Development Of OPC CLIENT/SERVER

OPC technology and OPC Client/Server development approach are studied in this thesis. Its significance lies in discussing the OPC solution for the information system integration of enterprises, researching the development modes and processes of the OPC DA Client/Server, and accelerating the information integration between industrial control software and commercial management software.OPC inner mechanism based on COM/DCOM and the interaction of Client/Server system components are analyzed. At the same time OPC DA Client/Server application scheme is designed and implemented. The development consists of two parts: the design and its realization of OPC Client; the development approach and its practice of OPC Server. Several difficulties such as multi-thread programming, OPC interfaces' realization and multi-view displays are overcome during the OPC Client's development. The development is completed at source code level according to OPC DA specification. As a test program, the OPC Client can connect multi OPC Servers at the same time, manage them, and maintain data. The development of OPC Server is focused on building a uniform developing platform first. Then the development flows for the OPC Servers of a PC-Based I/O card and a LonWorks system are designed respectively, and at last the two OPC Servers are completed based on the uniform developing platform. Experimental tests for an OPC application are carried out by using the third-party software. The results proved that the OPC DA Client/Server system developed conforms to the OPC standard specification. It unified the communication between the industrial fieldbus devices level and the process management level. It also provides a good foundation for further information integration with commercial management level. Research results are practical for enterprise information integration.