MCGS在PLC工作状态监控系统中的应用

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MCGS组态软件在PLC工作状态监控系统中的应用可编程控制器(PLC)自问世以来,以其可靠性高、通用性强等优点,广泛应用于工业自动化的各个领域。在使用PLC对各种制造装备、自动化生产线等进行控制时,必须对各类故障做出实时正确的反应;若发生意外,应及时处理。因此,为提高控制系统的整体效益,需要对PLC工作状态监控功能提出一定的要求。目前,常用的PLC工作状态监控方式主要有两种。一种是利用与PLC配套的编程软件所具有的监控功能,当PLC工作在监控方式时,在上位机的监控界面中,以PLC程序语句闪烁等形式表示故障报警,监控者需要根据PLC程序内容推测故障环节,再予以排除。其技术要求高,现场工作有较大的困难。另一种方法是用VC++、VB等程序设计语言编制监控程序软件包,在上位机中以直观的图形界面显示PLC及被控对象的工作运行状态,从而能够形象显示故障环节。但其软件设计工作难度高,编程量大,开发周期长。考虑到上述两种方法的不足,以MCGS工控组态软件为开发平台,通过相对容易的组态编程工作,较好实现可编程控制器工作状态监控的功能。现场总线技术是20世纪80年代后期发展起来的一种基于现场设备之间进行通讯的新型总线系统,它综合了数字通信技术、计算机技术、自动控制技术、网络技术和智能仪表等多种技术手段,从根本上突破了传统的“点对点”式的模拟信号或数字一模拟信号控制的局限性,构成一种全分散、全数字化、智能、双向、互连、多变量、多节点的通信与控制系统。现场总线则是连接智能现场设备和自动化系统的数字式、双向传输、多分支结构的通信网络,其基础是智能仪表。分散在各个工业现场的智能仪表通过数字现场总线连为一体,并与控制室中的控制器和和监视器一起构成现场总线控制系统(FieldBusControlSystem,FCS)。通过遵循一定的国际标准,可以将不同厂商的现场总线产品集成在同一套FCS中,具有互换性和互操作性。FCS把传统DCS的控制功能进一步下放到现场智能仪表,由现场智能仪表完成数据采集、数据处理、控制运算和数据输出等功能。现场仪表的数据(包括采集的数据和诊断数据)通过现场总线传送到控制室的控制设备上,控制室的控制设备用来监视各个现场仪表的运行状态,保存智能仪表上传的数据,同时完成少量现场仪表无法完成的高级控制功能。另外,FCS还可以通过网关和企业的上级管理网络相连,以便管理者掌握第一手资料,为决策提供依据。所以现场总线具有开放性、互操作性、系统结构的高度分散性、灵活的网络拓扑结构、现场设备的高度智能化、对环境的高度适应性等诸多突出特点。尽管目前对现场总线的研究尚未能形成一个完善的统一标准,但现场总线的高性能价格比将吸引众多工业控制系统采用。WorkinthePLCconfigurationsoftwareMCGSConditionMonitoringSystemProgrammableLogicController(PLC)sinceinception,withitshighreliability,highuniversality,itiswidelyusedinindustrialautomationfields.TheuseofPLCforvariousmanufacturingequipment,automatedproductionlines,andcontrolmustbemadeonallkindsofreal-timefaultrightresponse;ifanaccidentshouldbeatimelymanner.Therefore,inordertoimprovetheoveralleffectivenessofcontrolsystemsneedtoworkonthePLCtomakecertainstatemonitoringrequirements.Atpresent,thecommonlyusedconditionmonitoringPLCworkTherearetwoways.OneistheuseofmatchingwiththePLCprogrammingsoftwarewiththemonitoringfunction,whenthePLCworkinmonitoringmode,monitoringthePCinterfacetoflashtheformofPLCprogramstatementthatfailurealarm,monitorthecontentofthoseproceduresneedtoPLCspeculatedthatfailurelink,andthenbeexcluded.Thetechnicalrequirementsforhighon-siteworkmoredifficult.AnothermethodistouseVC++,VBandotherprogramminglanguagesmonitorprogrampackagepreparation,thehostcomputerinanintuitivegraphicalinterfacedisplaystheworkofthePLCandtheplantisrunning,whichcanlinktheimagedisplayfailure.However,thehighdegreeofdifficultyofitssoftwaredesign,programmingcapacity,longdevelopmentcycle.Takingintoaccounttheabovetwomethods,withaviewMCGSConfigurationSoftwareastheplatformtoarelativelyeasyconfigurationthroughprogramming,programmablelogiccontrollertoachievebetterworkingconditionmonitoringfunctions.Fieldbustechnologyisthe20thcentury,developedinthelate80sasacommunicationbetweenfielddevicesbasedonthenewbussystem,whichcombinesdigitalcommunicationstechnology,computertechnology,automationtechnology,networktechnologyandintelligentinstrumentsandothertechnicalmeans,afundamentalbreakthroughinthetraditionalpointtopointoftheanalogsignalordigitalananalogsignalcontrollimitations,constituteafullydistributed,fullydigital,intelligent,two-way,interconnect,multi-variable,multi-nodecommunicationandcontrolsystem.Fieldbusintelligentfielddevicesareconnectedanddigitalautomationsystem,two-waytransmission,multi-branchstructureofthecommunicationsnetwork,basedonsmartmeters.Scatteredinvariousindustrialfieldbydigitalfieldbusintelligentinstrumentsasasingleentity,andwiththecontrolroomandmonitorthecontrollerandtogetherconstitutethefieldbuscontrolsystem(FieldBusControlSystem,FCS).Byfollowingcertaininternationalstandards,differentvendorscanbeintegratedfieldbusproductsinthesamesetofFCSwithinterchangeability,andinteroperability.FCScontrolofthetraditionalDCSfunctionfurtherintothesiteundertheintelligentinstrument,intelligentinstrumentcompletedbytheon-sitedatacollection,dataprocessing,controlalgorithms,anddataoutputfunction.Fieldinstrumentdata(includingcollectionofdataanddiagnosticdata)senttothecontrolroomthroughthefieldbuscontroldevice,thecontrolroomcontrolequipmentusedtomonitortheoperationalstatusofeachfieldinstrument,preservationintelligentinstrumentuploaddatasimultaneouslysmallfieldinstrumentcannotbecompletedadvancedcontrolfunctions.Inaddition,FCScanalsobesuperiorgatewayandenterprisemanagementnetworkconnectedtomanagementfirst-handinformation,providethebasisforthedecision.Therefore,thefieldbusisopen,interoperability,systemarchitecture,ahighlydecentralized,flexiblenetworktopology,on-siteequipment,highlyintelligent,highlyadaptabletotheenvironmentandmanyotheroutstandingfeatures.Althoughcurrentstudieshavenotbeenabletofieldbustoformacompleteunifiedstandard,butthehighcostperformancefieldbuswillattractanumberofindustrialcontrolsystem.

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