Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!rice!Taffy.rice.edu!jack
From: jack@Taffy.rice.edu (Jack W. Howarth)
Newsgroups: comp.sys.mac.comm
Subject: Re: Using hardware handshaking
Message-ID: <1990Nov27.191021.14228@rice.edu>
Date: 27 Nov 90 19:10:21 GMT
References: <1990Nov26.183217.236@skbat.csc.ti.com>
Sender: news@rice.edu (News)
Organization: Rice University
Lines: 51

In article <1990Nov26.183217.236@skbat.csc.ti.com> dittman@skbat.csc.ti.com (Eric Dittman) writes:
>[I've figured out that this post didn't make it out earlier, so here is my
> request for help again.]
>
>I'm trying to use hardware handshaking between my Mac IIfx and an ATI 2400etc/e
>modem.  My cable is wired:
>
>DIN-8		DB25
>--------------------
>1		20
>2		8
>3		2
>4		7
>5		3
>6		N/C
>7		N/C
>8		7
>
>I've been told this is correct.  I'm using Smartcom II.  If I turn hardware
>handshaking on with SC II and configure the modem using AT&K3 (or AT&F2 which
>sets the modem up for V.42 operation) I can talk to the modem with no problems.
>After I call a remote system and the modem goes on-line, though, I don't get
>anything from the remote system, and the remote system doesn't get anything
>from my system.  Sending '+++' gets the modem back into command mode, though.
>Any ideas what I'm doing wrong?
>
>Thanks,
>Eric Dittman
>Texas Instruments - Component Test Facility
>dittman@skitzo.csc.ti.com
>dittman@skbat.csc.ti.com
>
>Disclaimer:  I don't speak for Texas Instruments or the Component Test
>             Facility.  I don't even speak for myself.


The best way to use hardware handshaking on a modem is to set the modem to
CPU connect rate at 9600 baud or 19200 baud and use the following settings
  AT\J0\V1\N3\Q3
or equivalents for your command set. J0 turns off the autobaud rate adjust 
between the modem and the CPU. V1 gives verbose messages which are good as
you'll get info about whether the connection is using MNP. N3 sets hardware
handshaking for flow control and Q3 sets error checking on. This setup with
hardware handshaking will connect with MNP if possible and at the highest 
baud rate possible. If MNP5 or v42bis is used, the higher baud rate between
the modem and CPU prevents that from bottlenecking the transfers (i.e. a
MNP5 connection at 2400 baud with 9600 baud between modem and CPU.)
                     Cheers...
                                  Jack Howarth