I want to learn how to send ASCII code from Raspberry Pi 3 to a serial device. Communication protocol of Serial device via RS232 (TX, RX pins). I was trying to connect from kermit as follows but I failed; set line /dev/ttyS0 set carrier-watch off set speed 9600 set flow none set parity none set stop-bits 1 connect The circuit with RS232-TTL Converter [![enter image description here][1]][1] The circuit with USB-TTL Profilic converter [![enter image description here][2]][2] [1]: https://i.sstatic.net/yMEKf.jpg [2]: https://i.sstatic.net/BMvBc.jpg