PySerial and termios

Glazner yoavglazner at gmail.com
Mon Nov 30 22:38:25 CET 2009


On Nov 30, 7:41 pm, Grant Edwards <inva... at invalid.invalid> wrote:
> On 2009-11-30, a b <putumutu... at gmail.com> wrote:
>
> > I have a pain in the a** problem with pyserial- it works 90%
> > of time but on the 10% of time it thorows and termios.error
> > exception with the value (5, 'Input/output error') and i
> > cannot get rid of it :(
>
> Sounds like faulty converter or a bug in the device driver to
> me.
>
> > The system works as follows:
> > A device sends out rs485 data -> rs485 to rs232 converter converts it -
> >> an rs232->usb cable attatched to a computer reads the data. Until
> > now it hasn't bothered me too much since it hasn't been a lot
> > of data (every time i get this exception i unload the pl2303
> > module from kernel, then reload it, open the com port
>
> Does that get rid of the error?  If so, then it's definitely a
> problem with the converter or device-driver.
>
> > and hope it won't happen soon). But now the amount of data is
> > getting bigger and the exceptions in the log are quite
> > bothering already so if anyone has a good idea what could
> > affect it i'd be very glad... oh and the settings for the port
> > opening are: self.ser = serial.Serial(self.port,
> > self.baudrate, rtscts=0, xonxoff=0, timeout=0)
>
> Unless you want to try to troubleshoot the device driver and
> USB traffic, the only suggestion I have is to try different
> converters and/or different versions of the driver.
>
> --
> Grant Edwards                   grante             Yow! If Robert Di Niro
>                                   at               assassinates Walter Slezak,
>                                visi.com            will Jodie Foster marry
>                                                    Bonzo??

Try to use Portmon to see if your data is sent correctly.(if not, then
its the cable/converter)
http://technet.microsoft.com/en-us/sysinternals/bb896644.aspx
or another port monitor tool for other OS.



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