No, I’m not devoted to PX4; just far from it! I am using arducopter since several years with my pixhawk-1 and I’m fine. I tried PX4 because it was recommended for Pixhawk-3 (and preinstalled). So I will also try to install arducopter on Pixhawk-3.
But what correct wiring for FrSky-Telemetry? I have read about the following possibilities for connecting the telemetry from pixhawk-3 to a frsky-receiver:
connecting any of the Pixhawk-Telem-Ports and FrSky-SmartPort with special adapter cable, for example from C&T.
connecting Telem-3 directly to FrSky-SmartPort, using a wire for GND and another wire for signal (soldering TX and RX of Telem-3 together)
Are these two alternatives correct?