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From: c60b-1eq@web-1g.berkeley.edu (Noam Mendelson)
Newsgroups: comp.dcom.modems
Subject: Re: DSZ ZMODEM problem
Keywords: zmodem dsz
Message-ID: <1991Mar18.164403.8899@agate.berkeley.edu>
Date: 18 Mar 91 16:44:03 GMT
References: <9857@jjmhome.UUCP> <1991Mar16.190010.21805@cs.wayne.edu> <3811@gmuvax2.gmu.edu>
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In article <3811@gmuvax2.gmu.edu> esaffle@gmuvax2.UUCP (Ed Saffle) writes:
>>	I started the sending in unix and go to Procomm Plus and initialize
>>	the receiving and I got timeouts and had to abort the transmission.
>
>	I seem to have the same problem, but only across the phone lines.  I
>dial into a BBS when I am at home and no problem.  I can also start transfers
>between our mainframe and a UnixPC via direct connect serial cable and it'll
>start just fine and work for a little while....but then it starts getting
>the same errors.  I blame the last one, however, on the networking.

I have encountered similar problems before.  Apparently, ZMODEM escapes
certain characters which have special meaning to networks (like ^C, ^Y, etc.).
However, it seems that certain characters still bother the network.
Fortunately, both the IBM PC version of DSZ and Chuck Forsberg's ZMODEM program
for UNIX (available from wuarchive.wustl.edu under /mirrors/misc/zmodem I believe)
have an option to escape _all_ control characters ("-e").  I have found the -e
switch to improve the reliability of transfers, although there is an obvious
slowdown since all control characters must be escaped.  The resulting transfer
rate is about 180-200 cps at 2400 bps, which is acceptable but not very
desirable.
Also, I have found KERMIT to work flawlessly.  If you set the packet length to
about 1K (assuming you have a fairly clean connection), KERMIT will yield a
much higher transfer rate than ZMODEM with the -e option.  ProComm Plus does
support KERMIT transfers.

--Noam

c60b-1eq@web.Berkeley.EDU