Serial port gotcha with win32all
Lee Morgan
unknown at lee-morgan.net
Tue Oct 23 21:40:33 EDT 2001
Isaac, any chance of releasing uspp under a more liberal license?
ibarona at tid.es (Isaac Barona) writes:
> On Sat, 20 Oct 2001 10:01:13 GMT, Mark Hammond <MarkH at ActiveState.com>
> wrote:
>
> >Markus Demleitner wrote:
> >
> >> Hi,
>
> Hi Markus!!!
>
> >>
> >> I'm getting increasingly desperate. All I'm trying to do is
> >> attach a little serial gizmo that runs just fine when talked
> >> to from a linux box (using some homegrown python software) to
> >> a machine plagued by Windows 2000.
> >>
> >> Realizing that termios doesn't buy me much in win32, I soon
> >> ran across uspp which basically acts as a wrapper around the
> >> win32all or termios modules on the respective platforms.
>
> I am uspp's author, so I hope to help you.
>
> >>
> >> Under linux, uspp worked quite as well as my own termios-based
> >> code (perhaps not too surprisingly). Under win32, however,
> >> write()s seem to work but read()s consistently fail with a
> >> "incorrect paramater" exception in a call to win32file.ReadFile.
> >>
> >> Now, clearly the OpenFile succeded, and the handle didn't change
> >> between the open and the read, the error is not in the number
> >> of bytes to read (passing some weird object there causes a
> >> ParameterError, as expected), and in general I've not been
> >> able to gain any clue as to what is going on. The win32all
> >> sources seem somewhat intimidating, at least for me with
> >> no knowledge of the win32 API whatsoever.
>
>
> It seems that the interface in the overlapped I/O mode to the
> win32file.ReadFile function has changed in new versions.
>
>
>
> Harald Angelo sent me this patch that seems to correct the problem
> (not using overlapped I/O).
>
> self.__handle=CreateFile (dev,
>
> win32con.GENERIC_READ|win32con.GENERIC_WRITE,
> 0, # exclusive access
> None, # no security
> win32con.OPEN_EXISTING,
> win32con.FILE_ATTRIBUTE_NORMAL
> # |win32con.FILE_FLAG_OVERLAPPED
> ,
> None)
>
> Just now I am working in a new release of the library but in the
> meantime apply this patch and see what happend.
> Let me know the results.
>
> Greetings from Spain,
> Isaac.
>
>
> >>
> >> So -- can anyone give me a hint where to start getting a
> >> grip on this one?
> >
> >Look at the
> >
> >win32comport_demo.py sample - it seems to work just fine. Failing that, post the smallest possible code snippet you can come up with that demonstrates the problem.
> >
> >
> >Mark.
> >
> >
> >
>
--
Lee Morgan
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