I have tried different things, the thing I have changed, is the type of value who would be send from the sensor. The default : send(msg.setSensor(i).set(temperature,1)); gives me the following error in Control 4 : number 1 string UPDATE parent 26 room 1 subcategory 0 [string "Lua Code"]:120: bad argument #1 to 'SetVariable' (strValue should be a string) (ReceivedFromProxy) altid 5;0 id 40 temperature 23.5 I tried to add the lines : char charVal[6]; //temporarily holds data from vals dtostrf(temperature,6,1,charVal); and changed the send to : send(msg.setSensor(i).set(charVal)); But the same happens If I cast the temperature to int I got the it, but without decimals If I try with : String string = "24,8"; send(msg.setSensor(i).set(string)); No error in Control4, but the sent temperature is 1