PX4 Development Kit - X500 v2, Pixhawk 6x, Firmware V4.5.7, Mission-Planner, Radiomaster TX16S II ELRS, Receiver ER8GV 2,4 GHz ELRS

Hello, I have a Radiomaster TX16s transmitter and a Radiomaster ER8GV 2.4 GHz ELRS receiver. The RX has a connection for CRSF on the side. I connect this connector on the Pixhawk 6x with Telem3 (Serial5). VCC to pin 1, GND to pin 6, TX and RX cross-connected. Parameters in Mission Planner SERIAL5_PROTOCOL = 23, RSSI_TYPE = 3, SERIAL5_OPTIONS = 0 . Save the parameters and then reboot FC . The transmitter has no connection to the FC, and I cannot calibrate the transmitter. What is wrong?
Peter

How did you confirm the transmitter and Radiomaster ER8GV 2.4 GHz ELRS receiver are binded? What is the LED status indicating?

If bind is okay, double check this.

On F4/F7 based autopilots the UART MUST be DMA enabled for reliable operation in CRSF protocol mode.