The Research And Design Of OPC Data Access Server

With the developing of computer technology, more and more softwares and hardwares are used in industry control field and system integration becomes harder than before. So it is very necessary to use uniform standard for communication for both user and vender.OPC is such a standard that we need. OPC means OLE (Object Linking and Embedding) for Process Control , and it provides a uniform standard to object-oriented developments of industrial automation software. OPC was put forward in solving communication between application software and drivers of various devices. It makes the work more efficient by separating the two parts. Consequently, the repeated developments are reduced in the integrated system. OPC represents the future development trend of communication standards in process control system.First the background of the OPC and details of OPC data access specification was introduced in this paper. Systematic analysis was also done to COM/DCOM technique which is the foundation of OPC technique. Then author introduced how to use ATL to design the OPC server as well as the method which solved problem encountered in the process of design. This is the core of this paper. Finally, the test of the OPC server was explained in the paper. It not only implemented the base functions of the OPC server that conformed to the OPC specification, but also implemented optional function of address space browse by designing the OPC address space.