Research On The Key Technologies Of Real-time Ethernet Reliability

Motion control is widely used in the industrial automation, it includes the computer numerical control which indicates the national industrial development and the general motion control which used in other industries. With the development of Ethernet in recent years, industrial Ethernet becomes more and more popular in motion control platform. Based on EtherMAC which was proposed by the group, this paper studies the reliability of the real-time Ethernet, the application layer protocol with CANOpen, the forward error correction and EtherMAC ring redundant network.The reliability and function safety theory of real-time Ethernet is studied. The reliability of different network topologies is calculated and compared and the ring redundant network has the highest reliability. The packet error rate is calculate and it confirms that the real-time Ethernet must have error detection or error correction capability. The faults that may lead the failure of the real-time Ethernet and the preventive measures as specified in IEC61508and IEC61784are researched. The safety measures taken in the mainstream real-time Ethernet are analyzed.The application layer protocol based on CANOpen of EtherMAC is designed and it allows easy function-appending and upgrading. The structure of EtherMAC frame is designed Cyclic redundancy check, sequence number and emergency object are employed to detect failure errors in communication.Different error correction models that used in communication system are analyzed and the forward error correction is chosen as EtherMAC error correction system. RS(15,11) is implemented in hardware circuit by Verilog. The error correction is embedded in the EtherMAC protocol and it can get a small delay with the implement in hardware.The redundant ring network EtherMAC-Ring is proposed. The synchronization between nodes in real-time Ethernet is studied. The distribute clocks in EtherMAC-Ring is built and the redundant data is realized. An FPGA-based slave node solution is proposed. An prototype system is built and its real-time performance is tested according to several experiments.