Toward a Holistic Delay Analysis of EtherCAT Synchronized Control Processes

  • Minyoung Sung University of Seoul, Korea
  • Ikhwan Kim University of Seoul, Korea
  • Taehyoun Kim University of Seoul, Korea

Abstract

This paper analyzes the end-to-end delay of EtherCAT-based control processes that use the events of message frames and global clock for synchronized operation. With the end-to-end delay defined as the time interval between the start of a process cycle and the actual input or output, we develop a holistic delay model for control processes in EtherCAT, by taking into account the time for in-controller processing, message delivery, and slave-local handling. Based on the measurements from a real EtherCAT control system, we discuss the average and deviation of the process delay as we vary the number of slaves and process cycle time. The experiment results show that the output delays are mainly increased by the average controller delay, whereas the input delays are more affected by the deviation rather than the average of the controller delay. Our in-depth analysis on the controller reveals that DMA time chiefly enlarges the controller delay for increasing number of slaves, while task release jitter is the main cause of the increased delay for longer cycle time. The presented delay model and evaluation results can be essentially used for the design of EtherCAT-based automation that requires highly synchronized operations, such as for coordinated motion and high-precision data sensing.

Author Biographies

Minyoung Sung, University of Seoul, Korea
Dept. of Mechanical and Information Engineering,Assistant Professor
Ikhwan Kim, University of Seoul, Korea
Dept. of Mechanical and Information Engineering,PhD student
Taehyoun Kim, University of Seoul, Korea
Dept. of Mechanical and Information Engineering,Associate Professor

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Published
2013-08-01
How to Cite
SUNG, Minyoung; KIM, Ikhwan; KIM, Taehyoun. Toward a Holistic Delay Analysis of EtherCAT Synchronized Control Processes. INTERNATIONAL JOURNAL OF COMPUTERS COMMUNICATIONS & CONTROL, [S.l.], v. 8, n. 4, p. 608-621, aug. 2013. ISSN 1841-9844. Available at: <http://univagora.ro/jour/index.php/ijccc/article/view/384>. Date accessed: 05 aug. 2020. doi: https://doi.org/10.15837/ijccc.2013.4.384.

Keywords

end-to-end delay; synchronized processes; EtherCAT; automation system