Cosy to Mitsubishi



I’m having some issues with the connection with some Mitsubishi PLC’s and HMI’s. I’m connecting to an FX5U and GS2110-WTBD. I’m using the latest version of the ewon cosy firmware, Gt Designer 2 and GX works 3.

I’m only able to connect to the FX5U via a direct connection and I am unable to reach it via IP address and I can oly stay online for a short period before I loose the PLC and have to go online again. I’m also unable to do online edits. I can reach the PLC web interface though.

HMI VNC access is fine when I am connected via eCatcher but when using m2web the VNC client never loads.

Thanks for the help


Here are some things you can try:

1) Follow this guide to make sure you have PLC Discovery enabled (please note: it is very important that you are using the latest version of eCatcher):

2) Adjust the color depth in eCatcher settings:

In the eWON Properties page in eCatcher, select “Configure LAN Devices & Firewall”

NHS1.png1178x595 71 KB

Go to the properties for the HMI:

NHS2.png607x581 24.9 KB

Click Advanced Options:

NHS3.png799x343 29.4 KB

And select 16-bit color depth:


3) Increase the timeout settings on the PLC and HMI

Keep in mind that not all HMIs work with M2Web.

Have you tried with M2Web mobile?



Thanks for the help Kyle,
Forcing the HMI to 24 bit works!

I can only connect to the PLC by discovery - I can ping using the Mitsubishi test software but there is no IP connection that works. The vnc client never disconnects so it doesnt look like a network issue, but you can only do full downloads


Great! So you are still having an issue with the PLC connection with the Mitsubishi software? Did you try increasing the timeout on the PLC?



Yes, it made no difference - when testing the connection the refusal is instant. Also when using direct connection it seems to not change anything.

I can see with wireshark that gxworks sends a ping and receives a response back.

Is it possible that this is the issue:


It’s possible. Can you create a Backup (with support files) using eBuddy and share it with me?


Hi Kyle, Please find the backup attached [color=red]MOVED TO STAFF NOTE[/color] (135.5 KB)


I have a couple more questions:

  1. Are you using DHCP on the PLC and HMI? I ask because you are running a DHCP server on the eWON. I would recommend you disable the DHCP server and use static addresses for the PLC and HMI.
  2. Are you using the USB port on the device? If so, how is it used?
  3. What are the proxy settings for? Is it to allow access to the PLC and HMI from the WAN network or something else?

There are two errors coming up in the logs related to the proxies:

epxy-Maximum sessions per port reached

esock-Socket function returned error

I’m going to create a ticket for you in our official ticketing system, so this issue can be escalated to the eWON folks in Belgium. It also looks like you are in the U.K. so they may just work directly with you or through another office in the EU. You should receive an email shortly from




And in the meantime, please double check you are following all of the steps in this document:


It looks like there is already a ticket open for this case with Sep Schraven. He will be able to help you in the morning because you are in his jurisdiction. If you do not get a response, please let me know.




Hi Joe,

I am going to have my associate in the UK, Siobhan, reach out to you regarding this issue.