'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function ReadValueFunction( _
   ByVal dataVariable As UADataVariable, _
   ByVal dataTypeId As UANodeId, _
   ByVal arrayDimensionList As IReadOnlyList(Of Integer), _
   ByVal readValueFunction As Func(Of Object) _
) As UADataVariable

'Usage
 
Dim dataVariable As UADataVariable
Dim dataTypeId As UANodeId
Dim arrayDimensionList As IReadOnlyList(Of Integer)
Dim readValueFunction As Func(Of Object)
Dim value As UADataVariable
 
value = UADataVariableExtension.ReadValueFunction(dataVariable, dataTypeId, arrayDimensionList, readValueFunction)

[Extension()]
[NotNull()]
public static UADataVariable ReadValueFunction( 
   UADataVariable dataVariable,
   UANodeId dataTypeId,
   IReadOnlyList<int> arrayDimensionList,
   Func<object> readValueFunction
)

[Extension()]
[NotNull()]
public:
static UADataVariable^ ReadValueFunction( 
   UADataVariable^ dataVariable,
   UANodeId^ dataTypeId,
   IReadOnlyList<int>^ arrayDimensionList,
   Func<Object^>^ readValueFunction
) 

Parameters

dataVariable

The data variable that will be modified and returned.

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

dataTypeId

Specifies the OPC UA data type of the variable value. For standard data types, see OpcLabs.EasyOpc.UA.AddressSpace.Standard.UADataTypeIds.

Because the OpcLabs.EasyOpc.UA.AddressSpace.UANodeId has an implicit conversion from System.String, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a string (representing the expanded text of the nodeId) in place of this parameter, and the corresponding OPC UA node Id will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the OpcLabs.EasyOpc.UA.AddressSpace.UANodeId.UANodeId Constructor(String) constructor instead.

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

arrayDimensionList

The size of each dimension of the array value.

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

readValueFunction

The read value function, i.e. the function that performs the read operation and returns the value that will be returned to the caller of the OPC UA Read.

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

Return Value

The array dimensions are specified as a list of integers, one for each dimension. Each element represents a dimension of the array, and the value of the element represents the maximum size of the array in that dimension. If the maximum size of certain dimension is unknown, the value of corresponding element is 0.

The specified array dimensions will be stored in the ArrayDimensions property, and exposed to OPC UA clients via the OpcLabs.EasyOpc.UA.UAAttributeId.ArrayDimensions attribute. In addition, OPC Wizard will enforce the maximum array bounds automatically (where the specified array dimension is not 0).

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.

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