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FANUC Controller
Program/G-code · Intermediate · 30-60 minutes
Fanuc Alarm 360 - PARAMETER OF INDEX OF SUPERPOS CONTROL AXIS SET ERROR
Fanuc Alarm 360 indicates a checksum error in the built-in pulse coder (serial encoder) of the specified axis servo motor. This occurs when the CNC detects corrupted data transmission between the pulse coder and the servo amplifier, typically caused by pulse coder failure, contaminated encoder signals due to cable damage or noise interference, or amplifier feedback circuit malfunction.
360
Fanuc Alarm 360 - PARAMETER OF INDEX OF SUPERPOS CONTROL AXIS SET ERROR
PARAMETER OF INDEX OF SUPERPOS CONTROL AXIS SET ERROR
Fanuc PS360: The parameter setting for superimposed control axis index has an error. The superimposed control configuration references an invalid axis.
Root Cause Summary
Fanuc Alarm 360 indicates a checksum error in the built-in pulse coder (serial encoder) of the specified axis servo motor. This occurs when the CNC detects corrupted data transmission between the pulse coder and the servo amplifier, typically caused by pulse coder failure, contaminated encoder signals due to cable damage or noise interference, or amplifier feedback circuit malfunction.
Safety
- Ensure machine is in emergency stop and servo power is OFF before disconnecting encoder cables
- Absolute position will be lost if encoder is replaced - machine will require complete re-homing and reference point establishment
- Use anti-static precautions when handling encoder electronics and servo amplifier boards
- ⚠️ CRITICAL: Engage emergency stop and turn OFF servo power before disconnecting encoder cables
- ⚠️ POSITION LOSS: Replacing encoder requires complete machine re-homing and reference point establishment
- Be aware of potential mechanical hazards when working near servo motors and axes. Ensure the axis is properly supported before disconnecting any components.
- High voltages are present within the servo amplifier. Only qualified personnel should perform repairs or adjustments within the amplifier.
- Always disconnect power to the machine before replacing the encoder battery. Some batteries may contain hazardous materials and should be disposed of properly.
- Support axis properly before disconnecting components to prevent mechanical hazards
- Disconnect machine power before replacing encoder battery and dispose of batteries properly
- High voltages present in servo amplifier - only qualified personnel should perform repairs
- When working with servo amplifiers, be aware of the risk of electric shock. Ensure proper grounding and lockout/tagout procedures are followed.
- Exercise caution when moving axes manually after replacing the encoder. The axis may move unexpectedly if the encoder was not properly initialized.
- Secure the axis to prevent unintended movement before disconnecting any mechanical components.
- Be aware of pinch points and moving parts when working near the servo motor and axis.
- Use proper lifting techniques when handling heavy components such as servo motors and gearboxes.
Causes and Fixes
- 1
Check servo amplifier LED status. A red LED or alternating red/green typically indicates encoder feedback fault. Note the LED pattern for amplifier diagnostics.
- 2
Navigate to DIAGNOSIS screen > SYSTEM > SERVO and check diagnostic numbers D0300-D0399 (encoder data) for the faulting axis. Look for erratic position data or zero readings indicating encoder signal loss.
- 3
Swap the motor with encoder cable from a known good axis to isolate whether fault is in motor encoder or amplifier feedback circuit. If alarm follows the motor, encoder is defective.
Ensure machine power is OFF and all motion is locked out before disconnecting motor and encoder cables. Mark all connections clearly.
- 4
Replace the servo motor with pulse coder assembly. After replacement, perform encoder offset adjustment from SYSTEM > PMC > SETTING > ENCODER menu or parameter 1815 (APZ setup) and verify with test jog movements.
Call a technician if:
- ·Motor replacement required
- ·Servo amplifier replacement needed
- ·Encoder calibration required
- ·Multiple related servo alarms present
Prevention
- Regular encoder cable inspection
- Maintain proper cable separation from power lines
- Keep encoder connectors clean and dry
- Monitor servo diagnostic screens during PM
Common Mistakes
- Ignoring cable routing requirements
- Using parameter masking instead of fixing root cause
- Forcing motor shaft movement during inspection
- Replacing motor without checking cables first
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