Real-time Performance Study of EPA Periodic Data Transmission

Authors: Liu Ning, Zhong Chongquan, Teng Hongfei

Abstract:

EPA (Ethernet for Plant Automation) resolves the nondeterministic problem of standard Ethernet and accomplishes real-time communication by means of micro-segment topology and deterministic scheduling mechanism. This paper studies the real-time performance of EPA periodic data transmission from theoretical and experimental perspective. By analyzing information transmission characteristics and EPA deterministic scheduling mechanism, 5 indicators including delivery time, time synchronization accuracy, data-sending time offset accuracy, utilization percentage of configured timeslice and non-RTE bandwidth that can be used to specify the real-time performance of EPA periodic data transmission are presented and investigated. On this basis, the test principles and test methods of the indicators are respectively studied and some formulas for real-time performance of EPA system are derived. Furthermore, an experiment platform is developed to test the indicators of EPA periodic data transmission in a micro-segment. According to the analysis and the experiment, the methods to improve the real-time performance of EPA periodic data transmission including optimizing network structure, studying self-adaptive adjustment method of timeslice and providing data-sending time offset accuracy for configuration are proposed.

Keywords: EPA system, Industrial Ethernet, Periodic data, Real-time performance

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1057069

References:

[1] L. Winkel and Karlsruhe, "Real-Time Ethernet in IEC 61784-2 and IEC 61158 Series", in IEEE International Conference on Industrial Informatics, Singapore, 2006, pp. 246-250
[2] M. Felser, "Real-time Ethernet - Industry Prospective", Proceedings of the IEEE, Vol.93, No.6, 2005, pp. 1118-1129.
[3] Industrial communication networks - Profiles -Part 2: Additional fieldbus profiles for real-time networks based on ISO/IEC 8802-3, IEC, 2007.
[4] G. Bernat, A. Burns, and L. Albert, "Weakly Hard Real-time Systems", IEEE Transactions on Computers, Vol.50, No.4, 2001, pp. 308-321.
[5] IEC/PAS 62409: Real-time Ethernet for Plant Automation (EPA) (R) 14, IEC, 2005.
[6] M. Xueqin, "Exposition of Six Type of Communication Protocols of Real-Time Ethernet," Process Automation Instrumentation, Vol.26, No.4, 2005, pp. 1-6.
[7] G. Lu, Y. Haibin, W. Hong, and X. Aidong, "Architecture of EPA Network", Computer Engineering, Vol.30, No.17, 2004, pp. 81-82.
[8] C. Lei, F. Dongqin, J. Jianxiang, and C. Jian, "Study on Real-time Characteristics of Ethernet in Industrial Application", Journal of Zhejiang University (Engineering Science), Vol.38, No.6, 2004, pp. 670-675.
[9] W. Ping, W. Haowen, Y. Ming-hua, and Z. Yanfang, "Conformance test method and implementation of EPA protocol state machine", Computer Integrated Manufacturing Systems, Vol.13, No.3, 2007, PP. 621-624.
[10] L. Zhuohan and Z. Chongquan, "Research on the Test Method of Real-time Performance of EPA", Process Automation Instrumentation, Vol.27, No.10, 2006, PP. 4-6.
[11] V.B. Lortz, K.G. Shin, and J. Kim, "MDARTS: A Multiprocessor Database Architecture for Hard Real-Time Systems", IEEE Transactions on Knowledge and Data Engineering, Vol.12, No.4, 2000, PP. 621 - 644.
[12] W. Zhi, W. Tianran, and S. Yeqiong, "Survey of Real-time schedule theory and the State-of- the- art of its Application in Industrial Real-time Communication System (Part one)", Information and Control, Vol.31, No.2, 2002, PP. 146-152.
[13] F. Dongqin, H. Wenjun, J. Jianxiang, and C. Jian, "EPA-based Open Network Control System", in The Fourth International Conference on Control and Automation, Dalian China, 2003, PP. 976-980.