On the accuracy of the distributed clock mechanism in EtherCAT

EtherCAT is a network protocol conceived for the use in factory automation environments, which relies on realtime Ethernet technology and is characterized by very high efficiency. Besides high performance, support for synchronous operation is provided as well thanks to a mechanism known as distributed clock, which enables sampling and actuation to be carried out with highly-accurate timings. This can be profitably exploited, for instance, in motion control applications. In this paper several aspects concerning the behaviour of the distributed clock mechanism have been analysed and the accuracy it achieves evaluated by means of measurements carried out on a real network set-up. Results confirm that very good precision is effectively achieved.