# EtherCAT

Protocols · `EtherCAT` · verification: source checked

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.

## Specification

| Property | Value |
|---|---|
| Transports | ethernet_l2, udp |
| Architecture | master slave |
| Encoding | binary |
| Standard body | EtherCAT Technology Group (ETG) |
| Standard ref | IEC 61158 |

### Default ports

| Port | Transport | Secure | Purpose |
|---|---|---|---|
| 34980 | udp | false | EtherCAT Port |

## Connected

- Related: [IO-Link](https://machineschema.com/protocol/io-link.md), [Safety over EtherCAT (FSoE)](https://machineschema.com/protocol/fsoe.md)
- Supported by: [Beckhoff CX5130](https://machineschema.com/hardware/beckhoff-cx5130.md), [Beckhoff CX8010](https://machineschema.com/hardware/beckhoff-cx8010.md), [Beckhoff CX8110](https://machineschema.com/hardware/beckhoff-cx8110.md), [Beckhoff CX8210](https://machineschema.com/hardware/beckhoff-cx8210.md), [DENSO Robotics VMB 1506 mm](https://machineschema.com/hardware/denso-robotics-vmb-1506mm.md), [DENSO Robotics VMB 1804 mm](https://machineschema.com/hardware/denso-robotics-vmb-1804mm.md), [Epson RC800-A](https://machineschema.com/controller/epson-rc800-a.md), [FANUC R-50iA](https://machineschema.com/controller/fanuc-r-50ia.md), [JAKA Intelligent Visual Perception Robot](https://machineschema.com/hardware/jaka-intelligent-visual-perception-robot.md), [JAKA K1](https://machineschema.com/hardware/jaka-k1.md), [JAKA S5](https://machineschema.com/hardware/jaka-s5.md), [JAKA Zu35](https://machineschema.com/hardware/jaka-zu35.md)

## 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.

## Sources

1. [EtherCAT Technology Group: Technology](https://www.ethercat.org/en/technology.html) (accessed 2026-10-25)
2. [IANA Service Name and Transport Protocol Port Number Registry](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=ethercat) (accessed 2026-10-25)

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JSON: https://machineschema.com/protocol/ethercat.json  
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite Machine Schema and the original sources.