You can control the OT externally via a MIDI cable. I wouldn’t want to but it’s possible.

I swear I saw a mention of indicators on the display for MIDI IN/OUT activity, something like one pixel being lit for either but I can’t find it in the manual just now so maybe my memory is wrong. There are MIDI monitors in software like MIDIOX if that’s any help. Maybe go from PC MIDI OUT -> OT MIDI IN, OT MIDI THRU -> PC MIDI IN and then monitor the input.