| Industrial Ethernet fieldbus technology has been widely used in industrial. EtherCAT(Ethernet for Control Automation Technoloy) has high synchronicity, perfectreal-time performance and flexible topology among them. Meanwhile the embedded platform has been widely used in industrial due to its hardware scalability, good system stability and low cost. So developing EtherCAT bus master based on the embedded platform has certain significance. The main contents are as follows:According tothe demand of EtherCAT master using in industrial control functions, embedded platform based on ARM + FPGA is proposed to implement EtherCAT master. Finite State Machine(FSM) implemented methodis adopted to design a compact EtherCAT master, including configuring the slaves and monitoring the state of slaves etc. Network card based on FPGA has been designed to improve the stability and speed of the link layer; According to the loop back characteristic of EtherCAT frames, Network card driver based on polling mode without affecting the real-time performance of system, has been designed to reduce the complexity of the system. In order to improve the real-time performance of the system, the real-time Linux operating system based on Xenomai has been build and analyzed, and meanwhile the periodic communication task has been synchronized by interrupts to obtain the accuracy of the periodic task and to further improve the real-time of system. At the same time, distributed clock function among master and slaves has been achieved to improve the synchronization performance of the system.Based on the ARM + FPGA embedded motion controller experimental platform, the effectiveness of Ether CAT master has been verified by the compatibility, synchronization performance and real-time performance test. The results showed that the function of the system has satisfied the requirements of the compact EtherCAT master, with good synchronization performance and real-time performance. |
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