serial port in linux (raspbian)

Question

I need to receive data using a serial port in an application written in C, in Linux (raspbian).

This is for a half-duplex data acquisition (by RS485) so when any device is sending data, all the others must be listening.

The problem is that every char received on the serial port of the raspbian machine is sent back to the external device (in modem terminology - echo ). This happens even when the application is not running.

This must be a configuration of the serial port (in my case an USB to rs232 converter), but i can't find a way to solve this.

The output of the stty command is:

stty -F /dev/ttyUSB0
speed 9600 baud; line = 0;
-brkint -imaxbel

Thanks

Answer 1

Off the top of my head, it's

stty -F /dev/ttySX raw -echo -echoe -echok -echoke

There could be couple more flags, from the man page:

   [-]crterase
          echo erase characters as backspace-space-backspace

   * crtkill
          kill all line by obeying the echoprt and echoe settings

   * -crtkill
          kill all line by obeying the echoctl and echok settings

   * [-]ctlecho
          echo control characters in hat notation ('^c')

   [-]echo
          echo input characters

   * [-]echoctl
          same as [-]ctlecho

   [-]echoe
          same as [-]crterase

   [-]echok
          echo a newline after a kill character

   * [-]echoke
          same as [-]crtkill

   [-]echonl
          echo newline even if not echoing other characters

   * [-]echoprt
          echo erased characters backward, between '\' and '/'