The Study, Based On The Can Bus Network Of Distributed Measurement And Control System

CAN bus is widely used in the industry control domain because of its advantages such as high reliability, good real time performance, low price and easy realization. Compared to the traditional control system, the distributed measurement and control network system based on CAN bus can reduce the complexity and cost of system, and can also increase the stability and flexibility of system. This paper proposes the whole design scheme, system structure, hardware design and software design of measurement and control system based on CAN bus through the analysis of the composing of CAN field bus network and communicating protocol. And last, the effectiveness and practicality of this system are validated through experimental method. The main tasks finished are as follows.Firstly, a new protocol for user layer communication which is named CAN_Protocol is presented based on CAN bus specification CAN2.0A and CAN2.0B. This protocol adopts the form of standard frame and the format of "order + parameter".Secondly, the electrical signal harmonic analysis node is designed based on DSP TMS320F2812. The hardware circuit of this node is designed, including CAN bus interface circuit, signal conditioning circuit, synchronization square wave transform and phase-locked loop frequency circuit and so on. The software of this node is designed, including the initialization of CAN controller eCAN, the transmission and the interrupt reception of the message, the measurement of electrical parameter and harmonic analysis arithmetic and so on.Thirdly, the high-precision and wide-range frequency measurement node is designed based on AT89C52 and CAN controller SJA1000. The hardware circuit of this node is designed, including CAN bus interface circuit, address decoder and bus buffer interface circuit, I/O output register circuit, three-channel gating circuit and timing counter 8254 circuit and so on. The software of this node is designed, including the initialization of CAN controller SJA1000, the transmission and the interrupt reception of the message, high-precision frequency measurement algorithm and so on.Fourthly, application software of PC node is designed, including the communication management software of PC node based on DLL of USB/CAN card and Visual C++, and the monitoring software of PC node based on OPC Client development kit, Visual C++ and KingView. The communication between all nodes of the CAN network, data report and web publishers of PC node are all realized. Finally, the distributed measurement and control network system based on CAN bus is constructed using harmonic analysis node, frequency measurement node and application software of PC node which are designed by myself. The communication between PC node and other nodes is realized using the protocol CAN_Protocol for user layer communication which is designed by myself. The availability and realization of the network system, which is designed by myself, is validated by experiment in the end.