Question

Sometimes I do not get any data in via the serial interface and I want to catch this case with an exception in the following way:

ser          = serial.Serial(3)
ser.baudrate = 115200
timeout      = 1

while (some condidion)
  try:
    dump = ser.read(40)
  except ser1.SerialTimeoutException:
    print('Data could not be read')

ser.close()

However, when I run this program, the exception is never caught when no
data is in the buffer and I am stuck in an endless loop. Anyone an idea
what I am doing wrong here?

Answer 1

I didn’t even know about that exception. After having a look at the API documentation, you’ll see that this exception only applies to write().

If you read(), you’ll just have a shortened or even empty output.

And this applies only if you have opened the connection with a timeout. Something like serial.Serial(3, timeout=.1).