ReadValue<TValue>(IEasyUAClient,UAReadArguments) Method

Reads a value of an attribute, converts it to the specified type, and throws an exception if the operation fails.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<ExtensionAttribute()>
<JetBrains.Annotations.CanBeNullAttribute()>
Public Overloads Shared Function ReadValue(Of TValue)( _
   ByVal client As IEasyUAClient, _
   ByVal readArguments As UAReadArguments _
) As TValue

'Usage
 
Dim client As IEasyUAClient
Dim readArguments As UAReadArguments
Dim value As TValue
 
value = IEasyUAClientExtension2.ReadValue(Of TValue)(client, readArguments)

[Extension()]
[JetBrains.Annotations.CanBeNull()]
public static TValue ReadValue<TValue>( 
   IEasyUAClient client,
   UAReadArguments readArguments
)

[Extension()]
[JetBrains.Annotations.CanBeNull()]
public:
static TValue^ ReadValuegeneric<typename TValue>
( 
   IEasyUAClient^ client,
   UAReadArguments^ readArguments
)

Parameters

client: The client object that will perform the operation.
The value of this parameter cannot be null (Nothing in Visual Basic).
readArguments: An arguments object that specifies what to read from the OPC-UA server.
The value of this parameter cannot be null (Nothing in Visual Basic).

Type Parameters

TValue: The type to convert the attribute value to.

Return Value

The attribute value converted to type .

This method can return null (Nothing in Visual Basic).

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.
OpcLabs.EasyOpc.UA.OperationModel.UAException	The OPC UA operation has failed. This operation exception in uniformly used to allow common handling of various kinds of errors. The System.Exception.InnerException always contains information about the actual error cause. This is an operation error that depends on factors external to your program, and thus cannot be always avoided. Your code must handle it appropriately.

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.

OpcLabs.EasyOpc.UA.OperationModel.UAException

The OPC UA operation has failed. This operation exception in uniformly used to allow common handling of various kinds of errors. The System.Exception.InnerException always contains information about the actual error cause.

This is an operation error that depends on factors external to your program, and thus cannot be always avoided. Your code must handle it appropriately.

Remarks

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.

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

IEasyUAClientExtension2 Class
IEasyUAClientExtension2 Members
Overload List

Documentation Home, Send Feedback. Resources: Knowledge Base, Product Downloads. Technical support: Online Forums, FAQ.

Missing some example? Ask us for it on our Online Forums! You do not have to own a commercial license in order to use Online Forums, and we reply to every post.