104105

Check the NC program line where the alarm occurred and identify the D-number being called (look for D1, D2, etc. or tool change commands).

Navigate to the tool offset table (Settings > Offset > Tool Offset or use soft key 'Offset' then 'Tool') and verify that the called D-number exists and has valid data entries.

Check machine data MD18120 (MM_NUM_CUTTING_EDGES_IN_TOA) to verify the maximum number of D-numbers allowed per tool and ensure your program doesn't exceed this limit.

Modifying machine data requires manufacturer password and may affect machine operation

If D-number is missing, create the offset entry in the tool offset table or modify the NC program to call a valid D-number, then reset the alarm and restart the program.

Perform a complete power cycle of the control (wait 30 seconds after power-down) to allow the system to reinitialize the tool data structures.

Ensure machine is in a safe position and all programs are saved before power cycling

Access the tool offset table and systematically verify each D-number entry for the active tool shows numeric values (not asterisks or blank fields indicating corruption).

If corruption is found, restore tool offset data from a previously saved backup file using Archive > Load or re-enter the tool offset values manually.

Ensure backup file is current and valid before loading

Check system battery voltage (Diagnostics > Service > Battery) and replace if below 3.0V to prevent future data loss, then perform a complete data backup.

Low battery can cause repeated data corruption issues

In the tool list (Settings > Tool > Tool List), verify that the T-number being called has a valid TOA (Tool Offset Array) assignment and the correct number of cutting edges defined.

Check machine data MD18102 (MM_NUM_TOOL_CARRIER) and MD18110 (MM_NUM_CUTTING_EDGE_TOOL) to ensure tool management is properly configured for your machine setup.

Document current MD values before making any changes

Review the NC program syntax - ensure proper format is used (T=tool_number D=offset_number for 840D) and that D-number selection occurs after the tool is fully loaded.

If using tool management with magazine, verify in Diagnostics > Tool Management that the tool location, duplo number, and adapter settings are correctly configured and synchronized.