PLC外文文献翻译.docx

PLC外文文献翻译.docx

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PLC外文文献翻译

外文翻译

题目ProgrammableLogicController

目录

ProgrammableLogicController（PLC）1

1.AboutProgrammableLogicController（PLC）1

2.INTRODUCTION2

3.OPERATIONSEQUENCE4

3.1TheInputandOutputScans5

3.2TheLogicScan5

4PLCSTATUS6

5.MEMORYTYPES7

6.SOFTWAREBASEDPLCS8

7.SUMMARY8

8.PRACTICEPROBLEMS8

9.PRACTICEPROBLEMSOLUTIONS9

中文翻译11

1.PLC介绍11

2．指令12

3．运行顺序13

3.1输入输出扫描14

3．2逻辑扫描14

4．PLC状态显示15

5．存储器类型16

6．基于软件的PLC系统16

7．概要17

8．实际问题17

9．实际问题解答17

ProgrammableLogicController（PLC）

1.AboutProgrammableLogicController（PLC）

PLC（programmablelogiccontrollers）isthecontrolhubsforawidevarietyofautomatedsystemsandprocesses.Theycontainmultipleinputsandoutputsthatusetransistorsandothercircuitrytosimulateswitchesandrelaystocontrolequipment.Theyareprogrammableviasoftwareinterfacedviastandardcomputerinterfacesandproprietarylanguagesandnetworkoptions.

ProgrammablelogiccontrollersI/Ochannelspecificationsincludetotalnumberofpoints,numberofinputsandoutputs,abilitytoexpand,andmaximumnumberofchannels. Numberofpointsisthesumoftheinputsandtheoutputs.PLCmaybespecifiedbyanypossiblecombinationofthesevalues. Expandableunitsmaybestackedorlinkedtogethertoincreasetotalcontrolcapacity. Maximumnumberofchannelsreferstothemaximumtotalnumberofinputandoutputchannelsinanexpandedsystem.PLCsystemspecificationstoconsiderincludescantime,numberofinstructions,datamemory,andprogrammemory. ScantimeisthetimerequiredbythePLCtocheckthestatesofitsinputsandoutputs.Instructionsarestandardoperations（suchasmathfunctions）availabletoPLCsoftware.Datamemoryisthecapacityfordatastorage.Programmemoryisthecapacityforcontrolsoftware.

AvailableinputsforprogrammablelogiccontrollersincludeDC,AC,analog,thermocouple,RTD,frequencyorpulse,transistor,andinterruptinputs.OutputsforPLCincludeDC,AC,relay,analog,frequencyorpulse,transistorandtriac.ProgrammingoptionsforPLCincludefrontpanel,handheldandcomputer.

Programmablelogiccontrollersuseavarietyofsoftwareprogramminglanguagesforcontrol.TheseincludeIEC61131-3,sequentialfunctionchart（SFC）,functionblockdiagram（FBD）,ladderdiagram（LD）,structuredtext（ST）,instructionlist（IL）,relayladderlogic（RLL）,flowchart,C,andBasic.TheIEC61131-3programmingenvironmentprovidessupportforfivelanguagesspecifiedbytheglobalstandard:

SequentialFunctionChart,FunctionBlockDiagram,LadderDiagram,StructuredText,andInstructionList.Thisallowsformulti-vendorcompatibilityandmulti-languageprogramming.SFCisagraphicallanguagethatprovidescoordinationofprogramsequences,supportingalternativesequenceselectionsandparallelsequences.FBDusesabroadfunctionlibrarytobuildcomplexproceduresinagraphicalformat.Standardmathandlogicfunctionsmaybecoordinatedwithcustomizablecommunicationandinterfacefunctions.LDisagraphiclanguagefordiscretecontrolandinterlockinglogic.ItiscompletelycompatiblewithFBDfordiscretefunctioncontrol.STisatextlanguageusedforcomplexmathematicalproceduresandcalculationslesswellsuitedtographicallanguages.ILisalow-levellanguagesimilartoassemblycode.Itisusedinrelativelysimplelogicinstructions. RelayLadderLogic（RLL）,orladderdiagrams,istheprimaryprogramminglanguageforprogrammablelogiccontrollers（PLC）.Ladderlogicprogrammingisagraphicalrepresentationoftheprogramdesignedtolooklikerelaylogic. FlowChartisagraphicallanguagethatdescribessequentialoperationsinacontrollersequenceorapplication.Itisusedtobuildmodular,reusablefunctionlibraries.Cisahighlevelprogramminglanguagesuitedtohandlethemostcomplexcomputation,sequential,anddataloggingtasks.ItistypicallydevelopedanddebuggedonaPC. BASICisahighlevellanguageusedtohandlemathematical,sequential,datacapturingandinterfacefunctions.Programmablelogiccontrollerscanalsobespecifiedwithanumberofcomputerinterfaceoptions,networkspecificationsandfeatures. PLCpoweroptions,mountingoptionsandenvironmentaloperatingconditionsareallalsoimportanttoconsider.

2.INTRODUCTION

ForsimpleprogrammingtherelaymodelofthePLCissufficient.AsmorecomplexfunctionsareusedthemorecomplexVonNeumanmodelofthePLCmustbeused.AVonNeumancomputerprocessesoneinstructionatatime.Mostcomputersoperatethisway,althoughtheyappeartobedoingmanythingsatonce.ConsiderthecomputercomponentsshowninFigure1.

Figure1SimplifiedPersonalComputerArchitecture

Inputisobtainedfromthekeyboardandmouse,outputissenttothescreen,andthediskandmemoryareusedforbothinputandoutputforstorage.