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Data Change Subscription Events in UA vs DA

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24 Oct 2024 08:19 #13241 by support
Regardless of how the OPC DA or OPC UA "bundles" the data changes in the notifications, QuickOPC API is designed in such a way that it invokes event/callback per change. Even if there were more changes bundled together by the server, you will receive them one by one.

Hence I do not understand your question. The sentence "In OPC DA it used to return an array of tags that trigged the event." simply cannot be right with QuickOPC. You always receive just one "tag" in the event.

Regards

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23 Oct 2024 14:59 #13237 by kre.br
I am currently using OpcLabs.QuickOpc v5.80.347

Though I would be open to other solutions.

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23 Oct 2024 14:15 #13236 by support
Hello.

Is this a general question to to the OPC specifications, or are you using our QuickOPC product? If so, which version?

Regards

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22 Oct 2024 17:51 #13232 by kre.br
Greetings.

When subscribed to tag(s), I noticed that triggered events only contain one tag per event.

I.e. I'll subscribe to Temperatures and Flow, but per event, I will get Temperatures in the first event, then I will get Flows in second event. (Obv, if the data change event triggered).

In OPC DA it used to return an array of tags that trigged the event.

I.e. If both tags Temps/Flow triggered the data change event, it would return [ Temps , Flows ] in a single event, at the interval of poll time.


I read through much of the documentation around data change events, but I have not found a way to replicate this.

is this possible?

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