Hi MANOWAR©,
Those Xpt4 and other like it, work as a wall transmitter that will send its signals to PLC only. Nice little units and very well made. Set the first botton to the HC/UC and the rest will follow with the proceeding UC. All you need to hook them up is to have any livewire with a neutral to connect too.
The UC that are set can be to any module or macro you like. By pressing the botton will trigger any unit set to that HC/UC. The same is done to any RF transmitter or remote, set the first botton the desired HC/UC and the rest will follow in order of UC.
These units are also nice because you can buy a single, double, triple or quad bottons to fit into the units and a standard Decora cover fits on them nicely.
Hope that helps.
BaBaLou.