ekm.py

import serial, time

ser = serial.Serial(
   port='/dev/ttyUSB0',
   baudrate=9600,
   parity=serial.PARITY_EVEN,
   stopbits=serial.STOPBITS_ONE,
   bytesize=serial.SEVENBITS,
   timeout=0.5
)

if ser.isOpen():

    try:
      time.sleep(0.5)  
      numOfLines = 0
      REQUEST = "x2f\x3f\x30\x30\x30\x30\x30\x30\x30\x31\x37\x36\x36\x31\x21\x0d\x0a"

      while True:
         print("parametro: " + REQUEST)
         ser.write(REQUEST)
         time.sleep(3)
         
         response = ser.readline()
         print("request data: " + response)

         numOfLines = numOfLines + 1
         if (numOfLines >= 5):
            break

      ser.close()
    except Exception, e1:
      print "error...: " + str(e1)

else:
    print "no se puede abrir el puerto serial"