231-81B0

Power down and inspect connections

Turn off machine power completely. Inspect X116/X117 connections at both the CC card (in TNC cabinet) and the inverter module indicated by the alarm parameter Po. Check for bent pins, contamination, or loose connector locks.

Ensure complete power isolation including DC bus discharge (wait 5 minutes) before touching inverter connections.

Verify cable shield continuity

Using a multimeter, verify cable shield continuity from CC connector housing to inverter connector housing. Resistance should be less than 1 ohm. Check that shield is connected at both ends to connector housings, not internal pins.

Heidenhain inverter bus cables must have 360-degree shield contact at connector housings. Pigtail shield connections cause common-mode noise issues.

Reseat or replace cable

Disconnect and reconnect X116/X117 at both ends, ensuring audible click of connector lock. If cable shows any damage or alarm persists, replace with genuine Heidenhain inverter bus cable (do not substitute with generic cables).

Maximum cable length for inverter bus is 30 meters total. Excessive length or daisy-chaining too many modules causes timing errors.

Identify affected inverter module

Note the Po (position) and Dev (device) parameters from the alarm. Cross-reference with your inverter layout documentation to identify the physical inverter module. Typical layout is sequential from CC card outward.

Access MOD > PLC > PlcMonitor > Inverter Status to see real-time communication status of each inverter module and confirm which module is faulting.

Check inverter LED status indicators

On the physical inverter module, observe the status LEDs (typically on front panel). A red LED or no communication LED activity indicates module-side communication failure. Compare with functioning adjacent modules.

Do not touch inverter components with power applied. Observe LEDs only.

Perform module swap test

Power down completely. Swap the suspect inverter module with an identical axis module (same power rating). Power up and observe if alarm follows the module (module fault) or stays at same bus position (cable/CC fault).

After swapping modules, you may need to reassign axis parameters in MOD > Inverter Configuration to match the new physical layout, or swap the motor feedback cables to keep configuration unchanged.

Replace defective inverter module

If alarm follows the module, replace with new or known-good UM inverter module. After replacement, verify configuration in MOD > Inverter > Module Configuration matches the installed hardware type and firmware.

New inverter modules may require firmware update to match TNC control version. Use MOD > System > Firmware Update > Inverter to synchronize versions.

Check for multiple inverter communication alarms

Review TNC error log (MOD > System Information > Error Messages) to see if multiple inverter modules show communication errors. Multiple modules failing simultaneously suggests CC card issue rather than individual module problems.

Single module errors point to that module or its cable; multiple module errors point upstream to CC card or power supply issues.

Verify CC card seating and connections

Power down. Open TNC control cabinet and verify CC card is properly seated in its slot on the MC main computer board. Check that X116 outgoing inverter bus cable is securely connected to CC card.

Use proper ESD precautions when handling CC card. Wear grounding strap and avoid touching component pins.