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Define a "private" server, log data and export data

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20 Feb 2024 17:42 #12567 by support
Examples for OPC client and subscriber development in Python are now on GitHub: github.com/OPCLabs/Examples-QuickOPC-Python .

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21 Nov 2023 13:34 #12396 by support
Note: QuickOPC now supports Python in much better way, cleaner syntax, and public packages (pypi.org/project/opclabs-quickopc/) on Python Package Index . See What's new in QuickOPC 2023.2 for more information. And, over 270 examples are available in the User's Guide!

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24 Aug 2019 18:25 #7654 by support
Of course you have multiple options to do the client development as well. The OPC Foundation's stack and examples (on GitHub) are one possibility. There are then other implementations and libraries, some free, some commercial. Our QuickOPC is one of them. So, you can go with the OPC Foundation - and there are some client-side examples as well. In our view, the OPC Foundation is too "low level" and complicated to use, and that's what our software tries to resolve.

If you have an OPC server (identified by an endpoint URL), and the server has some nodes in it (identified by node Ids), reading a node value or subscribing to it is easy with QuickOPC. For the simplest examples, see www.opclabs.com/products/quickopc/languages-and-tools/csharp . Here is a copy:

The code below (in C#) reads and displays a monitored item value, using QuickOPC:
// Obtain value of a node and display it in a message box 
MessageBox.Show(EasyUAClient.SharedInstance.ReadValue(
    "http://opcua.demo-this.com:51211/UA/SampleServer",
    "nsu=http://test.org/UA/Data/;i=10853").ToString());
The code below subscribes to changes of a monitored item value, and displays the value with each change:
// The callback is a lambda expression that displays the value 
EasyUAClient.SharedInstance.SubscribeDataChange(
    "http://opcua.demo-this.com:51211/UA/SampleServer", 
    "nsu=http://test.org/UA/Data/;i=10853", 1000,
    (_, args) => Console.WriteLine(args.AttributeData.Value));

Of course this can be done in many different ways and is meant for illustration. More information and examples are in our documentation.

Best regards
The following user(s) said Thank You: Peloso

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22 Aug 2019 15:09 #7642 by Peloso
I have none of them !
I'm trying to follow a tutorial found in the OPC foundation for the development of a specific server, but some parts of the tutorial are not so easy to understand. The next step is going to be the client definition and the data management. As you said this is what you might be helpful in... So let's start from this point, if you want. I'll take care of the server development with a visual studio application...if I'll be able.

At this point, how do I star to with the definition of the client connection and the data call?

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22 Aug 2019 14:46 #7641 by support
Hello,
thank you for the drawing.

You have not marked which parts you have and which you want to develop. Is it correct to think that you do have the PLC and you have an OPC UA Server that communicates with the PLC, and the part you want to develop is the client?

Note: We (OPC Labs) specialize in tool for OPC Client development. We do not provide tools for OPC Server development.

Best regards

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22 Aug 2019 07:52 #7640 by Peloso
Thanks for the answer, you can find a schematic flow chart of the idea in the attachments (sorry I wrote it down myself).
I don't understand what you mean for "intended communication".
Anyway, I've tried to use the python script with openOPC to call the server and import data, but I wasn't able.
So I looked in the documentation seeing some scripts suitable to call single or multiple objects, but I've always used Matlab, so I don't know which part of them to take.
Attachments:

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22 Aug 2019 06:16 #7639 by support
Hello.

Can you put together a schematic drawing of what you have in mind? What I mean is a couple of boxes (such as the PLC, the OPC UA Server, the OPC UA Client, etc.), and how they relate together (whether one is contained in the other, or that they communicate - using lines on the schema). And, describe the intended communication means between them, and mark which parts you have are which parts you want to create.

As to ourselves, we can possibly help with developing the OPC UA Client part, if it is needed in your solution. We do not provide tools for OPC UA Server development.

Best regards
The following user(s) said Thank You: Peloso

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21 Aug 2019 16:42 #7637 by Peloso
Hi there,
I'm a newbie in the OPC UA. I'm a mechanical engineer actually, but I'm down with my master thesis and I'm looking for a smart solution to some data manipulation. The goal is to take some data from a PLC and, as written in the subject, I want to define some kind of protect connection in a OPC UA server, log data with specific tags and then export and manipulate them. I look at the documentation provided in the site, but I just can put all the things I need together.

PS:
I want to use the OPC UA protocol because I just believe in it and... it's something new that the research world in my specific field is not using that much.
Can you help me on that?

I'm hoping on a feedback guys, I can't go any further with what I know.

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