EL
ErrorLib
Brands
||
  1. Home
  2. Mitsubishi Electric
  3. MELSEC iQ-R I/O Module
  4. 3040H
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.

3040H

Start-up in Normal Mode with Safety Validated

Mitsubishi Electric · MELSEC iQ-R I/O Module

What does 3040H mean?

This error occurs when the I/O module with diagnostic functions is started in normal mode, but its safety module function remains enabled. The module will not operate normally until the safety module function is successfully disabled, as indicated by 'Disable (0)' in Validation status area (Un\G5377).

Common Causes

  • I/O module with diagnostic functions started in normal mode while the safety module function is still enabled.
  • 'Enable (1)' is stored in Validation status area (Un\G5377), indicating the safety function is active despite being in normal mode.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Set Command area for module invalidation (Un\G5376) to 1234H.

  2. 2

    Turn on and off 'Operating condition setting request' (Y12).

  3. 3

    Verify that Validation status area (Un\G5377) now stores 'Disable (0)'. If not, recheck Un\G5376 value and cycle Y12 again.

  4. 4

    Reset the CPU module, or cycle the programmable controller's power to restart the I/O module with diagnostic functions.

  5. 5

    Check that the ALM LED on the I/O module is off, indicating normal operation.

Browse all codes in this manual (56)
Verified technical data. Last updated: April 2026

Related Faults

00A12HFailure of Disabling Safety Module1000HPower Shutoff1100HTransmission Interval Monitoring Time Range Error
Source: Mitsubishi Electric MELSEC iQ-R I/O Module
Open Manual (Page 120)Search more codes in this manual