Help On First Steps For MQTT Bindung

(OpenHAB 2.5)
I am trying to connect to a MQTT broker and get data from it.

According to the docs I did the following:

  • Installed MQTT Binding
  • Created the broker connection (can be seen in Services and shows “Online” in Things
  • Created a new thing and used the configured broker connection as bridge
  • Within the thing I created an new channel of type “Number Value”
  • Configured this channel with a label and a channel-id as well as the topic to subscribe to. Left other things empty
  • Created a new items (in PaperUI) through linking the thing to a “new item”
  • Finally, created in the sitemap a text element linked to the above item.

However, I do not see any data on my sitemap. Nor do I see any updates regarding the data of this channel. I simply used mosquitto_pub to publish a message simply “400”.

But I do not see any further details about OpenHAB having got the message received.

I´Can someone guide me to configure an MQTT item somehow? Currently I just want to display, modifying will follow later.

Thanks a lot!


You’ll have to show us all your configuration, including details on your Mosquitto setup.


thanks for taking care of this issue here.
As I went again through all these settings I added the availability channel to it and it appears to be working now…
So the following is just for completeness. Looks like I have to configure the availability now matter why:

What should I show you in detail? I will post some screenshots.
First, the MQTT broker works fine; I tested this with the mosquitto_pub and mosquitto_sub commands.

I am free to create topics from my device just as I will.
First, the broker settings:

These are the thing’s settings.

I configured the LWT topic for availability ON/OFF and it works just fine when publishing “ON” or “OFF” through mosquitto_pub -t "Heizung_avail" -m "ON" -r.
See log:
2021-01-11 12:34:26.374 [hingStatusInfoChangedEvent] - 'mqtt:topic:17ed64b6' changed from OFFLINE to ONLINE

Now this is how it looks in the channel configuration for the thnig:

And the channel configuration is this. I did not configure any additional stuff:

And that’s the item:

Hi again,

additional question now as the above appears to be working. My channel posts messages as key/value pair like this:

I am only interessted in the number of the “boostcount” value so I added a REGEX to the channel settings (REGEX transformation is installed):

Unfortunately I does not appear to be working for a reason I do not get. Someone having examples how to use the REGEX stuff here?
I alreaady tried:


None appears to be working, instead I see in the log:
2021-01-11 12:55:49.572 [WARN ] [ab.binding.mqtt.generic.ChannelState] - Incoming payload 'boostcount=0' not supported by type 'NumberValue'

Any clue?



Ok, looks like I read too much. The REGEX-Documentation told me a different expression than I should use in MQTT bindung. Don’t ask me why.

However, the following works:

Ok, playing around now and see if I can get my OpenHAB to send MQTT commands.