Design And Implementation Of Protocol Conversion Method Of Real-time Industrial Ethernet

With the development of industry 4.0 and intelligent manufacturing,the real-time data of manufacturing site and non real-time data of production management and optimization layer need to be transmitted in the same network.However,the current industrial Ethernet standards are not compatible with each other,and can not coexist with non real-time data.In this case,time-sensitive network emerges.It opens up the information technology layer and operation technology layer,and realizes a new industrial network architecture of "one network to the end" of interconnection and interoperability.At present,equipment of currect industrial Ethernet can not be eliminated immediately.All manufacturers are committed to bringing their own protocols closer to TSN.But some industry Ethernet who do not use the standard Ethernet frame format and rely on the special communication chip can not directly integrate with the standard industrial Ethernet.This paper studies the method of protocol conversion between this kind of non-standard real-time Ethernet and standard industrial EthernetIn this paper,the development of industrial Ethernet and the status quo of protocol conversion between different networks are introduced.The significance of this topic is illustrated by analyzing the shortcomings of the existing protocol conversion methods of non-standard real-time Ethernet.Based on the analysis of non-standard real-time Ethernet protocol conversion requirements,this paper proposes a protocol conversion method of "standard network controller packet analysis+FPGA gateway real-time forwarding".By studying the non-standard real-time Ethernet communication mechanism,the packet analysis function and real-time communication function of the special communication chip are completed by IPC and FPGA respectively,which replaces the special communication chip.In this paper,the key technologies of the protocol conversion method proposed in this paper are described from three aspects:FPGA real-time forwarding scheme,non-standard real-time Ethernet data frame format research and upper computer package analysis program development.In this paper,EtherMAC,which is developed by the research group and uses the standard Ethernet frame format is used as the standard real-time Ethernet.In view of the two periodic communication modes of collective frame communication and single frame polling communication,Panasonic RTEX and Yaskawa MIII are taken as examples respectively.The detail process of the method is described from three aspects:communication mechanism and data frame format research,upper computer package analysis program development and FPGA function implementation.In order to support the protocol conversion method with TSN network,this paper uses FPGA realizing the basic function of TSN-IEEE802.1AS clock synchronization protocol.This paper describes the process of implementing IEEE802.1AS clock synchronization protocol with FPGA from three aspects:the selection of the master clock,the measurement of the path delay and the process of clock synchronization.At last,the impact of the common crystal oscillator clock drift is reduced through the clock frequency compensation circuitFinally,the validity of the protocol conversion method is tested by RTEX and MIII servo equipment test-bed.The results show that this method can fully meet the protocol conversion requirements of non-standard real-time Ethernet,and does not reduce the transmission performance of the original protocol.In addition,a clock synchronization test platform is built to test the clock synchronization performance.The results show that the clock accuracy is sub microsecond,which lays a foundation for the application of this method in TSN.