What causes FANUC alarm 047?

Part program contains an illegal G-code or M-code combination for this alarm type. Missing or incorrect address word in the program block. Axis or parameter value out of range for the commanded function. Required option not enabled on this CNC for the commanded function. Conflict between active modal states and the commanded function.

How do I fix FANUC alarm 047?

1. Note the block number shown on the alarm screen and locate that block in the program. 2. Review the command in that block against the Fanuc programming manual for alarm 47. 3. Check for missing address words, incorrect values, or conflicting G-code combinations. 4. Verify any required CNC options are enabled if using advanced functions. 5. Correct the program and verify the fix before restarting machining.

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FANUC Controller

Program/G-code · Intermediate · 5-30 minutes

Alarm 047

Fanuc 47 - Cannot use g31 with compensation

This alarm occurs when a G31 (skip function) command is programmed while cutter compensation (G41/G42) is active. The Fanuc control cannot execute skip functions during cutter compensation because the skip signal creates an unpredictable stopping point that conflicts with the compensation lookahead calculation.

FANUCProgram/G-codeIntermediate5-30 minutes

047

Fanuc 47 - Cannot use g31 with compensation

CANNOT USE G31 WITH COMPENSATION

Root Cause Summary

This alarm occurs when a G31 (skip function) command is programmed while cutter compensation (G41/G42) is active. The Fanuc control cannot execute skip functions during cutter compensation because the skip signal creates an unpredictable stopping point that conflicts with the compensation lookahead calculation.

Safety

Verify corrected program or parameters before resuming machining

Causes and Fixes

1
Review the part program at the line number indicated by the alarm. Identify the G31 block and check preceding blocks for active G41 or G42 commands.
2
Insert G40 (cancel cutter compensation) in a block before the G31 skip function command. Ensure the G40 block includes adequate linear movement to safely exit compensation mode.
Never cancel compensation in an arc move (G02/G03). Always use a linear move (G01) of at least one tool radius length.
3
After the G31 skip function completes, you may re-engage cutter compensation with G41/G42 if needed for subsequent operations.
4
Reset the alarm, return to program start or the appropriate restart point, and re-run the program to verify the correction.

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