question from beginner

dario keygrand at libero.it
Thu Sep 8 18:14:15 CEST 2005


Thanks Dennis. In effect stringZVEI doesn't remain empty after the
.read method, then the loop is executed 1 time.

How could be a 'while' loop to wait a no empty string from the serial
port?

Dario.

Dennis Lee Bieber ha scritto:

> On 7 Sep 2005 07:14:37 -0700, "dario" <keygrand at libero.it> declaimed the
> following in comp.lang.python:
>
> > Hi, Im new on phyton programming.
> > On my GPRS modem with embedded Phyton 1.5.2+ version, I have to receive
> > a string from serial port and after send this one enclosed in an
> > e-mail.
> > All OK if the string is directly generated in the code. But it doesn't
> > works if I wait for this inside a 'while' loop. This is the simple
> > code:
> >
> 	First -- post the real code file would help -- the indentation of
> the first two statements below is wrong.
>
> > global stringZVEI
> >
> 	This does nothing at the top level -- if only makes sense INSIDE a
> "def" block, where it has the effect of saying "this variable is not
> local to the function"
>
> >   while stringZVEI=='':
> >       MOD.sleep(10)
>
> 	There is something wrong with
>
> 	import time
> 	time.sleep(<seconds>)
> ????
>
> >       a=SER.send(' sono nel while stringZVEI==st vuota')
> >       stringZVEI = SER.readbyte()
>
> 		#for debug
> 		print "%2X " % stringZVEI
>
> >       a=SER.send(' stringZVEI=')
> >       a=SER.send(stringZVEI)
> >
> > MOD and SER are embedded class maked by third part.
> >
> > >From my very little debug possibility it seem that loop is executed 1
> > time only nevertheless stringZVEI is still empty. The line
> >       a=SER.send(' stringZVEI=')
> > work correctly but
> >
> > a=SER.send(stringZVEI)
> >
> 	What does .readbyte() do if there is no data to be read? Since your
> loop is based on a totally empty string, if .readbyte returns /anything/
> (even a "null" byte -- 0x00) your loop will exit; and a null byte may
> not be visible on the send...
>
> --
>  > ============================================================== <
>  >   wlfraed at ix.netcom.com  | Wulfraed  Dennis Lee Bieber  KD6MOG <
>  >      wulfraed at dm.net     |       Bestiaria Support Staff       <
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