Mysterouse failure... sendfax

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Hi.

Jeff Barrow wrote:
> > > 05/31 12:40:02 sendfax: experimental test release 1.1.6-May05
> > [..]
> > > 05/31 12:42:28 yS0 fax_send: 'AT+FDT'
> > > 05/31 12:42:28 yS0 fax_wait_for(CONNECT)** found **
> > > 05/31 12:42:28 yS0 sending f3.g3...
> > > 05/31 12:42:29 yS0 page complete, 7834 bytes sent
> > > 05/31 12:42:29 yS0 sending DLE '.'
> > > 05/31 12:42:48 yS0 connection hangup: '+FHS:54'
> > 
> > Well, it's the typical "the remote end has just hung up and I can't get a
> > response back" problem. It usually happens if the modem has a fairly bad
> > end-of-page timing, there was too much line noise, the remote end failed
> > for some other reason, or whatever.
> > 
> > As fax is half-duplex, you can't know at that place whether the third page
> > *really* arrived at the remote site -- as you didn't get the final "yes,
> > fine, I got it" code, you have to assume it failed, and that's what the
> > modem signalling with +FHS:54.
> BUT the modem responded with
> 05/31 12:42:48 yS0 got response: 'OK'

This is meaningless, if it has signalled "+FHS:<whatever>" before.
+FHS:xx means "the connection is now, finally, and irrevocably terminated,
and the result code is <xx>". 00 meaning "all is fine", everything else
meaning "something *very bad* has happened".

> and then the log shows
> 05/31 12:42:48 ##### failed transmitting f3.g3: phone="[OMIT]",
> 	+FHS:54, dev=ttyS0, time=165s, acct=""

Sure: it was an erroneous end-of-page. Just believe me, or read the
standard documents yourself to see how it works.

> This was one of those strange modems that I had to tell it to ignore the
> carrier detect line during transmission (error on page 2), btw.
> 
> Oh, and here's the ending of a 10-page transmission to a newer fax
> machine:
> 05/31 15:07:29 yS0 got response: 'OK'
> 05/31 15:07:29 yS0 fax_send: 'AT+FDT'
> 05/31 15:07:29 yS0 fax_wait_for(CONNECT)** found **
> 05/31 15:07:30 yS0 sending f10.g3...
> 05/31 15:07:33 yS0 page complete, 10152 bytes sent
> 05/31 15:07:33 yS0 sending DLE '.'
> 05/31 15:07:42 yS0 connection hangup: '+FHS:00'
> 05/31 15:07:42 yS0 got response: 'OK'

Now this is perfectly ok. "+FHS:00" means "I have hung up, and all is
nice and beautiful".

[..]
> The only difference I saw was that the fax_send: 'AT+FCLASS=0' line shows
> up before the success line, where that SAME line showed up AFTER the
> failure line before... 

Just look closely again. +FHS:54 vs. +FHS:00. There's a meaning to that
code, you know...?

> could it be a time-out problem with sendfax?

I really appreciate if people start guessing around before trying to
understand the fax protocol... *sigh*

gert


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Gert Doering - Munich, Germany      gert@greenie.muc.de
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