Can't connect to pixhawk4 from system console


I follow the

and want to connect to system console
Connect to the fmu debug port using usb2serial cable

and set putty like below, when power on pixhawk4 ,I can get some "!@#$!@#$!@#$@$@#$…"In the console

I dont know it means what

Can anyone help me???

@elton-choi,do you have some advise?? Thanks s lot


Is ground connected? Are you sure you’re using the correct COM port? You can check that by disconnecting whatever cable you’re using and checking if the port disappears.