Serial port gotcha with win32all

Lee Morgan unknown at lee-morgan.net
Wed Oct 24 03:40:33 CEST 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



More information about the Python-list mailing list