330-008F

Check keylock switch position

Physically verify the keylock switch on the machine control panel is turned to position 1 (SOM_1/Manual mode).

Never force the keylock switch - it may be mechanically interlocked with other safety systems.

Verify SOM_1 activation

Press the operating mode key and confirm SOM_1 is displayed and active on the TNC screen before attempting mode change.

The status bar should clearly show 'Manual' or 'SOM_1' when properly selected.

Execute proper mode sequence

From SOM_1, now select the desired target mode (SOM_2 MDI or SOM_3 Handwheel) using the operating mode keys.

Always follow the sequence: SOM_4 → SOM_1 → SOM_2/3 for safe mode transitions.

Check safety status display

Navigate to MOD → Settings → Machine Parameters and check safety input status or use PLC status display to verify all safety circuits.

Never bypass safety interlocks - resolve the underlying safety condition first.

Inspect physical safety devices

Verify all safety doors are properly closed, emergency stops are released, and light curtains are clear of obstructions.

Check door limit switches and safety relay status LEDs on the electrical panel.

Reset safety system if required

If safety devices are properly positioned, perform a safety system reset using the designated reset button or key sequence.

Some systems require a specific reset sequence: E-stop release → safety reset → mode selection.

Check PLC status

Access PLC diagnostics via MOD → Settings → PLC and review any active blocking conditions or custom mode change restrictions.

Look for custom M-functions or PLC markers related to operating mode control.

Review machine builder documentation

Consult machine-specific documentation for any custom mode change sequences or conditions required by the machine manufacturer.

Machine builders often implement additional safety logic beyond standard Heidenhain requirements.

Clear blocking conditions

Address any machine-specific conditions such as tool change completion, workpiece clamping status, or custom safety interlocks as defined by the PLC program.

Check for active auxiliary functions (M-codes) that may need to complete before mode changes are allowed.

Check program status

Verify no NC program is active, paused, or in an interrupted state by checking the program status display and current block information.

Look for 'STOP', 'INTERRUPTED', or 'PAUSED' indicators in the status bar.

Reset program state

If a program is active, properly stop it using the STOP key, then press the END key to reset the program to the beginning.

Ensure machine is in a safe position before resetting active programs.

Clear any active tool calls

Verify no tool change is in progress and clear any pending tool calls or auxiliary functions that may be blocking the mode change.

Check the auxiliary function display for any pending M, S, or T functions.

Check operating mode parameters

Navigate to MOD → Settings → Machine Parameters and verify parameters related to operating mode control (typically MP7xxx series) are correctly configured.

Compare current parameter values with machine documentation or backup parameter files.

Verify safety parameter settings

Check safety-related machine parameters (MP1xxx series) to ensure proper configuration of safety interlocks and mode change permissions.

Only modify safety parameters if you have proper authorization and documentation.

Restore from backup if necessary

If parameter corruption is suspected, restore machine parameters from a known good backup file after consulting with machine documentation.

Parameter restoration may affect machine calibration and should be done with caution.