236-A204

Identify Affected Drive

Note the drive number %1 from alarm display. Cross-reference in MOD > Machine Configuration > Axis Assignment to determine which physical axis and inverter module corresponds to this number.

Drive numbering starts at 0 for X-axis. On multi-UMC systems, note which cabinet and module position matches the alarm number.

Inspect ProfiNet Cable Integrity

Physically trace the green ProfiNet cable from TNC PL6xxx communication board to the affected UEC/UMC inverter. Check for kinks, cuts, or loose M12/RJ45 connections at both ends. Verify cable click-lock engagement.

Do not disconnect ProfiNet cables while control is powered on - this may cause additional alarms or configuration loss.

Verify ProfiNet Topology

Access MOD > Device Management > ProfiNet and check network topology diagram. Affected drive will show red icon or 'No Response' status. Verify daisy-chain sequence matches physical installation.

ProfiNet requires proper line termination. Last device in chain must have termination resistor active or termination plug installed.

Test Cable with Known Good

If available, temporarily swap the ProfiNet cable with a known working segment. Use only industrial ProfiNet-certified cables (CAT5e minimum, shielded). Standard Ethernet patch cables may cause intermittent failures.

Heidenhain recommends max 10m cable length between ProfiNet nodes. Longer distances require ProfiNet switches with IRT capability.

Check Drive Status LEDs

Inspect the affected UEC/UMC module front panel. Normal operation shows solid green LED. Red or flashing patterns indicate fault conditions. Refer to drive label for LED code interpretation specific to UEC/UMC series.

Do not open drive enclosures. High voltage DC bus remains energized for several minutes after power disconnect.

Verify DC Bus Voltage

Check DC bus voltage display on UMC/UEC unit or measure at DC bus terminals. Nominal 560-590VDC for 400VAC supply, 280-310VDC for 230VAC. Low bus voltage prevents ProfiNet processor operation.

If multiple drives show 236-A204 simultaneously, suspect common DC bus supply fault rather than individual drive failures.

Review Drive Diagnostic Buffer

Access MOD > Diagnostics > Drive Status and select affected axis. Review error history buffer for fault codes that occurred immediately before ProfiNet loss. Common precursors: overcurrent, overtemperature, encoder faults.

UEC/UMC units log last 10 fault events with timestamps. Compare these timestamps to TNC PLC log for correlation.

Power Cycle Affected Drive

Disconnect AC supply to the affected drive amplifier only (use individual circuit breaker if available). Wait 30 seconds, reconnect power. Observe startup LED sequence. Press CLEAR ALARMS on TNC after drive initialization complete.

Ensure machine is in safe state and emergency stop is available. Power cycling may cause unexpected axis movements if holding brake circuits are affected.

Verify GDFN File Compatibility

Access MOD > Device Configuration > ProfiNet and check GDFN file version for affected station. File must match exact UEC/UMC hardware model and firmware version. Navigate to MOD > Software Versions to confirm inverter firmware matches GDFN specification.

After UEC/UMC firmware updates, GDFN files must be updated on TNC. Copy correct GDFN from TNC:\system\profinet\gsd\ directory using Heidenhain DiskManager.

Check ProfiNet Station Address

Compare station address in MOD > Device Configuration > ProfiNet with physical address setting on UEC/UMC (set via rotary switches or software depending on model). Duplicate addresses cause communication failures. Station address range: 1-254.

On UMC systems, station address is typically programmed via ProfiNet rather than hardware switches. Check machine manufacturer documentation for address assignment scheme.