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How to use handles when using SubscribeMultipleMonitoredItems()

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27 Aug 2021 14:04 #10158 by Restrepo

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27 Aug 2021 13:41 #10157 by support
Hello,

the customer should pass his "tag" object as the State argument to the SubscribeXXXX call. The event notifications will then contain this State, and he will just typecast the State to the type of tag object, and he is done. No lookup is needed, based on integers or strings, so it is as fast as it can get. The handles should only be used for UnsubscribeXXXX (and ChangeXXXX) calls, and nothing else.

More information:

- opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User%2...0by%20an%20object%20state.html

- opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User%2...y%20subscribed%20entities.html

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

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27 Aug 2021 13:01 #10156 by Restrepo
Hello Z,

I am currently working with a customer that is trying to update its local tag data structure whenever a value changes in the OPC UA Server. He used to do it with another toolkit by utilizing the handle return by the call as such:

mTags[handle].Value = e.Attribute.Value;

My question to you is, does the toolkit exposes the handles as System.Int32[]? The customer would like to use the integer for the indexing rather than using the NodeID.identifier String.

Could it be that we can use " e.Arguments.NodeDescriptor.NodeId.Identifier" as a way of identifying the tag that changed? Something like:

static void easyUAClient_DataChangeNotification(object sender, EasyUADataChangeNotificationEventArgs e)
{
mMyOPCTags[e.Arguments.NodeDescriptor.NodeId.Identifier].value = e.AttributeData.Value;
}

I just think that a string based index would not be as efficient though.


I tried to look in the documentation, but unfortunately, I failed to find any clues if this is possible with the toolkit so any guidance will be appreciated. Thank you.

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