Fanuc alarm SP0742: RIGID TAP ALARM : LSI OVERFLOW
spindle alarm (rigid tapping) · Fanuc 0i-D
What it means
An overflow occurred in the spindle distribution LSI on the CNC during rigid tapping. This is essentially a system-level fault: the accumulated spindle position data exceeded the capacity of the dedicated hardware counter. It is rarely caused by cutting conditions and usually follows abnormal mode transitions or a genuine CNC hardware defect.
Likely causes
- System error in the spindle distribution LSI on the main board
- Mode change command issued mid-tap corrupting the rigid tap sequence
- Electrical noise disturbing the spindle interface bus
Triage note: If repeatable after power-up, contact Fanuc service; often points to main board replacement.
Need the part urgently?
Send us alarm SP0742 with your machine details — typical RFQ turnaround is 24–48h.