VelbusLink can connect to Velbus through a HomeCenter plug. Can I do the same using .NET? Or do I have to install a second USB interface?
HomeCenter is licensed software that checks which software connects to it, so you will need to check if your license allows this.
There are a number of other Velbus to TCP servers out there.
As you’d expect, almost all of them are mentioned in this forum, somewhere…
Unless you specifically need to access your installation via Home Center.
Update - Jan 2017
There is now a GitHub page with instructions on how to install GuntherVB’s JVelbusD TCP server
github.com/openremote/Documentation/wiki/JVelbusD-installation-instructions
And HomeCenter uses a different (I think undocumented) protocol