You wont see the foreign devices in the T3000 tree for now, we’re working on that, but you can certainly use the Bacnet objects in the foreign device in your programs, trendlogs and alarms of the T3 controller environment. See the section on ‘network programming’ in this forum for examples on how to do that.
Update: Here’s the link.
The other thing you can do is see the bacnet objects on your 3rd party device using the Bacnet tool, navigate from T3000 → Tools → Bacnet tool.