[hylafax-devel] Re: ["Dr. Harald Pollack" <Harald.Pollack@datanews.at>] Re: Re: My RTN patch and many other changes/enhancements, thOR

[Steve Williams <steve@genie96.com>]

Hi Dmitry/Harald/All,

First, I can see that this is almost a "religious" topic, but I am not an
"evangalist".

I agree 100 % that doing an AT&W in an application is a horrible thing.  
But, sometimes we don't have choices in the software we run ( read
government supplied...) I did learn something in that I WAS NOT aware that
there is any physical limit to the number of "saves" to the NVRAM.  This
is GOOD information to know.

Question Dmitry/Harald, , do you have any experience on what happens when
the NVRAM "wears out"?

Now, to explain my background a bit...

We have 18 modems on an AIX computer that we use to support our clients
Canada wide.  Those modems do LOTS of things.  We use UUCP to communicate
to our clients, our clients use UUCP to communicate to us.  We use the
modem pool to send in information to the Government, and our support staff
have direct access to the modems ( yes, they DO know what AT commands are
).

We also have a few other data communication applications that use our
modem pool to communicate to hospital labs, etc ( and unfortunately, one
of those is the ones that does the at&w with bogus codes...and we don't
have the source code for it and I don't want to a binary patch too
much..).

On top of all that, we use the modems for sending faxes to our clients,
and I run the Calgary TPC Cell.

The only thing we don't use the modems for is for incoming fax.

Now....

I agree that ATZ is an adequate ( my words, not yours ) to resetting the
modem if there is ONLY ONE APPLICATION accessing the modem.  ( sorry to
shout!!).

In a mixed data/fax/human fingers environment, where the status of the
modem is completely unknown, ATZ just doesn't cut it.  I don't really see
any command that does the job adequately.  As far as I am concerned, in a
mixed environment, where you can't depend on the state of the modem, the
only way is to set the modem to factory defaults and then program the
whole thing from scratch.... AT&F is the only SURE BET for resetting the
modem!!

That is a rather drastic approach ( which HylaFAX does not take ), but it
does program most of the IMPORTANT things each time before it sets the
modem status to "Running and Idle".  HylaFAX is FANTASTIC in it's
reliability in our environment, and I feel that a large part of it is not
making too many assumptions about status of the modem.

Enough about ATZ...it's not that important in my book, but I just wanted
to clarify my personal experiences.


As for flow control...

Most modems have the ability to have different flow control schemes for
data and for fax.

I agree that more modems work with xon flow control IN FAX MODE.

xon flow control in DATA MODE causes NO END OF GRIEF with file transfers.

Which is more important I guess depends on the environment....

But, HylaFAX does have the flexibility to switch to xon flow control when a
fax connection is established.

Some of the config skeleton files have:
ModemAnswerFaxBeginCmd: "<19200><xon>" # lock line rate & switch flow control

Again, it's not a big issue, but I really think that things should default
to what is going to cause the LEAST amount of problems, and in data mode,
hardware flow control causes WAY FEWER problems than xon/xoff flow
control.

Harald appears to have INTENSE experience with the fax side of things, and
I do acknowledge that things that have been talked about are WAYYYYY above
my head.  However, there are two of us supporting over 350 cpu's across
Canada, each one with a modem on them, and I know what works ( from the
seat of pants approach...hence, I didn't know about AT&W having limited
#'s of use ).  My statements are based on trial and error over the last 15
years, ( 300 baud accoustical coupled on CP/M!!) and ALOT of bruises on my
forehead trying to get some pretty complicate environments working.


Thanks for reading... and have a great weekend!!
> 
> --=-=-=
> 
> 
> Sorry, but I have to forward this. Harald! Please do not leave the list,
> here is at least one person (me) who needs your comments :-) Just ignore
> messages, that exasperate you, I will fight their authors myself :-)))
> 
> 
> --=-=-=
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> From: "Dr. Harald Pollack" <Harald.Pollack@datanews.at>
> To: "Dmitry Bely" <dbely@mail.ru>
> Date: Fri, 14 Apr 2000 08:22:10 -0100
> Reply-To: "Dr. Harald Pollack" <Harald.Pollack@datanews.at>
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> Subject: Re: [hylafax-devel] Re: My RTN patch and many other changes/enhancements, third edition :-)
> Message-Id: <E12fzTx-000AJT-00@mx5.mail.ru>
> 
> On Thu, 13 Apr 2000 13:44:33 -0600 (MDT), Steve Williams wrote:
> 
> Hello Dmitry!
> 
> The following is EXACTLY THE REASON WHY, I have had decided to cancel participation on Hylafax 
> mailinglist!!!
> 
> >> 8. Default value for ModemResetCmds is now "ATZ". (ModemSoftResetCmd
> >> parameter was never used :-)) (faxd/ModemConfig.c++, man/config.4f)
> >> 
> >
> >This is REALLY bad!!  ATZ sets modems to totally random settings, depending
> >on how the last program did that did an AT&W had configured the modem.
> 
> Such applications HAVE TO BE REMOVED from harddisk is quick as possible!!!!
> 
> >I know FOR A FACT that one of our apps that dials out does an ATE0Q1&W ( turns
> >off echo and result codes and saves it ).
> 
> This behaviour is ANNOYING, first because it leave the modem in an unuseable setup, and second, 
> WRITING to the non volatile RAM (NV_RAM, which is in fact an EEPROM) of modem by AT&W is LIMITED 
> to a few thousand times!!!
> 
> >When HylaFAX starts up, and does 
> >an ATZ, things are going to break because it will NEVER see an OK come back.
> 
> As long as any people use such applications, there is no way to make behaviour of HylaFax 
> better!!!
> 
> >My personal opinion is that ATZ has ABSOLUTELY no place in ANY config file 
> >because there is no predicting what exactly it will do.
> 
> ATZ is the ONE AND ONLY initialisation!!!!!!!!!!!!!!!!!!
> 
> >
> >> 
> >> 10. Default value for ModemFlowControl is now XONXOFF -- I think, reasonable
> >> default for the most modems. (faxd/ModemConfig.c++, man/config.4f)
> >> 
> >
> >Humm... what is the default now?  I would personally say that HARDWARE flow
> >control would be the preferable Default flow control.
> 
> This is also a very bad asumption!
> 
> AThat way, if people
> >are using DATA mode for binary file transfers, there won't be suspicious 
> >"hangs" when XOFF characters get sent to the modem.
> 
> This is also a fault of the operating system and not of the fax application!!!
> 
> My blood-pressure raises to letal high values, if I must read such nonesense like above. I think 
> I will retire from this mailing list as soon as possible again!
> 
> 
> Mit herzlichen Gruessen / Yours sincerely
> 
> Dr. Harald Pollack
> 
> Harald.Pollack@DATAnews.at
> 
> 
> --=-=-=
> 
> 
> Hope to hear from you soon,
> Dmitry
> 
> --=-=-=--
> 
> 
> 
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> 


-- 
	Steve Williams, Calgary, Alberta, Canada
	Genie Computer Systems Inc.
	steve@genie96.com

"A man doesn't begin to attain wisdom until he recognizes that he is 
 no longer indispensable."
- Admiral Richard E. Byrd ( 1888-1957 )

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