What causes FANUC alarm 235?

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 235?

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 235. 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 235

Fanuc 235 - Illegal skip axis

Alarm 235 ILLEGAL SKIP AXIS occurs when a skip function (G31) command specifies an axis that is not configured, not available, or improperly formatted in the part program. This typically happens when the programmed axis does not exist in the machine configuration or when the skip command syntax is incorrect for the specific Fanuc control model.

FANUCProgram/G-codeIntermediate5-30 minutes

235

Fanuc 235 - Illegal skip axis

ILLEGAL SKIP AXIS

Root Cause Summary

Alarm 235 ILLEGAL SKIP AXIS occurs when a skip function (G31) command specifies an axis that is not configured, not available, or improperly formatted in the part program. This typically happens when the programmed axis does not exist in the machine configuration or when the skip command syntax is incorrect for the specific Fanuc control model.

Safety

Verify corrected program or parameters before resuming machining

Causes and Fixes

1
Review the alarming G31 block in the part program and identify all axes specified in the skip command.
2
Access parameter 1020 (number of controlled axes) and verify which axes are configured on the machine (typically displayed on the POSITION screen).
3
Compare the programmed axis letters in the G31 command against the actual configured axes. Remove or replace any axis letters that are not part of the machine configuration.
4
If the axis should exist, check parameters 1022-1025 (axis name assignments) to verify proper axis letter assignment and consult machine documentation before making parameter changes.
Changing axis parameters requires machine manufacturer approval and will affect all programs.

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