120-0027

Complete power cycle

Turn off the main power to the control cabinet for at least 30 seconds (not just E-Stop or control restart). This clears all memory allocations and resets the operating system's resource management completely.

Ensure machine is in a safe state and all axes are secured before removing power.

Check system resource usage

After restart, access MOD function, navigate to System Information, and check memory usage and process statistics. Look for unusually high memory consumption or low available system memory (should have >100MB free on most TNC models).

On iTNC 530 and TNC 620/640 controls, normal system memory usage at idle should be below 60%. Higher values indicate resource leaks.

Disable third-level programs temporarily

In MOD - Machine Parameters - CfgPgmMgt, set CfgPLC[0].active = 0 to disable PLC startup, then restart control. If alarm clears, a third-level program or PLC cycle is causing resource exhaustion.

You can also rename SYS\plc.dir to SYS\plc.old to prevent all PLC programs from loading during diagnostic startup.

Review recent configuration changes

Check if alarm appeared after adding new third-level functions, LSV2 connections, or remote desktop services. Remove recently added services one at a time to identify the resource consumer.

Attempt safe mode boot

Power on control while holding the keys CE + 0 simultaneously (timing varies by TNC model) to boot with minimal configuration loading. If control boots successfully, configuration files are suspect.

On TNC 640, you may need to use the System Loading screen accessed during POST - consult your specific control version documentation.

Restore TNCopt.sys from backup

Navigate to MOD - Restore Machine Configuration. Select a dated backup of TNCopt.sys from before the alarm first appeared. The control maintains automatic backups in SYS\backup directory.

Restoring TNCopt.sys will revert all machine parameters to the backup date. Document current critical parameters before restoring.

Check configuration file integrity

Access file manager in Programming & Editing mode, navigate to TNC:\SYS directory, and verify TNCopt.sys exists and has reasonable file size (typically 100-500KB depending on configuration complexity). Zero-byte or excessively large files indicate corruption.

Compare file size and date with backup versions. TNCopt.sys should not change daily unless parameters are actively being modified.

Rebuild configuration if necessary

If no valid backup exists, use machine manufacturer's master configuration file or Heidenhain default TNCopt.sys from installation media. Copy to SYS directory via TNCBackup or direct file transfer, then restart control.

Check system error logs

Access MOD - System Information - Error Messages. Look for kernel errors, segmentation faults, or system service failures logged immediately before the 120-0027 alarm. Document exact timestamps and error codes.

Errors referencing 'msgQ', 'queue', 'IPC', or specific process IDs (PID) in the log provide critical diagnostic information for Heidenhain service.

Perform filesystem check

Boot control into service mode (consult your TNC model's service documentation for boot procedure). Run filesystem check utility on system partition. This verifies integrity of OS files and fixes filesystem corruption.

Filesystem operations should only be performed by trained service personnel. Improper execution can render the control unbootable.

Verify software version compatibility

In MOD - System Information - NC Software, verify that NC software version matches the PLC software version and any third-party software installed. Mismatched versions can cause system-level failures.

After any software update, both NC and PLC software should show the same build number. Mixed versions indicate incomplete update installation.