4184H

Ethernet I/F Error - Communication Buffer Full

Mitsubishi Electric · MELSEC System Q/L Series

What does 4184H mean?

The communication processing buffer has run out of space, preventing further communication. This typically occurs due to consecutive reception of request messages using the MC protocol or when received data is not read promptly, causing the buffer to overflow.

Common Causes

  • Communication processing buffer ran out of space due to consecutive reception of MC protocol request messages.
  • Communication processing buffer ran out of space because received data read is not performed or cannot keep up with the volume.
  • Insufficient space in the communication processing buffer, disabling communication.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    For MC protocol, send a new request only after receiving a response to the previous request.

  2. 2

    For socket communication, enable received data read.

  3. 3

    For socket communication, decrease the number of data sent from the target device.

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Verified technical data. Last updated: March 2026

Related Faults

Source: Mitsubishi Electric MELSEC System Q/L Series
Mitsubishi Electric Error 4184H: Ethernet I/F Error - Communication Buffer Full — Troubleshooting Guide | ErrorLib