C-Bus How to connect

I’m fairly new to Smarthings having previously used Homeseer. So far very impressed. I’m trying to connect a few existing devices and would appreciate some advice.
I have some C-Bus2 lighting and have no idea how I would connect this. Any basic advice much appreciated.
Also any news of Cytech Comfort connection? That would be awesome!

I’m also looking for somthing like that.

I have connected my C-Bus to MQTT and then ST to MQTT too. This works OK but is tedious to set up.

I had hoped to write a C-Bus device driver for ST but I don’t think it’s do-able with the current ST Hub capabilities.

Checking in. I am also looking for a solution to integrate ST into my home alarm system running on C-Bus. Hopefully something comes along.

Hi - sorry to resurrect this old thread, but I am struggling to connect my c-bus system to ST using MQTT. Are you still using this method?

I have a working pi using C-Gate, and with a working Mosquito system. The correct configuration is escaping me and a few pointers would be helpful if you are still using this. If you are able/willing to help then please post and I will describe the steps I have taken so far.


I link Schneider/Clipsal C-Bus lighting (not Alarm or HVAC) into SmartThings via two paths. One is MQTT and the other uses virtual ‘group’ device in ST updated via the ST cloud API via another ‘helper’ embedded device that can handle the. local IP communication to C-Bus. Unfortunately neither of these would be useful to you as I utilise a C-Bus to Ethernet gateway to monitor and control the lighting (not the CNI or C-Gate).

On and off I have been working on using a Raspberry Pi running C-Gate to directly update ‘group’ devices in ST but as I don’t need that solution it’s not been a priority.

With the recent announcement that ST is ceasing support for developers and their code submissions my interest in ST has waned. I will not be perusing this as it’s a dreadful omen and quite honestly there are other controllers better suited to this application with local processing and IP comms. This obviates the need for the intermediary Pi so I’d rather invest my time and build my home system around those.

I believe in the C-Bus forums there has been discussion of linking C-Bus to MQTT - maybe using a Pi and C-Gate and that is your critical step to get working. Once that is in place the MQTT to ST bridge works OK and you can layer NodeRed in between if needed (I do this as it allows topic mapping and some logic smarts). Those latter steps are common with my implementation so I can maybe help more if you can get the C-Bus <> MQTT bit working.


Hi Kevin

Thanks for getting back to me. Like you I have a lighting only system, though my unit does not have an ethernet interface.

Since I wrote the message I have made quite good progress - my little Raspberry pi now has:

  • a working C-Gate interface (which works well with homebridge to link to Apple’s Homekit). I use a usb-serial cable, converted to a socket at the pi (ser2socket)
  • a working MQTT service
  • a working cgateweb service to interface the C-Gate to MQTT
  • a working Node-RED service (which allows me - in theory, at least - to translate between ST and cgateweb postings)
  • and I start manually smartthings-mqtt-bridge on the pi

All of the above seems to work well - by manually posting to MQTT either the cbus or the ST topic I can control my lights. I can see the node-Red translation working in the latter case. The bridge traffic (as far as I can tell anyway) is only one way ST->MQTT - but that’s fine for now.

On my ST I have installed the bridge device handler, the bridge device, and - for testing purposes - just one simulated switch. And occasionally all this works. But only occasionally. Most of the time nothing happens, then periodically all the MQTT messages get posted at once (cue light flashing crazily) and then things work for a while, and then - for no good reason I can see - stop.

My goal for doing all of this was to be able to use a logic engine like CoRE to control my c-bus lights. I am beginning to think that there may be a better home automation solution than ST. It seems to me that there are not a huge number of UK c-bus installations. Homekit isn’t there yet, so I’d be interested to hear

  • did you encounter similar issues with ST working? If so, where is the weak point - the pi bridge, the device, the ST bridge, … ?
  • what home automation direction are you headed in for your c-bus? It seems to me that everything I am doing is held together with string at the moment.


My C-Bus Ethernet gateway is not the official CNI - it is a different device that notifies you about C-Bus ‘events’ and allows C-Bus control commands to be sent.

Having said that if you have got the C-Bus to MQTT bit working we’ve both achieved the same end result and so we should be able to get this working bi-directionally.

I jumped in fairly early when the ST MQTT code was released so memory is a bit faded but I do recall making some ‘sticky plaster’ changes to the code to avoid race conditions that happened. From your experience I suspect you’re seeing the same.

I need to look at what I did but I remember creating dual topics in MQTT and having some logic in NodeRED that intelligently updated between the two (i.e. the ST updates and the C- Bus updates based on an additional field in both topics indicating where the update request originated (ST or C-Bus). This healed the race condition.

Let me take a refresher course and see what I did and hopefully we’ll get you going. As always time is elusive but I’ll post back.


BTW my chosen controller for C-Bus is Vera (I also have Loxone, Fibaro, AMX and Crestron) - a true controller junkie. Vera handles local processing and direct UDP Ethernet comms so dovetails nicely with the Ethernet controller I use on C- Bus so that is a big +. MQTT and xAP allow all my controllers to play together as one ‘harmonious’ (cough) system.

Hi - yes, the C-Bus/MQQT stuff (cgateweb) seems to work well on my Pi. No issues at all posting on MQTT to control lights.

And when smartthings-mqtt-bridge and node-red are running (the latter listening for ST postings, then changing the case on on/off and posting the result to the C-Bus topic), I can post ST topics and control lighting too, with no issues.

The issue I seem to be having is on the ST hub, I suspect. If I reboot the hub then I can control lights from a simulated switch on the app, which informs a bridge smartapp, and device - they communicate to the port on the Pi. But then - as I said above, randomly - they stop communicating. Though occasionally they start again

I haven’t tried 2-way communication yet - yes, I’ll need to think a bit about the loopback-avoiding logic. But that’s secondary at the mo.

I’ll have a look at the Vera - thanks.