Applied Research Of CANopen Protocol In RTU Communication Control Module

CANopen protocol is one kind of an open standard application layer protocol for CANbus,CANopen specification complete works in addition to the application layer andcommunication protocols,including a variety of framwork,suggestions,as well as the standardequipment specifications,interfaces and application technical specifications. And it supportsequipments interoperability and interchangeability which are made of different manufacturers.RTU is responsible for the field data collection,monitoring and control of industrialequipments,it is very suitable for harsh working environment. According to the background ofoil field,CANopen protocol used in RTU not only could gather and transmit data,but alsocould achieve real-time monitoring of devieces.This paper first presents a monitoring system based on the CANopen protocol which isused in RTU,and gives the hardware design of the RTU which takes AT91SAM7X256microprocessor as main controller.Secondly,CAN bus is described in detail,as well as objectdictionary,PDO object,SDO object,NMT object,special features object and so on of CANopenprotocol. In order to increases the reliability and real-time of embedded RTU system,selectesμC/OS-Ⅱ which is open-source,real-time embedded operation system.Finally,according to the functional requirements of the monitoring system, the CANopenprotocol has been implemented in RTU and tested. The experimental results show that thecommunications among master and slave RTU nodes based on CANopen protocol work well，and have the characteristics of reliability and real-time.