Opening Connection, Connection Established, Closing Connection, Connection Closed appearing continuously

[codekundan]

Hi Milo Team,
I am new to OPC-UA. I am using Eclipse Milo Client SDK. I am using Windows OS. I am creating a Java Desktop client application which shows values from Mitsubishi PLC. I am using Mitsubishi MXOPC UA Server. I am able to read and write values to the PLC. But one thing which caught my attention was this continuous "Opening Connection, Connection Established, Closing Connection, Connection Closed" logs. I don't know whether is it normal behaviour or unexpected one. I am using a single client instance by making a Singleton Design Object. So why this continuous opening and closing of Connection? I am attaching a pic below for better understanding.

[kevinherron]

Are you sure these messages have anything to do with your Milo client? They read like that software is trying to establish its own connection to something.

[codekundan]

@kevinherron As I am new to OPC-UA, i am not sure about it. That's why I asked whether is it Normal behaviour or an Unexpected one. But, I will explain my search. When I connect the MX OPC UA Configurator Tool (the above pic Tool) to Mitsubishi PLC, it just shows two logs of "Opening Connection, Connection Established". Now when i connect my program(using Milo Client SDK) to MXOPC UA Server of Mitsubishi, it shows "Opening Connection, Connection Established, Closing Connection, Connection Closed" continuously in loop. When I close the program, this continuous looping of "Opening Connection, Connection Established ...." gets stopped. That is why I thought of asking you, whether is it Normal or Unexpected behaviour. If it is unexpected behaviour then I will do more search and get you acquainted with it. Thanks and Regards.

[kevinherron]

There doesn't appear to be any OPC UA traffic in your capture.

[codekundan]

I captured this pcap file when i connected the milo client to Mitsubishi MX OPC UA Server 2.03 at the starting itself. The continuous message of "Opening Connection, Connection Established ....Connection Closed" starts coming as soon as I connect milo client sdk.

[codekundan]

Actually, the problem I am facing is like this. When I start my Java application, it tries to create client connection. The moment client is created, the continuous "Opening Connection, Connection Established, Closing Connection, Connection closed" message starts coming in the log window. Letting it remain like that, I tried to write values to some PLC addresses. Here's the strange thing happens. Some tags have the values and some don't. I checked StatusCode of all the tags I am writing. Some showed true for (statusCode.isGood()) while some showed false for (statusCode.isBad()). Can it be happening because of this "Continuous Opening Connection, Closing Connection" problem?

[codekundan]

Will share pcap file with some OPC UA traffic also.

[kevinherron]

Make sure the capture is taken on the same server that is running your application.

I don't know what these messages in MX OPCUA server mean because I don't work for Mitsubishi. My only guess would be that your Client is constantly reconnecting for some reason, or there are multiple connections, and the capture will show if that's happening.