofarealtimesystemsinceoutputresultsmustbeproducedinresponsetoinputconditionswithinaboundedtime,otherwiseunintendedoperationwillresult.Feat
4、uresControlpanelwithPLC(greyelementsinthecenter).Theunitconsistsofseparateelements,fromlefttoright;powersupply,controller,relayunitsforinputandoutput.ThemaindifferencefromothercomputersisthatPLCsarearmoredforseverecondition(dust,moisture,heat,cold,etc)and
5、havethefacilityforextensiveinput/output(I/O)arrangements.TheseconnectthePLCtosensorsandactuators.PLCsreadlimitswitches,analogprocessvariables(suchastemperatureandpressure),andthepositionsofcomplexpositioningsystems.Someevenusemachinevision.Ontheactuatorsi
6、de,PLCsoperateelectricmotors,pneumaticorhydrauliccylinders,magneticrelaysorsolenoids,oranalogoutputs.Theinput/outputarrangementsmaybebuiltintoasimplePLC,orthePLCmayhaveexternalI/OmodulesattachedtoacomputernetworkthatplugsintothePLC.PLCswereinventedasrepla
7、cementsforautomatedsystemsthatwouldusehundredsorthousandsofrelays,camtimers,anddrumsequencers.Often,asinglePLCcanbeprogrammedtoreplacethousandsofrelays.Programmablecontrollerswereinitially6西北工业大学明德学院本科毕业设计论文adoptedbytheautomotivemanufacturingindustry,wher
8、esoftwarerevisionreplacedthere-wiringofhard-wiredcontrolpanelswhenproductionmodelschanged.ManyoftheearliestPLCsexpressedalldecisionmakinglogicinsimpleladderlogicwhichappearedsimilartoelectricalschematicdiagrams.Thee
