An arbitration-based access scheme for EtherCAT networks

EtherCAT is a very popular solution for connecting control applications to field devices in industrial environments, which is based on Ethernet transmission technology. Even though EtherCAT features a very high level of communication efficiency, that permits thousands of I/O points to be periodically exchanged between the controlling device and the decentralized periphery with cycle times well below lms, it is not able to cope in a proper way with event-driven systems, where lots of devices may be producing asynchronous information sporadically and unpredictably. In this paper, a modification to the basic EtherCAT access scheme is proposed, which enables a CAN-like arbitration to take place in such networks in order to select the most urgent event pending for transmission.