Applied Research Of CANopen Protocol For Autobody Based On RTOS

CAN bus has been widely used as the means of communication among the automotive electronic control units, but the application layer protocol of CAN bus is not unified, as only the physical layer and data link layer are defined in the specification of CAN bus, so the different automobile manufacturers may use different CAN application layer protocols in their cars, which greatly damages the openness and connectivity of the car bus communication system, affects interchangeability and interoperability of the standard accessories, as well as causes duplications of development efforts and wastes of resources,but also hinder the development of automotive networking technologyseriously. As a standard protocol of CAN application layer recommended by CiA, CANopen has been popularized in the field of industrial automation. When CANopen protocol is applied to the autobodyCAN-bus communication network, the unification and standardization of the automobile CAN network application layer protocols can be promoted. Whereas real time operating system (RTOS) is involved to implement CANopen communication management and other functional scheduler in consideration of the needs of improving real-time response characteristics of the complex communications nodes.Based on the relevant investigation, μC/OS-II real-time operating system and CANopen protocol have been analyzed in-depth. The μC/OS-II real-time operating system istransplanted to STM32 systemsuccessfully, MicroCANopen protocol stack is modified and improved specifically, and CANopen protocol is implemented on the μC/OS-II operating system. Also,the CANopen communication framework for autobody network has been constructed. The experimental test system is built to verify the feasibility of the scheme andrationalization of CANopen protocol implementation, which mainly includes the designof hardware and software for autobodycommunication nodes, man-machine interface system based on μC/GUIfor the central control node and the PC monitoring software based on Lab VIEW. In addition, the message transmission of CANopen slave node and the message exchange between central control node and function nodes are tested, and the network load rate is analyzed.The result proves that the applying of CANopen protocol to the autobody communication network is entirely feasible.The communication framework of CANopen protocol on automotive electronic control units based RTOS has been establishedsuccessfully, which lays the foundation of applying CANopen protocol to the autobody communication system and is of important reference significance to the openess and standard unification of high-level protocol of autobody CAN network.