XBeeModem.py bypasses the XBee's 802.15.4 capabilities and simply uses it modem for communications

XBeeModem.py

#!/usr/bin/env python

"""XBeeModem.py bypasses the XBee's 802.15.4 capabilities and simply uses it modem for communications

    You don't have to master 802.15.4 and a large set of XBee commands
    to make a very simple but potentially useful network.  At its core,
    the XBee radio is  a modem and you can use it directly for simple serial communications.

    Reference Materials:
        Non-blocking read from stdin in python - http://repolinux.wordpress.com/2012/10/09/non-blocking-read-from-stdin-in-python/
        Non-blocking read on a subprocess.PIPE in python - http://stackoverflow.com/questions/375427/non-blocking-read-on-a-subprocess-pipe-in-python

    Originally Created By:
        Jeff Irland (jeff.irland@gmail.com) in March 2013
"""

# imported modules
import os                   # portable way of using operating system dependent functionality
import sys                  # provides access to some variables used or maintained by the interpreter
import time                 # provides various time-related functions
import fcntl                # performs file control and I/O control on file descriptors
import serial               # encapsulates the access for the serial port
from pretty import switchColor, printc  # provides colored text for xterm & VT100 type terminals using ANSI escape sequences

# text colors to be used during terminal sessions
ERROR_TEXT = 'bright red'
CMD_INPUT_TEXT = 'normal'
CMD_OUTPUT_TEXT = 'bright yellow'
TERM_OUTPUT_TEXT = 'purple'
TERM_INPUT_TEXT = 'bright purple'


if __name__ == '__main__':
    serial = serial.Serial()
    serial.port = '/dev/ttyUSB0'
    serial.baudrate = 9600
    serial.timeout = 1
    serial.writeTimeout = 1
    serial.open()

    # make stdin a non-blocking file
    fcntl.fcntl(sys.stdin, fcntl.F_SETFL, os.O_NONBLOCK)

    # post startup message to other XBee's and at stdout
    serial.writelines("RPi #1 is up and running.\r\n")
    print "RPi #1 is up and running."

    switchColor(CMD_OUTPUT_TEXT)
    print "Entering loop to read and print messages (Ctrl-C to abort)..."

    try:
        while True:
            # read a line from XBee and convert it from b'xxx\r\n' to xxx and print at stdout
            switchColor(TERM_OUTPUT_TEXT)
            line = serial.readline().decode('utf-8')
            if line:
                print line

            # read data from the keyboard (i.e. stdin) and send via the XBee modem
            switchColor(TERM_INPUT_TEXT)
            try:
                line = sys.stdin.readline()
                serial.writelines(line)
            except IOError:
                time.sleep(0.1)
                continue

    except KeyboardInterrupt:
        printc("\n*** Ctrl-C keyboard interrupt ***", ERROR_TEXT)
        serial.writelines("RPi #1 is going down.\r\n")

    finally:
        switchColor(CMD_INPUT_TEXT)