Design And Realization Of OPC Data Access Server Based On DLL

OPC is the abbreviation of Object Linking and Embedding (OLE) for Process Control. Itis a kind of general industrial standard, used for standard software and hardware interface. Itprovides a unified standard for industrial automation software object-oriented development. Itis the application of Microsoft’s Object Linking and Embedding technology in ProcessControl. There are many kind of OPC servers, including data access server, warning serverand historical data access server, etc., and this paper mainly studies the OPC data accessspecification, and developed according to the standard OPC data access server. OPC dataaccess server program development is a very complicated job, must fully understand OPCdata access specification and COM technology, and need to understand Microsoft’s ATL andMFC technology. The background of OPC technology are reviewed firstly in this paper, thenintroduces its main characteristics and development status, and the use of core technologyCOM were explained, and then analyses the OPC server program design theoretical basis anddesign method, then introduces the internal data structure of the OPC server program. As forpackaging data items, in this article that is realized by reading SQL server2005data in adatabase, so this paper will also involves SQL server2005database operation.