Code 126-0112: Switch-off port on incorrect bus system
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical Switch-off port on incorrect bus system 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 output for switching off the machine after the control shutdown was defined for the wrong bus system. The permitted bus systems are external PL assemblies with HSCI interface or internal PL assemblies. [Error correction] - Check the IO configuration and correct it if required 10/2023 [11]
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 126-0112 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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