Does the LON USB U10/20 interface work on Windows 8/8.1?

@Alex, yes OpenLDV 4.0 (driver package) requires Microsoft .NET Framework 3.5 SP1. You can get an installer for .NET 3.5 SP1 here:

https://www.microsoft.com/en-us/download/details.aspx?id=25150

There is information on installing it on Windows 8.1 here:
https://msdn.microsoft.com/en-us/library/hh506443(v=vs.110).aspx