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Filter subscriptions

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13 Apr 2022 17:00 #10808 by support
Replied by support on topic Filter subscriptions
Hello.

I do not have C++ example at hand, but there is an example for this available in other COM-based tools: Object Pascal, PHP, VB6. Writing the same in C++ should not be especially difficult.

Here it is: opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User%2...e%20nodes%20with%20filter.html

Note: The SubscribeDataChange method in COM does not have these more advanced options. You need to switch to SubscribeMultipleMonitoredItems.

Does it help?

Best regards

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13 Apr 2022 07:38 - 13 Apr 2022 09:50 #10805 by federica
Filter subscriptions was created by federica
Hi,

I'm using QuickOPC COM, developing in C++.

I want to be notified when a particular tag in the OPC server will change its value.
I'm only interested in receiving new data only when the value has changed.
How can I add a filter to the "SubscribeDataChange" function (like "UADataChangeTrigger.StatusValue")?

Thanks,
Federica
Last edit: 13 Apr 2022 09:50 by federica.

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