EtherCAT is an Ethernet based automation bus.
In the slaves, the Ethernet frame is processed on the fly: the Fieldbus Memory Management Unit (FMMU) in each node reads the data addressed to it, while the telegram is forwarded to the next device. Similarly, input data is inserted while the telegram passes through. The telegrams are only delayed by a few nanoseconds
ETG means Ethercat Technology Group. We the University of Applied Sciences Western Switzerland are a member of the ETG Group.