Opener for Comelit 2738w (Simplebus 2)

AndreUniverse · November 2, 2024, 5:20pm

Greetings, firstly, I hope this is the correct place to post.
I’ve researched quite a bit on older posts in hopes to find a working solution to get the Opener to talk to the Comelit 2738w on our new flat, but no luck. There were some people looking for help but no working solution.
I tried messing around with it and at some point even got past step 2 of the configuration, but I believe it was a “false positive” as I couldn’t either get past step 3 nor repeat the success on step 2.

Anyway, today I was looking online for more info on Comelite simplebus 2 and the specific intercom we have and I found someone who made their own device to communicate with the Comelit bus, this person was nice enough to expose the process online so I imagine it would be simple for the wizards at Nuki to take that info and get the Nuki Opener to talk with Simplebus 2 devices.

I’ll leave the GitHub link here

GitHub link

Looking forward to some feedback

essayeur · November 6, 2024, 11:26pm

hello;
you said;" this person was nice enough to expose the process online"
please wher is it; could you explain or copy? thanks a lot
Eric

AndreUniverse · December 16, 2024, 5:09pm

Hi Eric, I’m sorry that I only reply now.
I somehow missed the notification that there had been a reply to this thread.

I did include the link on my initial post

github.com/plusvic/simplebus2-intercom

README.md

main

Overview
--------

Simplebus2 is a two-wire door entry system created by the Italian company Comelit. It supports both audio and video, and it's widely used in residential buildings, specially across Europe.

The building where I live has one of those systems, so I wanted to understand how it worked in order to solve a practical problem: getting notified when someone is ringing my doorbell. I work from home and usually wear noise-cancelling headphones while working, which means that I can't hear the doorbell. I wanted to install a complementary notification system, such as a light that turns on, or something that vibrates on my desk.

In this project I'm sharing my findings about how the Simplebus2 system works, and a detailed description of the devices I've built.

How it works
------------

The Simplebus2 door entry system uses only two wires for carrying both DC power and signals to the intercom devices installed on each apartment. All the devices share the same two wires, hence the "bus" word in the name. Those two wires are not polarized, they are labeled the same way (L) and can be connected arbitrarily to the intercom devices. Of course, being DC there's a GND and a Vcc, but devices are prepared to accept both wires in any of the two possible ways. This is done by putting a full-bridge rectifier at the device's input.

The DC voltage in the bus is 22-34V according to the manufacturer (in my particular case it is 26.5V), and signals are mounted on top of this DC offset. When someone calls an apartment from the building's entry door, a message is transmitted over the bus. All the intercom units in the building can see the message, but only the unit in the target apartment reacts to the message. Each intercom unit has its own 8-bits address, which is configured via a 8-way DIP switch during installation. See the interior of a Comelit 2738W intercom with the DIP switch in red:

![9254781621186832244](https://user-images.githubusercontent.com/182937/119274313-8b263380-bc0f-11eb-9708-aa4b1010644b.jpeg)


Multiple units can share the same address, this is common practice when two or more intercoms are installed in the same apartment. Simplebus2 messages are 18-bits long, structured as follows:

This file has been truncated. show original

essayeur · January 27, 2025, 6:53pm

Thanks a lot; i am not a rugular on GithUb…thanks