Raspberry Pi Pixhawk Cube connection

I am trying to connect raspberry pi 4 to Pixhawk Cube orange via TTL.
I am using /dev/ttyUSB0 and the baud is 57600 and I can’t get a heartbeat.
What am I doing wrong. Please help.
Thank you

Your question is missing a lot of details. Are you using the UART pins on the RPi and a telemetry port on the FC (ttyS0 or ttyAMA0), or a USB cable (ttyACM0), or a USB to UART adapter and a telemetry port (ttyUSB0/1/2…)?
Which software do you use on the RPi?

I am using MAVLink
and the UARTS Pin in RPi 4 directiy to the telem2 port ttyAMA0

hello, would like to ask if you have resolved this?

I connected raspberry pi to cube via usb cable and it worked. Also read this entry, I think you would be able to solve it as well.

You could try connecting through telem ports. You can look the assigned rx tx pins in the telem ports of the cube and connected it to the r-pi’s UART.

The FC on mine is ttyAMA0 and i configured the baudrate to 921600