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FANUC Controller
Program/G-code · Basic · 10-20 minutes
Fanuc Alarm 317 - ILLEGAL THREAD COMMAND IN THREAD CUTTING CYCLE
Alarm 317 occurs when the G76 threading cycle detects a zero, negative, or improperly formatted value for thread height (depth of cut per pass) or total thread depth. This is a program syntax error that prevents the control from calculating valid cutting passes for the thread profile.
317
Fanuc Alarm 317 - ILLEGAL THREAD COMMAND IN THREAD CUTTING CYCLE
SYSTEM ALARM 317
Fanuc alarm 317: SYSTEM ALARM 317. This alarm indicates a fault condition detected by the Fanuc control. Refer to the alarm number and name to identify the specific system or function involved.
Root Cause Summary
Alarm 317 occurs when the G76 threading cycle detects a zero, negative, or improperly formatted value for thread height (depth of cut per pass) or total thread depth. This is a program syntax error that prevents the control from calculating valid cutting passes for the thread profile.
Causes and Fixes
- 1
In EDIT mode, locate the G76 threading cycle block in the active program. Verify the thread height specification: For 0i/16i/18i series check the 'Q' address value (finish pass allowance and height); for 30i/31i/32i series check both the first G76 block 'Q' value (minimum depth of cut) and verify it is positive and non-zero.
- 2
Check parameter 5130 (Thread Cutting Display) to confirm threading cycle format. Bit 0 determines whether thread height is specified as radius or diameter value. Ensure the programmed value accounts for this setting.
- 3
Correct the G76 command: For G76 P011060 Q0100 R0050 format, ensure Q value (minimum depth of cut in 0.001mm or 0.0001inch) is positive. For older format G76 X__ Z__ I__ K__ D__ F__ P__, ensure the 'D' address (depth of first cut) is positive.
- 4
Execute a dry run with SINGLE BLOCK active to verify the corrected G76 cycle calculates proper threading passes without alarm. Monitor CURRENT POSITION display to confirm tool path calculation.
Call a technician if:
- ·Persistent alarm after parameter correction
- ·Macro programming errors beyond operator skill level
- ·Parameter 5142 corruption suspected
Prevention
- Always validate G76 parameters against thread specifications
- Use thread calculation worksheets for complex threading
- Implement parameter range checking in macro programs
- Maintain standard G76 templates for common thread types
Common Mistakes
- Using decimal points in P parameter compound values
- Forgetting leading zeros in 6-digit P parameter
- Confusing thread pitch with thread height in calculations
- Copy-pasting G76 blocks without updating all parameters
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