1A4FH

Mixed Axis Program Simultaneous Start Forbidden

Mitsubishi Electric · MELSEC iQ-R Motion Controller

What does 1A4FH mean?

This minor error occurs when attempting to execute a simultaneous start instruction (START) that includes a mix of real axis programs and command generation axis programs. The system does not support mixed program starts, and this action will prevent the control from initiating.

Common Causes

  • Attempted simultaneous start (START instruction) with a combination of real axis programs and command generation axis programs.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Separate the real axis programs and command generation axis programs.

  2. 2

    Execute simultaneous start instructions only with programs of the same axis type (either all real axis or all command generation axis).

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Verified technical data. Last updated: March 2026

Related Faults

Source: Mitsubishi Electric MELSEC iQ-R Motion Controller