Design And Implementation Of A Field Bus Based On Ethernet

Non-uniform standard, low bandwidth and incompatible with commercial network are the three major issues in the development process of Field bus. With its uniform standard, high-bandwidth, and high speed, Ethernet, which has extended from the management layer to the field devices, will eventually replace the Field bus. In short term, there are some problems to be resolved in the replacement. So, a combination Ethernet and Field bus become a trend.In the above context, as a part of the subject "Bus-based all-digital high-end CNC device", which is an important subject of "high-end CNC machine tools and basic manufacturing equipment", an Ethernet-based Field bus, which can be used for the communication between a numerical control system and digital servo, and can be reach ms level real-time and the us-level synchronization, should be designed and implemented.Based on the real-time mechanism of the existing Ethernet-based Field bus, for the digital servo control system application, we have determined to replace the Ethernet CSMA/CD scheduling mechanism by the lumped-frame real-time scheduling mechanism, and given the overall design, the network model, network topology, frame format, transmission model of the slave station, and the overall design of the MAC layer. In the FPGA platform, we have impletion the MAC layer, and through the protocol verification system, verified and analyzed the real-time protocol, and we reached the ms-level real-time requirement.In addition, based on the existing synchronization mechanism, we also have given an interval-based synchronization mechanism, and analyzed its applicability in the lumped-frame scheduling mechanism.