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FANUC Controller
Program/G-code · Intermediate · 5-30 minutes
Fanuc 189 - Involute interpolation format error
Alarm 189 occurs when the involute interpolation G02.2/G03.2 command contains invalid syntax, missing required parameters, or geometrically impossible conditions. The control cannot calculate a valid involute curve path with the programmed values. This is strictly a programming format or parameter error in the part program.
189
Fanuc 189 - Involute interpolation format error
INVOLUTE INTERPOLATION FORMAT ERROR
Fanuc PS program alarm 189: INVOLUTE INTERPOLATION FORMAT ERROR. 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 189 occurs when the involute interpolation G02.2/G03.2 command contains invalid syntax, missing required parameters, or geometrically impossible conditions. The control cannot calculate a valid involute curve path with the programmed values. This is strictly a programming format or parameter error in the part program.
Safety
- Verify corrected program or parameters before resuming machining
Causes and Fixes
- 1
Review the involute interpolation block in the program. Verify format: G02.2 or G03.2 X_ Y_ I_ J_ R_ (or F_) with all required parameters present.
- 2
Check that I and J values correctly specify the center point of the base circle relative to the involute start point.
- 3
Verify the base circle radius (R or F parameter) is programmed and is a positive value.
- 4
Ensure the end point coordinates (X, Y) are properly specified and the involute curve is geometrically possible from start to end.
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