Hello:
Can't give you an answer on how to get the midi to work in relation to your connection setup. Midi settings are numerous and tricky.

However, I can suggest the PR602 can play the midi directly. If it's possible, copy the midi file on a floppy disk. Then load it on the PR602. I don't have a PR602, it should have a load option of either SMF or midi, pick one and you should be able to play it directly. I'm also assuming the PR602 has a floppy drive.

Hope this helps...

Anthony