A complete real-time Ethernet solution for numerical control systems

This paper proposes a complete real-time Ethernet (RTE) solution including master and slave controllers for numerical control (NC) systems. To meet the development tendency of NC systems moving toward multi-axis coordination, high speed and high precision, one type of RTE architecture is built up with a dual ring topology. The function blocks of master/slave nodes are designed to realize the real-time communication capabilities using embedded CPU and field programmable gate array (FPGA) technologies. To reduce the minimum achievable cycle time, a cut-through transmission mechanism is employed to decrease the process latency at slave nodes, and the synchronization frame is optimized to shorten the frame duration. In order to synchronize the nodes of RTE-based NC systems accurately, a time synchronization strategy is scheduled and a proportion-integration (PI)-based phase-locked loop (PLL) is designed to keep the master clock and the slave clocks in step stably. The theoretical analysis and experimental results show that the proposed RTE solution can achieve good real-time performance with low process latency and high time-synchronization accuracy, which satisfies the real-time communication requirements of RTE-based NC systems in an economical way.