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1、电子与信息工程学院本科毕业论文(设计)外文文献翻译译文题目：ProgrammablelogiccontrollersHardware,softwarearchitecture学生姓名：吴凡专业：电气工程及其自动化指导教师：李东京2012年12月Programmablelogiccontrollers:Hardware,softwarearchitectureManyrespects,thearchitectureoftheprogrammablelogiccontroller(PLC)resemblesagenera
2、l-purposecomputerwithspecializedinput/output(I/O)modules.However,someimportantcharacteristicsdistinguishaPLCfromageneral-purposecomputer.Mostimportant,aPLCismuchmorereliable,designedforameantimebetweenfailuresmeasuredinyears.Second,aPLCcanbeplacedinanindustrial
3、environmentwithitssubstantialamountofelectricalnoise,vibration,extremetemperatures,andhumidity.Third,PLCsareeasilymaintainedbyplanttechnicians.BasicPLChardwarearchitectureThebasicarchitectureofaPLCconsistsofmaincomponents-theprocessormodule,thepowersupply,andth
4、eI/Omodules.Theprocessormoduleconsistsofthecentralprocessingunit(CPU)andmemory.Inadditiontoamicroprocessor,theCPUalsocontainsatleastaninterfacetoaprogrammingdeviceandmaycontaininterfacestoremoteI/Oandothercommunicationnetworks.Thepowersupplyisusuallyaseparatemo
5、dule,andtheI/Omodulesareseparatefromtheprocessor.ThetypesofI/Omodulesincludediscrete(on/off),analog(continuousvariable),andspecialmoduleslikemotioncontrolorhigh-speedcounters.ThefielddevicesareconnectedtotheI/Omodules.DependingontheamountofI/OandtheparticularPL
6、Cprocessor,theI/Omodulesmaybeinthesamechassisastheprocessorand/orinoneormoreotherchassis.Upuntilthelate1980s,theI/OmodulesinatypicalPLCsystemwereinchassisseparatefromthePLCprocessor.Inthemoretypicalpresent-dayPLC,someoftheI/Omodulesarepresentinthechassisthatcon
7、tainstheprocessor.SomePLCsystemsallowmorethanoneprocessorinthesamechassis.SmallerPLCsareoftenmountedonaDINrail.ThesmallestPLCs(oftencalledmicro-PLCsornaon-PLCs)includethepowersupply,processor,andalloftheI/Osinonepack-age.Somemicro-PLCscontainabuilt-inoperatorin
8、terfacepanel.Formanymicro-PLCs,theamountofI/Oislimitedandnotexpandable.Basicsoftware,memoryarchitecture(IEC61131-3)TheIEC61131-3standarddefinesamemoryandprogrammodelthatfoll
