What causes FANUC alarm 375?

Angular axis control (G12.1 or similar) is being commanded while synchronous control (G114/G115) is already active on the same axis. Program attempts to enable angular axis control while composite control (mixed control) is active, which is not permitted simultaneously. Superimposed control (G126/G127) is active on an axis that is required for angular axis control operation. Parameter settings for angular axis control conflict with the current synchronous or composite control axis assignments. Program logic error where angular control modal is not properly cancelled before switching to sync or composite control modes.

How do I fix FANUC alarm 375?

1. Check the CNC program for any active G-codes related to synchronous control (G114, G115), composite control, or superimposed control (G126, G127) that may still be modal when angular control is commanded. 2. Ensure that all synchronous, composite, and superimposed control modes are cancelled (G113, G125, etc.) before the angular axis control command is executed in the program. 3. Review parameters 8010-8013 (angular axis control settings) and verify the axis assignments do not overlap with axes currently used in sync or composite control configurations. 4. Add explicit cancel blocks in the program before angular control commands, such as cancelling sync control with G113 and confirming modal state is clear before issuing G12.1 or angular control G-codes. 5. Check the program for missing or misplaced cancel codes after a tool change or subprogram call that may leave a sync or composite mode active unexpectedly. 6. If the machine uses multiple spindles or turrets, verify that the axis involved in angular control is not assigned to a different channel currently running synchronous or composite operations.

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FANUC Controller

Servo/Axis · Intermediate · 30-60 minutes

Alarm 375

Fanuc Alarm 375 - CANNOT ANGULAR CONTROL (SYNC/MIX/OVL)

Fanuc alarm 375 occurs when angular axis control (C-axis or rotary axis positioning) is attempted while synchronous axis control, composite axis control, or superimposed control is already active on that axis. The system cannot execute angular control commands when these mutually exclusive motion control modes are engaged simultaneously.

FANUCServo/AxisIntermediate30-60 minutes

375

Fanuc Alarm 375 - CANNOT ANGULAR CONTROL (SYNC/MIX/OVL)

FANUC ALARM 375

Root Cause Summary

Fanuc alarm 375 occurs when angular axis control (C-axis or rotary axis positioning) is attempted while synchronous axis control, composite axis control, or superimposed control is already active on that axis. The system cannot execute angular control commands when these mutually exclusive motion control modes are engaged simultaneously.

Causes and Fixes

1
Navigate to SYSTEM > PARAM and check parameter 1801 (synchronous control axis number). Verify if the alarming axis number appears in parameters 1801-1832 series.
2
Check PMC ladder or part program for G51.2 (synchronous control ON) command without corresponding G51.2 P0 (OFF) before angular control is attempted.
3
Review DIAGNOSIS > PARAMETER screen #200 (axis control status) to confirm synchronous control flag is set for the angular axis.
4
Issue G51.2 P0 command to cancel synchronous control before executing angular axis commands (G0 C_, M19, etc.), or restructure program logic to separate these functions.
Canceling synchronous control may affect coordinated motion on gantry systems. Verify mechanical safety.

DIY Feasiblehigh confidence

Call a technician if:

·Servo amplifier hardware failure
·Parameter corruption requiring factory defaults
·Mechanical binding in angular axis

Prevention

Avoid simultaneous activation of conflicting axis control modes
Implement proper G-code modal group management
Regular parameter backup and verification
Monitor servo diagnostic signals during complex operations

Common Mistakes

Attempting to use angular control while G96 constant surface speed is active
Not resetting system after parameter changes
Ignoring composite axis configuration conflicts
Forgetting to cancel superimposed coordinate transformations

Related Alarms

401 414 416 430

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