Dual-Channel Measurement System for Real-Time Ethernet

Abstract

Real-time Ethernet (RTE) is widely used in industrial automation and high performance motion control field. Its minimum cycle time is down to less than 100μs and cycle jitter is less than 1μs, making many existing network and protocol analyzers cant meet the requirements of time accuracy in measurement system for RTE. In this paper, a low-cost and open measurement system is proposed to analyze the time characteristics (cycle time, cycle jitter, end-to-end delay, etc.) and protocol (Ethernet type, length, detailed info, etc.) of real-time Ethernet. The measurement system is consisting of a FPGA-based hardware device and a PC-based monitor station. The hardware device has dual channels that allow detecting two nodes data frame simultaneously. Ethernet data frames through channels are transmitted immediately; at the same time, all data frames will be duplicated and sent to the monitor station with precise timestamp for frame analysis. A prototype of measurement system has been realized to verify feasibility and performance. Result of the experiment shows that the maximal delay time brought in by measuring device is only 120ns and the accuracy of time stamp is down to 5ns; the parser is created in the monitor PC for analysis the time characteristics and protocols of real-time Ethernet.