What causes FANUC alarm 287?

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 287?

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 287. 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 287

Fanuc 287 - Look ahead parameter error

Alarm 287 occurs when the CNC's look-ahead function encounters incompatible parameter settings or program commands that violate look-ahead processing rules. This typically happens when AI contour control, AI nano smoothing, or high-speed machining parameters are incorrectly configured, or when the part program contains geometry that conflicts with the active look-ahead settings.

FANUCProgram/G-codeIntermediate5-30 minutes

287

Fanuc 287 - Look ahead parameter error

LOOK AHEAD PARAMETER ERROR

Root Cause Summary

Alarm 287 occurs when the CNC's look-ahead function encounters incompatible parameter settings or program commands that violate look-ahead processing rules. This typically happens when AI contour control, AI nano smoothing, or high-speed machining parameters are incorrectly configured, or when the part program contains geometry that conflicts with the active look-ahead settings.

Safety

Verify corrected program or parameters before resuming machining

Causes and Fixes

1
Check parameters 1700, 1701, 1702 (look-ahead control parameters) for valid values per your specific control model and manual.
2
Verify parameters 1720-1729 (AI contour control) and 1750-1759 (AI nano smoothing) are properly configured if these features are enabled.
Changing these parameters affects machining accuracy and surface finish. Document original values before modification.
3
Cross-check parameter 1601#2 (look-ahead enable bit) is set correctly to match your intended operation mode.
4
Reset the control after parameter changes and test with a simple program before running production parts.

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