http://www.echelon.com/support/downl...01A_ReadMe.htm

System Requirements
Microsoft® Windows 7 (64-bit and 32-bit), Windows Server 2008 R2 (64-bit), Windows Vista (32-bit), Windows XP (32-bit), or Windows Server 2003 (32-bit)†

† Note: OpenLDV 4.0 runs as a 32-bit application on both 64-bit and 32-bit versions of Windows. It cannot be called from a 64-bit client application. In order to use OpenLDV on 64-bit Windows, the OpenLDV client application must be compiled as a 32-bit application. For unmanaged C++ applications built using Windows compilers, this means that the application must be build for the “Win32” platform, not the “x64” platform. For managed .NET applications (such as C#), this means that the application must be built for the “x86” platform, not the “x64” or “Any CPU” platforms.

So in other words, this will allow you to run a 32-bit Niagara-AX installation on a 64-bit Windows box and have access to a USB Lon interface.