Fanuc alarm 55: Switching request/state mismatch during motor activation
αi SPM · Fanuc αi SPM
What it means
In αi spindle-switching or output-switching control, the mismatch between the switching request signal (SPSL/RSL) and the power-lead state check signal persisted while the motor was active. The drive refuses to run in an undefined switching state.
Likely causes
- Power-lead switching magnetic contactor faulty
- Contact-check I/O wiring defective
- Ladder performs switching during motor activation (not permitted)
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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Magnetic contactor / switch unit
amplifier · Common cause
Need the part urgently?
Send us alarm 55 with your machine details — typical RFQ turnaround is 24–48h.