pyserial time based repeated data request

Question

I am writing an application in python to acquire data using a serial communication. I use the pyserial library for establishing the communication. What is the best approach to request data in an interval (eg every 2 seconds). I always have to the send a request, wait for the answer and start the process again.

show example of the code you have. Makes it more clear what to recommend. — David Bern, Aug 28 '17 at 06:53
Serial communication never offering used a `time.sleep()` functions. Send request >> wait data `while ser.inWaiting() < 1 : data=ser.read(ser.inWaiting()); if data : break;` >> make new request ! Opps need a `try-except` for what happen on serial bus! — dsgdfg, Aug 28 '17 at 07:01

score 0 · Answer 1 · answered Aug 28 '17 at 06:40

0

if this a "slow" process, that does not accurate time precision, use a while loop and time.sleep(2) to timeout the process for 2 seconds.

answered Aug 28 '17 at 06:40

sancelot

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score 0 · Answer 2 · answered Aug 28 '17 at 07:31

I thought about using a separate thread to prevent the rest of the applicaiton from freezing. The thread takes a function which requests data from the instrument.

class ReadingThread(Thread):
    '''Used to read out from the instrument, interrupted by an interval'''
    def __init__(self, controller, lock, function, queue_out, interval=3 , *args, **kwargs):
        Thread.__init__(self)
        self.lock = lock
        self.function = function
        self.queue_out = queue_out
        self.interval = interval        
        self.args = args
        self.kwargs = kwargs

        self.is_running = True

    def run(self):
        while self.is_running:
            with self.lock:
                try:
                    result = self.function(self.args, self.kwargs)
                except Exception as e:
                    print(e)
                else:
                    self.queue_out.put(result)
            time.sleep(self.interval)

    def stop(self):
        self.is_running = False

pyserial time based repeated data request

2 Answers2