ABB DCS培训课程T31514 CommunicationRevAWord格式.docx
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14.2.1General3
14.2.2MMSCommunicationPrinciple3
14.2.3Accessvariables4
14.2.4MMSVariableRules5
14.2.5VariableAttributes5
14.3ReadingDatafromanAccessVariable6
14.3.1PerformanceConsiderationsandStructuredAccessVariables7
14.4SetupanMMSCommunication8
14.4.1HowtoConfiguretheAccessDataType8
14.4.2HowtoDefinetheAccessVariable10
14.4.3HowtoReadAccessVariablesfromAnotherApplication11
14.4.4HowtoExtendParameters13
14.5OtherFunctionBlocksintheMMSCommLib15
14.5.1SIL2certifiedfunctionblocks15
14.6CommunicationtoOtherDevices17
14.6.1CommunicationLibraries17
14.6.2HardwareConfiguration18
14.6.3SoftwareConfiguration18
14.6.4AddressSyntax20
14.7HowtoConfigureaSerialCommunicationChannel21
14.7.1SerialConnect21
14.7.2SerialListen22
14.1GeneralInformation
14.1.1Objectives
Oncompletionofthischapteryouwillbeableto:
∙DescribetheprincipleofMMScommunication
∙Createanddefineaccessvariables
∙Configurecommunicationbetweencontrollers
∙ExplaintheuseofthedifferentMMSblocks
14.1.2Legend
<
>
Indicatesakeyname.
|Indicateswhenyougofromonemenutoasub-menu.
BoldIndicatesamenunameoranoptioninamenu,orfilestructures
““Indicatesdialogboxbuttons,tabs,instructionsetc.
Indicatesstart/explanationofstudentactivity
14.2
MMSCommunicationbetweenApplications
14.2.1General
MMSstandsforManufacturingMessageSpecification.Itistheprotocolusedtocommunicateonthecontrolnetworkbetweenapplicationsandalsototheconnectivityserverforthe800xAAspectSystem.
MMSsupportstransferofsimpleandstructuredvariables,programdownloadandalarmhandling.MMSisalsousedtodefineandmakedataavailableasAccessvariables.
GenerallytheMMScommunicationbetweenAC800Mcontrollersshouldbelimitedifpossiblebecauseitwillusethecontroller’sCPUcapacity.
14.2.2MMSCommunicationPrinciple
MMScommunicationhandlescommunicationbetweenapplicationswithinoneAC800Mcontrollerandbetweenapplicationsallocatedtotwocontrollers.
Theapplicationsmayexistinthesamecontroller:
Orindifferentcontrollersonthecontrolnetwork:
RememberthatinControlBuilderProfessionaloneapplicationdoesnotnecessarilycorrespondtoonecontrolsystem.Itispossibletoexecutetwoapplicationswithinthesamecontroller.Eveninthiscasethough,weneedtouseMMScommunicationwithAccessVariablesifwewantexchangedatabetweenthetwoapplications.
NOTE!
TheMMScommunicationshouldbelimitedandnotbeusedforalotofdata.
Forinstance:
don’twriteanapplicationinonecontrollerandusetheIOsofanothercontrollerforthisapplication.
14.2.3
Accessvariables
ForcommunicationbetweentwoApplications,Accessvariablesaredefined.AnAccessvariableisavariablethatissharedonthenetwork.
Bysharingalocal(orglobal)variableasanAccessvariable,itcanbepickedupbyanysystemonthenetwork,aslongasthetwosystemsinquestionshareacommonprotocol,suchasMMS,COMLIetc.
AccessVariablesaredefinedintheControllerHardwarepartoftheProjectExplorer:
Accessvariablesaredefinedinaparticularcontroller.TheremaybemanyAccessvariablesdefined.Suchvariablesaremappedintovariablesexistingintheapplicationsrunninginthatcontroller.ThismappingisdoneintheAccessVariableEditor.
Thevariableintheapplicationwhichismappedcanbeanyvariableexistinganywhereinthewholeapplication:
∙VariableinaprogramorControlModule
∙Variable(globalorlocal)intheapplication
14.2.4
MMSVariableRules
MMSvariablescanonlybeaccessedbytheirnamewhichisastring.ThenamingrulesaredefinedinMMSratherthanaspartofcontrolbuilder,thereforetherearesomedifferencesintheserulescomparedtothestandardnamingrulesforvariablesinprogramsetc.
∙AnMMSaccessvariablenamecanbeupto32characterslongandcontainletters,digitsandthecharactersdollar($)andunderscore(_).
∙NospacesarepermittedinthenameofanMMSvariable
∙MMSvariablenamesarecasesensitive,i.e<
TANK4>
isnotthesamevariableas<
tank4>
.
∙Theaccessvariablenamecannotbeginwithadigitorthedollar($)character.
∙Theaccessvariablemaybemappedtoanytypeofsimplevariableor(moreimportantly)toanytypeofstructuredvariable.
∙Astructuredvariablecanhavemixeddatatypecomponents
14.2.5VariableAttributes
BydefaultAccessvariablesareRead/Write.IfyouwanttomakethevariableReadOnlythensettheattributeintheAccessvariabletableto‘ReadWrite’
Iftheattribut