Code 231-C6F0: Amplitude test in axis %1: pos. encoder is incorrect,
Issue Description & Safety Warning
The Heidenhain TNC Series CNC has triggered a critical Amplitude test in axis %1: pos. encoder is incorrect, 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
test %4 [Cause of error] The internal test of encoder-amplitude monitoring at the position inputs revealed an error: Test 1: The test for "Amplitude too low" failed. Test 2: The test for "Amplitude too high" failed. - The entry in posEncoderInput/analogOffset does not match the wiring of the position encoder. - Incorrect entry in machine parameter posEncodeType (e.g. analog encoder signal selected for digital encoder) - Position encoder cable is interrupted, or encoder cable is defective - Position encoder is defective - CC controller unit is defective [Error correction] - Compare/check the entry in MP posEncoderInput/analogOffset to the position encoder cabling - Check the entry in machine parameter posEncodeType - Check the position encoder cable / Exchange the cable - Exchange the position encoder - Exchange the CC controller unit - 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-C6F0 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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