MQTT Switch not sending ON command

Setup, Configuration and Use Items & Sitemaps
1

I have a device that subscribes to device/kueche/licht/set to receive commands. When its state changed, it publishes to device/kueche/licht. This works fine when using an android app to publish and subscribe to those topics. I can also see the correct traffic on a linux laptop using mosquitto_pub and mosquitto_sub.

However, I’m having trouble configuring an item to send the correct commands. Here’s my current item configuration:

Switch Licht_kueche “Licht Küche” (gTest) {mqtt="<[piffi-mosquitto:device/kueche/licht:state:ON:1]",
mqtt="<[piffi-mosquitto:device/kueche/licht:state:OFF:0]",
mqtt=">[piffi-mosquitto:device/kueche/licht/set:command:ON:1]",
mqtt=">[piffi-mosquitto:device/kueche/licht/set:command:OFF:0]"}

(no line breaks in the actual code)

What works: when I publish using the android app, the device changes its state and this is immediately reflected by the item. When the device is ON (after I switched it on using android), I can only use the item to switch it off.

Why? What’s wrong with my config?

2

Hello Christoph,

the binding of the item is wrong. You should once configure your binding (mqtt) and within the " you describe the commands:

Switch Licht_kueche "Licht Küche" (gTest) {mqtt="<[piffi-mosquitto:device/kueche/licht:state:ON:1], <[piffi-mosquitto:device/kueche/licht:state:OFF:0], >[piffi-mosquitto:device/kueche/licht/set:command:ON:1], >[piffi-mosquitto:device/kueche/licht/set:command:OFF:0]"}
3

OK that makes sense, I just didn’t adapt the examples correctly.

Furthermore, I conclude that it’s not possible to mix MQTT for status and a REST interface for commands?

4

The in-bound binding config strings should be in this format:

Switch Licht_kueche "Licht Küche" (gTest) { 
mqtt="<[piffi-mosquitto:device/kueche/licht:state:MAP(onoff.map)],
>[piffi-mosquitto:device/kueche/licht/set:command:ON:1],
>[piffi-mosquitto:device/kueche/licht/set:command:OFF:0]"}

with transform/onoff.map containing something like:

0=OFF
1=ON

You can add other bindings to the item, like if you wanted to send commands via HTTP:

Switch Licht_kueche "Licht Küche" (gTest) { 
mqtt="<[piffi-mosquitto:device/kueche/licht:state:MAP(onoff.map)]",
http=">[*:POST:http://www.domain.org/kueche/licht/?status=%2$s]" }

So the item gets its state from MQTT, but forwards its commands over HTTP.

5

both suggested solutions work well, but the second one:

Switch Licht_kueche "Licht Küche" (gTest) { 
mqtt="<[piffi-mosquitto:device/kueche/licht:state:MAP(onoff.map)],
>[piffi-mosquitto:device/kueche/licht/set:command:ON:1],
>[piffi-mosquitto:device/kueche/licht/set:command:OFF:0]"}

seems to be slightly more responsive. Does the number of bind statements have such a visible effect on performance?

6

I just tried two config parts instead of four or three and that seems to work too:

Switch Licht_kueche "Licht Küche 2" (gTest) {mqtt="
  <[piffi-mosquitto:device/kueche/licht:state:MAP(kueche_licht.map)],
  >[piffi-mosquitto:device/kueche/licht/set:command:*:MAP(kueche_licht_set.map)]
"}

kueche_licht.map:

0=OFF
1=ON

kueche_licht_set.map:

OFF=0
ON=1

Also, line breaks seem to be allowed - is that correct?

Simplifying further:

Switch Licht_kueche "Licht Küche 3" (gTest) {mqtt="
  <[piffi-mosquitto:device/kueche/licht:state:default],
  >[piffi-mosquitto:device/kueche/licht/set:command:*:MAP(kueche_licht_set.map)]
"}

because the device sends “0” and “1” which openHAB seems to interpret correctly. Great!

Not quite - I get warnings:

[WARN ] [.c.i.events.EventPublisherImpl] - given new state is NULL, couldn't post update for 'Licht_kueche'

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