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FANUC Controller
Program/G-code · Basic · 10-20 minutes
Fanuc Alarm 320 - ILLEGAL MOVEMENT AMOUNT IN DRILLING CYCLE
Alarm 320 occurs when the CNC detects a negative value for the cutting depth (Q word) or shift amount (P word) in high-speed peck drilling cycle G74 or back boring cycle G75. The control cannot execute these canned cycles with negative movement values as they violate the fundamental logic of these drilling operations.
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Fanuc Alarm 320 - ILLEGAL MOVEMENT AMOUNT IN DRILLING CYCLE
SYSTEM ALARM 320
Fanuc alarm 320: SYSTEM ALARM 320. This alarm indicates a fault condition detected by the Fanuc control. Refer to the alarm number and name to identify the specific system or function involved.
Root Cause Summary
Alarm 320 occurs when the CNC detects a negative value for the cutting depth (Q word) or shift amount (P word) in high-speed peck drilling cycle G74 or back boring cycle G75. The control cannot execute these canned cycles with negative movement values as they violate the fundamental logic of these drilling operations.
Causes and Fixes
- 1
Review the active program block that triggered the alarm. Check the G74 or G75 line for the Q word value - it must be a positive value representing incremental depth.
- 2
In EDIT mode, navigate to the alarm-triggering block. For G74, verify Q__ is positive (typical range 0.1-50.0mm or 0.005-2.0 inch). For G75, verify Q__ represents positive retract/shift amount.
- 3
Correct the Q value to a positive number appropriate for the material and tool. Example: Change 'G74 R3. Z-50. Q-5. F100' to 'G74 R3. Z-50. Q5. F100'.
- 4
Reset the alarm using RESET key, verify program syntax in background edit, and test cycle in single block mode with feed rate override at 50%.
Ensure Z-axis final depth (Z word) is also correctly programmed as negative value below initial R plane for proper drilling direction
Call a technician if:
- ·Complex macro programming issues
- ·Repeated alarms after program corrections
- ·Suspected control system parameter corruption
Prevention
- Always validate drilling cycle parameters before program execution
- Use positive values for all drilling cycle travel distances
- Implement parameter range checking in macro programs
- Test programs in DRY RUN mode first
Common Mistakes
- Using negative R values thinking they represent direction
- Forgetting to initialize macro variables
- Incorrect coordinate system setup
- Copy-paste errors from different machine orientations
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