The current OBDSim way of talking to an FB is by using dbus and fbd. That's really not an ideal approach, for two reasons:
1) It uses DBus
2) It relies on Linux.
If you're on linux, then go ahead and use it [I wrote the example dbus plugin script you'd need]
A smarter developer than I could easily write a plugin for obdsim to talk directly to the FB. Plugin writing in OBDSim is really easy, and documented in a README file in the source.
Lemme know a bit more about what you're actually trying to do, and I'll see if I can provide more advice