Field bus is an open digital communication technology which conforms to intelligent field instrument. its original intention is to use digital communication instead of one-to-one I / o connection mode, to extend the digital communication network to the industrial process site, and the intelligent electric device of our company applies the field bus such as profibus, Modbus, ff, hart etc. Through the serial port ( RS485 / RS232 ) can easily exchange data information, status information, control information and so on to implement remote digital control; Using field bus technology, can meet the international standards of the various intelligent equipment docking, thoroughly realize the decentralized control of the monitoring system, improve the system integration and data transmission density, extend the effective control distance, and improve the anti-jamming performance and scalability of the system. The fieldbus can be added to the electric device according to the requirements of the site.