Mitsubishi L02CPU-P Ethernet not responding

2 posts in this topic

We have an application using a Mitsubishi L02CPU-P with a built in ethernet module.

At one time the TCP/IP interface became irresponsive and a hard reset was required.

The device is configured for binary communication and works fine using a GOT therminal and also operates fine when queried from a GX Works application.

During debugging of a custom MELSEC application the TCP/IP interface stopped responding and could no longer be located using GX Works and the GOT terminal also lost contact.

The L02CPU-P continued running the control application, but could no longer be contacted. The only way to recover was using the L02CPU-P reset button.

I have heard developers being restrictive using the TCP/IP interface remotely over VPN and unstable connection due to the risk of hanging the device and not being able to recover without a personal visit to the device.

Any experience from L02CPU-P devices requiring hard reset to come "online" again? Or does it enter some default state due to some internal exception handling?

Edited by Flodis

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I am starting to understand at least one MC-protocol or MELSEC "module" hast to be installed/activated on the PLC to enable communication.

When I query the PLC with the magic "Detect Now" button in the GX Works "Ethernet Configuration (Built-in Ethernet Port)"

In the "Host Station" column of the module list there is only one item "Module With No Profile Found" with Protocol UDP.

  • What Ethernet software module should I add to the PLC config for PLC to respond to MELSEC commands?
  • How do I write the added setting back to the PLC without affecting anything else?



Enabling the MELSEC protocol

At lest this forum can be used as a cloud storage for documentation answering my own questions:

Dear Flodis, maybe you can find useful information in the MELSEC-L CPU Module User's Manual (Built-In Ethernet Function) - Page 38?


Edited by Flodis
Solution found

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