with open('com1', 'r') as f:

gert gert.cuykens at gmail.com
Fri Apr 3 19:21:31 CEST 2009


On Apr 3, 3:44 pm, "Gabriel Genellina" <gagsl-... at yahoo.com.ar> wrote:
> En Thu, 02 Apr 2009 20:04:14 -0300, gert <gert.cuyk... at gmail.com> escribió:
>
> > On Apr 2, 8:53 pm, Kushal Kumaran <kushal.kuma... at gmail.com> wrote:
> >> On Thu, 2 Apr 2009 10:01:02 -0700 (PDT)
> >> gert <gert.cuyk... at gmail.com> wrote:
> >> > from subprocess import *
> >> > check_call(['mode', 'COM1:9600,N,8,1,P'],shell=True)
> >> > while True:
> >> >     with open('com1', 'r') as f:
> >> >         for line in f:
> >> >              print(line)
>
> >> > This works very well except for one thing. After a reboot I have to
> >> > launch 1 time any windows serial exe application no mater with one,
> >> > that just opens an closes the com port, before i can launch this
> >> > script. The script keeps on working even after closing and reopening
> >> > it, until i reboot the pc. Then again I have to launch one time a
> >> > serial.exe and close it again. The exe does not run anything in the
> >> > background it just does something in windows python does not do when
> >> > it reads from the com port after a fresh reboot.
>
> >> > And i really appreciate it if somebody knew what it was.
>
> >> I don't know why you're getting this behaviour, but have you tried using
> >> a python library for accessing the serial port?  
> >> Seehttp://pyserial.wiki.sourceforge.net/pySerial.
>
> > I am sorry but I don't think pyserial will work on python3.x and I
> > also like to know whats going on before I consider it.
>
> A real Windows program accessing the serial port is likely to use  
> SetupComm, SetCommState, and other functions in addition to CreateFile.
> Seehttp://msdn.microsoft.com/en-us/library/aa363196(VS.85).aspx
>
> pySerial takes care of all those details, as suggested.
>
> > Maybe its a bug in open() on windows?
>
> open() doesn't care about the file name; it's the OS that interprets  
> "com1" as a serial port.

I do understand, and I went looking into pySerial, but it is a long
way from getting compatible with python3.x and involves other libs
that are big and non pyhton3.x compatible.

Also I can not imaging activating a com port wouldn't be possible with
a check_call dos instruction. I can already configure com with mode.




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