Code 330-0027: MC pos. deviation too large %2
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical MC pos. deviation too large %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 calculated position deviation between the speed encoder and the position encoder is greater than the value from the parameter CfgAxisSafety->positionDiffRef or CfgAxisSafety->positionDiffRun. - Excessive difference between the positions calculated from the position encoder pulses and the speed encoder pulses - During initial operation: Incorrect standardization of speed encoder pulses (e.g. incorrect screw pitch entered) - Excessive backlash - Defective coupling, gear, etc. - Belt torn [Error correction] - Switch the control off and on again - Check CfgAxisSafety->positionDiffRef, CfgAxisSafety->positionDiffRun - During initial operation: Check the standardization of speed encoder pulses (enter the correct screw pitch) - Check the backlash - Repair the defective coupling, gear, etc. - Replace the belt - 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 330-0027 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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