Begins a continuous analog generation, calling a provided function
         at a rate of 10Hz

        :param aichans: name of channel(s) to record (analog input) from
        :type aichans: list<str>
        :param update_hz: Rate (Hz) at which to read data from the device input buffer
        :type update_hz: int

def start_continuous(self, aichans, update_hz=10):
        """Begins a continuous analog generation, calling a provided function
         at a rate of 10Hz

        :param aichans: name of channel(s) to record (analog input) from
        :type aichans: list<str>
        :param update_hz: Rate (Hz) at which to read data from the device input buffer
        :type update_hz: int
         """
        self.daq_lock.acquire()

        self.ngenerated = 0 # number of stimuli presented during chart run
        npts = int(self.aifs/update_hz) #update display at 10Hz rate
        nchans = len(aichans)
        self.aitask = AITask(aichans, self.aifs, npts*5*nchans)
        self.aitask.register_callback(self._read_continuous, npts)
        self.aitask.start()