may ask why you are doing this? i dont own a dslr so i have no clue why one would need to analyse the Lens protocol?
In future i wish to have digital SLR camera. I can to fit many non-AF lens (they are cheap and have good quality), but i need to focus by hands. In DSLR with crop factor 1,6 this is very hard.
DSLR and SLR have AF sensor but hi is activates only with original lens. 1 man decompile EOS lens protocol and create chip, who emulate 45 1,4 EOS lens and activate AF sensor. With AF confirmation chip focusing by hand easier and faster. Of course i can buy chip, but I wish to try making camera "software" version of this chip.
For better analyse lens protocol need osciloscope but i dont have it. Need measure Hz of clock pin. I know in new lens Hz are change in time so need measure old lens (older - better) like my 28-80.
If someone have EOS EF Extension tube, osciloscope and old eos lens pls measure clock pin. In macro ring you have access to all pins (of course you need detach something).
to open EF Extension tube you need Remove 4 screws in camera mounting ring.
detail see Modifying Canon EF Extension tube for EOS 300D lens
Added: Good news. I found internal servise manual in public acess. They got some info about Lens-Body protocolhttp://ozerki.net/photosight/PhotoDocs/Manuals/partlist/Lens/CanonServiceManual(EF-50-28-15).zip
(page 22 -30)