Research And Implementation Of OPC Technology Based On CORBA

OPC (OLE for Process Control) is a defined set of interfaces, based on OLE/COM and DCOM technology, for truly open software application interoperability between automation/control applications, field systems/devices and business/office applications.OPC is based on DCOM (Microsoft Distributed Component Object Model), a network-aware architecture of COM technology that allows one program to use the interface of another program to get information from it (as long as it is programmed as a COM component).Because OPC is DCOM dependent, it can just be used in Microsoft platform, so its application is limited.CORBA(Common Object Request Broker Architecture), one of the best distributed object-oriented technologies, has the advantages of attractive features, such as, inter-platform(hardware and operating systems), implementation language independence, interoperability and portability. CORBA has been widely used in distributed applications. It is therefore significant to map OPC into CORBA to break through the DCOMlimitation and promote the application of OPC technique.The thesis investigates the feasibility to map OPC technique into CORBA. My work is focused on the following four aspects.1 , The conversion of OPC DA IDL(OPC Data Access Interface Description Language) file to CORBA IDL: the OPC technique is a set of interfaces described in MIDL(Microsoft IDL language) based on DCOM. So the most fundamental work to map OPC into CORBA is to convert OPC's MIDL description to CORBA IDL.2, Successful development of a CORBA OPC DA server and a client: we use the conversed CORBA OPC DA IDL files to create a server and a client based on CORBA OPC DA, which supports the real-time information exchange.3, Implementation of a CORBA-DCOM communication bridge:Through the bridge CORBA OPC DA server(client) and DCOM OPC DA client(server) can nicely communicate, which solves the compatibility between the new CORBA OPC DA and the old DCOM OPC DA and extends the current application of OPC.4, A real case study: we developed a CORBA OPC client in JAVA language and apply it in a power factory. The result shows that our technique scheme is feasible.