234-0005

Access error log details

Press MOD key, navigate to System -> Error Messages. Note the complete error text, internal error number, and timestamp. Document any pattern of when alarm occurs.

Error log may show specific module names (e.g., NC_KERNEL, PLC_TASK) that pinpoint the software component causing the failure.

Boot into Service Mode

Power off control, then power on while holding MOD and CE keys simultaneously until Service Mode menu appears. This bypasses normal startup routines.

Service Mode operations can affect control configuration. Document current settings before making changes.

Check file system integrity

In Service Mode, select 'Check File System'. Allow complete scan of TNC hard drive. Note any reported errors or bad sectors. Repair if prompted.

File system errors often accumulate after repeated power interruptions or emergency stops during write operations.

Reload system software

Using original Heidenhain installation media (DVD or USB), boot from external media and select 'Reinstall System Software'. Choose option to preserve machine parameters if available. Complete full installation process.

Ensure you have backup of all NC programs, tool tables, preset tables, and machine parameters before reinstalling. Use TNCbackup utility if possible.

Restore from known-good backup

If TNCbackup file exists, restore complete system configuration after software reload. Navigate to MOD -> System -> TNCbackup -> Restore and select verified backup file.

Regular TNCbackup snapshots are essential. Set up automatic daily backups to network location to prevent data loss during software failures.

Run memory diagnostic test

Boot into Service Mode and select 'System Diagnostics' -> 'Memory Test'. Run extended memory test (may take 20-30 minutes). Note any reported memory errors or failing addresses.

Memory errors often show as intermittent failures at specific addresses. Multiple errors across different ranges indicate systemic hardware failure.

Check hardware error log

In Service Mode, access 'Hardware Log' to check for ECC memory errors, parity errors, or bus errors. These indicate hardware-level memory problems.

Continuing to operate with failing memory can cause data corruption in NC programs and parameter tables.

Verify memory module seating

Power down completely and disconnect from mains. Open control cabinet, locate RAM modules on MC motherboard. Carefully remove and reseat each module, ensuring positive lock engagement. Clean contacts with contact cleaner if oxidation present.

Use ESD precautions. Wear grounding strap and work on anti-static mat. Follow lockout/tagout procedures before accessing control interior.

Replace suspected memory modules

If memory test shows errors, replace RAM modules with Heidenhain-approved parts matching exact specifications (type, speed, voltage). Use only modules from Heidenhain parts list for your specific TNC model.

TNC controls are sensitive to memory timing. Generic PC memory may appear compatible but cause intermittent errors. Always use Heidenhain part numbers.

Boot without PLC execution

Enter Service Mode and select option to 'Start without PLC'. If control boots successfully without alarm, PLC program is implicated. If alarm still occurs, PLC is not the cause.

Starting without PLC disables all machine-specific logic. Machine won't function normally but confirms if PLC is causing the software error.

Review recent PLC changes

Access PLC program editor (PLC -> Edit). Review any recently modified sections. Look for timer overflows, array boundary violations, or improper use of system markers (especially markers above 8000).

Improperly used system markers can interfere with NC kernel operations and cause unpredictable errors.

Check PLC cycle time violations

In PLC operating mode (MOD -> PLC), monitor 'Cycle Time' display. If maximum cycle time exceeds 20ms consistently, PLC program is too complex or contains blocking operations that starve NC kernel.

TNC controls require PLC cycle time under 20ms. Excessive time indicates inefficient code or infinite loops in conditional statements.