231-A810

Identify affected axis and position

Read the alarm message to identify which axis (%1 parameter shows axis name). Check Position Display (Status > Positions) to see current axis coordinates.

Check configured traverse range

Press MOD key > Machine Parameters > Search for 'CfgAxisTravRange' > Select the affected axis > Review maxNegTravRange value. This defines the negative limit.

Clear alarm and jog axis to safe position

Press CE key to acknowledge alarm. Switch to Manual mode and carefully jog the affected axis in positive direction away from the limit switch boundary.

Ensure no mechanical obstructions exist before jogging axis. Use reduced feed rate override for initial movement.

Verify reference point validity

Navigate to Manual mode > Datum Set soft key > Check if reference point markers (R) are displayed for all axes. If missing, perform Reference Point Search sequence per machine manufacturer procedure.

Verify machine specifications

Consult machine manufacturer documentation to confirm correct negative traverse range for the affected axis. Note the maximum negative travel distance from machine zero.

Keep a backup copy of all machine parameters before making changes. Use MOD > Data Transfer > Backup Machine Parameters.

Access traverse range parameters

MOD key > Machine Parameters > CfgAxisTravRange > Select affected axis (X, Y, Z, etc.) > Locate maxNegTravRange parameter.

Adjust maxNegTravRange parameter

Enter correct negative traverse limit value (typically negative number, e.g., -500.000 for 500mm negative travel). Value must match mechanical limit switch positions and machine geometry.

Incorrect parameter values can lead to mechanical crashes. Verify values with machine builder documentation before saving changes.

Save parameters and reboot control

After parameter modification, save changes via MOD menu. Perform control restart (Reboot via MOD > Service > Reboot) to ensure parameters are active. Re-run reference point search after reboot.

Check reference point status

In Position Display (Status > Positions), verify that reference point marker (R) is displayed for all axes. Missing R indicator means reference point is invalid.

On iTNC 530 and TNC 620/640, reference status is also shown in the status bar at the top of the screen.

Inspect encoder battery voltage

Navigate to MOD > Diagnosis > EnDat Encoder > Select affected axis encoder. Check battery voltage status. For absolute encoders, check EnDat error messages in diagnostic display.

Low encoder battery can cause position loss during power-off cycles. Replace battery if voltage is below specification (typically 3.0V minimum).

Perform reference point search

Switch to Manual mode > Press Datum Set soft key > Select Reference Point Search. Execute reference sequence for affected axis according to machine-specific procedure (may require specific order for multi-axis machines).

Clear alarm and verify position

After successful reference point search, press CE to clear alarm. Verify Position Display shows correct coordinates and reference markers. Test jog axis through full travel range at reduced feed rate to confirm limits.

Review active NC program or MDI command

Press STOP/CANCEL key. Check Program Run > Current Block display to identify the NC block that triggered the alarm. Note the coordinate values for the affected axis.

Use the Test Run mode (Program Run > Test Run soft key) with reduced override to identify problematic coordinates before actual machining.

Analyze coordinate values against limits

Compare the programmed coordinate value with maxNegTravRange parameter (MOD > Machine Parameters > CfgAxisTravRange). Calculate if coordinate exceeds limit considering active datum shift (Status > Positions > show preset and REF values).