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OPC DA Validate Items

16 Mar 2023 11:35 #11617 by gkalipershad
Replied by gkalipershad on topic OPC DA Validate Items
Thank you for letting me know. I will pass this information along to the customer.


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16 Mar 2023 00:30 #11616 by support
Replied by support on topic OPC DA Validate Items

QuickOPC/OPC Data Client does not have a way to call ValidateItems.

Subscribing to an item that is invalid behaves as follows:
- Subscription handle is returned as normally.
- The ItemChanged event handler/callback will be called with an error in the Exception property of the event arguments, indicating the problem.
- Eventually (on a quite slow rate), when not unsubscribed, the component will retry adding the item - for the case when an invalid item becomes valid (e.g. configurtaion change).

Best regards

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15 Mar 2023 21:37 #11615 by gkalipershad

Are there any code examples for Validating OPC DA tags before they get added to a subscription group? Here is a screenshot of the OPC Diags for my OPC DA Server where I have another OPC DA Client triggering the ValidateItems call.

I have a user that wants to do this with QuickOpc because they formerly accomplished this with another OPC wrapper. We are having trouble getting it to work as expected. The problem is that they are using 2017.1 and I am not certain there was a method call for this back then. Even if it was not an option until a newer version, I would still be interested in an example if you have one.


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