EtherCAT

EtherCAT is a real-time industrial Ethernet fieldbus. One MainDevice sends a frame that passes through every SubDevice in the segment, and each SubDevice reads its data and inserts its own while the frame moves on. Frames run directly on Ethernet layer 2, identified by EtherType 0x88A4.

Source checked7/7 values · 2026-10-25

Specification

2 sources

Transports	ethernet l2, udp
Architecture	master slave
Encoding	binary
Standard body	EtherCAT Technology Group (ETG)
Standard ref	IEC 61158

Default ports

IANA assignments

34980UDPEtherCAT Port

Study notes

Processing on the fly: SubDevices handle the frame as it passes, without storing and forwarding it, which keeps cycle times short.
The MainDevice is the only node in a segment allowed to actively send an EtherCAT frame.
Originally developed by Beckhoff Automation. Maintained by the EtherCAT Technology Group (ETG), founded in 2003.