UAReadArguments Constructor(UAEndpointDescriptor,UANodeDescriptor,UAReadParameters)

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
Public Function New( _
   ByVal endpointDescriptor As UAEndpointDescriptor, _
   ByVal nodeDescriptor As UANodeDescriptor, _
   ByVal readParameters As UAReadParameters _
)

'Usage
 
Dim endpointDescriptor As UAEndpointDescriptor
Dim nodeDescriptor As UANodeDescriptor
Dim readParameters As UAReadParameters
 
Dim instance As New UAReadArguments(endpointDescriptor, nodeDescriptor, readParameters)

public UAReadArguments( 
   UAEndpointDescriptor endpointDescriptor,
   UANodeDescriptor nodeDescriptor,
   UAReadParameters readParameters
)

public:
UAReadArguments( 
   UAEndpointDescriptor^ endpointDescriptor,
   UANodeDescriptor^ nodeDescriptor,
   UAReadParameters^ readParameters
)

Parameters

endpointDescriptor: Endpoint descriptor. Identifies the OPC-UA server.
nodeDescriptor: Node descriptor. Identifies the node in OPC server's address space.
readParameters: Contains parameters for OPC-UA read operations, such as the maximum age of the value.

Exceptions

Exception Description

Exception	Description
System.ArgumentNullException	A `null` reference (`Nothing` in Visual Basic) is passed to a method that does not accept it as a valid argument. This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

System.ArgumentNullException

A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

Remarks

You can obtain nodeDescriptor e.g. by calling one of the browsing methods on OpcLabs.EasyOpc.UA.EasyUAClientCore object.

Example

// This example shows how to read data value of 3 nodes at once, from the device (data source).
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

namespace UADocExamples._EasyUAClient
{
    partial class ReadMultiple
    {
        public static void FromDevice()
        {
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            // or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            // Instantiate the client object
            var client = new EasyUAClient();

            // Obtain attribute data. By default, the Value attributes of the nodes will be read.
            // The parameters specify reading from the device (data source), which may be slow but provides the very latest
            // data.
            UAAttributeDataResult[] attributeDataResultArray = client.ReadMultiple(new[]
                {
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10845", 
                        UAReadParameters.FromDevice),
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853", 
                        UAReadParameters.FromDevice),
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10855", 
                        UAReadParameters.FromDevice)
                });

            // Display results
            foreach (UAAttributeDataResult attributeDataResult in attributeDataResultArray)
            {
                if (attributeDataResult.Succeeded)
                    Console.WriteLine("AttributeData: {0}", attributeDataResult.AttributeData);
                else
                    Console.WriteLine("*** Failure: {0}", attributeDataResult.ErrorMessageBrief);
            }
        }

        // Example output:
        //
        //AttributeData: 51 {System.Int16} @11/6/2011 1:49:19 PM @11/6/2011 1:49:19 PM; Good
        //AttributeData: -1993984 {System.Single} @11/6/2011 1:49:19 PM @11/6/2011 1:49:19 PM; Good
        //AttributeData: Yellow% Dragon Cat) White Blue Dog# Green Banana- {System.String} @11/6/2011 1:49:19 PM @11/6/2011 1:49:19 PM; Good            
    }
}

# This example shows how to read data value of 3 nodes at once, from the device (data source).
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python .
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
import time

# Import .NET namespaces.
from OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.OperationModel import *


endpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer')
# or 'http://opcua.demo-this.com:51211/UA/SampleServer' (currently not supported)
# or 'https://opcua.demo-this.com:51212/UA/SampleServer/'

# Instantiate the client object.
client = EasyUAClient()

# Obtain attribute data. By default, the Value attributes of the nodes will be read.
# The parameters specify reading from the device (data source), which may be slow but provides the very latest
# data.
attributeDataResultArray = client.ReadMultiple([
    UAReadArguments(endpointDescriptor, UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10845'),
                    UAReadParameters.FromDevice),
    UAReadArguments(endpointDescriptor, UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10853'),
                    UAReadParameters.FromDevice),
    UAReadArguments(endpointDescriptor, UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10855'),
                    UAReadParameters.FromDevice),
    ])

# Display results.
for attributeDataResult in attributeDataResultArray:
    if attributeDataResult.Succeeded:
        print('AttributeData: ', attributeDataResult.AttributeData, sep='')
    else:
        print('*** Failure: ', attributeDataResult.ErrorMessageBrief, sep='')

print()
print('Finished.')

' This example shows how to read data value of 3 nodes at once, from the device (data source).
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _EasyUAClient
    Partial Friend Class ReadMultiple
        Public Shared Sub FromDevice()

            ' Define which server we will work with.
            Dim endpointDescriptor As UAEndpointDescriptor =
                    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
            ' or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            ' or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            ' Instantiate the client object
            Dim client = New EasyUAClient()

            ' Obtain attribute data. By default, the Value attributes of the nodes will be read.
            ' The parameters specify reading from the device (data source), which may be slow but provides the very latest
            ' data.
            Dim attributeDataResultArray() As UAAttributeDataResult = client.ReadMultiple(New UAReadArguments() _
               {
                   New UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10845",
                        UAReadParameters.FromDevice),
                    New UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853",
                        UAReadParameters.FromDevice),
                    New UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10855",
                        UAReadParameters.FromDevice)
               })

            ' Display results
            For Each attributeDataResult As UAAttributeDataResult In attributeDataResultArray
                If attributeDataResult.Succeeded Then
                    Console.WriteLine("AttributeData: {0}", attributeDataResult.AttributeData)
                Else
                    Console.WriteLine("*** Failure: {0}", attributeDataResult.ErrorMessageBrief)
                End If
            Next attributeDataResult

            ' Example output:
            '
            'AttributeData: 51 {System.Int16} @11/6/2011 1:49:19 PM @11/6/2011 1:49:19 PM; Good
            'AttributeData: -1993984 {System.Single} @11/6/2011 1:49:19 PM @11/6/2011 1:49:19 PM; Good
            'AttributeData: Yellow% Dragon Cat) White Blue Dog# Green Banana- {System.String} @11/6/2011 1:49:19 PM @11/6/2011 1:49:19 PM; Good            
        End Sub
    End Class
End Namespace

Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

Reference

UAReadArguments Class
UAReadArguments Members
Overload List

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