Development Of Distributed Control System Based On Field Bus

Created in 1975, Distributed Control System has developed for nearly 30 years . Now DCS is at the crest of its application . Traditional DCS uses technology which mixes digital signals and analogy signals. However, with the development of computer and network technology, the disadvantages of traditional DCS are being increasingly exposed. It' s difficult for traditional DCS to accommodate the requirement of modern enterprises.This paper introduces the development history, characteristic, structure and the application status of DCS. It will analyze some shortcomings of traditional DCS, introduce FieldBus technology (which is growing quickly), and point out the development direction of DCS. It will then put forward a viewpoint that the combination of traditional DCS and FieldBus technology is the control system model which is most suitable for the situation in China. Based on these theories, we designed and realized a kind of DCS based on FiledBus—LN2000 distributed control system. This control system can satisfy the control and management requirements of manufacturing processes on different scales. It has many prominent characteristics, for example: a communication system that is high speed , and reliable and open; configuration software that is simple and easy to use; an algorithm of process control that is rich and practical; in addition to high precision, modularized framework and intelligent structure. This paper will introduce the major structures and components of the system, and elaborate on the hardware design of I/O intelligent modules, (including :the choice of CPU and ADC, the solve scheme of cold end compensation for measuring temperature, the circuit design of CAN communication system, the design of anti-jamming of system, etc). The software design of intelligent modules will also be introduced in this paper. This will include the software design of CAN communication system, ADC and compensation for measuring temperature, etc.