Fanuc alarm SP0756: SPINDLE-1 ILLEGAL AXIS DATA
safety/dual-check alarm · Fanuc 30i/31i/32i-B
What it means
Dual Check Safety alarm raised on the first spindle: the spindle-related axis/safety data exchanged between the CNC and the spindle control channel failed validity checks. It indicates the spindle safety monitoring received illegal data rather than simply overspeed. Power-cycle is required after correcting the cause; check the serial spindle link and safety data configuration first.
Likely causes
- Illegal or corrupted safety/axis data from the spindle side of the cross-check
- Serial spindle communication disturbance (JA7B optical/electrical link)
- Mismatched spindle software/parameters after a drive swap
Triage note: Second-spindle counterpart is SP0786.
Need the part urgently?
Send us alarm SP0756 with your machine details — typical RFQ turnaround is 24–48h.