On Mar 29, 4:26 pm, "Diez B. Roggisch" <[EMAIL PROTECTED]> wrote: > 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.
Transmit observed minus expected to cluster. What kind of tables does the input device build? -- http://mail.python.org/mailman/listinfo/python-list