Flexy connecting to OPC UA server

Hi I’m trying to connect my Ewon Flexy running firmware 14.2s0 to an OPC UA client. I configure the IO server, but when I go to create my tags, I only get the OPCUA Server not ready message in the address field. When I try to connect to the same opc ua server using the same settings from UaExpert, I can connect without any problems. I don’t see any errors in the event log. Are there any known issues with connecting to OPCUA servers in 14.2s0?

It seems like similar behavior to Connection problem to OPC UA server as client via IO server minus the “it’s working on another system” piece. It’s not clear how that one got resolved.

Hello @atai,

I’m not aware of any active issues with the OPC UA server with FW 12.2s0. What is the OPC UA client you are connecting with? does it show any other messages besides it is not ready? Could you share a screen shot of the message and setup?


Hi Deryck,

I’m using Cogent DataHub as my OPC UA server. It is set to accept anonymous connections and use security policy none. I’ve attached screenshots of my IOserver setup and the message I receive in the tag setup screen. I’ve also included screenshots of UaExpert which is an OPC UA Client that is successfully reading data from my OPC UA server.

There are no errors in the Ewon event log that would indicate communication errors. I’ve watched the network traffic and I see that the Flexy and my OPC UA server are communicating. I just don’t know why I can’t browse my tag list.

Hi Atai,

Sorry I did have this backwards, i was thinking the ewon was the server. To clarify I am also not aware of the ewon having any issues connecting to servers.

What is the LAN IP of the ewon? Are you able to ping both the ewon LAN and the OPC server from the network? Does the client provide any logs about an attempted connection?

Can you use ebuddy to take a backup with support files for me to take a look at?


There’s not much to the backup, but here you go.

I know the Flexy and the OPC UA server can communicate. I am publishing a tag on the Flexy in modbus that I can see in the DataHub (it also has a Modbus master). I did a wireshark trace to watch communication between the two devices and messages are definitely getting passed.

eWON_opctests.tar (114 KB)

Hi Deryck,

I don’t know how much you interact with support from other regions. I know MAC Solutions in the UK is a distributor for both HMS products and the Cogent DataHub. If there are known issues, the support team in that region might know about them.



Hi Deryck,

I figured it out! (Don’t you love a ticket where the customer figures it out themselves :blush: )

The Flexy couldn’t handle the server’s endpoint name. Cogent DataHub sets its endpoint name by default to “CogentDataHub/DataAccess.” If I switched it to “”, then my endpoint URL on the Flexy changed to

opc.tcp://IPAddress:port rather than opc.tcp://IPaddress:port/CogentDataHub/DataAccess . At that point, I could then browse my tags.

Thanks for your help.


I am glad to hear you have resolved the issue. I was looking at this this morning and had the same result. I am not sure why the end point does not work with their default configuration. I am checking with some colleagues on this.