The Modem Cannot Connect When Answering; File Transfer Is Slower Than It Should Be; Data Is Being Lost - Multitech MultiModemDSVD User Manual

MultiModemDSVD User Guide

The Modem Cannot Connect When Answering

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File Transfer Is Slower Than It Should Be

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Data Is Being Lost

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Autoanswer might be disabled. Turn on autoanswer in your datacomm program
or send the command ATS0=1 (ATS0=2 if you have Caller ID service) to your
modem in terminal mode.
You might have an older UART. For best throughput, install a 16550AFN UART
or a Multi-Tech ISI serial port card. See the "Quick Start" chapter for information
on how to identify your UART.
If you are running under Windows 3.1 and have a 16550AFN UART, you must
replace the Windows serial driver, COMM.DRV, to take full advantage of the
UART's speed.
If you are using a slow transfer protocol, such as Xmodem or Kermit, try Zmo-
dem or Ymodem/G instead.
Is your line noisy? If there is static on your line, the modem has to resend many
blocks of data to insure accuracy. You must have a clean line for maximum
speed.
Are you downloading a compressed file with MNP 5 hardware compression en-
abled? Since hardware data compression cannot compress a file already
compressed by an archiving program, the transfer can be marginally slower with
data compression enabled than with it disabled.
Does your Internet service provider (ISP) use the same 56K protocol as your mo-
dem? The default setting of your modem is to connect using either the K56flex or
the V.90 protocol, depending on which one the ISP modem is using. If your ISP
uses the X2 protocol, the maximum speed you will be able to connect at is 33,600
bps. Check with your ISP to see which protocols it supports, and check the Multi-
Tech Web site for the latest developments in V.90.
Try entering the &V1 command to display information about the last connection,
making a screen print of the connection statistics, and checking for parameters
that might be unacceptable.
If you are using data compression and a high speed serial port, set the serial port
baud rate to four times the data rate.
Your UART might not be reliable at serial port speeds over 9600 bps or 19,200
bps. Turn off data compression, reset your serial port speed to a lower rate, or
replace your serial port with a faster one.
Make sure the flow control method you selected in software matches the method
selected in the modem. If you are using the modem with a Macintosh, you might
have the wrong cable for hardware flow control.