EL
ErrorLib
Brands
||
  1. Home
  2. Heidenhain
  3. TNC CNC Controllers
  4. 231-A091
About·Privacy·Terms

ErrorLib — Industrial Fault Code Library

Disclaimer: ErrorLib is an independent technical reference tool. While we aim for accuracy, always verify with the manufacturer’s official service manuals before performing maintenance on industrial equipment. ErrorLib is not affiliated with the brands listed.

231-A091

Drive lock through safety software (MC)

Heidenhain · TNC CNC Controllers

What does 231-A091 mean?

This error indicates that a drive (or multiple drives) has been locked by the safety software of the MC (Machine Control) module. This occurs when an emergency stop is active (due to -ES.A or -NE1 signal) and an attempt is made to switch on a drive, or due to an internal software error.

Common Causes

  • Emergency stop activated (by MC) via -ES.A or -NE1 signal.
  • Attempt to switch on a drive while the system is in an 'emergency stop' condition.
  • Internal software error within the MC module.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify the status of the emergency stop circuit and the -ES.A or -NE1 signals. Ensure the E-stop is reset.

  2. 2

    Check the wiring of the emergency stop circuit to the MC module for integrity, shorts, or breaks.

  3. 3

    Confirm that all safety doors and interlocks are closed and secured, as they might trigger an emergency stop condition.

  4. 4

    Verify the software version of the MC module and update it if a known bug fix is available.

Browse all codes in this manual (47)
Verified technical data. Last updated: April 2026

Related Faults

231-A001Cancelation of brake-test call monitoring231-A002Cancelation of brake-line-test call monitoring231-A003SPLC commissioning mode active
Source: Heidenhain TNC CNC Controllers
Open Manual (Page 465)Search more codes in this manual