I am trying to figure it out for model 4700W, see my post in the general Comelit compatibility thread: Comelit compatibility - #36 by Davince . Your system seems to be quite similar (Bus system, also with S+ and S- connection). In the general thread it is mentioned that Comelit bus system is encrypted (or at least for some models), so I am trying to figure out how the Analogue wiring should be. It probably requires a bit of soldering.