Manufacturers of consumer electronics don't seem to be the most
DIY-friendly bunch. I have a feeling you'll have to figure the protocol
out yourself. I gave up trying to get info on the Pioneer "P-bus". If I
had a changer to go with my changer-control deck I'd give a shot at
figuring it out, but as it is, people like us are not important to Sony
and Pioneer. You'd think that a good service manual would contain that
information, but service manuals have gotten pretty slim.

I once complained to NEC about the lack of real information in service
manuals. The answer I got(perhaps more frank than poilically correct) was
that the company did not think there was anyone in the U.S. smart enough
to need that much information.

Cheers,
Bob