What is CoE in EtherCAT?

CoE is the abbreviation for CANopen over EtherCAT. It is a protocol that allows CANopen communication to be carried over an EtherCAT network.

CoE (just like CANopen) uses SDOs (Service Data Objects) to read and write data to and from devices on the network. It also uses PDOs (Process Data Objects) for real-time data exchange. Individual registers are addressed using 16-bit indexes and 16-bit subindexes, similar to CANopen.

Most EtherCAT devices use CoE as their primary communication protocol, making it easier to integrate them into existing CANopen-based systems.

Source: EtherLab Ethercat master, v1.6 documentation, section 6.1