MQTT-Broker to MQTT-Client communication. What am I doing wrong?

Hi there,
first of all: thank you very much for your efforts in supporting open-source-software.
I’m on my first bigger diy project and ran into the following problem: I try to make a smart ventilation out of some pc-fans. I supply them by a zigbee-led-rgb-controller, which is working fine. I can set the fan-speed by adjusting “brightness” in zigbee2mqtt-frontend and “select” one or the other fans as green (0,255,0) or blue (0,0,255) colour. So far, so good.
Now i want to implement this in openhab3. Later, the fans shall operate automated. For now, i even fail to control it via openhab at all. I’ve tried to send a mosquitto_pub message which didn’t work out:

mosquitto_pub -u openhabian --pw *** -t "Zigbee2mqtt/Testlüftung/set" -m {"brightness":250}

I created a channel in the mqtt-broker, with zigbee2mqtt/Testlüftung as topic - but this too doesn’t trigger the fan.
I tried some tutorials, but it seems to me that, at some point, some information for a noob like me is missing. And it didn’t work out in the end too… Please help. What kind of information do you need?
Thanks in advance!

  • Platform information:
    • Hardware: Raspberry Pi 3 B
    • OS: openHABian
    • Java Runtime Environment: ?
    • openHAB version: 3
  • Issue of the topic: I set up a MQTT-Broker and try to communicate with a MQTT-Thing
  • Please post configurations (if applicable):
    • Items configuration related to the issue
    • Sitemap configuration related to the issue
    • Rules code related to the issue
    • Services configuration related to the issue
  • If logs where generated please post these here using code fences:

Show us the data in MQTT Explorer (install it if you don’t have it, and connect it to your broker) when you perform the above operations.

Alright, these are two commands changing the colour / “selecting the other fan”.


Hi, to narrow down the problem, maybe I’m just asking if the command given above should work with this topic (zigbee2mqtt/Testlüftung, as given in my screenshot)? Or is there some false syntax etc? Or is it necessary to give all the attributes the leg-controller can handle, even if the value hasn’t been altered?
Thanks in advance!

Alright, with a little bit of trial and error (and I rtfm), I manage to send something via command-line that actually alters the values in mqtt explorer. So I assume, the command reaches my zigbee2mqtt controller(?). Unfortunatly, it’s not happening (reaching the led-controller). If I use the zigbee2mqtt-frontend, it works like a charm. Any ideas?
For example:

mosquitto_pub -u openhabian --pw *** -t "zigbee2mqtt/Testlüftung/brightness" -m "50"

→ screenshot