I connect a device via serial port and it is display HEX code.
But I can not find where can switch the ASCII or HEX.
Royal TSX uses the built-in "screen" command for serial port connections. I have to admit I'm not an expert on this topic so I don't know if it's possible to instruct screen to switch the mode.
Maybe you have more insights or can find the relevant information in the man page of screen?