Research And Application Of OPC In SCADA System

Nowadays，as industrial automation system popularly appling，Distributed ControlSystem and Supervisory Control And Data Acquisition system have been usedextensively．SCADA system is not a full control system, but rather focuses on thesupervisory level. SCADA systems are used not only in most industrial processes: e.g.steel making,power generation and chemistry,but also in some experimental facilitiessuch as nuclear fusion. However，traditional control systems such as Distributed ControlSystem(DCS)and SCADA system are comprehensively implemented in industry．But,itis difficult to interconnect and interoperate with other control systems or instrumentsproduced by other companies，due to the reason that the traditional control systemadopted custom-defined special communication networks and particular communicationprotocols that lack standard interface to other control systems．With the appearance ofOPC(OLE for Process Control)technology in interface，it is possible to realize systemintegration between DCS and SCADA system．OPC(OLE for Process Control)is basedon Microsoft’s OLE(Object Linking and Embedding)／COM(Component Object Model)technologies，which is an industry specification andstandard generated to settle the communication problem between industry clientcomputer and various equipment drivers．Firstly,this thesis introduces the development of SCADA system,and the birth anddevelopment of OPC technology,then introduces the background of the subject and themain work of author. Secondly,this thesis discusses COM fundamental knowledge，suchas COM object，COM interface，COM connectable object，ATL，WTL and soon．Thirdly,this thesis studies OPC technology based on COM．On the basis ofdiscussing OPC fundamental knowledge，this thesis discusses OPC Data AccessSpecification，which is the base of OPC asynchronous communication，discusses OPCbrowsing address space methods，which is easier to check items in OPCServer．Finally，this dissertation develops an OPC Data Access Server in terms of OPCData Access Specification which can be connected with APCS3000SCADA system．...