Support for Viessmann PlusBus
Since 2020 the Viessmann Vitodens 2xx and 3xx range of gas boilers do not support KM-Bus or OpenTherm any longer. Viessmann decided to "upgrade" the interface on this boilers to PlusBus. This is an in-house developed protocol which they claim is an evolution from KM-Bus. However there is zero information to be found online about this protocol. Nor are there any 3rd party thermostats that support it. So at this point I can only conclude it to be completely proprietary, closed and unsupported to external parties. Basically Viessmann decided to vendor lock-in its users as much as possible to their own solutions (e.g. Vitotrol and Vicare Smart Climate, which are very very poor speaking from experience).
For Tado users who have such a boiler this means they can only be controlled by relay. The boiler will still modulate but only based on its internal heating curve. Tado can only manipulate this by turning it on or off. Off course efficiency and comfort wise this is not ideal.
The Vitodens 2xx/3xx are very expensive boilers (probably the most expensive I can find in my area). One of the reasons being their best in class modulation range. These "premium" boilers are targeted towards consumers who want to maximize efficiency. The same goes for Tado.
My Tado system was bought via Viessmann. The Tado packaging and app is even customized to show a big logo "Viessmann with Tado"
So basically I now have this two very expensive systems who claim to work together and be super efficient. But actually they barely communicate with each other and thereby loose effiency, comfort, overal ease of use and user insight. I would urge both Tado and Viessmann to sort this out!