Hi Rasmus, how are you? As far as I know you don't need a special cable to use digital marks, all you need is to have a lens file loaded. I also own a cPro and use them any now and then in combination with "physic" marks and they have worked well so far. What did happen to me in one of the last job with the MiniLF I've been, on was that I had the sync data function on (without being aware of that). So, since the LDS pins of the mount were on too and we were using Cooke s7i, the lens data automatically popped up in my HU. When this happens you loose the possibility to use premarked rings, digital marks and (if you have a range finder in the daisy chain) the focus track function. I ended up switching off both the pins on the mount and the data sync function on my HU since we didn't need to have the iris and focus values embedded as metadata.

Other thing that could explain the message you get is that you assigned to the user button another function similar such as "distance mark" (only available when you have a rangefinder connected).

As for your other question, I think you are referring to this

you can find it in the Cmotion website, going to this link and scrolling down

https://cmotion.eu/page/cpro

Also, in the home page, if you scroll all the way down you can download the cable guide, a huge PDF where you can find info about the cable of all the Cmotion universe

Hope it helped

Cheers