330-0081

Check Limit Switch Status

Navigate to MOD > Machine > Axis Status to view current limit switch states for all axes. Identify which axis (%2 parameter) triggered the alarm.

Do not attempt to move axes while limit switches are active

Inspect Physical Limit Switches

Visually inspect the limit switch hardware on the affected axis for mechanical damage, proper mounting, and electrical connections.

Check for debris or coolant contamination affecting switch operation

Manual Axis Recovery

Use Manual mode with reduced feedrate to carefully move the axis away from the limit switch in the opposite direction.

Use incremental jog with small steps (0.1mm) when near limits

Verify Software Limits

Check machine parameters MP1010-MP1013 (software limit switches) to ensure they are set correctly relative to hardware limits.

Software limits should be 2-5mm inside hardware limits for safety margin

Check Active Coordinate System

Press POS key to view current position display and verify active coordinate system (G54, G55, etc.) and datum values.

Compare workpiece coordinates to machine coordinates for discrepancies

Verify Preset Table

Navigate to Tables > Preset Table and check preset values for the active coordinate system. Ensure values are within machine travel range.

Incorrect preset values can cause crashes even with valid part programs

Recalibrate Work Coordinates

Use Manual mode to establish correct workpiece datum using touch probe or edge finder, then update preset table with verified values.

Always perform a dry run with Graphics simulation after coordinate changes

Test Program Limits

Use Program Run > Graphics to simulate the complete program and verify all moves remain within software limits before execution.

Enable 'Show machine envelope' in graphics to visualize travel limits

Check Following Error Values

Navigate to MOD > Machine > Servo Status to view current following error values for all axes and compare to MP1230 (maximum following error).

Following errors >0.1mm typically indicate servo tuning or mechanical issues

Inspect Mechanical Binding

Manually check axis movement for binding, excessive friction, or mechanical obstructions that could cause servo lag.

Ensure machine power is off when manually moving axes

Verify Servo Parameters

Check servo tuning parameters MP1410-MP1420 (position loop gain, velocity feedforward) for proper values matching axis characteristics.

Compare current parameters to machine documentation or backup files

Perform Servo Optimization

Use TNC's automatic servo optimization function in MOD > Machine > Servo Optimization to retune axis parameters if mechanical issues are resolved.

Only perform servo optimization with proper mechanical setup

Review Program at Alarm Point

Check the NC block where alarm occurred for coordinate values and verify they are within machine travel envelope defined by MP1010-MP1013.

Use Program Run > Single Block mode to isolate problematic moves

Verify Tool Length Compensation

Check Tool Table (Tables > Tool Table) for excessive or incorrect tool length values that could cause Z-axis limit violations.

Incorrect tool lengths can cause spindle crashes into workpiece or table

Validate Program Origin

Confirm program was written for correct machine configuration and work envelope. Check for inch/metric unit mismatches.

Use UNIT INCH or UNIT MM at program start to ensure correct units

Modify Program Coordinates

Edit NC program to correct coordinate values or add appropriate coordinate transformations (TRANS, ROT) to fit within machine limits.

Use TNC's program editor with syntax checking to validate changes

Verify Limit Switch Parameters

Check MP1020-MP1023 (limit switch polarity) and MP1030-MP1033 (limit switch enable) for correct configuration matching hardware setup.

Incorrect limit switch polarity can cause immediate alarms on startup

Review Safety Parameters

Examine MP1200 (positionDiffNom) and related safety monitoring parameters to ensure they match machine mechanical characteristics.

Safety parameters should be set by qualified service personnel only

Compare to Backup Configuration

Load known good machine parameter backup from TNC memory or external storage to identify parameter changes.

Always create parameter backup before making changes

Contact Heidenhain Support

If parameter discrepancies are found, contact Heidenhain technical support with machine serial number and parameter comparison data.

Incorrect safety parameters can compromise machine and operator safety