Serial I/O problem with pywin32 ?

[Impotent Verse]

On 3 Sep, 16:33, "Diez B. Roggisch" <de... at nospam.web.de> wrote:
> Xavier schrieb:
>
>
>
> > Hi,
>
> > I try to access to a Bluetooth GPS data-logger with Python. I use
> > pySerial.
>
> > Sending and receiving little messages (~100 char) works fine. However,
> > when I ask the GPS to dump the trails, it returns some Mbytes and here
> > is the problem : in the stream of bytes, I randomly losts chunks of
> > ~100bytes.
>
> > I tried USPP and pyBlueZ instead of pySerial : same problem.
>
> > It doesn't like it is a bufferoverun bug from me because :
> >  - the GPS seems to wait when I do not read the stream,
> >  - there is never more than 200 inWainting() characters,
> >  - my code to test it is quite simple :
>
> >   seriallink = serial.Serial("COM40")
> >   fileName = "data.dump"
> >   out = open(fileName, 'w')
> >   while 1:
> >     c = seriallink.read()
> >     out.write(" %0.2X" % ord(c))
> >     print "*",
> >   out.close()
>
> > (with pyBluez :
> > sock=BluetoothSocket( RFCOMM )
> > sock.connect(("00:0A:...", 1)))
>
> > I tried my program on two different PC with two Bluetooth dongle,
> > (with pySerial, USPP, pyBluez).
> > The same things are :
> >  - windows
> >  - the GPS (which works fine with the dumper program of the
> > constructor)
> >  - pyWin32
>
> > I've found another guy with a similar problem :
> >http://www.generation-nt.com/reponses/rs232-entraide-142097.html
> > He says:
> >  - no problem with little messages
> >  - lost of one byte every hour when receiving a lot of data
>
> > Any known problems with pywin32 and serial I/O when downloading a big
> > stream of data ?
>
>  From my experience with serial lines I'd say: that's the culprit. They
> tend to be rather unreliable, as there is no real protocol ensuring data
> integrity.
>
> You might consider downloading chunks of data if that's somehow
> possible, and re-try failed chunks.
>
> Diez

Could be hardware flow control. See this sometimes on the bluetooth
connections that are using Serial Port Protocol and the hardware flow
control hasn't been physically implemented.

Do you lose data after exactly the same amount of data has been
received?