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  9. Data Change event detected more than once

Data Change event detected more than once

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03 Dec 2013 08:20 #1586 by support
Replied by support on topic Data Change event detected more than once
You are welcome.

A related suggestion: Calling SubscribeMonitoredItem in a loop results in multiple calls to the target OPC-UA server, which is not efficient. If you experience slow performance of this loop, use a single call to SubscribeMultipleMonitoredItems instead.

Best regards

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03 Dec 2013 06:42 #1585 by yaire
Replied by yaire on topic Data Change event detected more than once
My bad,
your advice did the trick.

Thank you very much,
Ya'ir.

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02 Dec 2013 12:05 #1583 by support
Replied by support on topic Data Change event detected more than once
If you are calling the code below for each monitored item, then you are adding an event handler each time. And each instance of the event handler is, in turn, called.
Change your code to add the event handler just once.
The following user(s) said Thank You: yaire

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02 Dec 2013 09:25 #1581 by yaire
Data Change event detected more than once was created by yaire
Hello,

When my service is listening to more than one data change, OPC UA detects too many events.
For 2 tags data change, it doubles the events.
For 3 tags data change, it triples the events.
i.e. when tags increase by 1 every 1000 ms, and scan rate set to 1000 ms.
In a 60 second period, I expect 60 events for 1 tag data change, 120 events (60 per each) for 2 tags data change, and 180 events (60 per each) for 3 tags data change.
I get 60 events for 1 tag data change (as expected), 240 events (120 per each) for 2 tags data change, and 540 events (180 per each) for 3 tags data change.

I'm using this code snippet:
m_EasyUAClient.MonitoredItemChanged +=new EventHandler<EasyUAMonitoredItemChangedEventArgs>(m_EasyUAClient_MonitoredItemChanged);
m_EasyUAClient.SubscribeMonitoredItem(
i_TransactionInfo.OpcServerUrl,
nodeId,
i_TransactionInfo.ScanRateSeconds.Value * 1000,
state);

Ya'ir.

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