Fagor alarm 4184: ERROR 818: Error on the absolute track (FAGOR SSI absolute encoder)
CNC 8055 SERCOS drive error (DDS) · Fagor DDS drives
What it means
SSI absolute position cannot be computed - incremental analog component collapsed below ~0.20 Vpp or absolute track unreadable.
Likely causes
- steel tape/glass disk contaminated or scratched
- machine speed exceeds encoder rating (absolute track skipped)
- mounting tolerances violated (gap/alignment)
- reader head or encoder internally damaged
Triage note: Clean the tape per manual (no solvents on coating), verify max speed vs scale spec, then substitute head. If analog channel reads <0.2 Vpp at the drive with scope, head is done.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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LA-840 (length per axis)
LA absolute steel-tape linear scale · Primary suspect
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SAF10-420-5-A / SAS-770-3
SA absolute compact scale (legacy protocols) · Common cause
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HAF-27-D90-2
Absolute angular encoder (rotary applications) · Common cause
Need the part urgently?
Send us alarm 4184 with your machine details — typical RFQ turnaround is 24–48h.