MQTT Binding and linked items

[sl4m (Simon)]

Dear all,
i am currently building a small external touch panel with Arduino ESP32 and 2.8" Touch Panel.
With this device i want to externally control any kind of OpenHab items via MQTT.
In order to do this i created a new MQTT Topic and one Channel per item which i want to control.
For example:

Stehlampe Schlafzimmer is a echo control smart plug for a light in the bedroom.

However, it is not completly working as expected:

In case i turn on and off the item Stehlampe Schlafzimmer in the BasicUI the light is switched on and off and the ESP32 is receiving the MQTT publication MQTT_item_link/Schlafzimmer_Stehlampe/state ON/OFF. Also the button on the external screen is activated and deactivated accordingly.

In case i send MQTT_item_link/Schlafzimmer_Stehlampe/set ON/OFF the light is also switched on and off. However, the OpenHab item Stehlampe Schlafzimmer is not updated accordingly.

Can someone help me? Did i do the configuration wrong?
Thank you alot!

[rossko57]

You might look at this similar application for ideas

Marketplace MQTT Event Bus

Update: Complete rewrite to use the rule templates published to the Marketplace. There is no need to code this or copy/paste code to make this work. There is a Remote openHAB binding which replaces this capability in most cases. See openhab-addons/bundles/org.openhab.binding.remoteopenhab at main · openhab/openhab-addons · GitHub . However there may be use cases where MQTT is preferred, such as integration with a non-openHAB service. Introduction What’s an Event Bus? There are times when one…

The MQTT binding channel provides no means to copy Item state updates to a remote service, only commands. So, there it is done by rule and Action.

@sl4m

the light is also switched on and off. However, the OpenHab item Stehlampe Schlafzimmer is not updated accordingly.

This would be the business either of autoupdate feature (enabled by default on each Item) or of whatever binding gets updates from the real device.

You’ve not applied any channel link profiles here, have you?

[sl4m (Simon)]

Thank you for the hint with the MQTT 2.5 Event Bus.
However, I managed to solve the issue by setting the linked items to “follow”.
By doing so the status is updated bi-directional.

Edit: Forgot to mention: Also i had to set the item to “Enforce an auto update”