Glmdjq毕业设计机械外文翻译.docx
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Glmdjq毕业设计机械外文翻译
生命是永恒不断的创造,因为在它内部蕴含着过剩的精力,它不断流溢,越出时间和空间的界限,它不停地追求,以形形色色的自我表现的形式表现出来。
--泰戈尔
VisualizationofPLCProgramsusingXML
M.BaniYounisandG.Frey
JuniorprofessorshipAgentenbasedAutomation
UniversityofKaiserslautem
P.0.Box3049,D-67653Kaiserslautem,Germany
Abstract-DuetothegrowingcomplexityofPLCprogramsthereisanincreasinginterestintheapplicationofformalmethodsinthisarea.Formalmethodsallowrigidprovingofsystempropertiesinverificationandvalidation.OnewaytoapplyformalmethodsistoutilizeaformaldesignapproachinPLCprogramming.However,forexistingsoftwarethathastobeoptimized,changed,orportedtonewsystems.ThereistheneedforanapproachthatcanstartfromagivenPLCprogram.Therefore,formalizationofPLCprogramsisatopicofcurrentresearch.Thepaperoutlinesare-engineeringapproachbasedontheformalizationofPLCprograms.ThetransformationintoavendorindependentformatandthevisualizationofthestructureofPLCprogramsisidentifiedasanimportantintermediatestepinthisprocess.ItisshownhowXMLandcorrespondingtechnologiescanbeusedfortheformalizationandvisualizationofanexistingPLCprogram.
I.INTRODUCTION
ProgrammableLogicControllers(PLCs)areaspecialtypeofcomputersthatareusedinindustrialandsafetycriticalapplications.ThepurposeofaPLCistocontrolaparticularprocess,oracollectionofprocesses,byproducingelectricalcontrolsignalsinresponsetoelectricalprocess-relatedinputssignals.ThesystemscontrolledbyPLCsvarytremendously,withapplicationsinmanufacturing,chemicalprocesscontrol,machining,transportation,powerdistribution,andmanyotherfields.Automationapplicationscanrangeincomplexityfromasimplepaneltooperatethelightsandmotorizedwindowshadesinaconferenceroomtocompletelyautomatedmanufacturinglines.
Withthewideningoftheirapplicationhorizon,PLCprogramsarebeingsubjecttoincreasedcomplexityandhighqualitydemandsespeciallyforsafety-criticalapplications.ThegrowingcomplexityoftheapplicationswithinthecomplianceoflimiteddevelopmenttimeaswellasthereusabilityofexistingsoftwareorPLCmodulesrequiresaformalapproachtobedeveloped[I].Ensuringthehighqualitydemandsrequiresverificationandvalidationproceduresaswellasanalysisandsimulationofexistingsystemstobecarriedout[2].OneoftheimportantfieldsfortheformalizationofPLCprogramsthathavebeengrowingupinrecenttimeisReverse-engineering[3].ReverseEngineeringisaprocessofevaluatingsomethingtounderstandhowitworksinordertoduplicateorenhanceit.WhilethereuseofPLCcodesisbeingestablishedasatoolforcombatingthecomplexityofPLCprograms,ReverseEngineeringissupposedtoreceiveincreasedimportanceinthecomingyearsespeciallyifexitinghardwarehastobereplacedbynewhardwarewithdifferentprogrammingenvironments
VisualizationofexistingPLCprogramsisanimportantintermediatestepofReverseEngineering.ThepaperprovidesanapproachtowardsthevisualizationofPLCprogramsusingXMLwhichisanimportantapproachfortheorientationandbetterunderstandingforengineersworkingwithPLCprograms.
Thepaperisstructuredasfollows.First,ashortintroductiontoPLCsandthecorrespondingprogrammingtechniquesaccordingtotheIEC61131-3standardisgiven.InSectionⅢanapproachforRe-engineeringbasedonformalizationofPLCprogramsisintroduced.ThetransformationofthePLCcodeintoavendorindependentformatisidentifiedasanimportantfirststepinthisprocess.XMLandcorrespondingtechnologiessuchasXSLandXSLTthatcanbeusedinthistransformationarepresentedinSectionIV.SectionVpresentstheapplicationofXMLforthevisualizationofPLCprogramsandillustratestheapproachwithanexample.ThefinalSectionsummarizestheresultsandgivesanoutlookonfutureworkinthisongoingproject.
ⅡPLCANDIEC61131
Sinceitsinceptionintheearly‘70sthePLCreceivedincreasingattentionduetoitssuccessinfulfillingtheobjectiveofreplacinghard-wiredcontrolequipmentsatmachines.Eventuallyitgrewupasadistinctfieldofapplication,researchanddevelopment,mainlyforControlEngineering.
IEC61131isthefirstrealendeavourtostandardizePLCprogramminglanguagesforindustrialautomation.InI993theInternationalElectrotechnicalCommission[4]publishedtheIEC61131IntemationalStandardforProgrammableControllers.BeforethestandardizationPLCprogramminglanguageswerebeingdevelopedasproprietaryprogramminglanguagesusabletoPLCsofaspecialvendor.Butinordertoenhancecompatibility,opennessandinteroperabilityamongdifferentproductsaswellastopromotethedevelopmentoftoolsandmethodologieswithrespecttoafixedsetofnotationstheIEC61131stand