eBus device general question & control devices cohabitation


I’m looking for a way to control my vaillant heating (VCW BE 346/3-5 H & calormatic 430 thermostat) with OH.
I contacted Vaillant and they told me the only way is to use some dry contact and that the bus was proprietary with no possibility to be interfaced.

I guess they don’t know about this kind of device (eBus interface) and the OH binding :slightly_smiling:

I tried to understand a lot from the german site (http://ebus-wiki.org/) using google translate but I can’t find answers to my questions:

  1. May I expect to be able to control the heating device with the rs-232 interface?
    I guess so, according the the OH binding which provides vrc430 config file but I’m not sure I truly understand the principle.

  2. Do I have to disconnect the calormatic 430 or could it live together with OH binding at the same time?

I mean where is the regulation logic actually done (inside the heating device or inside the calormatic thermostat device) ? If I can use both devices on the ebus, would it be that it’s the last which sets the heating on/or and temperature which wins. If so may I expect the calormatic 430 to display the temperature set point set from OH?

Thank you in advance for your help and comments :slight_smile: !

Hello @Glicu,

To 1:
Yes you can send commands to all bus participants and set room temperature etc. But you need a adapter to convert the eBus signal to a serial 232/usb/ethernet signal. You can buy such a adapter or build you own. But I would buy a usb variant. eBus is still complex enought.

To 2:
No, you not modify the existing installation. The regulation logic is still done by your controller. The eBus binding is an additional listener on the Bus and it is normally more a passive participant.

Who win if you write values? I think it simply works if you use the known configurations.


Thank you for you reply!
I’ve wired the dry contact to OH for now but I’m going to order the usb interface to get much control on the system (instead of just switching on/off).
I’m very familiar with electronic but I can’t find any precise english information about the ebus needs and as you said, the ebus is enough complex to avoid hardware problems… :slightly_smiling:

May I ask an other advice?
If I keep my existing controller (hang on the living room wall), once the temperature setpoint is reached in that room the heating device goes off so other rooms (in which I have OH connected temperature sensors) do not get heated anymore.
I guess the only solution is to make all the temperature/heating on-off logic inside openhab but the existing controller should then be removed shouldn’t it? Otherwise they would create conflict (there are only 3 modes in the existing controller : off, auto and manual).

Thank you!