Fanuc alarm 960: SUB CPU ERROR / DC24V POWER OFF
system alarm · Fanuc 0i-D
What it means
An illegal interrupt occurred in the sub-CPU section of the control - an interrupt that should never arise under normal execution. On multi-processor controls this points to the sub-CPU board or its peripheral circuits; Fanuc's own troubleshooting also flags abnormal 24 VDC input power as a possible trigger. If power cycling restores normal operation once, suspect electrical noise; recurrence condemns the sub-CPU hardware.
Likely causes
- Sub-CPU printed circuit board defective
- Abnormal or noisy 24VDC control power feed
- Electrical noise (poor earthing, missing surge suppression)
Triage note: Only present on configurations that use a sub-CPU (e.g. multi-path/large systems). Verify 24VDC quality before board replacement.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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Sub-CPU board per control model
backplane · Common cause
Need the part urgently?
Send us alarm 960 with your machine details — typical RFQ turnaround is 24–48h.