[Tutor] question about serial coms
nephish
nephish at xit.net
Mon Nov 14 23:22:33 CET 2005
ok, lock is something you wrote yourself ?
i can't find it in the docs. However, i think i can essentially build
the same thing.
the serial module i use is pyserial. pyserial.sourceforge.net.
the docs are a wee bit on the sparce side. But i think i can pull it
off. Thanks for your help.
shawn
On Tue, 2005-11-15 at 10:58 +1300, Hans Dushanthakumar wrote:
> I believe that the drivers take care of that, however, I did use locks to make sure that there were no conflicts.
>
> In the listener thread I had something along the lines of:
>
> Acquire lock
> readline() from the ser port
> Release lock
>
> And in the sender thread,
>
> Acquire lock
> send msg over ser port
> Release lock
>
> Cheers
> Hans
>
> -----Original Message-----
> From: nephish [mailto:nephish at xit.net]
> Sent: Tuesday, 15 November 2005 10:47 a.m.
> To: Hans Dushanthakumar
> Cc: Hugo González Monteverde; tutor
> Subject: RE: [Tutor] question about serial coms
>
> well thats encouraging, did you have to do anything special to prevent an error when trying to read or write at the same time ?
>
> thanks
> sk
>
>
> On Tue, 2005-11-15 at 09:29 +1300, Hans Dushanthakumar wrote:
> > Ive worked on a similar application. I used one thread to read from the serial port and another one to handle the writes.
> >
> > -----Original Message-----
> > From: tutor-bounces at python.org [mailto:tutor-bounces at python.org] On
> > Behalf Of Hugo González Monteverde
> > Sent: Tuesday, 15 November 2005 7:36 a.m.
> > To: nephish
> > Cc: tutor
> > Subject: Re: [Tutor] question about serial coms
> >
> > Hi Nephish,
> >
> > Are you using pyserial or rolling your own? Normally you can write and read to the /dev/ttySXX file at the same time; since they're special files, not ordinary files, the driver handles that.
> >
> > Handling both writing and reading in your program's flow control is a wholly different matter, though. You might need to use select() to avoid blocking.
> >
> > Are you using two completely different scripts for reding and writing?
> >
> > There is some valuable info, if not about python, in the Serial Programming howto, at:
> >
> > http://www.tldp.org/HOWTO/Serial-Programming-HOWTO/
> >
> >
> > Hugo
> >
> > nephish wrote:
> > > Hey there,
> > > i am developing on a linux computer with the serial module. Now, i
> > > already am able to recieve info from a serial RS232 device and
> > > process everything ok. What i need to do now is write to the serial
> > > device, but i also need to be able to not interrupt the script that
> > > is reading from it.
> > > I guess my question is, do i have to interrupt the reading script
> > > to write to the same RS232 device ?
> > > and if so, how do i do that?
> > >
> > > thanks,
> > > shawn
> > >
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