Fagor alarm 4205: SERCOS ring error

What it means

Generic Sercos bus failure that dropped the ring out of phase 4; the accompanying VALUE bit-codes identify the source (e.g., 0x00000002 broken fiber, 0x00000100 AT loss, 0x00000200 MST loss, 0x00008000 AT transmission error, 0xFFFF0000 SERCON RAM access failure). Decoding those bits pinpoints which segment or node broke the loop.

Likely causes

• optical fiber damaged, kinked or unplugged
• drive reset or power loss during operation
• Sercos board (SERCON) hardware fault
• connector contamination breaking light budget

Replacement parts

We supply the following units for this alarm — tested, warranty-backed:

• SERCOS fiber-optic ring cable assembly

  cable · Common cause

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