Code 231-8320: PIC: Actual value does not equal the nominal value %1
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical PIC: Actual value does not equal the nominal value %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] Possible cause: The measurement range of current of the inverter is not set to the range specified in the configuration. This message can appear, for example, if a new CC controller unit has been installed or there was an unexpected change to the configuration. "PIC" designates a microcontroller inside the inverter that switches and reads back the measurement range of current. - Nominal value (value in column S of the power module table) = 1, however: - There is no PIC - PIC can't be switched - Access to PIC is deactivated (machine parameter motEncCheckOff, Bit16=1) - Nominal value (value in column S of the power module table) = 0, however: - Access to PIC is deactivated (machine parameter motEncCheckOff, Bit16=1) and PIC was already switched to 1 [Error correction] - Check the power module entered in the machine configuration - Check the nominal value of the PIC (value in column S of the power module table) - Perhaps change the PWM frequency (to >= 5 kHz) - Perhaps exchange the power module
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 231-8320 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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