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FANUC Controller
Program/G-code · Intermediate · 5-30 minutes
Fanuc 12 - Illegal command in g71
Alarm 012 occurs when the G71 roughing cycle contains programming errors or prohibited commands within the cycle definition. This is typically caused by incompatible G-codes, missing parameters, incorrect block formatting, or commands that cannot be executed during a canned cycle operation.
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Fanuc 12 - Illegal command in g71
ILLEGAL COMMAND IN G71
Fanuc PS program alarm 12: ILLEGAL COMMAND IN G71. This alarm is triggered by an illegal or incorrectly formatted command in the part program, or a programming condition that the Fanuc control cannot execute.
Root Cause Summary
Alarm 012 occurs when the G71 roughing cycle contains programming errors or prohibited commands within the cycle definition. This is typically caused by incompatible G-codes, missing parameters, incorrect block formatting, or commands that cannot be executed during a canned cycle operation.
Safety
- Verify corrected program or parameters before resuming machining
Causes and Fixes
- 1
Locate the G71 block in the program and identify the start block (e.g., N10) and end block (e.g., N50) parameters.
- 2
Review all blocks between the defined start and end blocks for prohibited commands such as G70-G76 cycles, G27-G30 reference point returns, M06 tool changes, or G04 dwells.
- 3
Check any G02/G03 arc commands in the finish shape for correct I, K, or R parameter formatting and valid arc geometry.
- 4
Remove or relocate prohibited commands outside the G71 cycle definition and re-run the program.
Ensure the finish shape remains geometrically valid after modifications.
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