Fanuc spindle alarm C7 means an invalid reference angle cycle is set for learning control in angle synchronization mode — the third of the learning-control configuration trio (with C4 and C5). In angle-synchronized learning, the correction is stored per angular division of the spindle revolution — and the configured number of divisions is too small to be valid.
Fanuc's fix
Increase the setting of parameter 4425 (number of divisions per cycle) in learning control. Note the dual role: in time-synchronization mode 4425 is the learning cycle (range 20–4800, alarm C4 when invalid); in angle-synchronization mode it is the divisions per revolution — and C7 says it is set too low for the mode.
Practical notes
- Correct against the application's commissioning record — the division count is chosen for the part profile's angular detail, and arbitrary increases waste correction memory while arbitrary decreases blur the learned profile.
- C7 after a mode change (time-sync application switched to angle-sync, or a new job using a different mode) means 4425 was left set for the other mode — the parameter needs per-mode values managed in the job setup.
Tip: If your machine alternates between learning-control jobs in different modes, put 4425's correct value into each job's setup documentation — the C4/C7 pair is almost always a mode/value mismatch rather than anything broken.
Related guides
- Fanuc spindle alarm C4 (time-sync learning cycle)
- Fanuc spindle alarm C5 (compensation element)
- Fanuc αi drive alarms index
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