[comp.sys.mac.comm] Problems using ZTerm and sz/rz

okamoto@hpcc01.HP.COM (Jeff Okamoto) (03/22/91)

I'm having a strange problem with ZMODEM file transfers and am
wondering if anyone can help.

I'm using ZTerm 0.85 on a Mac II running 6.0.5 with a fair number of
INIT's.  I have a Racal-Vadic 9600 baud modem which speaks V.32
connected to the modem port.  On the Unix machine at work, I'm using
sz version 3.03 5-09-89 and rz version 3.00 4-19-89.  The bank of
modems that eventually connect to the Unix machine are connected
via a dialback system.

The symptom: when uploading both text and binary files, I will get
ZRPOS errors which will eventually cause the file transfer to fail.
For a while, these consistently occurred after 1024 bytes had been
transferred, but recently, the transfer went as far as 20K before
the ZRPOS's started.  The weird part is that downloading text and
binary files has never failed (yet).

I have tried forcing the mode of the transfer with options to rz and
options in ZTerm.  I believe I have also tried escaping control
characters (-e option to rz).  I have tried cutting down the packet
size in ZTerm to 256 characters.  None of these seems to make any
difference.

The ROM in my modem WAS recently upgraded, and the time of the change
vaguely corresponds to the difficulties I'm having.  I do not believe
any of the non-volatile settings were changed.  I also don't quite
understand why, if this is the true cause of my problem, I should
still be able to download, but not upload.

To add to the craziness, just last night, I managed to upload a small
binary file and it came through okay.

My first question is: what would cause rz to begin issuing ZRPOS's?
My second question is: why is this happening?

The EC (error correction) LED on the modem is on while I am connected.
I believe the modems are using MNP5.  The cable connecting my modem to
the Mac is a standard cable (ie, it isn't a hardware handshake-capable
cable).

I would appreciate any help or suggestions that you might have to
offer.

Dave.Alverson@samba.acs.unc.edu (Dave Alverson) (03/25/91)

> The symptom: when uploading both text and binary files, I will get
> ZRPOS errors which will eventually cause the file transfer to fail.

Your best bet for upload problems is th try setting the window limit
in the ZModem Parms dialog.  Try 1024 or 2048 and see if that helps.

  -- Dave Alverson

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dbert@geech.gnu.ai.mit.edu (Douglas Siebert) (03/25/91)

In article <1970001@hpcc01.HP.COM> okamoto@hpcc01.HP.COM (Jeff Okamoto) writes:
>I'm having a strange problem with ZMODEM file transfers and am
>wondering if anyone can help.
>
>I'm using ZTerm 0.85 on a Mac II running 6.0.5 with a fair number of
>INIT's.  I have a Racal-Vadic 9600 baud modem which speaks V.32
>connected to the modem port.  On the Unix machine at work, I'm using
>sz version 3.03 5-09-89 and rz version 3.00 4-19-89.  The bank of
>modems that eventually connect to the Unix machine are connected
>via a dialback system.
>
>The symptom: when uploading both text and binary files, I will get
>ZRPOS errors which will eventually cause the file transfer to fail.
>For a while, these consistently occurred after 1024 bytes had been
>transferred, but recently, the transfer went as far as 20K before
>the ZRPOS's started.  The weird part is that downloading text and
>binary files has never failed (yet).
>
>I have tried forcing the mode of the transfer with options to rz and
>options in ZTerm.  I believe I have also tried escaping control
>characters (-e option to rz).  I have tried cutting down the packet
>size in ZTerm to 256 characters.  None of these seems to make any
>difference.
>
>The ROM in my modem WAS recently upgraded, and the time of the change
>vaguely corresponds to the difficulties I'm having.  I do not believe
>any of the non-volatile settings were changed.  I also don't quite
>understand why, if this is the true cause of my problem, I should
>still be able to download, but not upload.
>
>To add to the craziness, just last night, I managed to upload a small
>binary file and it came through okay.
>
>My first question is: what would cause rz to begin issuing ZRPOS's?
>My second question is: why is this happening?
>
>The EC (error correction) LED on the modem is on while I am connected.
>I believe the modems are using MNP5.  The cable connecting my modem to
>the Mac is a standard cable (ie, it isn't a hardware handshake-capable
>cable).
>
>I would appreciate any help or suggestions that you might have to
>offer.


I had this problem before also the first time I ever tried to upload a file
using Zmodem.  The fix I used was to simply use "rz -e" at the unix end to
escape all control characters.  In Zterm I think in the Zmodem settings part
you can change the receive command it sends, so just add a "-e" before the
carriage return and you *should* have no problems.  But I won't guarantee that,
because once doing that didn't fix that problem when I routed through a couple
of machines before my eventual destination, which is strange because the route
(the *shortest* one I can take) involves going through a Gandalf modem server
thingy and then through an annex and on to my destination.  With all that in
between the unix system and myself I can't figure out why another machine or
two in between would muck things up.  Oh well, just try the -e and see if that
works.

--
________________________________________________________________________
Doug Siebert                                     dbert@gnu.ai.mit.edu
MBA Student (2nd year)
The University of Iowa

nolan@helios.unl.edu (Michael Nolan) (03/25/91)

Another possible fix is the -w option.  Try -w 2048 and see if that helps.
Sometimes the problem is that the connection between the modem bank and
the unix system is much faster than the modem line, so things get kinda
backed up somewhere.  The -w option makes sure that sz on the unix box doesn't
get too far ahead of rz on your Mac.

Michael Nolan
nolan@helios.unl.edu

okamoto@hpcc01.HP.COM (Jeff Okamoto) (04/05/91)

A while ago, I wrote:

> I'm having a strange problem with ZMODEM file transfers and am
> wondering if anyone can help.

Through a combination of:
	upgrading rz to version 3.01,
	setting the window limit to 2048,
	and setting the subpacket limit to 512,

I finally managed to get the files to upload.  Now I get to try
the latest version of sz and rz that are available on simtel20.

Thanks go to Dave Platt, Doug Siebert, Dave Alverson, Ralph Carpenter,
jtn@potomac.ads.com, and todd@premises1.quotron.com for all their
suggestions and help.
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