mqtt autodiscovery programmers guide

[akamming]

I build my own ESP8266 solution for managing my heating using this library: http://ihormelnyk.com/opentherm_library

made a python plugin which retrieves the Opentherm values every 10 sec and then converts them to domoticz devices (and with http commands to control the heating)

but actually i don't like this 10 sec heartbeat, so would like to start using mqtt to update realtime when needed instead of this polling mechanism. using normaal mqtt updates commands with manually devices created in domoticz is quite easy (did a test). But i would like to use the autodiscovery protocol, so the devices are created automatically

where can i find info on the autodiscovery and how to program this?

[waltervl]

In the home assistant documentation. A link to this HA documentation is in the Domoticz MQTT wiki. But to make it easy It is here https://www.home-assistant.io/integrati ... -discovery

[waltervl]

By the way, there is a OpenTherm mqtt Autodiscover project here https://github.com/rvdbreemen/OTGW-firmware

[akamming]

In the home assistant documentation. A link to this HA documentation is in the Domoticz MQTT wiki. But to make it easy It is here https://www.home-assistant.io/integrati ... -discovery

Aha tx just what i was looking for

[akamming]

By the way, there is a OpenTherm mqtt Autodiscover project here https://github.com/rvdbreemen/OTGW-firmware

Tx for the hint. But this opentherm gateway. I am using other hardware..

[akamming]

tx for the hints here. Already much further. can create mqtt messages for switches and sensors. However i struggle to get one for a setpoint

does anyone have sample mqtt payloads for the autodiscovery mqtt message which creates a setpoint device?

Most ideally a "mosquitto_pub full commandline to create a setpoint device

e.g. how should i change the one belew so it creates a setpoint instead of switch:

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mosquitto_pub -r -h 127.0.0.1 -p 1883 -u <user> -P "<pw>" -t homeassistant/light/kitchen/config -m '{ "~": "homeassistant/light/kitchen", "name": "Kitchen", "unique_id": "kitchen_light", "cmd_t": "~/set", "stat_t": "~/state", "schema": "json", "brightness": true }

[waltervl]

As indicated check the otgw as example, there are some setpoints examples in it.
https://github.com/rvdbreemen/OTGW-firm ... mqttha.cfg

[akamming]

a check tx, so it should be something like this:

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%homeassistant%/sensor/%node_id%/TrSet/config ; {"avty_t": "%mqtt_pub_topic%", "dev": {"identifiers": "%node_id%", "manufacturer": "Schelte Bron", "model": "otgw-nodo", "name": "OpenTherm Gateway (%hostname%)", "sw_version": "%version%"}, "uniq_id": "%node_id%-TrSet", "device_class": "temperature", "name": "%hostname%_Room_setpoint", "stat_t": "%mqtt_pub_topic%/TrSet", "unit_of_measurement": "°C", "value_template": "{{ value }}", "state_class" : "measurement" }

will try .. tx!

[akamming]

now the next issue: domoticz logs it creates new devices. However they are not created anymore.

e.g.

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mosquitto_pub -r -h 127.0.0.1 -p 1883 -u <user> -P "<pwd>" -t homeassistant/light/kitchen3/config -m '{ "~": "homeassistant/light/kitchen3", "name": "Kitchen3", "unique_id": "kitchen_light_3", "cmd_t": "~/set", "stat_t": "~/state", "schema": "json", "brightness": true }'

results in a what seems to be a correct device

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2022-11-29 12:59:39.465  Status: zwave2mqtt: discovered: kitchen_light_3/Kitchen3 (unique_id: kitchen_light_3)

however no device kitchen3 or kichten_light_3 is created... (and yes.. accept new sensors is switched on)

how can i troubleshoot?

[waltervl]

I would switch on debugging in Domoticz if this is all logging you get.

[akamming]

I would switch on debugging in Domoticz if this is all logging you get.

this is weird.. restarted domoticz with loglevel all. and now the device is created which is weird, cause the command is in a script and i ran the same script... gonna do some more testing where this weird behaviour comes from.

tx for the tip anyway..

