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QuickOPC VBScript ASP example script not returning value, cont.

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14 Sep 2024 13:17 #13168 by support
Hello.
I do not quite understand the question, and also what is the reason behind asking it.

For start, if I just took the question literally, the answer would be simple:
opcda://localhost/Kepware.KEPServerEX.V5
Maybe that is what you were asking for. But I feel I need to add some explanation. In QuickOPC, the OPC (COM) server is always internally specified using the ServerDescriptor object. And in it, there are some truly critical properties, such as MachineName for the name of the computer, or ProgId for identification of the OPC server.

You *can* use the "OPC URL" string instead, and assign to ServerDescriptor.UrlString property. But all that it will do is that it will parse it, and then fill in the above mantioned properties. From that point on, the URL is no longer used. So, setting the UrlString to the string I gave as an example is equivalent to setting the MachineName to "localhost" and the ProgId to "Kepware.KEPServerEX.V5". Also, if you use some QuickOPC methods that take separate machineName and serverClass arguments, again what that does internally it is that just constructs the ServerDescriptor with these properties. So we are just talking about different ways of constructing or deconstructing the server information contained in the ServerDescriptor. But the URLs do not provide any additional functionality that would not be achievable otherwise.

Regards

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13 Sep 2024 22:00 #13167 by Kyle.Oshima@caltrol.com
This post is continuation of earlier post requested to be new topic (see QuickOPC VBScript ASP example script not returning value )

Doing further research, found following article on OPC Labs' blog: A (Partial) Story of OPC URLs

Article states "...We at OPC Labs have decided to support OPC URLs, but at the same time, we provide means to specify the OPC connections in a traditional way. You can pick whatever suits you better."

Can you provide example how to specify OPC URL connection syntax to explicitly specify local machine host OPC client is to connect?

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