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外文文献原稿及译文
外文文献原稿和译文
原稿
AboutProgrammableLogiccontrollers(PLCs)
PLCs(programmablecontroller)isusedinavarietyofautomaticcontrolsystemandprocesscontrolhub.Theycontainmultipleinputandoutput,inputandoutputisusedtotransistorsandothercircuit,analogswitchandrelaytocontroltheequipment.PLCsoftwareinterface,standardcalculatorinterface,specializedlanguageprogrammingandnetworkequipment.
ProgrammablelogiccontrollerI/Ochannelrulesincludingallinputoutputcontactandcontact,toexpandcapacityandthelargestnumberofchannels.Contactnumberisthesumofinputandoutputpoints.PLCcanspecifyanycombinationofthesevalues.Extensionunitscanbestackorconnectedtoeachothertoincreasethetotalcontrol.Thelargestnumberofchannelsareinanextensionsystem,thetotalnumberofmaximuminputandoutputchannels.PLCsystemrulesincludescanningtime,numberofinstructions,datastorageandstorageprogram.ScantimeisusedtomonitorinputandoutputmoduleofPLCneedtime.StandardoperationinstructionisusedinPLCsoftware.Datastorageistheabilitytostoredata.Programmemoryistheabilitytocontrolsoftware.
UsedforprogrammablecontrollerinputdevicesincludingDC,AC,intermediaterelay,thermocouple,RTD,frequencyorpulse,transistorsandinterruptsignalinput;OutputdevicesincludeDC,AC,intermediaterelay,frequencyorpulse,transistor,three-terminaltwo-waythyristorswitchcomponents;PLCprogrammingequipmentincludingcontrolpanel,handleandcomputer.
Programmablecontrolisusedtocontrolavarietyofsoftwareprogramminglanguage.Theselanguagesincludingiec61131-3,sequentialtable(SFC),actionblockdiagram(FBD),ladderdiagram(LD),andthestructureofthetext(ST),instructionsequences(IL),relayladderdiagram(RIL),flowcharts,ClanguageandBasiclanguage.Iec61131-3programmingenvironmentcansupportfivelanguages,withinternationalstandardstoregulate,SFC,respectively,FBD,LD,STandIL.Thisallowsmorevendorcompatibilityandavarietyoflanguages.SFCisakindofgraphlanguage,itprovidestheprogramminginordertocooperate,cansupporttheorderselectionandtiedforchoice,tochoosebetweenthem.RuntimeFBDwithabig,establishedthecomplicatedprocess,intheformofgraphs.Standardmathematicalandlogicaloperationcanbecombinedwithuserinteractionandinterfaceoperation.LDissuitablefordiscretecontrolandinterlocklogicdiagramlanguage.ItisfullycompatiblewithFBDondiscretecontrol.STisakindoftextlanguage,usedforcomplexmathematicalandcomputationalprocess,languageisnotapplicabletochart.ILissimilartothecombinationofcodinglow-levellanguages.Itisusedinrelativelysimplelogicalinstructions.Relayladderdiagramandladderdiagramisusedforprogrammablecontrollerisanimportantprogramminglanguage.Ladderdiagramprogrammingisdesignedtorelaylogicdiagramrepresentationoftheprogram.Flowchartisagraphiclanguage,foruseinacontrolleroroperationsdescribedintheorderofapplicationsoftware,itisusedtoestablishastandardcomponentofrecycledruntime.Clanguageisahigh-levelprogramminglanguage,suitableforprocessingthemostcomplicatedcalculation,acontinuousdataacquisitiontask.IttypicallyruninPCdebugging.BASIClanguageisusedtohandlethenumberofconsecutivedataacquisitionandinterfaceoperationofhigh-levellanguage.
Programmablecontrolleralsospecificationofmanycomputerinterfaceequipment,networkrulesandcharacteristics.PLCenergyequipmentandrunningenvironmentisalsoveryimportant.
Thedevelopmenthistoryofprogrammablecontroller
In1968,generalmotors(GM),accordingtotheneedsofthedevelopmentofthemarketsituationandputforwardthe"manyvarieties,smallbatch,newcarbrandmodel"strategy.Toimplementthisstrategy,relyingontheoriginalindustrialcontroldeviceobviouslynot,andtheremustbeakindofnewindustrialcontroldevice,itcanbewiththechangeoftheproducts,flexibleandeasilychangecontrolschemetodifficulttomeetthedifferentrequirementsofcontrol.
In1969,thefamousAmericandigitalequipmentcorporation(DEC)accordingtothefunctionrequirementsofGM,developedthenewindustrialcontroldevice,andtheGMofavehicletorunautomatedproductionlineforthefirsttimetosucceed.Accordingtothisnewtypeofindustrialcontroldevicescanbeprogrammedtochangecontrolschemethischaracteristic,andthesituationofthespecializedforLogiccontrol,saysthenewindustrialcontroldevicefortheProgrammablecontrol(ProgrammableLogicController),hereinafterreferredtoasPLC.
