def serial_ports():
    """ Lists serial port names
        :raises EnvironmentError:
            On unsupported or unknown platforms
        :returns:
            A list of the serial ports available on the system
    """
if sys.platform.startswith('win'):
    ports = [('COM%s' % (i + 1)) for i in range(256)]
elif sys.platform.startswith('linux') or sys.platform.startswith('cygwin'):
    ports = glob.glob('/dev/tty[A-Za-z]*')
elif sys.platform.startswith('darwin'):
    ports = glob.glob('/dev/tty.*')
else:
    raise EnvironmentError('Unsupported platform')
Listing available com ports with Python