Research On Application Layer And Gateway Of The Ethermac Real-time Ethernet Based On CANopen

Real-time Ethernet technology overcomes the drawbacks of the traditional field-bus and has become the new era in the development of field-bus, being more and more widely used in the field of industrial automation where the numerical control system is a representative technology.An open, simple and flexible application layer protocol is needed for the real-time Ethernet to communicate efficiently and a uniform application layer protocol is requested that different real-time Ethernet technologies can be interconnected to the others. The thesis designs the application layer protocol of the EtherMAC real-time Ethernet field bus based on CANopen and studies the gateway between CAN and EtherMAC based on EtherMAC slave.The implementing strategy is also given.First of all, the development of real-time Ethernet is reviewed. Then the characteristics and the application layer protocol of the main-stream Ethernet field-bus are introduced.The advantages of the real-time Ethernet taking the CANopen as the application layer protocol is pointed out.Secondly, the thesis investigates the structure and some key profiles of the CANopen protocol.Then the timing performance of CAN bus is discussed, which leads to the necessity that CANopen should be moved to the application layer of real-time Ethernet for better timing performance.Thirdly, the characteristics of innovative EtherMAC real-time Ethernet field-bus are introduced, including the advantages of the data link layer and the disadvantages of the existing application layer. Then the design of the application layer of EtherMAC based on the CANopen protocol is studied.The implementing of the communication objects and the format of the EtherMAC frame including the objects based on CANopen are also given out.Then, the master with the application layer of EtherMAC based on CANopen is proposed on Windows operating system.The object dictionary of the master is given out.The procedures dealing with the boot-up of the application layer network and the communication objects such as PDO, SDO and EMCY are discussed sequently. After the function of EtherMAC slave with the application layer of EtherMAC based on CANopen is researched, the implementing strategy is given. Considering the extensive application of the standard CANopen devices, the gateway, named CANopen coupler, between EtherMAC and CAN bus based on EtherMAC slave is proposed. The solutions for the issues such as the synchronous property in CANopen networks connected to different CANopen couplers and the EtherMAC frames can not accommodate all data simultaneously because information from a single point is too enormous to be contained.Finally, a group of I/O ports of the EhterMAC slave is used to perform systematic verification of the the implementation of the application layer. Ultrac-TW series motors produced by Phase company are connect to the couplers as standard CAnopen slaves to verify the design of the coupler.