here is the step by step process i use (mixing to 32 tracks)...
1. make sure your dm3200 interface is set to 32 in and 32 out
2. in protools, set each track output to a corresponding input(s) on the dm3200
3. in the dm3200, set your routing CH 1 - 30 to slot 1 inputs 1 through 30
4. mix your session (make sure you monitor through the stereo mix)
5. set your output slot 1 try 31 and 32 to stereo L and stereo R
6. when you are ready to record, create a stereo audio track in protools using inputs 31 and 32, arm the track for record and record
you should see waveforms in the mix track as you record your final mix
cheers,
moleif