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ErrorLib — Industrial Fault Code Library

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1500H

Safety I/O HOLD time exceeded error

Mitsubishi Electric · MELSEC iQ-R I/O Module

What does 1500H mean?

The duration for which the I/O system remained in a HOLD state exceeded its pre-set time limit. This typically occurs in safety-critical applications when there are issues with system switching or communication with Safety Integrity Level 2 (SIL2) Process CPUs.

Common Causes

  • An error occurred on the switching of systems incorporating SIL2 Process CPUs, causing an extended HOLD state.
  • An error occurred in communications with a SIL2 Process CPU, leading to the prolonged I/O HOLD condition.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check all components and logic involved in the switching of systems that utilize SIL2 Process CPUs for any errors.

  2. 2

    Verify the integrity and functionality of communication links and protocols with the SIL2 Process CPU for any detected errors.

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

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Source: Mitsubishi Electric MELSEC iQ-R I/O Module
Open Manual (Page 203)Search more codes in this manual