外文翻译--基于plc监控应用平台的发展.doc

徐州工程学院毕业设计(论文)I英文原文DevelopmentofamonitoringandcontrolplatformforPLC-basedapplicationsS.Dana,A.Sagahyroon,A.Elrayes,A.R.Al-Ali,R.Al-AydiAbstractThispaperdiscussesthedesignandimplementationofaplatformtoremotelymonitorandcontrolPLC-basedprocessesoverTCP/IPorbyusingtheGSMnetwork.Theplatformisbuiltusingindustry-standardoff-the-shelfPLCs.IntegratedwitheachPLCarecommunicationprocessorsthatcanbeusedforconnectivitytothenetworkandtoaGSMmodem.Thecommunicationprocessormodule(Ethernetmodule)usedinthiswork,providesanindustrialcompatibleprotocoloverTCP/IPthatachievesthesamefunctionalityasProfinetbutatamuchhigherbandwidth(10/100Mbps).Additionally,amobile-basedcommunicationprotocolthatfacilitatesremotemonitoringandcontrolofPLCsusingSMSmessageshasalsobeendeveloped.Theintenthereistoprovidesystemuserswithaback-upcommunicationmechanismincaseofanetworkfailure.©2007ElsevierB.V.Allrightsreserved.1.IntroductionTherecentgrowthofnetworkstechnologyandspeciallythewidespreadoftheInternethavepromotedthedevelopmentofdistributedmeasurementsystemsforavarietyofindustrialapplications.Thesedistributedmeasurementsystemscanbeusedinthemonitoringandcontrolofvariousinstrumentsinthenetwork1,2.AProgrammableLogicController(PLC)ismicroprocessorbasedcontrolsystemthatcanbeprogrammedtosense,activateandcontrolindustrialequipmentandthereforeincorporatesanumberofinput/outputterminalsforinterfacingtoanindustrialprocess.AcontrolprogramstoredinthePLCmemorydeterminestherelationshipbetweentheinputsandoutputsofthePLC.PLCsareintelligentautomationstationsthatpossesshighlyusefulanddesirablefeaturessuchas3:Robustness.Highdegreeofscalability:modernPLCfamilieshaveawidespectrumofCPUtypesthatallowseasyscalabilityinfunctionalityandperformance.Extensibility:themodulardesignofPLCsenablestheextensionwithawiderangeofdigitalandanalogI/Omodules.Also,variousintegratedtechnologymodulesareavailableforvariousapplicationareas.徐州工程学院毕业设计(论文)IISophisticatedcommunicationcapabilities:modernPLCshavecommunicationportsthatprovideforcentralizedordistributedconnectivity.Powerfuldevelopmentenvironment:modernPLCfamiliescomewithacrossdevelopmentenvironmentthatsupportdifferentlanguagesforprogrammability,allowssemigraphicalhardwareconfigurationandofferstrongdebuggingmechanisms.Remoteaccesstocontrolandmonitorvariousdevicesinanindustrialsettingisofvaluetoengineersandautomationfacilities.CurrentimplementationsofremotePLCmonitorandcontrolusededicatedPCsorwebserversconnectedtothePLC.Fig.1illustratesacommonarchitectureusedinindustry.Asshown,PLCsareconnectedtothenetworkthroughacomputer.ThePLCsystemisusuallyinterfacedtothiscomputerusingtheserialPortorProfibus.ThesetypesofsystemsaredisadvantagedbythededicateduseofaPCtoaccessthePLCsystem.Thearchitecturealsodoesnotmakeuseoftheadventsandstridesmadeinareassuchastelecommunicationsandwebtechnology.InrecentyearsandduetotheeverincreasingcapabilitiesofPCcomputingandtheinfluxofnetworkprotocolsandstandards,therehasbeenasurgeinthedesignandimplementationofdistributedmeasurementandcontrolsystemsforindustrialapplications.Typically,thesesystemsarebasedontheclientserverarchitecturewhilesecuringcommunicationusingtheTCP/IPprotocol46.ModernPLCscomewithembeddedwebserversthatprovideopenaccesstousefulrealtimeinformationanddiagnosticsthatcanbeviewedviaanystandardwebbrowser.Thisremoteaccessibilityprovidesseveraladvantagesovermoretraditionalsolutions.Forexample,aproblemcaneasilybediagnosedandperhapsfixedremotely；alsoengineerscanhaveremoteaccesstothePLCCPUconfigurationtoolsandhenceallowingforremoteupload/downloadandconfigurabilityviatheintranetorinternet.InthispaperwewilldiscussthedesignandimplementationofanetworkedplatformforremotemonitoringandcontrolofPLCs.TheplatformisbuiltaroundtheSiemensS7seriesofPLCs.ThesePLCshaveanintegratedcommunicationprocessorthatcanbeusedtoprovideaccessibilitytotheinternet.Themonitoringandcontrolcanbeaccomplishedinawiredorwirelessenvironment,viaanintranetorinternethenceprovidingforacompletesolutionfortheremotemonitoringandcontrolofindustrialprocesses.WewillalsodiscusstheutilizationoftheGSMnetworkandtheoperationofacommunicationprotocolthatusesSMSmessagingtocommunicatewiththePLCstationsandaDatabaseServerintegratedwiththesystem.Thepaperisorganizedasfollows:inSection2wedescribetheoverallsystemarchitecture；sectionthreeincludesadiscussionofthesoftwareaspectsofthesystem.Sections4and5presentthecommunicationsmethodologyfollowedinthisprojectandthepaperisconcludedinSection徐州工程学院毕业设计(论文)III6.Fig.1.PC-basedremoteaccessibility.2.SystemarchitectureTheproposedsystemarchitectureisillustratedinFig.2.Thesystemconsistsofthefollowingcomponents:SimaticS7200/300PLCsystemsandCommunicationProcessors(CPs).EachCPhasanintegratedcommunicationinterface(hardwareandsoftware)thatallowsthePLCtocommunicateinaLAN,WANorviaaGSMnetwork.Clientsandadministratorareconnectedtotheprocessviathenetwork(orwirelessly).Privilegescanbesetorresetbyadministratorstoallowforortolimitthevariousclientsoptions.ADatabaseServerconnectedtotheprocessviathenetworkfordataloggingandeventrecording.AvarietyofnetworkoptionsincludingGSM-basedaccessibility.ThePLCsystemEthernetmoduleisacommunicationprocessorfortheS7familyusedto徐州工程学院毕业设计(论文)IVconnectthePLCtothenetwork.AnadditionalcommunicationprocessorisusedtoallowcommunicationbetweenthePLCandtheGSMmodemovertheserialport(RS232).Intheproposedimplementation,thePLCsystemreportsremotelythestatusoftheprocesstotheDatabaseServer.TheDatabaseServerrecordsthestatusofthePLCintime-basedtablesandperformsanyrequireddataanalysis.Thesystemalsoreceivesandexecutescommandsfromadministratorsandclientstocontroltheprocess.GSMconnectivityisalsoimplementedtoallowuserswithdifferentprivilegestoaccessthestatusofthemandatoryfunctionsofthePLCandallowthemtocontrolthesefunctions.EthernetandGSMconnectivityofthePLCsisimplementedusingtheCP343,andtheCP340communicationprocessors7.TheSystemsoftwarewasimplementedmainlyusingSimaticManager7andJava.TheSimaticManagerenvironmentisusedforcommunicationwiththePLCsystem.Theproposedarchitectureallowsforprogramming,reprogramming,andconfiguringthesystemremotely.TheJavaapplicationisdevelopedusingtheS7-APIs(S7-ApplicationProgrammingInterfaces)toestablishthecommunicationbetweentheDatabaseServerandPLCstation8.Forexample,usingtheseAPIs,wecaninstantiateobjectsthatwillconnecttheDatabaseServertothePLCstationbyspecifyingtheIPAddressandtheS7addressoftheCPUcontainedinthePLCunit.ThePLCisconnectedtotheprocesssensorsandactuatorsusingI/Omodules.AftertheJavaapplicationrunningontheserversideestablishestheconnectiontoPLCusingtheS7-APIs,itthenusestheJavaDatabaseConnectorTechnology(JDBC)tostoretheretrieveddatathatreflectsthestatusofvariousPLCparametersintheDatabaseTables.JDBCisatechnologythatallowsJavatoconnecttoDatabaseservers.ItcontainstherequiredJavalibrariesthatincludeallthenecessarymethodsrequiredtoconnecttotheDatabaseServerandexecuteSQLstatements.TheoverallsystemallowsuserstosetprocessvaluesusingthePLC.Forexample,userscansetanoutput(actuateamotor)orchangethevalueofamemorycell(memorybit,byte,word,flag,etc.).Thesystemenvironmentalsoprovidesforobtainingthereadingsofinputvalues(sensorsreadings)aswellascapturingthestatusofthePLC.AChartplottercanbeusedtoconvertreadingsfromthePLCsintocharts.Anerrorreportingmechanismthatprovidesadministratorswithusefuldiagnosticinformationisalsoincludedinthecompleteenvironment.SystemadministratorscanalsoquerythestatusoftheprocessusingtheGSMnetworkintheformofSMSmessages.Finally,theproposedsystemarchitectureisscalablewiththeabilitytomonitoracompletenetworkofPLCsspreadingaroundtheIntranetorInternet.