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OPC UA .NET C# - pass callback when subscribing multiple items

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19 Sep 2022 15:05 #11095 by support
The SubscribeMultipleDataChanges method is available since QuickOPC 2021.3: kb.opclabs.com/What%27s_new_in_QuickOPC_2021.3#OPC_UA_Client-Server .

Either upgrade QuickOPC, or use the approach from the code I provided to achieve the same.

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

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19 Sep 2022 14:36 #11094 by amlynar
OPC Labs QuickOPC 2020.3

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19 Sep 2022 14:28 #11093 by support
Hello.

Which QuickOPC version are you using?

Regards

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19 Sep 2022 14:02 #11092 by amlynar
The SubscribeMultipleDataChanges extension method seems to be documented on the link you sent, but it doesn't recognize it in my program. Below is the error I receive with the directives I am using. Can you provide an example for passing a DataChangeCallback in the EasyUAMonitoredArguments.

using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.OperationModel;

"Error CS1061 'EasyUAClient' does not contain a definition for 'SubscribeMultipleDataChanges' and no accessible extension method 'SubscribeMultipleDataChanges' accepting a first argument of type 'EasyUAClient' could be found (are you missing a using directive or an assembly reference?)

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17 Sep 2022 12:34 #11091 by support
Hello.

you are probably looking for the SubscribeMultipleDataChanges extension method: opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User's...scribeMultipleDataChanges.html .

The other way to do this is to use the DataChangeCallback property (opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User's...uments~DataChangeCallback.html ) in each of the the EasyUAMonitoredArguments passed to the SubscribeMultipleMonitoredItems method.

This is what, internally, the SubscribeMultipleDataChanges does anyway. Its implementation (the code is simplified) looks like this:

 
static public int[] SubscribeMultipleDataChanges(
this IEasyUAClient client,
UAMonitoredItemArguments[] monitoredItemArgumentsArray,
EasyUADataChangeNotificationEventHandler dataChangeCallback)
{
    return client.SubscribeMultipleMonitoredItems(monitoredItemArgumentsArray
.Select(arguments => new EasyUAMonitoredItemArguments(dataChangeCallback, arguments)).ToArray());
}
 


Best regards/S pozdravem

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16 Sep 2022 18:56 - 17 Sep 2022 11:14 #11089 by amlynar
OPC UA .NET C# was created by amlynar
I am switching from OPC DA to OPC UA. In OPC DA the SubscribeMultipleItems method comes with a callback argument. For OPC UA the SubscribeMultipleMonitoredItems method does not come with a callback argument. How can I implement a callback for SubscribeMultipleMonitoredItems in OPC UA?

OPC DA Example:
 
easyDAClient1.SubscribeMultipleItems(items.ToArray(), (_, e) => {
                    if (e.Vtq != null && e.Vtq.HasValue)
                    {
String tag = e.Arguments.ItemDescriptor.ItemId.ToString();
object value = e.Vtq.Value;
itemChanged(tag, value);
                    }
                    });
 
 

OPC UA Example:
 
easyUAClient1.SubscribeMultipleMonitoredItems(items.ToArray());
 
Last edit: 17 Sep 2022 11:14 by support. Reason: code formatting

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