Applicable Systems
Series 0i
Series 16/18/21
Alpha
Beta
Symptoms
Position control system error due to NC or servo system fault preventing reference point return completion.
Possible Causes
- Servo motor overload or mechanical binding
- Servo amplifier fault or parameter error
- Encoder or pulse coder disconnection
- Power supply voltage abnormality
Troubleshooting Steps
- Step 1: Check the diagnostic display (DGNOS) for detailed servo error information
Identify the specific servo error type and axis - Step 2: Inspect the servo motor and mechanical components for binding or overload
No mechanical binding; motor turns freely - Step 3: Check the servo amplifier status LEDs and connections
Amplifier shows normal status (green LED) - Step 4: Verify servo parameters (motor series, rotation direction, feedback pulses)
All servo parameters match the motor specification - Step 5: If the error persists, replace the faulty component (amplifier, motor, or encoder)
New component eliminates the alarm
How to Reset
To reset servo alarm 405: 1) Identify and resolve the root cause (mechanical, electrical, or parameter). 2) Press RESET on the CNC panel. 3) If alarm persists, power cycle the CNC and servo amplifier. 4) Re-perform reference point return. Caution: Do not repeatedly reset without fixing the root cause; this may damage the servo system.
Frequently Asked Questions
- Q: What does 405 mean on Fanuc FANUC 0/0i/30i Series?
Position control system error due to NC or servo system fault preventing reference point return completion.
- Q: How do I fix 405 on Fanuc?
Follow the troubleshooting steps: Check the diagnostic display (DGNOS) for detailed servo error information
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Source: FANUC CNC System Alarm Manual (doc.eleok.com)
Category: CNC
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