NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/comp/os/coherent/5702

Internet Message Format | 1992-11-18 | 3.2 KB

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From: [e-mail] (Dave Ratcliffe)
Newsgroups: comp.os.coherent,comp.unix.questions
Subject: Re: rz problems at 9600 baud
Summary: Handshaking problem
Message-ID: <[e-mail]>
Date: 15 Nov 92 22:14:27 GMT
References: <[e-mail]> <[e-mail]>
Followup-To: comp.unix.questions
Organization: Data Factory Services, Harrisburg, Pa.
Lines: 50


 In article <[e-mail]>, [e-mail] (Kevin Hanrahan) writes:
 > [e-mail] (John D. Boggs) writes:
 >
 > >Has anyone experienced problems using rz/sz at 9600 baud?  I just
 > >bought a 9600 baud modem and am experiencing problems I've never had
 > >before (at 2400).  I give my remote host the sz command, then call rz
 > >using minicom's receive feature, and the computer proceeds to give me
 > >all sorts of error messages one after the other (sometimes getting some
 >
 > The error messages sound like the same problem we have here, but
 > our setup is somewhat different.  We have PC's connected to our
 > network through serial connections to TRW ACU's.  These run
 > at 9600 bps, but there is no modem involved.  I have also been
 > unable to use sz/rz to my PC at home thru a dialup which also
 > uses a TRW ACU.  A friend of mine has successfully used sz/rz
 > over a 9600 bps modem that does not go thru one of these TRW boxes.

The symptoms described by John sounds suspiciously like problems I had
here for quite some time also using sz/rz. Here's what I eventually
found:

There was a simple handshaking problem.  I'm using a Trailblazer+ locked
at 19200 to the cpu but had callers at 2400 having blown transfers and
transfer rates (with all the errors counted in) of less than 300 bps.  A
temporary fix was to use the sz -w1024 [filename] command to send files
with a window of 1024 bytes.  This forced the speed a bit slower than a
normallly operating 2400 connection but it at least worked temporarily
by forcing a break every 1024 bytes of transfer to allow an ACK/NAK to
come down.  This blows the streaming capability of Zmodem but DOES work.
Note that this is with sz on a Unix machine sending to a DOS machine
with a 2400 baud connection.  The same problem is likely if you are
connecting at 9600 to a system with a modem locked to it's host at
19200.  UPLOADING to such a system (using rz) probably won't cause
problems.

I cured this royal pain by installing FAS drivers and 16550AFN Uarts.
The previously non-existant handshaking now deals with it all and I no
longer need the sz -w1024 command. A simple fix in the end. BTW, I'm
using a Digiboard DigiCHANNEL PC/8 under Microport SYSV/386 here.

As usual, your mileage may vary and this might not even be the problem
you two are having but it's a place to look.

Good luck.

--
 ...uunet!wa3wbu!frackit!dave -or-                       |  Dave Ratcliffe  |
 frackit![e-mail] -or- [e-mail] -or-   |  Sys. <*> Admin. |
 vogon1!compnect!frackit![e-mail]            | Harrisburg,  Pa. |