What causes FANUC alarm 279?

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 279?

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 279. 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 279

Fanuc 279 - Rigid tapping not ready

Alarm 279 occurs when a G84 or G74 rigid tapping cycle is commanded but the spindle or control is not properly configured for synchronized rigid tapping operation. This typically happens when required parameters are not set, the spindle doesn't have position feedback, or the tapping mode is called while the spindle is in the wrong mode or state.

FANUCProgram/G-codeIntermediate5-30 minutes

279

Fanuc 279 - Rigid tapping not ready

RIGID TAPPING NOT READY

Root Cause Summary

Alarm 279 occurs when a G84 or G74 rigid tapping cycle is commanded but the spindle or control is not properly configured for synchronized rigid tapping operation. This typically happens when required parameters are not set, the spindle doesn't have position feedback, or the tapping mode is called while the spindle is in the wrong mode or state.

Safety

Verify corrected program or parameters before resuming machining

Causes and Fixes

1
Verify spindle has a position coder installed by checking for actual spindle position display on the screen (not just RPM).
2
Check parameter 4000#0 (RGT) - must be set to 1 to enable rigid tapping function.
Parameter changes require control restart and may affect other operations.
3
Verify parameter 4001 (gear ratio) and 4002 (position coder pulses) are correctly set for your spindle configuration.
4
If spindle has no encoder, change program to use standard tapping cycle G84.2/G74.2 with tapping head, or use G84.3 for non-synchronized tapping if available.

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