serial_test.py

import select
import serial

serial_dev = '/dev/ttyS1'

select_timeout = 30

port = serial.Serial(serial_dev, timeout=None)
port.flushInput()

data = ''
while True:
    ready, _, _ = select.select([port],[],[], select_timeout)
    
    # timeout reached
    if not ready:
        if data:
            print "remaining data: " + repr(data)
        data = ''
        
    for fd in ready:
        char = port.read(size=1)
        if char == '\r':
            print "received: " + repr(data)
            data = ''
        elif char!='':
            data += char