EL
ErrorLib
Brands
||
  1. Home
  2. Heidenhain
  3. TNC CNC Controllers
  4. 231-A021
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-A021

Cancelation of brake line test. Guard door open

Heidenhain · TNC CNC Controllers

What does 231-A021 mean?

This error indicates the cancellation of a brake line test. The primary cause is that one or more guard doors were detected as open during either the brake control test or the brake line test, which is a safety interlock violation.

Common Causes

  • Guard door(s) were open during the brake control test or brake line test.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Ensure all guard doors are securely closed and properly latched before initiating and throughout the brake control test or brake line test.

  2. 2

    Verify the correct operation of all guard door safety interlock switches and sensors.

  3. 3

    Inspect the wiring of the guard door safety circuit for damage or loose connections.

  4. 4

    Confirm that all safety circuit components, including interlocks, are functioning correctly and registering the closed state of the doors.

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 455)Search more codes in this manual