What causes FANUC alarm 143?

Incorrect G-code programming, such as invalid scaling, coordinate rotation, or cylindrical interpolation parameters. Numerical data overflow due to excessively large coordinate values or scaling factors. Incompatible G-code commands used in the same program block.

How do I fix FANUC alarm 143?

1. Review the G-code program and identify the block or blocks that may be causing the data overflow. Check for any scaling, rotation, or cylindrical interpolation commands. 2. Verify that the numerical values used in the problematic G-code commands are within the valid range for your CNC machine and control system. 3. Try simplifying the G-code program by breaking down complex operations into multiple, less intensive steps. 4. If the issue persists, consult the Fanuc control's programming manual for guidance on proper usage of the affected G-code commands. 5. As a last resort, consider modifying the part program to avoid the problematic operations or seek assistance from a Fanuc control specialist.

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FANUC Controller

Program/G-code · Intermediate · 30-60 minutes

Alarm 143

Fanuc Alarm 143 - COMMAND DATA OVERFLOW

Alarm 143 COMMAND DATA OVERFLOW occurs when calculated coordinate values exceed the CNC's internal data storage capacity during coordinate transformation operations. This typically happens when scaling (G51), coordinate rotation (G68), or cylindrical interpolation (G07.1) produces coordinate values that exceed the maximum allowable internal data range, usually ±999999.999 or the machine's software stroke limit.

FANUCProgram/G-codeIntermediate30-60 minutes

143

Fanuc Alarm 143 - COMMAND DATA OVERFLOW

FANUC ALARM 143

Root Cause Summary

Alarm 143 COMMAND DATA OVERFLOW occurs when calculated coordinate values exceed the CNC's internal data storage capacity during coordinate transformation operations. This typically happens when scaling (G51), coordinate rotation (G68), or cylindrical interpolation (G07.1) produces coordinate values that exceed the maximum allowable internal data range, usually ±999999.999 or the machine's software stroke limit.

Causes and Fixes

1
Review the active program for G51 scaling commands and note the P scale factor value. Check if coordinates being scaled exceed 100000mm or if scale factor is greater than 5.0 when applied to large workpiece coordinates.
2
Navigate to SYSTEM > PARAM and verify parameter 5001-5004 (software stroke limits for each axis). Ensure scaled coordinate calculations do not exceed these limits during transformation.
3
Modify the part program to reduce scale factor or reposition the workpiece coordinate system (G54-G59) closer to machine zero to reduce absolute coordinate values before scaling is applied.
4
If scaling is not required, verify G50 (scale cancel) is commanded before the problem block. Check for missing scale cancel commands from previous operations or subroutines.

DIY Feasiblehigh confidence

Call a technician if:

·Parameter corruption suspected
·Alarm persists after all transformations cancelled
·System requires software update for extended data range

Prevention

Keep scaling factors between 0.1-10.0 range
Avoid combining multiple coordinate transformations unnecessarily
Use incremental programming (G91) with large coordinate values
Regularly cancel unused transformations with G50/G69/G07

Common Mistakes

Forgetting active G51 scaling from previous operations
Using machine coordinates with active transformations
Applying scaling after coordinate rotation instead of before
Not accounting for work offset values in transformation calculations

Related Alarms

144 145 146

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