Does anyone know if a datasheet is available for the Canon 24-105mm diaphragm unit? I'm wondering if there's a way to use an Arduino or suchlike to control the diaphragm via the flex cable, but I can't find any specs or datasheets anywhere.
NB: this answer was written when the question was asking about the shutter, rather than the diaphragm. It may be deleted soon.
There is no shutter in the 24-105; almost every camera system smaller than medium format has a focal plane shutter in the body, rather than a leaf shutter in the lens. The only exception I know of is the Pentax Q system.
The best answer I could find to this by googling was a "Pick and Place" blog article where the author describes what he's discovered about the EF-S mount connections:
It looks like you send signals on DIN's rising edge (DIN is the middle of the five small contacts), and controlling the diaphragm involves sending the $07$13 opcode, along with a two-digit hexcode value for the specific aperture setting you want. Opening it up to wide open uses the opcode $13$80.
I think. I could be wrong. I just did a quick google. :)