Research On OPC Technology And It's Application

Field bus control system (FCS, Field-bus Control System) as a link between control device for digital communication, has been widely application in the industrial process data acquisition and system monitoring. It Can not be directly realized the data transmission and information sharing between the different bus, to achieve information integration in a different field bus subnet is a urgent problems for the formation of an open control system.OPC (OLE for Process Control) specification is a industry standard as a technical support to Microsoft used in the process control and automation applications, including a group of interfaces. OPC technology is a key technology to realize information interaction between process management-level and field device-level control systems, and is an important means of realizing interoperability between different field bus protocols.This article describes the field bus and OPC technology, and proposes a program to achieve heterogeneous system integration using the field bus and the OPC technology:the respective OPC server and the client for different field bus segment have been developed, host computer software as OPC client program can access to each different field bus by the consistent OPC interface, accessing to each bus segment of data, to achieve communication and interaction between the different bus systems. As the development of different protocol standards of OPC servers has a great of reusability, the process of OPC standard data encapsulation is the same, only difference is that the data collection section, needing to be achieved according to different field bus protocols. At the same time, taking Modbus protocol application Widely into account, so this paper, Visual C++ as a development platform, WinTECH Software's OPC server development kit as a development tool to Modbus OPC Data Access Server as an example to regularly describe the development process and the design of OPC Data Access Server.The article describes realization of methods and steps of the design and development of OPC DA server and client, based on in-depth study of OPC DA specification and COM technology.Low-voltage distribution network monitoring has been designed, based on the Modbus-OPC server, it discussed in detail the development steps and implementation of OPC Server based on the Modbus fieldbus, giving the overall design of the program structure and the implementation process of the various parts. The OPC client has been compiled with Visual Basic6.0, the development of the functionality of the server has been tested respectively by the developed OPC client and Kingview. The results show that OPC server's data accessing has the versatility, OPC client and OPC server can achieve basic reading and writing operations.