OPC Studio User's Guide and Reference
ReadMultipleValues(IEasyUAClient,UAReadArguments[]) Method
Example 



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OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA Namespace > IEasyUAClientExtension Class > ReadMultipleValues Method : ReadMultipleValues(IEasyUAClient,UAReadArguments[]) Method
The client object that will perform the operation.

This is typically the EasyUAClient object.

The value of this parameter cannot be null (Nothing in Visual Basic).

Array of OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments. Array of argument objects specifying what to read from an OPC-UA server.

The value of this parameter cannot be null (Nothing in Visual Basic).

The individual elements of the parameter value cannot be null (Nothing in Visual Basic).

Reads values of multiple attributes, using array of argument objects as an input.
Syntax
'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function ReadMultipleValues( _
   ByVal client As IEasyUAClient, _
   ByVal readArgumentsArray() As UAReadArguments _
) As ValueResult()
 
'Usage
 
Dim client As IEasyUAClient
Dim readArgumentsArray() As UAReadArguments
Dim value() As ValueResult
 
value = IEasyUAClientExtension.ReadMultipleValues(client, readArgumentsArray)

Parameters

client
The client object that will perform the operation.

This is typically the EasyUAClient object.

The value of this parameter cannot be null (Nothing in Visual Basic).

readArgumentsArray
Array of OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments. Array of argument objects specifying what to read from an OPC-UA server.

The value of this parameter cannot be null (Nothing in Visual Basic).

The individual elements of the parameter value cannot be null (Nothing in Visual Basic).

Return Value

Array of OpcLabs.BaseLib.OperationModel.ValueResult. Returns an array of value objects. Each object contains the actual value of an attribute. The indices of elements in the output array are the same as those in the input array, readArgumentsArray.

This method never returns null (Nothing in Visual Basic).

The individual elements of the returned value are never null (Nothing in Visual Basic).

Exceptions
ExceptionDescription

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

The status codes of attributes should be 'good'; otherwise, a OpcLabs.BaseLib.OperationModel.ValueResult.Value of that attribute is not valid, and OpcLabs.BaseLib.OperationModel.OperationResult.Exception contains a non-null exception.

The size of the input array will become the size of the output array. The element positions (indices) in the output array are the same as in the input array.

This is an extension method (info: C#, VB.NET). In languages that have support for extensions methods (such as C# and VB.NET), you can use the extension method as if it were a regular method on the object that is its first parameter. In other languages (such as with Python.NET), you will call the extension as a static method, and pass it the object on which it acts as its first parameter.

 

This is a multiple-operation method. In a properly written program, it does not throw any exceptions. You should therefore not put try/catch statements or similar constructs around calls to this method. The only exceptions thrown by this method are for usage errors, i.e. when your code violates the usage contract of the method, such as passing in invalid arguments or calling the method when the state of the object does not allow it. Any operation-related errors (i.e. errors that depend on external conditions that your code cannot reliably check) are indicated in the result objects returned by the method. For more information, see Multiple-operation Methods and Do not catch any exceptions with asynchronous or multiple-operation methods.
Example
// This example shows how to read the Value attributes of 3 different nodes at once. Using the same method, it is also possible 
// to read multiple attributes of the same node.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-CSharp .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

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

namespace UADocExamples._EasyUAClient
{
    partial class ReadMultipleValues
    {
        public static void Main1()
        {
            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 values. By default, the Value attributes of the nodes will be read.
            ValueResult[] valueResultArray = client.ReadMultipleValues(new[]
                {
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10845"),
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853"),
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10855")
                });

            // Display results.
            foreach (ValueResult valueResult in valueResultArray)
            {
                if (valueResult.Succeeded)
                    Console.WriteLine($"Value: {valueResult.Value}");
                else
                    Console.WriteLine($"*** Failure: {valueResult.ErrorMessageBrief}");
            }


            // Example output:
            //
            //Value: 8
            //Value: -8.06803E+21
            //Value: Strawberry Pig Banana Snake Mango Purple Grape Monkey Purple? Blueberry Lemon^            
        }
    }
}
// This example shows how to read the DataType attributes of 3 different nodes at once. Using the same method, it is also possible 
// to read multiple attributes of the same node.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-CSharp .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

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

namespace UADocExamples._EasyUAClient
{
    partial class ReadMultipleValues
    {
        public static void DataType()
        {
            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 values.
            ValueResult[] valueResultArray = client.ReadMultipleValues(new[]
                {
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10845", UAAttributeId.DataType),
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853", UAAttributeId.DataType),
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10855", UAAttributeId.DataType)
                });

            // Display results.
            foreach (ValueResult valueResult in valueResultArray)
            {
                Console.WriteLine();

                if (valueResult.Succeeded)
                {
                    Console.WriteLine($"Value: {valueResult.Value}");
                    var dataTypeId = valueResult.Value as UANodeId;
                    if (!(dataTypeId is null))
                    {
                        Console.WriteLine($"Value.ExpandedText: {dataTypeId.ExpandedText}");
                        Console.WriteLine($"Value.NamespaceUriString: {dataTypeId.NamespaceUriString}");
                        Console.WriteLine($"Value.NamespaceIndex: {dataTypeId.NamespaceIndex}");
                        Console.WriteLine($"Value.NumericIdentifier: {dataTypeId.NumericIdentifier}");
                    }
                }
                else
                    Console.WriteLine($"*** Failure: {valueResult.ErrorMessageBrief}");
            }

            // Example output:
            //
            //Value: SByte
            //Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=2
            //Value.NamespaceUriString: http://opcfoundation.org/UA/
            //Value.NamespaceIndex: 0
            //Value.NumericIdentifier: 2
            //
            //Value: Float
            //Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=10
            //Value.NamespaceUriString: http://opcfoundation.org/UA/
            //Value.NamespaceIndex: 0
            //Value.NumericIdentifier: 10
            //
            //Value: String
            //Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=12
            //Value.NamespaceUriString: http://opcfoundation.org/UA/
            //Value.NamespaceIndex: 0
            //Value.NumericIdentifier: 12
        }
    }
}
Requirements

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

See Also