Development Of Batching Control System And Design Of Communication With Plc

With the development of hardware and software technology in the field of industrial control, traditional ingredient control is gradually being replaced by automated batching control. But our many small batching factories still face problems such as low accuracy, low reliability electromechanical components as well as lack of the data systems' supports. Therefore, a kind of low cost functional batching control system urgently needs to be developed for widespread use in order to improve the productivity of small batching plants.This project has developed an ingredients monitoring system, it can be used in many domestic small and medium batching plants, and it costs low. The system provides the cooperative control method between the host computer and lower computer. The upper computer commonly uses IPC or general PC; the lower machine usually uses PLC. This paper mainly covers the selection of monitoring plan, the development and selection of hardware and software, and the design of serial communication between SCADA software and lower computer.First, various control plans have been deliberated and detailed analysised, finally distributed control method of PC+PLC has been selected for this system. The advantages of this program is which is belong to a distributed system, easy to install and maintain, flexible. And the batching precision has been greatly improved.In aspect of development and selection of hardware and software, the host computer program is programed in a Visual C++ development platform. It makes full use of the C++ code in object-oriented encapsulation and flexibility, and makes the system control code more effective of optimization. Meanwhile, in the software part of the database design, taking into account small batching plants normally only need a small database, so the design uses the Access database. It is user-friendly, easy to use and manage. The whole system mainly uses modular programming, including several modules such as production management, recipe management, position management, materials management, report management and system calibration.Taking into account such factors as price, I choose Mitsubishi FX2N Series PLC as the company's site controller. In order to achieve communication between upper and lower computer, communication protocol is customed. Through the study of communication codes, MSCOMM serial communication controls are used for establishing communication modules. Then, the underlying communication between the two is successfully completed, and PC-site monitoring capabilities are reached.Finally, I do some research on accuracy issues of ingredient control process.