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.