OPC Studio User's Guide and Reference
WriteValueFunction<TValue>(UADataVariable,Func<TValue,UAStatusCode>,Int32[]) Method



OpcLabs.ServerOpcUA Assembly > OpcLabs.EasyOpc.UA.NodeSpace Namespace > UADataVariableExtension Class > WriteValueFunction Method : WriteValueFunction<TValue>(UADataVariable,Func<TValue,UAStatusCode>,Int32[]) Method
The type of the value of the data variable.
The data variable that will be modified and returned.

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

The write value function, i.e. the function that accepts the value to be written, performs the write operation, and returns the status code that is the result of the OPC UA Write.

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

The size of each dimension of the array value.

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

Makes data variable that consumes the attribute data using the write value function, and specifying array dimensions. The declared type is specified using generic type parameter.
Syntax
'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function WriteValueFunction(Of TValue)( _
   ByVal dataVariable As UADataVariable, _
   ByVal writeValueFunction As Func(Of TValue,UAStatusCode), _
   ByVal ParamArray arrayDimensions() As Integer _
) As UADataVariable
'Usage
 
Dim dataVariable As UADataVariable
Dim writeValueFunction As Func(Of TValue,UAStatusCode)
Dim arrayDimensions() As Integer
Dim value As UADataVariable
 
value = UADataVariableExtension.WriteValueFunction(Of TValue)(dataVariable, writeValueFunction, arrayDimensions)
[Extension()]
[NotNull()]
public:
static UADataVariable^ WriteValueFunctiongeneric<typename TValue>
( 
   UADataVariable^ dataVariable,
   Func<TValue^,UAStatusCode^>^ writeValueFunction,
   ... array<int>^ arrayDimensions
) 

Parameters

dataVariable
The data variable that will be modified and returned.

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

writeValueFunction
The write value function, i.e. the function that accepts the value to be written, performs the write operation, and returns the status code that is the result of the OPC UA Write.

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

arrayDimensions
The size of each dimension of the array value.

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

Type Parameters

TValue
The type of the value of the data variable.

Return Value

Returns the dataVariable, internally modified as defined by the method.

This method never returns 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

This method overload infers the OPC data type of the data variable from the TValue type.

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).

When you use the method overload without the array dimensions (arrayDimensions parameter), the method determines the array dimensions automatically from the TValue type parameter, and if the type is an array, the individual dimension elements are set to 0, meaning that the size of the array is not limited in any dimension. If you want to limit the size of the array in certain dimensions, you need to use this method overload (with arrayDimensions parameter), and specify the array dimensions explicitly.

In languages that support parameter arrays (methods with variable number of arguments), such as C# or VB.NET, the arrayDimensions parameter can be specified as one or more arguments of type System.Int32, without having to construct the array of dimensions explicitly.

The writeValueFunction is allowed to return null, which is interpreted as a "Good" status code.

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

See Also