As far as I can tell, you can get any of the MIDI channels. I looked at the “Simple MIDI Example” script, and almost all of the MIDI events are on the first channel (‘0’ in the script, but MIDI-Ch1). The script has one lonely trigger on the second MIDI channel (which is ‘1’ in the script). This is the blue trigger on the outermost circle. That trigger never sends a note-off, however, because it has a TriggerOffTime of ‘0’. You might want to bump that up, maybe to one second, like all the other triggers. You can do that via the inspector or you can add a line to the script in the appropriate spot:
iannix.execute("setTriggerOff current 1");
This lonely note on Ch2 has a pitch value of 42, a double-low F-sharp. Depending on the instrument you have on that channel — unless it’s a piano or tuba, it might be hard to hear (or even out of range), so bumping that up two or three octaves might tell you more.