WOLF/Kromschröder BM with ebusd + MQTT + Home Assistant – reading and writing WWSoll

[Boris4333]

WOLF/Kromschröder BM with ebusd + MQTT + Home Assistant – reading and writing WWSoll

Hi,

I have a WOLF/Kromschröder controller connected via eBUS and managed with ebusd 26.1.

I wanted to expose the domestic hot water target temperature (WWSoll) in Home Assistant as a writable MQTT Number entity.

Hardware / setup

The setup is:

WOLF/Kromschröder controller
→ eBUS adapter
→ ebusd
→ Mosquitto MQTT
→ Home Assistant

The controller is detected as:

15;Kromschroeder;  ;0204;-

The relevant ebusd circuit is bm.

eBUS messages

The configuration file contains:

r,bm,,WWSoll,Warmwasser-Solltemperatur,,15,5022,001300,value,,UIN,10,°C,Warmwasser-Solltemperatur
w,bm,,WWSoll,Warmwasser-Solltemperatur,,15,5023,001300,value,,UIN,10,°C,Warmwasser-Solltemperatur,suffix,,HEX:4,=5d010000,,

So the same message name has a read definition and a write definition.

Reading works with:

docker exec ebusd ebusctl read -c bm WWSoll

For example:

42.0

The MQTT state topic is:

ebusd/bm/WWSollIst

and publishes JSON such as:

{
  "value": {
    "value": 42.0
  }
}

Writing through MQTT works with:

docker exec mosquitto mosquitto_pub \
-h localhost -p 1883 \
-t 'ebusd/bm/WWSoll/set' \
-m '41'

The value can then be read back with:

docker exec ebusd ebusctl read -c bm WWSoll

and returns:

41.0

Changing it back to 42 works the same way.

Home Assistant MQTT Number

The important part was creating an MQTT Discovery configuration for a writable Number entity.

The working configuration is:

docker exec mosquitto mosquitto_pub \
-h localhost -p 1883 -r \
-t 'homeassistant/number/ebusd_bm_wwsoll/config' \
-m '{"name":"WW Soll Regler","unique_id":"ebusd_bm_wwsoll_number","state_topic":"ebusd/bm/WWSollIst","command_topic":"ebusd/bm/WWSoll/set","value_template":"{{ value_json.value.value }}","min":15,"max":65,"step":1,"unit_of_measurement":"°C","device_class":"temperature","mode":"box","device":{"identifiers":["ebusd_bm"],"manufacturer":"ebusd.eu","name":"ebusd bm"}}'

The important part for assigning the entity to the existing MQTT device was:

"device": {
  "identifiers": ["ebusd_bm"],
  "manufacturer": "ebusd.eu",
  "name": "ebusd bm"
}

After this, Home Assistant shows:

Device: ebusd bm
Control: WW Soll Regler
Sensors: WWSoll and WWSollIst

The final result is a writable temperature control in Home Assistant.

I tested it by changing:

42 °C → 41 °C → 42 °C

and verified that the value was written to the eBUS controller and returned correctly through MQTT.

I hope this is useful for anyone with a similar WOLF/Kromschröder setup.

If anyone sees a better/native way to make ebusd expose writable w, messages automatically as Home Assistant Number entities, I would be interested in hearing about it.