The Design And Implementation Of Embedded Master-slave Station Based On Industrial Ethernet EtherCAT

In recent years, along with Industry 4.0 proposed, industrial control automation technology is developing in direction of intelligent, network and integration. Since the constant improvement of the degree of automation, there are the higher request for the field bus in the data transmission capacity, compatibility between various equipments and protocols. With characteristics of a low cost, high reliability and high speed data transmission, Ethernet technology replaces the traditional field bus gradually. As a result, the world’s leading automation vendors have developed different industrial Ethernet standards according to their own needs and characteristics. The EtherCAT fieldbus technology developed by Beckhoff company in Germany has won the favor of the more and more manufacturers.In the basis, industrial Ethernet technology is researched, EtherCAT communications protocol and its application are discussed, the embedded system of ARM architecture is considered. Because of high degree of customization of embedded Linux system based on ARM architecture, an embedded EtherCAT system implementation scheme is proposed. The main research contents and results are as follows:Firstly, The EtherCAT communication principle is analyzed, and system structure is elaborated. Then EtherCAT protocol specification is introduced respectively from the perspective of the physical layer, link layer and application layer.Secondly, a scheme of EtherCAT master station control platform is put forward and it combines the CoDeSys soft PLC with embedded Linux. The embedded Linux system migration process is introduced in detail. The CoDeSys real-time operating system is running on the embedded Linux system platform.Thirdly, the hardware circuit of EtherCAT communications control board is designed. The STM32 and ET1200 is the main control chip of his EtherCAT communications control board. The Software protocol stack is designed and it includes the control program main function, control program initialization function and control cycle data processing function. The slave station device description file based on ET1200 is written.Fourthly, a movement control experimental device of EtherCAT network is built, using developed master-station, slave-station and Omron drives. The control program of a simple three-axis CNC system is designed in CoDeSys environment.Fifthly, the research work is summarized. Meanwhile, some prospects for further researches are put forward.