Software Development Of OPC Server Based On Optimal Control System

OPC (OLE for Process Control) is based on Microsoft's OLE (object linking and embedding)/COM (Component Object Model) technologies, which is an industry specification and standard that is set up to settle the communication problem between industry client computer and various equipment drivers. OPC technology specification is established by OPC foundation, which provides unified data accessing standard interface of software and hardware. Because it has more advancement and opening than traditional data access method, such as driver and DDE (Data Dynamic Exchange), OPC has been accepted and supported by more and more software and hardware manufacturers, and has become an acknowledged standard in industry control field.Firstly, the origin background, development history and current research of OPC technique are analyzed. Secondly, the paper gives the demand of real-time shared database---OPC server of the function of optimal control system which contains on-line real-time optimization, advanced process control, soft sensor, model simulation and abnormity prediction, etc. Thirdly, the theoretical foundation and the design method of OPC application are analyzed, and the function design of OPC server and the key technique of software development are given. Fourthly, using OPC Data Access Automation Interface Standard 2.05, the OPC Data Access Server is developed based on Visual C++ 6.0. Moreover, the shared memory between processes is designed and implemented. A section of shared memory on OPCDA server is built by the technology of memory mapping file, which has solved the problem of minimization of memory allocation in optimal control software. The paper also presents the design of OPC server label based on the demand of optimal control. Lastly, the OPC server is applied successfully into the optimal control software for the A3000 plant and SUPCON DCS.Using OPC server as real-time shared database of optimal control software system, it simplifies the optimal control system, improves the reliability and stability of software, achieves standard of data exchange among each module of optimal control software and realizes the opening of optimal control software and the interoperability with other systems. The preliminary application result shows the validity of software design and development of OPC server.