Sender sx --xmodem -vv file_to_send.txt < /dev/ttyUSB0 > /dev/ttyUSB0 Receiver rx --xmodem -vv received_file.txt < /dev/ttyUSB1 > /dev/ttyUSB1
https://www.adontec.com/Extended_XMODEM.pdf
- Work only over serial
- Is capable only to send, not to receive