Code 320-0059: IOC configuration has invalid PLC operand addresses
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical IOC configuration has invalid PLC operand addresses alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
[Cause of error] The IOC configuration contains PLC operand addresses, that exceed the permissible PLC memory area. Possible causes: - IOC configuration and PLC configuration file do not fit together - Initial servicing or new installation - Importing a backup The BUS diagnosis shows which operand range is affected. [Error correction] Confirm the error message and current interruption, and note the further error messages: - Either the areas for the affected operands must be enlarged in the configuration file for the PLC compiler, or - a restart is necessary in order to activate a new or changed configuration. - Inform your service agency
Source: HEIDENHAIN NC Error Messages — TNC7/640/620/320/128, CNC PILOT 640, MANUALplus 620 (10/2023)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Heidenhain TNC Series CNC Alarms
Heidenhain controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code 320-0059 on the TNC Series CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Heidenhain's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 4497 Heidenhain TNC Series CNC codes.
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