Canon Serial Weirdness

Yeah, I’ve been stuck with this for quite some time now and I have no idea what I’m looking for, other than….


and maybe some dark magic



We have a studio camera that’s got a Canon HJ17ex6.2B lens on it. This lens has servos for focus, zoom, and iris. There’s also a small OLED(?) display and menu navigation thing on the hand grip that lets you check and set some options on it.

The bottom of the servo grip has three sockets – one for the remote focus controller, and two for the remote zoom or serial remote controls. The two latter sockets are a 20 pin Hirose connector.

This is supposed to be connected to a Ross Video robotic head’s lens jack for remote operation from the Ross Cambot system.

Originally this was connected to an ancient Vinten robot with a cable that I still have, and connecting it to the lens doesn’t do anything interesting. Connecting Ross’s cable makes the lens go completely and immediately dead with no servo activity, and I have to power cycle the camera or unplug and reconnect the cable between the lens and the camera body to regain any function from it.

The only documentation I have found AT ALL on this 20 pin connector is a kinda weird manual page from Canon, and this diagram from Ross:
Ross Video serial cable for Canon lens

And from the Canon manual:

This is from the manual for a ZSD-300 “zoom servo demand” controller. Please note that pin 20 is not shown as to what its function may be. (?!)

And now, the Vinten robot cable… if I look inside the Hirose end of it, it appears to have wires landed only on 13, 15, 16, and 20. 20 and 15 are connected together at the far end of the cable. 19 and 20 are connected together on the Ross cable.
On the Vinten cable three of the four pins on the Lemo connector are used. This suggests to me that whatever pin 20 is— OH WAIT IT’S JUST GROUND, ha, the pins are listed out of order!

I had Ross send me another cable, it has the same pinout and same issue with making the lens power down. I tried another lens of the same model and the same thing happened.

What the heck do I need? I’m throwing this out here in case someone possesses the correct ARCANE KNOWLEDGE.

My best guess: I need to NOT ground pin 19, as it is open circuit on the Vinten cable. The mysterious runes in the Canon doc seem to suggest it might be used to determine whether you’re gonna use serial remote mode or an external control. Also they uh, helpfully, labelled these serial lines A/B X/Y, I dunno. My guess is the Vinten thing was using RS-232 style wiring since it only has three wires coming out (RS-422 and RS-232 can be kinda sorta bodged together with reasonable success).

Unsurprisingly, there is a band named Five Tons of Flax. I just started listening to the 7 album and it’s pretty funky!