Fanuc alarm SP9040: NO 1-ROT CS SIGNAL DETECT
spindle alarm (serial spindle, alpha i) · Fanuc 0i-D
What it means
The one-revolution signal from the Cs contour control position coder was not detected at all. Without the once-per-turn mark the spindle cannot establish absolute angle reference for Cs axis operation.
Likely causes
- Position coder completely dead or unplugged
- Broken one-rotation channel wiring
- Sensor gap so large that the mark pulse never registers
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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A860-0360-B101
Position coder (spindle encoder) · Common cause
Need the part urgently?
Send us alarm SP9040 with your machine details — typical RFQ turnaround is 24–48h.