set data polling rate for sleepy end device

        Args:
            iPollingRate: data poll period of sleepy end device

        Returns:
            True: successful to set the data polling rate for sleepy end device
            False: fail to set the data polling rate for sleepy end device

def setPollingRate(self, iPollingRate):
        """set data polling rate for sleepy end device

        Args:
            iPollingRate: data poll period of sleepy end device

        Returns:
            True: successful to set the data polling rate for sleepy end device
            False: fail to set the data polling rate for sleepy end device
        """
        print '%s call setPollingRate' % self.port
        print iPollingRate
        try:
            cmd = WPANCTL_CMD + 'setprop NCP:SleepyPollInterval %s' % str(iPollingRate*1000)
            print cmd
            return self.__sendCommand(cmd)[0] != 'Fail'
        except Exception, e:
            ModuleHelper.WriteIntoDebugLogger('setPollingRate() Error: ' + str(e))