Fagor alarm 4136: ERROR 254: Wrong reading of distance-coded reference marks (I0)
CNC 8055 SERCOS drive error (DDS) · Fagor DDS drives
What it means
During homing with a distance-coded (O-suffix) scale the drive reads inconsistent mark spacing - absolute-within-20 mm function unreliable.
Likely causes
- graduations dirty, oiled, or scratched on the glass/steel tape
- reading gap out of tolerance (head bracket knocked)
- axis speed outside the allowed window during mark sampling
- scale head electronics marginal
Triage note: Clean with approved optics cleaner and verify the gap spec first - most E254 calls end at cleaning, not replacement. Confirm homing speed parameter matches scale spec.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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S2OX-1140-5-A-T (match length/code)
Distance-coded linear scale (current S2/SV2 generation) · Common cause
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SOX/SOP legacy scale (match length)
Legacy S-series distance-coded scale · Common cause
Need the part urgently?
Send us alarm 4136 with your machine details — typical RFQ turnaround is 24–48h.