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Variable changes seem to accumulate for 1s before MultipleVariablesChanged event fires

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04 Aug 2017 11:23 #5412 by support
Unfortunately I cannot provide technical support for this issue with such an old version. If the question was about something that has a rough correspondence in the current version, it would be possible, but not with a feature that is long gone.

It is likely that there won't be any such problem with the current version. You can try it out for free (or try the 5.4x you have). Rewrite the code to use the ItemChanged event and check the behavior.

Should the issue manifest itself in the current version, we will provide support.

Best regards

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04 Aug 2017 07:23 #5411 by Christoph
Hello,

sorry I've forgotten to mention that.
Its indeed a legacy application still using QuickOPC-Classic 5.1.
I've already got a 5.4 license from another, more recent project but haven't had the time / reason for upgrading the old project.

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03 Aug 2017 15:12 #5409 by support
Which version are you using? We no longer have this event...

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03 Aug 2017 14:49 #5408 by Christoph
Hello,

I've got a C# application where I'm subscribing to a few opc variables.
Currently they are the ones provided by the server in your demo application which runs locally.
As I'll have to react quickly to changes on the plc, I'm subscribing to them with a rather small update interval.
To process the changes I'm handling the MultipleItemsChanged event.

Now it seems to me that the system is accumulating about 1 second of changes and then fires a MultipleItemsChanged event where several changes of the same variable are recorded.

Is there a way to reduce this "changes accumulation time"?
I'm not certain if this is a server or a client behavior, which would be relevant as I'll
communicate with a different opc server later on.

Code:
var subscriptions = new DAItemGroupArguments[]
{
    new DAItemGroupArguments(string.Empty, _ServerDesc, "Greenhouse.Sprinklers", 20, null);
    new DAItemGroupArguments(string.Empty, _ServerDesc, "Greenhouse.Temperature", 20, null);
    new DAItemGroupArguments(string.Empty, _ServerDesc, "Demo.Ramp", 20, null);
    new DAItemGroupArguments(string.Empty, _ServerDesc, "Demo.Single", 20, null);
    new DAItemGroupArguments(string.Empty, _ServerDesc, "Trends.Sine (1 s)", 20, null);
    new DAItemGroupArguments(string.Empty, _ServerDesc, "Trends.Sine (10 s)", 20, null);
    new DAItemGroupArguments(string.Empty, _ServerDesc, "Trends.Sine (1 min)", 20, null);
};
 
_Client = new EasyDAClient();			
_Client.MultipleItemsChanged += _Client_MultipleItemsChanged;
_Client.SubscribeMultipleItems(subscriptions);
...		
private void _Client_MultipleItemsChanged(object sender, EasyDAMultipleItemsChangedEventArgs e)
{
    Log("Got a MultipleItemsChanged event");
    foreach (var singleItem in e.ArgsArray)
    {
        Log("{0}: {1}", singleItem.ItemDescriptor.ItemId, singleItem.Vtq);
    }
}

Thanks for your effort,
Christoph

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