[Tutor] question about serial coms

[Hans Dushanthakumar]

Lock() is provided by the threading module.
see
http://docs.python.org/lib/module-threading.html 
&
http://docs.python.org/lib/lock-objects.html

Cheers
Hans


-----Original Message-----
From: nephish [mailto:nephish at xit.net] 
Sent: Tuesday, 15 November 2005 11:23 a.m.
To: Hans Dushanthakumar
Cc: Hugo González Monteverde; tutor
Subject: RE: [Tutor] question about serial coms

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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