EtherCAT Functional Principle

Automation networks are characterized by short data-length per node, typically less than the minimum payload of an Ethernet frame. Using one frame per node per cycle leads to low bandwidth utilization and thus to poor overall network performance.

EtherCAT takes a different approach, called processing on the fly (see (➜ # 1, EtherCAT Implementation) for more information).

With EtherCAT, the Ethernet packet or frame is no longer received, and then interpreted and copied as process data at every node.
Instead, the EtherCAT slave devices read the data addressed to them while the telegram passes through the device.
- Input data is inserted while the telegram passes through.
The frames are only delayed by a fraction of a microsecond in each node, and many nodes - typically the entire network - can be addressed with just one frame.