# Safety over EtherCAT (FSoE)

Protocols · `Safety over EtherCAT (FSoE)` · verification: source checked

Safety over EtherCAT (FSoE) is a safety protocol that carries safety-critical process data in safety containers over EtherCAT or other underlying communication systems. It uses a Black Channel approach, so the standard communication path is not considered safety-relevant. It is developed according to IEC 61508, standardized in IEC 61784-3, and supports safety applications up to SIL 3.

## Specification

| Property | Value |
|---|---|
| Transports | ethernet_l2, other |
| Architecture | master slave |
| Encoding | binary |
| Standard body | IEC |
| Standard ref | IEC 61784-3 |

### Data types

| Name | Description |
|---|---|
| Safety Container | Contains safety-critical process data and additional information used to secure this data; transported as part of process data. |

## Connected

- Related: [EtherCAT](https://machineschema.com/protocol/ethercat.md), [IEC 61508-1:2010](https://machineschema.com/standard/iec-61508.md)

## Safety

- The EtherCAT safety technology was developed according to IEC 61508.
- It is approved by TÜV Süd Rail.
- It is standardized in IEC 61784-3.
- The protocol is suitable for safety applications with a safety integrity level up to SIL 3.
- The communication system operates as part of a Black Channel and is not considered safety-relevant.

## Study notes

- FSoE stands for FailSafe over EtherCAT.
- Safety containers contain safety-critical process data and additional information used to secure the data.
- Safety containers are embedded in the cyclical communication's process data.
- A single EtherCAT channel can transfer both standard and safety-critical data.
- Safety containers can travel through fieldbus systems, Ethernet, copper cables, fibre optics, and wireless connections.
- In robotics, FSoE is used for safe motion control in an 8-kHz closed loop.
- Safety over EtherCAT frames can be routed via the EtherCAT Automation Protocol (EAP) on the process control level.
- Implementing FSoE in a device is stated to require little resources and can provide short reaction times.

## Sources

1. [Safety over EtherCAT (FSoE)](https://www.ethercat.org/en/safety.html) (accessed 2026-10-25)

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