Code 231-9240: Incorrect encoder type %1
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical Incorrect encoder type %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] - Selected encoder does not match the connected one Examples: EnDat is selected, but an incremental encoder is connected EnDat 2.1 is selected, but EnDat 2.2 is connected - The selected encoder is not supported by this CC [Error correction] - Check the machine parameter "motEncType" (or SYS in the motor table) - 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 231-9240 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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