Code:
//from the command line, set a USB serial adapter, then interact, ctrl-c to exit stty -F /dev/ttyUSB0 ospeed 57600 ispeed 57600 raw cat /dev/ttyUSB0 & cat > /dev/ttyUSB0
//from the command line, set a USB serial adapter and send and receive data stty -F /dev/ttyUSB0 ospeed 57600 ispeed 57600 raw echo -ne '?' > /dev/ttyUSB0 cat -v < /dev/ttyUSB0