Fagor alarm 4209: Error in the SERCOS ring (optical fiber)
CNC 8060/8065/8070 SERCOS ring error · Fagor 8060/8065/8070
What it means
Phase 4 lost with code 0x00000002 - broken optical fiber somewhere in the ring.
Likely causes
- fiber snapped at bend radius violation inside cabinet dressing
- optical module bore contaminated (dust/oil film)
- fiber kinked during recent service work
Triage note: Companion codes narrow location: 4210 MST loss (master sync) = check CNC-master segment; 4211 double-AT loss names the AXIS whose drive stopped answering - replace that drive's Sercos board or drive.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
- Request a quote →
QC-FBC-x (Quercus) / pre-terminated DDS fiber set
SERCOS fiber-optic cable · Primary suspect
Need the part urgently?
Send us alarm 4209 with your machine details — typical RFQ turnaround is 24–48h.