OPC Server Development Based On Siemens PLC

With the evolvement of computer control system's architecture and abundance field device emergence lead to difference communications, how to carry out integrating process control with business management has become a task that the new generation distributed control system is confronted with. OPC specification that is enacted by OPC foundation is a technology standard that implements this integration, it is a specification that is designed for field control. The article introduces OPC server's designing and developing technology based on siemens PLC. In this article, My job mainly includes: OPC server's structure designing, carry out OPC criterion which include OPCServer class, OPCGroup class,OPCItem calss and the interface class. This article implements the OPCDvData class which includes the communication to PLC by MODBUS protocol. Finally, we successfully test the OPC Server's Asynchronous read, writing and Asynchronous read and writing.