Hendrik van Rooyen schrieb: > Hi, > > I have been doing some tests on a device that > we are thinking of incorporating into a product, > and I have seen that reception on a serial port > at 115200 baud over about six metres of RS-232 > cable makes mistakes, to the order of 125 lines > with errors in them out of approximately 18.4 > million lines of 65 or so chars - about one errored > line in 147000, or one error character in 95 million. > > The PC that is making the errors is a 64 bit dual > core AMD machine running at 2 Gig, and I am > running stock standard Open Suse 10.3 with > the supplied Python 2.5. > > What kind of bothers me is the nature of the errors - > I seem to get only missing characters, as if an > interrupt was missed. There are no munged characters > as one would expect if the errors were bit related. > > Has anyone else seen anything like this, and am I worrying > needlessly? > > I realise that my production protocols will easily handle > this almost non existent level of error - but if this were in > microcontroller code that I had written myself, I would > suspect that I was spending too long in some critical > section of code.
RS232 is unfortunately as bad as a "protocol" as it can get. I've used it for communication with a microcontroller for just a few bytes every second. And it failed miserably, so I needed to implement a protocol on top of it. The machine spec is totally irrelevant - what is interesting is the serial hardware you use. Are you by any chance using a serial2usb-converter? I had nothing but troubles with these. if you have the chance, try & attach a machine with legacy rs232 port, and see if the errors still remain. Diez -- http://mail.python.org/mailman/listinfo/python-list
