Fagor alarm 4000: Sercos ring error
CNC 8055 SERCOS drive error (DDS) · Fagor DDS drives
What it means
SERCOS optical-fiber communication interrupted: ring broken, wrong baudrate/node-ID, incompatible drive firmware, or SERCOS board fault. All enables dropped, emergency output fired.
Likely causes
- fiber optic cable broken, bent past radius, or dirty connector
- drive powered down mid-operation (see error 4027)
- SERCOSID wheel mismatch / SERSPD(P120) baudrate mismatch
- CNC SERCOS board or drive SERCOS board failure
Triage note: Trace light physically around the ring OUT of CNC -> through each drive -> back IN. Remove drives from the ring one at a time; the segment that restores the ring locates the bad fiber or drive.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
- Request a quote →
QC-FBC-x (Quercus era) / DDS glass-fiber loop cable
SERCOS fiber-optic ring cable · Primary suspect
- Request a quote →
AXD/SPD drive SERCOS mezzanine board
Drive communication board (board-level swap) · Check if others ruled out
Need the part urgently?
Send us alarm 4000 with your machine details — typical RFQ turnaround is 24–48h.