From1968tonow,thePLChasexperiencedfourgeneration:
mostofthefirstgenerationofPLCwithamachinedevelopment,withthecorememorystorage,onlythelogiccontrolfunction.InthesecondgenerationofPLCproductsfor8-bitmicroprocessorandsemiconductormemory,PLCproductseriation.ThethirdgenerationofPLCproductwithhighperformancemicroprocessorandchipisusedingreatquantitiesinthePLCCPU,PLCspeedgreatlyimproved,thusenablingittodevelopinthedirectionofmulti-functioncommunicationsandnetworking.ThefourthgenerationofPLCproductsnotonlycomprehensiveuse16-bitand32-bithigh-performancemicroprocessors,high-performanceslicemicrocontrollerprocessor,RISC(Reducedinstructionsetcomputer)ReducedinstructionsystemCPUandotheradvancedCPU,andmorethanoneprocessorinaPLCconfiguration,multi-channelprocessing.Alsoproducedalargenumberofembeddedmicroprocessormodule,onlymakesthefourthgenerationofPLCproducthasthefunctionoflogicalcontrol,processcontrol,motioncontrol,datacontrol,networkedcontrolfunctionsreallyworthyofthenameofmulti-functionalcontroller.Atthesametime,thePLCnetworkcomposedofPLChasalsobeenrapiddevelopment.PLCandindustrialcontrolofPLCnetworkinfactoryenterprisesbecomethepreferreddevice,composedofPLCmulti-stagedistributedPLCnetworkbecomeindispensablefundamentalpartofCIMSsystem.PeoplespokehighlyoftheimportanceofPLCanditsnetwork,itisoneofthethreepillarsofmodern.
Selectingmachinemodel
MarketpopularPLCproductsmanufacturerinChinawiththefollowingcompanies:
(1)schneidercompany,includingtheintroductionofearlyfromModiconcompanybythetianjininstrumentinstrumentandmeterplantproducts,productsarenowQuantum,PremiumandMomentum;
(2)rockwellcompany(includingABcompany)PLCproducts,productsarenowSLCandMicroLogixControlLogixetc.
(3)ofSiemensPLCproducts,productsarenow400/300/S7-200series;
(4)gePLCproducts;
(5)thecompany'sproductssuchasomron,mitsubishi,Fuji,panasonic,oneofthemostpopularisthemitsubishiFXseries.
ThebasicprincipleofPLCselectionis:
intheinput/outputquantitymeettherequirementsunderthepremiseofshouldchoosethemostreliable,maintenance,andusethemostconvenientandcost-effectiveoptimalproducts.
SelectingI/O
PLCisanindustrialcontrolsystem,thecontrolobjectisindustrialproductionequipmentortheproductionprocessofindustrialproducts,workingenvironmentistheindustrialproductionfield.ItconnectstheindustrialproductionprocessisachievedbyI/Ointerfacemodule.PLChasalotofI/Ointerfacemoduleincludingswitchinputmodule,theswitchoutputmodule,analoginputmoduleandanalogoutputmoduleandspecialmodule,weshoulduseaccordingtothecharacteristicsoftheirimplementationoptions.
(1)determinethenumberofinput/output
Accordingtotherequirementsofthecontrolsystem,determinethenumberofinput/outputrequired,shouldincreasethesparequantityof10%20%,inordertoincreasecontrolfunctioninanytime.
(2)theswitchquantityinput/output
Switchinput/outputinterfaceandcantakethesignalsfromthesensorsandswitchesandcontrolequipment.Atypical24-240-vacinput/outputsignals,5-240-vdcinput/outputsignals.
(3)theanaloginput/output
Analoginput/outputinterfacecanacceptthesignalgeneratedbythesensor.Theseinterfacescanbeusedtomeasureturnoverrate,temperatureandpressure,andthustocontrolthevoltageorcurrentoutputdevice.Rangefortheseinterfaces-10-10v,+0to10v,4-20ma,or10to50ma.
SomemanufacturersonthePLCdesignspecialdedicatedanaloginterface,soitcanreceivelowlevelsignal.Ingeneral,thisinterfacemodulecanbeusedtoreceivedifferenttypesofthermocoupleandRTDmixedsignal.
(4)specialfunctioninput/output
WhenselectingaPLC,usermayfacedsomespecialtypesofinput/outputandsomebecauseofthelocationofthelimitedinput/outputandfastresponseandfrequencyproblemcausedbythenonstandardinput/output.Now,theusershouldconsiderwhethertoacceptbythemarketormanufacturerstoprovideaspecialmodule,throughadedicatedpartofthemoduleanddisposedata,soastoreducetheuseoftheCPU,improvetheefficiencyofthetaskprocessing,tominimizefailurecausedbyhighlimitcontrol.
PLCstatus
InaPLC,thelackofkeyboardandotherinputandoutputdevicesisaveryworthyofattention.InPLCfrontusuallyhaveacertainamountofstatusindicators.Usuallyindicatesthat:
Thestart-up-aslongasthePLCcharged,itwillbestarted.
Programisrunning-thiswillindicatewhetherrunningorifnoprogramisrunning.
Errordisplay-whenPLChasalargehardwareorsoftwareerrors,itwillbedisplayed.
Theselightsareusuallyusedfordebugging.AcertainnumberofbuttonwillalsobeprovidedtothePLChardware.Themostcommonbuttonisarun/programmingselectionswitch,wheninkeepingthestate,itwillbetransferredtotheprogramming;Whentheproductionstatu