问在pyfirmata中，如何设置字符串消息的处理程序？

EN

from logic.ModuleClass import Module
from events.EventDispatcherClass import Event
from pyfirmata import Arduino, util
import pyfirmata

class Comm(Module):
    """
    Handles the communication between python and arduino
    AttachTo: ""
    """

    NAME = "Communicator"

    def __init__(self, port):
        super(Comm,self).__init__(Comm.NAME)
        self.board = Arduino(port)
        # start an iterator thread so that serial buffer doesn't overflow
        it = util.Iterator(self.board)
        it.start()

        self.board.add_cmd_handler(pyfirmata.pyfirmata.STRING_DATA, self._messageHandler)

    def _messageHandler(self, *args, **kwargs):
        print args

    def update(self):
        super(Comm,self).update()

    def writeData(self,data):
        #print data
        self.board.send_sysex(pyfirmata.pyfirmata.STRING_DATA,data)

    def dispose(self):
        super(Comm,self).dispose()
        try:
            self.board.exit()
        except AttributeError:
            print "exit() raised an AttributeError unexpectedly!"+self.toString()

Firmata.sendString("test");