MQTT to Home assistant

[RobinC]

Hi,

I have FHEM running the MAX! radiator valves in my house. I recently set up an Opentherm Gateway to my boiler. I connected it to Home Assistant as it seemed easier. I would now like to connect the valves to Home assistant via MQTT.

I found this on Github: https://github.com/danielrheinbay/fhemMAX2HASS it seems to be exactly what I need.Unfortunately I can't get it running.

This is the client:
defmod mqtt MQTT2_CLIENT <192.168.1.203>:1883
attr mqtt lwt homeassistant/binary_sensor/fhem/availability offline
attr mqtt lwtRetain 1
attr mqtt msgAfterConnect -r homeassistant/binary_sensor/fhem/availability online
attr mqtt msgBeforeDisconnect -r homeassistant/binary_sensor/fhem/availability offline

setstate mqtt disconnected
setstate mqtt 2026-11-03 19:45:08 lastPublish homeassistant/binary_sensor/MAX.Kitchen/0f5c7f-panel/config:{"availability":[{"payload_available":"online","payload_not_available":"offline","topic":"homeassistant/binary_sensor/fhem/availability"},{"payload_available":"alive","payload_not_available":"dead","topic":"homeassistant/MAX.Kitchen/Activity"}],"availability_mode":"all","default_entity_id":"MAX-HeatingThermostatPlus-0f5c7f-panel","device":{"configuration_url":"http://192.168.1.134:8083/fhem?detail=MAX.Kitchen","identifiers":["0f5c7f"],"manufacturer":"eQ-3","model":"MAX! Radiator Thermostat Plus","name":"MAX.Kitchen","suggested_area":"MAX","sw_version":"1.0"},"device_class":"lock","entity_category":"diagnostic","payload_off":"locked","payload_on":"unlocked","state_topic":"homeassistant/MAX.Kitchen/panel","unique_id":"MAX-HeatingThermostatPlus-0f5c7f-panel"}
setstate mqtt 2026-11-03 19:46:07 state disconnected

I have tried to use MQTT explorer but it does not see anything if I point it at the FHEM installation.

I know that the MQTT broker is working on Home Assistant as it is receiving data from the OTGW.

One thing I have not done is to SAVE CONFIG, I revert to the old config with shutdown restart when I give up trying to make it work.

Can anyone help me work out what I have got wrong?

Thanks,

Robin

[Beta-User]

Can anyone help me work out what I have got wrong?

There are quite a few options to get this to work. Imo the "cleanest" way ist to use MQTT_GENERIC_BRIDGE (MGB), see especially https://wiki.fhem.de/wiki/MQTT_GENERIC_BRIDGE.

There are some attrTemplate to support the entire process, you may want to start with "base_settings_MQTT_GENERIC_BRIDGE" in the version "ATTRTVERSION_MGB_only".

There may also exist a template to set appropriate Attributes to the thermostats itself.

If needed, I could try to explain more in detail these days. Hope this helps as a starting point.

(btw: I don't use HomeAssistant, so for the yaml part, you might need additional help.)

[RobinC]

Thanks for the response. The solution I'm working from uses the client, the generic bridge and some code

Configure a connection to your MQTT broker using the MQTT2_CLIENT module:

define mqtt MQTT2_CLIENT <mymqttbroker.local>:1883
attr mqtt lwt homeassistant/binary_sensor/fhem/availability offline
attr mqtt lwtRetain 1
attr mqtt msgAfterConnect -r homeassistant/binary_sensor/fhem/availability online
attr mqtt msgBeforeDisconnect -r homeassistant/binary_sensor/fhem/availability offline

Note: If you configure more than one MQTT2_CLIENT device, specify which one to use in 99_myUtils.pm#L56.
Configure an MQTT Generic Bridge:

define mqttGenericBridge MQTT_GENERIC_BRIDGE
attr mqttGenericBridge IODev mqtt
attr mqttGenericBridge globalDefaults base="homeassistant" qos=2 retain=1
attr mqttGenericBridge stateFormat dev: device-count in: incoming-count out: outgoing-count

Add a trigger to call MAX2HASSdiscovery using the DOIF module:

define hass.MAXdiscovery DOIF ([":Activity",""]) ({MAX2HASSdiscovery("$DEVICE")})
attr hass.MAXdiscovery do always

Others have got this to work. My problem is I can't even see how to start troubleshhoting. In the Client it seems I have an MQTT message prepared:
homeassistant/binary_sensor/MAX.Kitchen/0f5c7f-panel/config:{"availability":[{"payload_available":"online","payload_not_available":"offline","topic":"homeassistant/binary_sensor/fhem/availability"},{"payload_available":"alive","payload_not_available":"dead","topic":"homeassistant/MAX.Kitchen/Activity"}],"availability_mode":"all","default_entity_id":"MAX-HeatingThermostatPlus-0f5c7f-panel","device":{"configuration_url":"http://192.168.1.134:8083/fhem?detail=MAX.Kitchen","identifiers":["0f5c7f"],"manufacturer":"eQ-3","model":"MAX! Radiator Thermostat Plus","name":"MAX.Kitchen","suggested_area":"MAX","sw_version":"1.0"},"device_class":"lock","entity_category":"diagnostic","payload_off":"locked","payload_on":"unlocked","state_topic":"homeassistant/MAX.Kitchen/panel","unique_id":"MAX-HeatingThermostatPlus-0f5c7f-panel"}

But it is not being received at Home Assistant. I tried to use MQTT explorer to listen to what is going on but I get a message Econn refused when I try to connect to port 1883 on the FHEM address.