Application Of CAN Bus In Intelligent Instrument

With developing and appearing of micro-electronics technology, Fieldbus technology has already attracted attention of all industries at home and abroad. CAN fieldbus is a technology which efficiently supports distributed real-time with a very high level of security. It attracted attention with a very high level of capability and a very high level of security and a very better of anti-jampping and a very fast of communication speed and a very low of maintenance cost and a particular design. It was regarded a fieldbus with expansibility. With rapid-developing of fieldbus technology the traditional instrument will be affected, and it will be replaced with the instrument based on fieldbus.It is realistic meaning to research and develop instrument based on fieldbus.For the request of instrument development, this paper adds CAN communication to RS-485 communication based on the intrinsic design of pH instrument. It researches the approach that insets CAN bus to intelligent instrument. It explores to consummate the instrument functions and to increase competitive abilities based on using restrieted space and resource of CPU .At the same time, it introduces the principle of the CAN communication and communicational protocol. It also introduces the constitution of microcomputer AT89C55, CAN controller SJA1000 and CAN transceiver. This paper analyzes and discusses capability and characteristic of fieldbus technology and analyze and research CAN protocol of CAN fieldbus. The design of communication module and pH instrument based on CAN field bus is discussed in detail. The software has realized that PC computer manage and control the instrument based on CAN fieldbus using the CAN communication module.It is proved that stability and real-time of instruments based on CAN fieldbus are better than traditional instruments. The error-delaying and data-switching and system-managing and anti-jamming of control system based on CAN fieldbus instruments are better than the system based on traditional instruments.