| With the scale of industrial production continues to expand,spatial location of sensors and actuators are scattered and far away from the control center.When this is the case,a possible solution,that is gaining increasing popularity,is to use distributed,configurable,remote I/O modules with communication capability.These I/O modules acted as an interface to field devices are placed in industrial field and located close to the sensors and actuators,have signals acquired and controlled.CANopen is a field level communication protocol,as it makes up for the limitations of CAN bus communication,and definites a powerful set of application layer management services,which is widely used in various fields of industrial automation distributed applications.However,the domestic research of CANopen is in the initial stage,further promotion is necessary.Based on the STM32F407 ZE controller,the switch and analog remote I/O modules were developed,and these modules’ configurable process and the transmission control of switch and analog singal is realized via CANopen.The circuits were designed and PCB boards were drawed in Cadence.In software,the eCOS real-time operating system and CANopen protocol stack were transplanted,the CANopen is embedded in eCOS,and the main tasks were encapsulated.In CANopen,object dictionary of the analog and switch module,PDO communication,SDO communication,Heart heartbeat,NMT network management were achived.In addition,this article configured the primary Node-IDs and baud rate by software,the Node-IDs and baud rate of the modules in the CANopen network could be dynamically changed by the LSS function of CANopen protocol.At last,we have tests of I/O modules in CANopen network,including Precision test,SDO,PDO,NMT network management and LSS function tests.As is shown by the test results,each module conforms to DS301 protocol,runs stably and it’s accuracy meets the specified scope.and each module’s Node-ID and baud rate could be changed by LSS master in CANopen network. |
