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FANUC Controller
Program/G-code · Intermediate · 30-60 minutes
Fanuc Alarm 373 - ILLEGAL HIGH-SPEED SKIP SIGNAL
Alarm 373 occurs in multi-path/multi-channel machining centers when two or more paths attempt to use the same high-speed skip signal (G31) simultaneously, or when the same skip signal number is assigned to multiple paths in parameters. This is a configuration conflict in synchronized multi-path operations where skip signal assignments must be unique per path.
373
Fanuc Alarm 373 - ILLEGAL HIGH-SPEED SKIP SIGNAL
SYSTEM ALARM 373
Fanuc alarm 373: SYSTEM ALARM 373. 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 373 occurs in multi-path/multi-channel machining centers when two or more paths attempt to use the same high-speed skip signal (G31) simultaneously, or when the same skip signal number is assigned to multiple paths in parameters. This is a configuration conflict in synchronized multi-path operations where skip signal assignments must be unique per path.
Causes and Fixes
- 1
Review the program blocks immediately before alarm occurrence. Check all active G31 commands across all paths. Verify if G31 P1, G31 P2, etc. use different P-numbers for each simultaneous path operation.
- 2
Navigate to SYSTEM > PROGRAM on each path controller display. List active programs on all paths and identify synchronized or simultaneous skip operations. Document which G31 Pn signal each path uses.
- 3
Modify NC program to assign unique skip signal numbers to each path. For example: Path 1 uses G31 P1, Path 2 uses G31 P2, Path 3 uses G31 P3. Ensure physical skip probe signals are wired to corresponding separate inputs.
- 4
Verify skip signal physical input assignments in DIAGNOSIS > PARAMETER > G31 SKIP or check parameters 6200-6207 series (skip signal input numbers). Confirm each path references different X-address input points for their respective skip signals.
Call a technician if:
- ·PMC ladder logic modifications required
- ·Multi-path parameter changes needed
- ·Custom macro debugging beyond basic level
Prevention
- Document skip signal assignments in program headers
- Use consistent signal numbering conventions across all programs
- Implement signal usage validation in custom macros
- Regular review of multi-path program coordination
Common Mistakes
- Copying G31 commands without changing signal numbers
- Not considering background process signal usage
- Ignoring multi-path signal conflicts
- Using variables for signal selection without validation
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