To upgrade an existing OPCHDA.NET based application usually only the following steps are required:

1. Open the solution in Visual Studio
   
2. Make sure that .NET4.x is selected as the target platform
   
   
3. Remove the OpcHdaWrapper.Net4.dll or OpcHdaWrapperB.Net4.dll reference
   
   
4. Add a reference to the OPCHDA.NET V9.0 (or newer) assemblies:
   - OpcHdaWrapperUA.Net4.dll    respectively    OpcHdaWrapperWpfUA.Net4.dll
   - OpcNetBase.Net4.dll
   in the OPCHDA.NET setup directory.
   
   
5. Add a reference to the OPCHDA.NET UA Option assembly
   - OpcHdaNetUaOption.Net4.dll
   in the OPCHDA.NET UA Option setup directory
   
   
6. Rebuild the application. No code changes are required.
   
   
7. Use the UA Client Configuration Utility to create a default UA configuration.
   Drag the application EXE file to the utility shortcut or start the utility and browse to the application.
   In the main dialog click the  Create UA Configuration  button 
   
   
8. Edit the default configuration to define proper names and create a certificate for the application.
   To access remote UA servers:
   - the exported client certificate needs to be copied to the server machine and imported.
   - the exported server certificate needs to be copied from the server machine and imported.