I have a couple of keyboard controllers (Panorama P4, Yamaha P35) and a mini drumpad (Korg Nanopad2), and today I wanted to map each controller to different instruments in FL Studio for a live session.
Jean-Michelle Jarre would feel at home here.
It's pretty easy to do in Reason -- "lock controller to device" or something equally intuitive -- but FL Studio didn't make it quite as easy. The docs are a little confusing and (while they did set me on the right track) didn't tell me the full story.
The first thing to do is to make sure each MIDI input device is mapped to a different port. I chose 1, 2 and 3 for my two keyboards (bass and piano) and drumpad (studio drum kit) respectively.
Then, for each instrument, go into the central settings menu and select the port you want the instrument to be controlled by. The input port is "---" by default, meaning that it'll only be played when selected.
Finally, create a new "blank" channel (FL Studio by default makes this a sampler; it doesn't matter at all) and select it. Unfortunately I haven't found a way to turn off midi input when a channel is selected, so this is the workaround which means that none of the channels will be selected while playing. The other controllers should still be sending input to their respective instruments.
For the record: I'm using Trilian for the bass (in this case an upright), Alicia's Keys for the piano, and Studio Drummer for the kit. I'm a big fan of both Spectrasonics and Native Instruments! I haven't done anything to the levels (they seem fine!) but if I were to use this for recording a track I'd put some more effort into the mix. For live performances there's a bit more room for error!
To expand this setup, my next instrument would be a Mark 1 from the Scarbee Vintage Keyboards library. Again, big NI fan; and there's something about that keyboard sound that made me fall in love when I heard it for the first time.