What is EtherCAT?

Ethernet for Control Automation Technology (EtherCAT) was developed by Beckhoff. It’s based on the CANopen protocol and on Ethernet but differs from internet communication or network communications in being specifically optimized for industrial automation control. The standards are defined and maintained by the EtherCAT technology group.

Using the OSI network model, Ethernet and EtherCAT rely on the same physical and data link layers. Beyond that, the two networks diverge by design as they’re optimized for different tasks. So Ethernet, for example, is designed to send large amounts of data through many different nodes. It’s able to route data to and from billions of separate addresses, allowing communication across vast networks.

EtherCAT is a fast and deterministic network, and processes data using dedicated hardware and software. It uses a full duplex, master-slave configuration, and accommodates any topology. It can process 1,000 I/O points in 30 microseconds and communicate with 100 servo axes in 100 microseconds. The axes receive set values and control data and report actual position and status. Axes are synchronized using a distributed clock technique that’s a simple version of IEEE 1588 and reduce jitter to less than 1 microsecond.

The EtherCAT protocol delivers fast throughput because messages are processed in hardware before they’re forwarded to the next slave. Slaves read data relevant to them as the data frame passes and they insert new data into that same data stream on the fly. This doesn’t depend on the run-time of the protocol stack, so processing delays are typically just a few nanoseconds.