OPC Studio User's Guide and Reference
OnWriteAttributeDataChanged Method



OpcLabs.ServerOpcUA Assembly > OpcLabs.EasyOpc.UA.NodeSpace Namespace > UADataVariable Class : OnWriteAttributeDataChanged Method
The old value of the property.

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

Called when the value of the WriteAttributeData property has changed.
Syntax
'Declaration
 
Protected Overridable Sub OnWriteAttributeDataChanged( _
   ByVal oldValue As UAAttributeData _
) 
'Usage
 
Dim instance As UADataVariable
Dim oldValue As UAAttributeData
 
instance.OnWriteAttributeDataChanged(oldValue)
protected virtual void OnWriteAttributeDataChanged( 
   UAAttributeData oldValue
)
protected:
virtual void OnWriteAttributeDataChanged( 
   UAAttributeData^ oldValue
) 

Parameters

oldValue
The old value of the property.

The value of this parameter cannot be 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.

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