
B-65285EN/03 TROUBLESHOOTING 3.TROUBLESHOOTING AND ACTION
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3.4.11 Alarm Code 21
The specified polarity of the position sensor is incorrect.
Troubleshooting when this alarm is issued
(a) Check the position sensor polarity parameter (bit 4 of
parameter No. 4001).
(b) Check the feedback cable of the position sensor.
3.4.12 Alarm Code 24
Serial communication data transferred between the CNC and spindle
amplifier module contains an error. (Note)
Troubleshooting when this alarm is issued
(a) Noise occurring between the CNC and spindle amplifier
module (connected via an electric cable) caused an error in
communication data.
Check the condition for maximum wiring length.
Referring to "Connection," in "FANUC SERVO
AMPLIFIER αi series Descriptions (B-65282EN)," check
the condition of electric cable connection.
(b) Noise exercises an influence because a communication cable
is bundled with the power lead.
If a communication cable is bundled with the power lead for
the motor, separate them from each other.
(c) A cable is faulty.
Replace the cable.
If an optical I/O link adapter is used, the optical link adapter
or optical cable may be faulty.
(d) The SPM is faulty.
Replace the SPM or SPM control printed circuit board.
(e) The CNC is faulty.
Replace the board or module related to the serial spindle.
NOTE
This alarm is issued also if the CNC power is off.
This is not a failure, though.