Frsky R-XSR

I have recently started working with the Px4 and i can not get the receiver to communicate with the Pixhawk 4. I have the Frsky R-XSR tried it every way i can think of except the right way i imagine.
Please can someone get me a drawing or maybe some insight.
I also have a Spektrum SPM4650, but have had problems integrating this in the past.
Please any help would be welcome…