@gohan Well, in my case, it is going to replace my thermostat, so I already have the 5 wire cable coming up from the basement for that which takes care of the hole in the wall. Since the main controller for the thermostat is in the basement, all I should need at the tablet side is a temp sensor. I will use the 5 wire cable to connect my 5 volt charger and probably a DS18B20 temp sensor to read the temp. In the basement, I will create an arduino node to read the temp and send it to the thermostat controller over my RS485 network. All the other thermostat controls will be handled by the tablet.