Glossary Updates12 new terms added to the glossaries · October 2, 2026, 22:44 CEST
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Glossary · Industrial communication

Safety over EtherCAT (FSoE)

Also known as: FailSafe over EtherCAT, FSoE

German: Safety over EtherCAT (FSoE)

In industrial communication, Safety over EtherCAT (FSoE, FailSafe over EtherCAT) is the functional safety communication protocol specified in IEC 61784-3-12, in which an FSoE main instance and FSoE subdevices exchange safety data in safety frames over EtherCAT or another channel according to the black channel principle.

  • Industrial communication
  • Functional safety
  • Standards

In one sentence

FSoE (IEC 61784-3-12) transmits safety data between safety controllers and devices over EtherCAT, using the black channel principle.

Example

A palletizer's safety controller reads the light curtain and emergency stop inputs via FSoE and sends Safe Torque Off to the servo drives over the same EtherCAT network that carries the motion data.

How it applies

  • Engineering: Each FSoE frame carries the safety data together with a CRC, a sequence number, a connection ID and a watchdog. Because these measures sit in the safety protocol, the EtherCAT devices and cables in between don't need to be safety-rated (Black channel).
  • Safety: The protocol is specified for safety functions up to SIL 3 per IEC 61508. The level a Safety function achieves depends on the whole chain of sensor, logic and actuator and has to be verified and validated; FSoE on its own makes nothing safe.
  • Commissioning: Every FSoE subdevice needs its unique FSoE address, usually set with switches or in the safety project. The configured watchdog time adds to the reaction time of every safety function using the connection.
  • Documentation: The documentation team documents FSoE addresses, watchdog times, the resulting reaction times, and the replacement procedure, which must restore the address before the safety function is used again.

FSoE vs. PROFIsafe

Both are safety profiles on the black channel principle. PROFIsafe runs on PROFINET and PROFIBUS; FSoE was developed for EtherCAT but its frames can also be tunneled over other networks. They aren't interoperable: a safety device speaks the profile of its network.

By knowledge.aitechdoc.world · Published September 28, 2026 · Last reviewed

Source: IEC 61784-3-12, Industrial communication networks — Profiles — Part 3-12: Functional safety fieldbuses — Additional specifications for CPF 12; EtherCAT Technology Group, ETG.5100

Definitions follow the cited standards and specifications. Where a source is a copyrighted publication, such as an ISO, IEC or EN standard, the definition is a close paraphrase, not a verbatim quotation, so as not to infringe copyright. We recommend reading the original publication. The sections “How it applies” are editorial commentary by AI TechDoc Knowledge and are not part of any standard.

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