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1988-07-01
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SETTING UP YOU MT224EH FOR HIGH SPEED OPERATION
July 1, 1988
Version 9
A. PURPOSE
=======
These instructions will help you get the most out of your new
MultiTech MT224EH modem by enabling RTS/CTS flow control. You
will be able to do the following:
use MNP level 5 protocol for error free communication
use data compression to communicate at data rates from 5%
to 100% faster
use the new protocols Imodem and Ymodem-G that depend on
the modem doing error correction
configure Qmodem 3.1A or Procomm Plus
In order to use data compression, you must transmit data to the
modem faster than it transmits data on the telephone line. These
instructions set your serial port for 9600 baud and the modem
for 2400 baud.
In order to for the modem to re-transmit garbled blocks of data
or to send out compressed data at 2400 baud while receiving
data from your computer at 9600 baud, it must have a way of
telling your communication program to stop transmitting new
data. For this the modem uses RTS/CTS flow control.
"The MultiTech 224E is one of the most popular 2400 baud modems
that incorporates MNP error correction into its circuitry.
Setting the various hardware and software parameters to enable
MNP and CTS/RTS flow control is somewhat tricky, and this
document is intended to simplify that task."
MultiTech publishes a fine reference manual that describes all
the switches and options available. You should read it for all
the details.
Unfortunately, the manual does not describe the COMBINATION of
all switches which must be set for effective MNP level 5 use,
nor does it say how to install popular communications software
to take advantage of MNP level 5. Therefore, I have provided
these instructions for a first time user who may be overwhelmed
with the choices in the manual and need a cookbook like this.
"The instructions are for the MT224EH models that have Class 5
MNP. For those older models that incorporate Class 3 MNP only,
some of the software switch settings will generate errors. These
will not affect modem operation. (MultiTech does have a program
to upgrade Class 3 MNP to Class 5 MNP; contact them for
information.)"
B. CAUTION
=======
In order to set up your system to take advantage of MNP level 5
you must do ALL, repeat ALL of the following as described in
this document:
1. have a correct modem cable
2. set the 8 hardware DIP switches under the MT224EH
3. set the 4 hardware DIP switches inside the MT224EH
4. set the 3 hardware jumpers inside the MT224EH
5. store MT224EH software configuration parameters
6. configure your communications program
You cannot do only some of these steps. All parameters and
settings must be MUTUALLY CONSISTENT for communication to take
place. If after following the directions below, your system
doesn't work, please double-check everything.
C. CORRECTIONS AND FEEDBACK
========================
I appreciate your feedback on how to improve this document.
Thanks.
Paul Thompson
leave a message on John Friel's Qmodem board 319-233-6157
or on the MultiTech board 612-631-0922
D. ACKNOWLEDGEMENT
===============
These instructions are an extension of a document originally put
together by:
S. David Klein
The Software Society PCBoard
201-729-7410
11/15/87
who writes, "These settings have been tested using Qmodem SST
3.1a with both the IModem and YModemG protocols with
artificially injected noise on the phone line, and we have been
unable to produce a bad file transfer. With a Class 5 connection (CONNECT RELIABLE COMPRESSED), using the alternate
settings given [below], we have achieved throughput of over 650
cps on an un-compressed document file, and over 290 cps on an
ARC file, a better than 20% improvement over normal 2400 baud
Class 3 connections."
(Quoted text is from David's document.)
E. PRE-CHECK
=========
Before using the MT224EH's advanced features, first see if the
normal set-up works.
Attach the MT224EH to your computer. Leave all settings as they
come from the factory. This includes hardware switches and
jumpers as well as software switches stored in RAM inside the
unit. (You can reset the software switches to factory default
with the command AT&F&W0. If the hardware switches or jumpers
have been messed with, check them carefully.)
Follow the directions in Qmodem SST 3.1A or Procomm Plus
documentation for installing a Hayes modem. Test communications. Hopefully, everything is fine and you are now ready to move on
to setting flow control.
(There are many things that can go wrong with communications:
bad cable, using wrong port, two serial cards set to the same
port address, wrong DIP switch settings, bad set-up strings in
your communications program, etc. It just makes sense to start
from a known situation; and there is more help for you if your
starting point is 100% Hayes emulation.)
F. CHECK YOUR MODEM CABLE
======================
Even though your cable may have worked for standard Hayes, it
may not be correct for flow control. Some cables have fewer
pins, or strap certain pins together. Your communications
program must have the ability to read the true state of CD and
CTS and to control RTS and DTR. All lines should be straight
through. See page 3-7 of your MultiTech user manual.
This set-up requires:
pin 2 SD Transmitted Data
pin 3 RD Received Data
pin 4 RTS Request to Send (used for flow control)
pin 5 CTS Clear to Send (used for flow control)
pin 6 DSR Data Set Ready
pin 7 SG Signal Ground
pin 8 CD Carrier Detect (used by communications program)
pin 20 DTR Data Terminal Ready (used by comm prog to hang-up)
pin 22 RI Ring Indicator
G. SETTING THE MULTI-TECH 224EH HARDWARE SWITCHES
==============================================
"The MT224E has two banks of DIP switches and three jumpers. One
bank of eight switches is accessible underneath the modem. These
8 option switches duplicate the Hayes 1200 switches. The other
bank of four switches and jumpers are accessible only by
removing the cover of the modem. (Refer to your owner's manual
pages 9-1 to 9-13 for instructions on opening the modem and
locating the switches and jumpers).
"The following settings will enable MNP error correction
(providing the modem that is called is so equipped) and CTS/RTS
flow control. They will also enable the full verbose response
set of the MT224 which will keep you apprised of what the modem
is doing, and will wait for dial tone before dialing. The
setting of the bank of eight switches should be as follows (up
refers to the OPEN position):
1-UP (DTR normal),
2-UP (verbose responses),
3-DOWN (enable command response),
4-UP (enable command echo),
5-UP (enable auto answer),
6-UP (CD & DSR normal),
7-UP (single line RJ11), and
8-DOWN (enable command mode)
"All of these are the factory default settings with the
exception of switch 1, which is reversed.
"The setting of the bank of four switches [located inside the
unit behind the front panel] should be as follows (up refers to
the OPEN position):
1-DOWN (CTS normal),
2-UP (Dial-up operation),
3-UP (wait for dial tone),
4-DOWN (asynch operation