| With the requirement enhancing of system, the scale has been expanding and the configuration has been more and more complex in the field of industrial control. The system integration has been accepted and focused on to guarantee the effective work of whole system. The control network is the key point of successful system integration. It integrates control equipments distributed in every corner of fields into one whole to achieve the function of system by open and normative communication protocol. However, the various kinds of field bus and industrial Ethernet have problems of openness and interoperability, which really increase difficulty of control system integration. OPC(OLE for Process Control) specification, which is based on the distributed component object model technology (COM/DCOM), provides the characteristic of open and flexible, and could solve the problems mentioned above in system integration.After studying the OPC specification system, the paper presents a method to achieve interoperability of industrial Ethernet and make integration more effective by applying OPC-DA in the application layer protocol of each standard. In addition, the paper implements an OPC-DA software-gateway based on the open industrial Ethernet standard Modbus/TCP, and which is more important, the server developing process used a modularization design method, separating it to several parts including OPC interface module, hardware drive module, HMI module. The modularization design method makes the process more general for other servers'development.Finally, the paper used the modularization design method to implement some other OPC software-gateways for sub-systems in a practical building system integration project. It proved the efficiency of OPC software-gateways in the work of system integration. |
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