Raise TimeoutError on timeout about pyserial HOT 3 CLOSED

Thanks for your reply, @zsquareplusc. Checking the length of the returned bytes did not work for me. console.read() timed out repeatedly and there were never any bytes returned.

If I requested a specified number of bytes with a timeout, I would either expect that exact number of bytes or an exception. I am not sure if it would also be OK to return all bytes that have been read up to the timeout. That would definitely need to be documented and users would need to check whether the received data is complete. I think there is little value in aborted data, because the timeout can strike at any given instance, so users would need to program every eventuality. In practice this means to handle as many cases as characters requested. Restarting the communication should be easier to program in most cases.

from pyserial.

You can detect that there was a timeout by checking the length of returned bytes versus the number of bytes requested. It is more like an EOF in Python, rather than a timeout error. That is also how some protocols are using the timeout, as packet delimiter.

An exception would be inconvenient in many cases. E.g. consider reading more than one byte but fewer arrive, the timeout strikes. Then you'd still expect to get the bytes, but how? Attached to the exception? Probably not where most people would expect to find data. When they would be returned with the current read() call, then the timeout exception would need be raised in the next call which is certainly also not what one would expect.

from pyserial.

I found a workaround of using threads that communicate over queues:

from threading import Thread

import serial
from queue import Queue


def _reader(console, queue_read):
    while True:
        try:
            response = console.readline().decode('ASCII')
        except TypeError:
            pass
        response = response.strip()
        if response != '':
            queue_read.put(response)

def _writer(console, queue_write):
    while True:
        message = queue_write.get()
        console.writelines([message.encode('ASCII')])

console = serial.Serial('/dev/ttyACM0', 9600, timeout=1)
queue_read = Queue(maxsize=1)
queue_write = Queue(maxsize=1)

Thread(target=_reader, args=([console, queue_read])).start()
Thread(target=_writer, args=([console, queue_write])).start()

while True:
    # TODO calculate conversation starter

    message = '123;123;123'
    queue_write.put(message)

    pulse_durations = queue_read.get()
    print(pulse_durations)

    # TODO calculate response

from pyserial.