Help for debugging needed: Status change of item not received by hardware


its my first post here so I hope it “fits” - sorry if not :wink:

Situation: I have a sensor in binding A (Homematic) and want to send its state to binding B (LCN). After some reading, I have created a “Number” item to receive the data from the sensor and a second item to couple the data to the LCN binding.

Number hmOutdoorTemp “Außentemperatur [%.1f °C]”
(gTerrasse) {
homematic=“address=MEQ0833315,channel=1,parameter=TEMPERATURE” }
Number lcnOutdoorTemp2 “Außentemperatur [%s °C]” (gTerrasse) {lcn="[%i:lcn:VAR.0.32.12.%iCelsius]"}

I created a rule that populates the value from the homematic item to the lcn item - this works. But I dont see any data going into the LCN bus when the values change, I tried “postUpdate” as well as “sendCommand”. When I inject data into the LCN bus target variable, it gets displayed on openHAB, so the binding itself looks ok to me.

Anybody can tell me what I am doing wrong or help me debugging this? Is this the right way at all to send data from one bus to another?