Code 330-0040: MC limit switch %2 -
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical MC limit switch %2 - 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] - Violation of the absolute negative limit position value (in the negative traverse direction) of the safety function SLP. - The calculated path of the tool exceeds the defined traversing range (software limit switch) of the machine. - The software limit switch (absolute position limit value) was reached in a manual operating mode. [Error correction] - Check the programmed coordinates. If required, edit the program. - Check the reference point. If required, set a new reference point. - Move the tool in the opposite direction. - 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 330-0040 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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