title: twisted serialport protocol
body: <p>I have looked at the python twisted examples for using a serialport (gpsfix and mouse) and other solutions given here on stackoveflow. However, it still isn't clear how to write a general serial port protocol. Can anyone provide a simple (but complete) example of a python twisted SerialPort program? </p>
  
  <p>I need to use /dev/ttySx as a serial port, and I need to both read an write from/to it.</p>