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ErrorLib — Industrial Fault Code Library

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3020H

Safety mutual monitoring error

Mitsubishi Electric · MELSEC iQ-R I/O Module

What does 3020H mean?

A moderate error was detected in the counterpart device involved in mutual monitoring for safety functions. This indicates a problem within the inter-device safety communication or logic, which can compromise the overall safety integrity of the system.

Common Causes

  • A moderate error state has occurred in the interconnected device that participates in safety mutual monitoring.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Access the counterpart device and check its specific error code(s) reported in its diagnostics.

  2. 2

    Take appropriate corrective actions based on the error code(s) found on the counterpart device.

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 203)Search more codes in this manual