I'd like this to somehow get to DJI developers.  I realize that this is a user community but I thought I would post it here in hopes that it will give others some benefit and perhaps it will make it into DJI.

I have a Canon EOS R5C and a DJI RS 3 Pro gimbal.  To make the start / stop button on the gimbal work, a USB-C cable needs to be connected from the camera's USB-C port to a particular USB-C port on the gimbal.

I discovered that some (most) of my USB-C to USB-C cables would not work but others would.  I bought a diagnostic tool and this is what I found.  (This is basically the limit of my USB-C understanding.)

With the higher bandwidth USB-C technologies as well as the power distribution technologies introduced into USB-C over the past few years, the cables now have a chip in them.  Note I said "now" -- so older cables do not.  And I guess you can still buy new cables without the chip but I'm not sure.  The chip is called the eMarker chip and it describes the capabilities of the cable -- the bandwidth as well as how much power can flow through it.

If the cable has one of these chips, the R5C to gimbal connection will not work.  It only works with cables that do not have an eMarker chip -- at least judging from my limited experimentation and diagnostic work.

The cables that came with the gimbal work.  A cable I bought in 2018 works.  Many of my other cables do not work.

I also have a Canon R5.  It exhibits the same problem.  So this might be a problem with Canon.  I am going to post this same message on their community board as well.

TL; DR - if the start / stop button on your gimbal isn't working, try changing out the USB-C cable.

Hi pedzan.
I was strugging same probrem.

Now it works with other USB-C cheap cable witch is No DJI No Canon.

Thanks for your great helping.

Hello Pedzan, Did you manage to change/control focus via the Gimbal as well? (when connected through USBC)

info7214 Posted at 12-6 02:28
Hello Pedzan, Did you manage to change/control focus via the Gimbal as well? (when connected through USBC)

I never tried.  It was always on my to do list but I never got to it due to various reasons.  If I discover how to do it, I'll update this thread.

Hope you are well! Thank you so much for your concern! I have forwarded it to our engineer for further checking! Please rest assured that l will update you on the answers once l get the response. Your patience and understanding are well appreciated!

Thank you for your feedback, due to the third-party cable has not been tested and adapted, there may be instability, we recommend to use the official cable from DJI.