230-04F3

Identify the affected module

Press MOD key, navigate to System → Error Messages, and review the detailed error log to identify the specific module number or type (e.g., PL, EIB, or CC module) that is causing the fault.

The error log often displays the bus address or slot number of the failed module, which helps locate it physically on the control cabinet.

Inspect CC bus cabling

Power down the control and inspect all cables connected to the CC module connectors on the rear of the TNC. Check for bent pins, damaged insulation, cable strain, and ensure proper connector locking mechanisms are fully engaged.

Always power down the complete system before disconnecting or reconnecting bus cables to prevent damage to control electronics.

Verify bus termination

Ensure the last module in the CC or PL expansion chain has proper termination installed according to the TNC hardware installation manual. Missing or incorrect termination causes communication errors on the module bus.

Termination resistors are typically small plugs or switches on the final module in the chain. Check the module's documentation for correct termination settings.

Test with minimal configuration

Disconnect all non-essential external modules except the one causing the fault. Power up the control to see if the alarm persists. This isolates whether the issue is with a specific module or the bus infrastructure itself.

Check module status LEDs

Inspect the LED indicators on each external module. Most PL and CC modules have status LEDs indicating power, communication, and error states. Red or flashing error LEDs indicate module-level faults.

Refer to the specific module's documentation for LED status codes. Each module type has different indicator patterns for specific fault conditions.

Review module diagnostics in PLC

Access MOD → System → PLC Configuration → Module Diagnostics to view the status and diagnostic information for each connected module. Look for modules showing 'Not Ready' or 'Fault' status.

The diagnostics screen often shows communication cycle times. Modules with erratic or missing cycle times are likely failing.

Swap suspected module

If a specific module is identified as faulty, power down the system and replace it with a known-good spare of the same type. Ensure the module address switches (if present) are set identically to the original module.

Use only genuine Heidenhain or approved modules. Third-party modules may not be compatible and can cause persistent communication errors.

Verify module power supply

Measure the voltage supplied to the module at its power connector (typically 24VDC for PL modules). Low or fluctuating voltage can cause module malfunction and trigger this alarm. Check for adequate current capacity of the power supply.

Check voltage under load during control operation, not just static voltage, as marginal power supplies can drop under load conditions.

Review PLC module configuration

Access MOD → System → PLC Configuration and compare the configured module list with the physically installed hardware. Verify module types, addresses, and slot positions match the actual installation.

After any hardware changes, the PLC configuration must be updated. Simply adding or removing physical modules without updating configuration will trigger this alarm.

Check module address settings

Verify that any address switches or jumpers on the external modules are set correctly according to the TNC's configuration. Each module on the bus must have a unique address that matches the control's expectations.

Duplicate addresses on the bus will cause communication conflicts and multiple modules may fail to respond properly.

Update PLC configuration if needed

If hardware has been changed, update the PLC configuration through MOD → System → PLC Configuration → Edit Configuration. Remove entries for modules no longer present or add new modules with correct type and address information.

After modifying PLC configuration, perform a full reboot (not just PLC reset) to ensure the changes are properly initialized during the boot sequence.