外文翻译可编程逻辑操纵器.pdf

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附录二外文文献及其翻译

Programmablelogiccontroller

Cynthiacooper

FromWikipedia,thefreeencyclopedia

Aprogrammablelogiccontrollerorsimplyprogrammable

controllerisadigitalcomputerusedforofindustrialprocesses,such

ascontrolofmachineryonfactory.Unlikegeneral-purpose

computers,thePLCisdesignedformultipleinputsandoutput

arrangements,extendedtemperatureranges,immunitytoelectrical

noise,andresistancetovibrationandimpact.Programstocontrol

machineoperationaretypicallystoredinbattery-backedor

memory.APLCisanexampleofasystemsinceoutputresultsmust

beproducedinresponsetoinputconditionswithinaboundedtime,

otherwiseunintendedoperationwillresult.

Features

ControlpanelwithPLC(greyelementsinthecenter).Theunit

consistsofseparateelements,fromlefttoright;,controller,units

forinputandoutput.

ThemaindifferencefromothercomputersisthatPLCsare

armoredforseverecondition(dust,moisture,heat,cold,etc)and

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外文翻译可编程逻辑操纵器--第2页

havethefacilityforextensive(I/O)arrangements.Theseconnectthe

PLCtoand.PLCsreadlimit,analogprocessvariables(suchas

temperatureandpressure),andthepositionsofcomplexpositioning

systems.Someevenuse.Ontheactuatorside,PLCsoperate,or

cylinders,magneticor,oranalogoutputs.Theinput/output

arrangementsmaybebuiltintoasimplePLC,orthePLCmayhave

externalI/