320-07D0

Access PLC Status Display

Press MOD key, select 'PLC' menu, then 'Status' to check PLC program status and error details.

Look for additional PLC error markers in the status display that may indicate specific memory sectors affected.

Reload PLC Program

Go to MOD > PLC > Transfer, select your PLC program file (.PLC extension) and reload it to NC memory.

Ensure machine is in safe position and all axes are stopped before PLC program transfer.

Verify PLC Program Integrity

After reload, check MOD > PLC > Info to verify program checksum matches the original file checksum.

Compare file size and timestamp with original PLC program to ensure complete transfer.

Restart PLC Runtime

Execute PLC STOP followed by PLC START from the PLC menu to reinitialize the runtime system.

PLC restart will reset all PLC markers and timers to initial state.

Check CF Card Status

Access MOD > System Info > Storage to check CF card health status and available space.

Look for 'Bad Blocks' count - any non-zero value indicates CF card degradation.

Backup Critical Files

Copy all PLC programs and NC programs to external USB storage via File Manager before CF card failure.

Do not remove CF card while NC is running - always power down first.

Test with Known Good PLC Program

Load a backup copy of the PLC program from external storage to verify if the issue is storage-related.

Keep master copies of PLC programs on separate media to avoid single point of failure.

Replace CF Card if Necessary

If storage errors persist, replace CF card with Heidenhain-approved industrial grade CompactFlash card.

Use only industrial-grade CF cards rated for continuous operation and temperature extremes.

Check System Error Log

Navigate to MOD > System Info > Error Log to review system-level errors that may affect PLC runtime.

Look for memory allocation errors or system resource conflicts preceding the PLC alarm.

Perform Soft Reset

Execute a controlled restart via MOD > System > Restart to reinitialize all system components including PLC runtime.

Save all active programs and tool data before system restart.

Clear PLC Memory

Use MOD > PLC > Clear Memory to completely clear PLC workspace and force fresh program load.

This clears all PLC variables - document any critical persistent values before clearing.

Monitor PLC Cycle Time

Check MOD > PLC > Diagnostics for PLC cycle time and CPU load to identify performance issues.

PLC cycle times over 10ms may indicate program complexity issues affecting checksum calculations.

Check Software Versions

Compare current NC software version (MOD > System Info > Version) with PLC program creation version in program header.

PLC programs show creation software version in the first comment lines when viewed in PLC editor.

Verify PLC Instruction Compatibility

Review PLC program for deprecated or version-specific instructions that may cause checksum errors.

Some PLC instructions changed format between major TNC software releases.

Recompile PLC Program

If using PlcDesign software, recompile the PLC source code with current TNC software version target.

Always maintain PLC source code files (.SRC) for recompilation with newer TNC versions.

Check System Temperature

Monitor NC cabinet temperature via MOD > System Info > Temperature - overheating can cause communication errors.

NC cabinet temperatures above 45°C can cause intermittent hardware communication failures.

Inspect Internal Connections

Power down and check all internal cable connections between NC main board and expansion modules.

Only qualified technicians should access internal NC hardware connections.

Run Hardware Diagnostics

Execute built-in hardware tests via MOD > Service > Hardware Test to identify communication path failures.

Hardware diagnostic results are logged and can be reviewed by Heidenhain service personnel.