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1、山东科技大学学士学位论文附录PACforIndustrialControl,theFutureofControlForthelastdecadeapassionatedebatehasragedabouttheadvantagesanddisadvantagesofPLC(programmablelogiccontrollers)comparedtoPC-basedcontrol.AsthetechnologicaldifferencesbetweenPCandPLCwane,withPLCusingcommercialofthesh
2、elf(COTS)hardwareandPCsystemsincorporatingreal-timeoperatingsystems,anewclassofcontrollers,thePACisemerginganewacronymcreatedbyAutomationResearchCorporation(ARC),standsforProgrammableAutomationControllerandisusedtodescribeanewgenerationofindustrialcontrollersthatcombine
3、thefunctionalityofaPLCandaPC.ThePACacronymisbeingusedbothbytraditionalPLCvendorstodescribetheirhighendsystemsandbyPCcontrolcompaniestodescribetheirindustrialcontrolplatforms.The“80-20”RuleDuringthethreedecadesfollowingtheirintroduction,PLChaveevolvedtoincorporateanalogI
4、/O,communicationovernetworks,andnewprogrammingstandardssuchasIEC61131-3.However,engineerscreate80percentofindustrialapplicationswithdigitalI/O,afewanalogI/Opoints,andsimpleprogrammingtechniques.ExpertsfromARC,VentureDevelopmentCorporation(VDC),andtheonlinePLCtrainingsou
5、rcePLCS.netestimatethat:•77%ofPLCareusedinsmallapplications(lessthan128I/O)•72%ofPLCI/Oisdigital•80%ofPLCapplicationchallengesaresolvedwithasetof20ladder-logicinstructionsBecause80percentofindustrialapplicationsaresolvedwithtraditionaltools,thereisstrongdemandforsimplel
6、ow-costPLC.Thishasspurredthe山东科技大学学士学位论文附录growthoflow-costmicroPLCwithdigitalI/Othatuseladderlogic.Ithasalsocreatedadiscontinuityincontrollertechnology,where80percentofapplicationsrequiresimple,lowcostcontrollersand20percentrelentlesslypushthecapabilitiesoftraditionalco
7、ntrolsystems.Theapplicationshatfallwithinthe20percentarebuiltbyengineerswhorequirehigherlooprates,advancedcontrolalgorithms,moreanalogcapabilities,andbetterintegrationwiththeenterprisenetwork.Inthe80sand90s,these“20percenters”evaluatedPCsforindustrialcontrol.ThePCprovid
8、edthesoftwarecapabilitiestoperformadvancedtasks,offeredagraphicalrichprogramminganduserenvironment,andutilized
