Fanuc spindle alarm d0 means that in tandem control, the speed polarity relationship between the master motor and slave motor is abnormal — two motors driving one spindle (tandem configurations on large machines) are reporting directions that contradict the configured relationship. If the drive believed both commands were being followed, the motors would fight each other — so it stops.
Fanuc's check
Check the rotation-direction setting — on FS16i-family controls, bit 2 of parameter 4353. This bit defines the master/slave direction relationship; it must match how the motors are physically mounted and wired (facing each other, same shaft, gear-coupled — each arrangement has its correct polarity).
When it appears
- Commissioning / after parameter work: the usual case — the bit is wrong or came from a different machine variant. Set it per the builder's documentation.
- After motor or cable replacement: U/V/W phase order swapped on ONE of the two motors reverses its actual rotation — the parameter is right, the wiring changed. Verify phase order on whichever motor was touched (the same reassembly trap as AL-29).
Tip: Never resolve d0 by flipping the parameter until the alarm clears — on a tandem pair, a polarity that is ‘quiet but wrong’ makes the motors load against each other, which shows up later as unexplained overload alarms and cooked windings. Verify the physical arrangement, then set the bit to match it, per documentation.
Related guides
- Fanuc spindle alarm 29 (phase-order errors)
- Fanuc spindle alarm 22 (overload)
- Fanuc αi drive alarms index
Tandem spindle configuration trouble? JJ Automation verifies tandem wiring and parameters and repairs large spindle drives at component level — on site in NCR. WhatsApp us or call +91 88022 12394.