serial_switcher.py

#!/usr/bin/env python

import serial
import time
import urllib2

turn_on = '$KE,REL,1,1\r\n'
turn_off = '$KE,REL,1,0\r\n'
state = False
url = 'http://wasteland.dev.it-the-drote.tk/tmp/led.state'

ser = serial.Serial('/dev/cu.usbmodem5d21', 9600)

while True:
    response = urllib2.urlopen(url)
    msg = response.read()
    print msg
    if msg == 'off\n':
        ser.write(turn_off)
    elif msg == 'on\n':
        ser.write(turn_on)

    time.sleep(1)