Functional safety is an integral part of modern network architectures and communication systems. EtherCAT offers the possibility of safety-related data transmission in parallel with standard data on the same network with the help of the Safety over EtherCAT protocol (FSoE = FailSafe over EtherCAT). With Safety over EtherCAT, the communication system is part of a Black Channel maintained by our EtherCAT master. Safety over EtherCAT is a certified technology developed according to IEC 61508 and standardized internationally in IEC 61784-3. The safety data is embedded in the standard process data as a container combined with additional data (CRCs, Connection IDs, etc) for its integrity. The safety connection between the FSoE (Safety) master and an FSoE slave is fully monitored in each safety cycle: The checksum of the safety frames, the connection ID and also a watchdog time for each FSoE frame transmission are all checked.