Code 330-0042: MC standstill monitoring %2
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical MC standstill monitoring %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] - The position error in an active safe operating stop (SOS) is greater than the value specified in the configuration parameter CfgAxisSafety->positionRangeVmin. - If during an emergency stop the axes and spindle are decelerated, and the axes come to a stop earlier than the spindle, then the axes are standstill-monitored for the value from CfgAxisSafety->positionRangeVmin until the spindle comes to a stop. - If the protective door is closed in the automatic mode (SOM 1), axes whose drives are switched off (e g. clamped axes) are standstill-monitored for the value from CfgAxisSafety->positionRangeVmin. - After the permissive button is released, the tool magazine axis continues to move for more than 3 seconds. - During the braking test, the axis exceeds the maximum permissible path in CfgAxisSafety->positionRangeVmin. It must be assumed that a holding brake for the axis is defective! - After triggering of an SS2 stop reaction and expiration of the SS2 stopping time, a position error greater than the value in the configuration parameter CfgAxisSafety->positionRangeVmin was detected. [Error correction] - If the error occurs during the brake test, the axis remains in the servo loop. The axis has to be moved to a safe position before you switch the machine off. It must be assumed that a holding brake is defective. - 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 330-0042 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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