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FANUC Controller
Program/G-code · Intermediate · 5-30 minutes
Fanuc 198 - Illegal command in egb
Alarm 198 occurs when the control encounters an illegal or improperly formatted command within an External Geometry Block (EGB) in the part program. This is typically caused by unsupported G-codes, incorrect syntax, missing parameters, or commands that violate EGB programming rules specific to Fanuc controls.
198
Fanuc 198 - Illegal command in egb
ILLEGAL COMMAND IN EGB
Fanuc PS program alarm 198: ILLEGAL COMMAND IN EGB. 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 198 occurs when the control encounters an illegal or improperly formatted command within an External Geometry Block (EGB) in the part program. This is typically caused by unsupported G-codes, incorrect syntax, missing parameters, or commands that violate EGB programming rules specific to Fanuc controls.
Safety
- Verify corrected program or parameters before resuming machining
Causes and Fixes
- 1
Locate the alarm line number in the program and identify the EGB block (typically between EGB and EGE statements).
- 2
Review all commands within the EGB block and verify only geometry definition commands (G00, G01, G02, G03) and basic coordinate movements are used.
Do not use canned cycles (G73-G89), tool compensation calls (G41/G42), or work offset commands within EGB blocks.
- 3
Remove or relocate any prohibited commands outside the EGB/EGE block structure.
- 4
Reset the alarm, return to program start, and test run in single block mode to verify the correction.
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