Research And Development On OPC Client And Server Based On New DCS

Distributed Control System (DCS), mainly for computer control and management in the process of production, is widely used in various fields of industrial process control. Drive program is applied to sharing information not only between smart devices, but also smart device and upper monitoring software because there is no uniform interface standard between the upper configuration software and on-site intelligent devices in traditional DCS systems. Drive program of each device requires developing according to the needs of application software. As a result, problems occur, such as drive program redundantly developed, equipment impossibly interchangeable, reform and upgrade difficulty, access violation and so on.Changes in development mode have taken place as OPC is used. The upper application software as OPC client could read data from OPC server which is provided by different device companies in the condition of following the OPC data interface protocol. At the meanwhile, OPC client does not need to contain any hardware communication program or care what the underlying hardware is. Flexible configuration of data and integration of multiple systems are implemented. In this paper, the OPC technology is studied in depth based on the specific needs of the new DCS configuration software.The topic is the major scientific research project of Science and Technology Office in Shandong Province, whose name is New Control System based on Industrial Ethernet and Fieldbus and item number is 31400004010437. Considering the idiographic requirement of development, the software design of OPC client and server based on the new DCS come true on the platform of Windows 2000, choosing Microsoft Visual C++ 6.0 as program development tool.In this thesis, research background, significance of the subject and the generation, development and current research status of OPC technology at home and abroad is introduced at first. Then, COM, which is short for Component Object Model and the key of OPC technology, is studied, as well as OPC Data Access and OPC History Data Access. Besides, according to OPCDA standard, the overall framework of OPC client and server is given, which is based on reseach of advanced configuration software. What is more, architecture and communication is analyzed and OPC client is designed to read data from OPC server local or remote. In addition, analysis of real-time database and historical database of the new DCS system and design of specific software solutions, OPC data access server and OPC history data access server with ATL and MFC are given. A large number of historical data to be read, which make the OPC history data access server slow and inefficient, multithreading is used to improve the efficiency of data acquisition. Moreover, OPC driver software design and implementation and driver program based on TCP/IP protocol is presented, which has been verified through the modbus slave software. At last, the new DCS configuration software realizes data remote access and real-time monitor with DCOM configuration of the OPC client and server. The test result proves that the design and implementation of the OPC client and OPC server based on the new DCS introduced in this paper is valid and feasible. This software has good application value as well.