Reaserch Of CANopen Protocol And Development Of CAN Communication Adapter

CANopen, as CAN application layer protocol, was widely recognized and applied in industrial field, to develop CANopen-based remote I/O devices is adapted to the domestic demand of bus products and effectively promoted bus-product company to develop independently, it was necessary, feasible and practical.This subject designed a remote I/O device module integrating one CAN bus interface, 8-point digital input/output,4-way 8-bit analog figure input. Hardware design based on ATMEL AT91SAM7X256 ARM7 chip, combind with power supply, crystal, reset circuits and CAN transceiver peripheral equipments, Not only strengthened data-processing capacity but also simplified the circuit, software programmed based on IAR developping enviroment for ARM, the protocol stack programme can be downloaded to chip through JTAG emulator, constructed a test CAN network with Schnaider PLC CANopen master node, and realized communication functions succesfully. And verified by experiments to reach the standards of products.The paper introduced CANopen protocol in detail and explained implementation of various communication objects in depth, node developping was according to DS-301 strictly,and through the preparation of protocol stack procedures, node initialization, communication parameter configuration, the state of the mechanism, data transmission and network monitoring and other functions were implemented. And discussed about views and methods to improve.There were two points of innovation: (1) multiple functions were implemented, as state-machine, heartbeat/node-guard, PDO trigger and analog up/low alarm functions were better designed to increase compatibility. (2) contact closely with application in industrial field, constructed test network with Schnaider products and successfully realized configuration and data transfer through network.