[akamming]

Steadily progressing. My devices are now autodiscovered. Works great.

Have another question i cannot find in mentioned autodiscovery docs above.

I programmed my ESP to send the discovery config message on (re)connect to MQTT and the update messages whenever a states changes. Works perfect, i can see realtime the values of my boiler in domoticz... and i can control the boiler setpoint, heating, hotwater, etc... using these autodiscovered devices.

That is: Until I restart domoticz. I then get a lot of "invalid/unhandled data received messages". which is fixed when i force the discovery mqtt messages being sent again (which results in domoticz recognizing the messages again and are mapped to the correct devices).

For sensors a fix could be to always send the disovery message before the value is sent to domoticz. However this will not fix the setpoints or the used switches. Whatever interval i choose to regularly send discovery messages: These will be unusable until the next discovery interval.

Is there some way domoticz can cache this info? If not: what is the best practice for when and how often the discovery messages should be sent?

[waltervl]

I believe this can be solved by setting retained mqtt messages on. Downside is that after deleting of the device and not deleting the retained mqtt message you get the deleted device back in Domoticz

[akamming]

I believe this can be solved by setting retained mqtt messages on. Downside is that after deleting of the device and not deleting the retained mqtt message you get the deleted device back in Domoticz

The ha docs specifically State not to use retained mesaages for this Reason. Any other suggestions?

UPDATE: The HA docs seem to contradict themselves. Now also found this link: https://github.com/home-assistant/home- ... y.markdown, stating

Retain: The -r switch is added to retain the configuration topic in the broker. Without this, the sensor will not be available after Home Assistant restarts.

where i read somewhere else this is bad practive (if you delete a device it will be rediscovered). Anyway not happy with it.

I will do some testing, see what works better: Retained messages or periodically publishing the discovery messages.

[waltervl]

I guess you won't delete a lot of devices. At least I don't.

[mgugu]

I Use this discovery method to automate domoticz devices creation.
Works fine for switch and light but for sensors, looks like a bit more complicated and undocumented.
For example when I try to create a gas counter (would like a P1 smart meter for example) with these config messages:

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Arduino/sensor/gas/config
{
  "device_class": "gas",
  "name": "gas",
  "state_topic": "Arduino/sensor/gas",
  "unique_id": "0x0015bc004f00d3ab_gas",
  "unit_of_measurement": "m3"
}

I get a General/Custom Sensor and not a gas counter.
(Note that a first state update is necessary to see the device in domoticz, not the case for switch or light).
This works if I use "energy" device_class.
Is there some documentation about device classes already implemented in domoticz ?
Thanks

[waltervl]

There is no documentation. Best to do some sniffing in the code https://github.com/domoticz/domoticz/bl ... scover.cpp

[mgugu]

@waltervl Thanks for the link

[akamming]

tx for all the help. It is working better and better.

But i do have an additional question: I'd also like to have the opentherm faultcode of my boiler published to mqtt/domoticz. (use case is i can set alarms on it. E.g. send push notification when domoticz detects an error)

So íd like to have a device with just a number and no unit of measurement. According to HA docs this shoulld be possible ("A sensor is a read-only entity that provides some information. Information has a value and optionally, a unit of measurement.")

so i created using the following autodiscovery message:

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{
  "value_template": "{{ value_json.value }}",
  "device_class": "None",
  "state_topic": "domesphelper/sensor/Faultcode/state",
  "json_attributes_topic": "domesphelper/sensor/Faultcode/state",
  "name": "Faultcode",
  "unique_id": "Faultcode"
}

The issue is that devices is created in domoticz, the value is also correctly sent to domoticz, however unit of measurement becomes "??" in domoticz... (instead of no unit of measurement)

I already tried adding

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"unit_of_measurement": "",

to the discovery message the result is the same (unit of measurement becomes "??" instead of having no unit of measurement)

any idea how to fix this?

[mgugu]

I also needed such device. The best I found for 0-100 numbers is to setup a light with only brightness : "brightness_state_topic". No need to specify a device class