Code 231-8B40: No drive release %1
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical No drive release %1 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] - Inverter not ready - No pulse release for the power module - Uz too high - Power-fail signal active - With M controls: I32 input inactive - With P controls: Drive enabling at X50 inactive In addition, for 246 261-xx (digital current controller): - For the given axis an illegal motor model (e.g. linear motor) was selected. - The CC receives a "Drive on" command for a nonexistent axis. - The power module is not ready when the field orientation starts. Readiness of the power module is detected through the Ready signal on the PWM cable. - The power module is not ready when the current controller adjustment begins. [Error correction] - Inform your service agency - Check the activation and wiring of the pulse release - Check Uz - Check the emergency stop circuit - For a non-regenerative system: Is the braking resistor connected? - For a regenerative system: Is the energy recovery activated? - Check the cable ground and shield - Exchange the power module - For SIEMENS power converter (inverter): Exchange the interface card - Exchange the drive control board
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 231-8B40 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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