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Haas Controller
Program/G-code · Intermediate · 10-60 minutes
Haas 331 - RANGE ERROR | Haas CNC Alarm
Alarm 331 fires when a G31 probing cycle completes its programmed move without receiving a valid trigger signal from the probe skip input. The control expects the probe stylus to contact the workpiece and change the probe input state before reaching the target coordinates, but no contact was detected.
331
Haas 331 - RANGE ERROR | Haas CNC Alarm
RANGE ERROR
This alarm indicates that a commanded position or movement exceeds the allowable software or hardware travel limits defined in the machine parameters. The MOCON board monitors axis position feedback from the encoders and compares it against the parameter-defined stroke limits and rapid traverse limits. When triggered, all axis motion is halted immediately to prevent crashes or damage to the machine structure.
Root Cause Summary
Alarm 331 fires when a G31 probing cycle completes its programmed move without receiving a valid trigger signal from the probe skip input. The control expects the probe stylus to contact the workpiece and change the probe input state before reaching the target coordinates, but no contact was detected.
Safety
- Always remove probe from spindle when checking battery or stylus to prevent accidental spindle rotation or probe damage
- Ensure spindle is in M05 (stopped) and machine is in RESET or controlled jog mode when manually deflecting probe to test signals - do not test during program run
Causes and Fixes
- 1
Verify workpiece position and setup
Check that workpiece is properly fixtured and positioned within the programmed probe target area. Verify work coordinate system (G54-G59) offsets are correct.
Use the probe manually in MDI mode with a short G31 move to test contact before running the full program
- 2
Check probe target coordinates
Review G31 line in program to ensure X, Y, Z target coordinates will intersect with actual workpiece geometry. Verify feed rate is appropriate (typically F10-F50).
Ensure probe target is beyond expected contact point but not so far as to risk collision
- 3
Inspect probe stylus condition
Check stylus for damage, bending, or loose connections. Verify stylus length matches tool offset in tool table and probe calibration data.
A bent stylus will change the effective probe radius and may miss the intended contact point
Call a technician if:
- ·Probe interface module failure suspected
- ·Parameter changes don't resolve issue
- ·Electrical cabinet work required
Prevention
- Regularly calibrate probe using G37 cycle
- Inspect probe cables during preventive maintenance
- Keep spare probe stylus assemblies in stock
- Document working probe parameter settings
Common Mistakes
- Not checking probe input status before troubleshooting hardware
- Forgetting to recalibrate probe after stylus replacement
- Setting probe target coordinates too close to expected contact point
- Ignoring bent or damaged stylus condition
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