TX2 J17 used as UART occurs data error

J17(/dev/ttyTHS2) used as UART, baudrate is 115200. It can send and receive data, but the data is wrong. For exemple, another coputer send the data “0x55”, but J17 receives the data as “0x00”. J17 send the data “0x55”, another computer receives the data as “0x55 0x00”.
What is the problem, please?

Normally using 115200 8N1 is quite reliable (faster speeds tend to require two stop bits). The wiring does have to be of good quality. How long is your cable? Is it twisted pair? Is the cable shielded?

Sometimes serial terminal programs do more than just transfer bytes. Are you using some sort of serial terminal? If not, what is interpreting the bytes you’re viewing?

Thank you, linuxdev! Problem is solved. The UART-USB used is 5.5V, and not compatible with J17, which is 3.3V. After I change another cable, all work well.