Sbus on Pixhawk not detected when battery plugged in

I am currently confused about my hexa setup. I am using Taranis x7 and rx X8R on Sbus.
If I use USB power QGC can detect but if I plug in battery, other calibration worked but Sbus stoped and became undetected. Ithe same with other rx such as XBR.
Anybody can help me…