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1、.外文文献原稿和译文原稿AboutProgrammableLogiccontrollers（PLCs）PLCs(programmablecontroller)isusedinavarietyofautomaticcontrolsystemandprocesscontrolhub.Theycontainmultipleinputandoutput,inputandoutputisusedtotransistorsandothercircuit,analogswitchandrelaytocontroltheequipment.PLCsoftwareinterface,standardcal
2、culatorinterface,specializedlanguageprogrammingandnetworkequipment.ProgrammablelogiccontrollerI/Ochannelrulesincludingallinputoutputcontactandcontact,toexpandcapacityandthelargestnumberofchannels.Contactnumberisthesumofinputandoutputpoints.PLCcanspecifyanycombinationofthesevalues.Extensionunitsca
3、nbestackorconnectedtoeachothertoincreasethetotalcontrol.Thelargestnumberofchannelsareinanextensionsystem,thetotalnumberofmaximuminputandoutputchannels.PLCsystemrulesincludescanningtime,numberofinstructions,datastorageandstorageprogram.ScantimeisusedtomonitorinputandoutputmoduleofPLCneedtime.Stand
4、ardoperationinstructionisusedinPLCsoftware.Datastorageistheabilitytostoredata.Programmemoryistheabilitytocontrolsoftware.UsedforprogrammablecontrollerinputdevicesincludingDC,AC,intermediaterelay,thermocouple,RTD,frequencyorpulse,transistorsandinterruptsignalinput;OutputdevicesincludeDC,AC,interme
5、diaterelay,frequencyorpulse,transistor,three-terminaltwo-waythyristorswitchcomponents;PLCprogrammingequipmentincludingcontrolpanel,handleandcomputer.Programmablecontrolisusedtocontrolavarietyofsoftware..programminglanguage.Theselanguagesincludingiec61131-3,sequentialtable(SFC),actionblockdiagram(
6、FBD),ladderdiagram(LD),andthestructureofthetext(ST),instructionsequences(IL),relayladderdiagram(RIL),flowcharts,ClanguageandBasiclanguage.Iec61131-3programmingenvironmentcansupportfivelanguages,withinternationalstandardstoregulate,SFC,respectively,FBD,LD,STandIL.Thisallowsmorevendorcompatibilitya
7、ndavarietyoflanguages.SFCisakindofgraphlanguage,itprovidestheprogramminginordertocooperate,cansupporttheorderselectionandtiedforchoice,tochoosebetweenthem.RuntimeFBDwithabig,establishedthecomplicatedprocess,intheformof
