Fanuc spindle alarm C5 means an invalid value is set for the highest or lowest degree of a dynamic characteristic compensation element (Gx) in learning control. Another learning-control configuration alarm: the compensation filter that shapes the learned correction is defined outside its valid range.
Fanuc's fix
Decrease the setting of parameter 4427 (highest degree) or 4428 (lowest degree) of dynamic characteristic compensation element Gx. One or both values exceed what the function accepts — reduce them to the application's documented values.
Practical notes
- These parameters are set during the learning-control application's commissioning (typically by the machine builder or process engineer) — correct them against the commissioning record, not by trial and error: Gx shapes how aggressively the learned profile is compensated, and arbitrary values degrade the very accuracy learning control exists to deliver.
- C5 appearing on a previously-working machine → a restore or edit brought foreign values — the usual forensic story (see wrong-data guide).
Tip: Keep the learning-control parameter set (4425–4428 and friends) in the machine's documentation as its own annotated block — these values embody process know-how that a generic parameter backup preserves but doesn't explain.
Related guides
- Fanuc spindle alarm C4 (learning cycle invalid)
- Fanuc spindle alarm C7 (angle synchronization cycle)
- Fanuc αi drive alarms index
Learning-control parameters in a mess? JJ Automation restores and verifies learning-control configurations against commissioning records — on site in NCR. WhatsApp us or call +91 88022 12394.