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FSOE Qualifying Test: Domain 6: FSoE configuration parameters

FSOE Qualifying Test · Work through your exam, one topic at a time.

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Domain 6: FSoE configuration parameters

Domain 6 tests configuration choices that determine whether FSoE works safely in a real network: FSoE address, watchdog time, slave-to-slave communication, and safe I/O mapping.

Core rules

  • FSoE address: identifies the safety node or connection endpoint in the FSoE configuration. It must be unique where required and must match the master's project. It is not the same as the runtime connection identifier, although both are addressing-related.
  • Watchdog time: configured per connection; must exceed the worst-case cycle plus jitter and remain below the process safety time. Document the calculation; do not tune it casually.
  • Slave-to-slave communication: allows safe data from one FSoE slave to be consumed by another slave, reducing master round-trip latency. The master configures the relationship; both slaves must support it; CRC, sequence and watchdog checks still apply end-to-end.
  • Mapping: safe inputs and outputs are assigned to exact bits/bytes in the safe data container. Master and slave must use the same mapping, data width, and byte order. Unused bits should be defined, not left ambiguous.
  • Changes to address, watchdog, mapping, or slave-to-slave links are safety-relevant configuration changes and need re-verification.

Worked example

A project uses a 4 ms EtherCAT cycle and a 60 ms process safety time. A 20 ms watchdog gives five cycles of margin and trips well before 60 ms. Slave A sends two safe input bytes to slave B by slave-to-slave communication; the master configures the link and B's mapping. B checks the connection identifier, CRC, sequence, and its own watchdog. If A's address is duplicated by another device, the connection setup or frame acceptance fails; the fix is to correct the address, not to extend the watchdog.

Traps

Setting watchdog equal to the cycle. Duplicating FSoE addresses. Assuming slave-to-slave communication bypasses CRC or watchdog checks. Mapping inputs and outputs in reverse order. Changing watchdog time to stop intermittent trips without checking process safety time.