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How to get notification when an OPC UA array variable is modified?
August 11, 2014
10:38, EEST
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Allan
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July 22, 2014
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If I create an array using a method like SampleConsoleServer.createAnalogItemArray(), how can I arrange to be notified when the array is modified?

I tried using a method like SampleConsoleClient.subscribe(NodeId nodeId), but that does not seem to work for array variables created by this method.

I would have expected that the client’s DataChangeListener would be notified when the server calls node.setValue() on the return value from createAnalogItemArray().

August 11, 2014
12:44, EEST
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Allan
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After some experimenting, I found out that the callbacks in the client are only called if the array reference itself is new.
If the same array is used and only the contents are updated before calling setValue(), nothing happens.

August 11, 2014
13:03, EEST
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Jouni Aro
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December 21, 2011
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Yes, it seems that the array elements are not compared, when the method checks if the value is really changing. However, it should compare the timestamps as well – depending a bit on whether you use setValue(DataValue) or setValue(Object). The latter will create a new timestamp using the current time. If you use the former, make sure that your timestamp changes.

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