In our previous episode, Armin Diehl said: > that is the same as in the standard serial.pp: > > Result := fpopen(DeviceName, O_RDWR or O_NOCTTY); > > and this fpopen will block as long as minicom is not started on that > device. Yes. And seems that minicom turns of xon/xoff. You could try to verify that by disabling it with stty.