Thu May 19, 2016 4:40 am
Hi Chris,
jkinkennon's description of how the matrix works is clear enough, but I think that the point you are missing is that MIDI isn't involved at all in this part of the circuit.
All the matrix wiring (and the switch contacts connected to it) does is to allow a further block of circuitry (the 'encoder') to determine which switches are open or closed at any particular time. The advantage of the matrix wiring arrangement is the simplification of only needing 16 wires connected to the encoder rather than the 62 wires which would be needed if each switch was connected to the encoder individually.
It is the encoder (rather than the matrix) which transforms the information from the switches into MIDI messages and sends these messages on to the MIDI port on the computer.
If you want to know how the MIDI encoder does this, and what the messages look like, just ask again.
Nick