Modem Cannot Connect When Answering; File Transfer Is Slower Than It Should Be; Data Is Being Lost; There Are Garbage Characters On The Monitor - Multitech MultiModem II MT5600BA-V92 User Manual

Modem Cannot Connect When Answering

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The default DTR Control command (&D2) inhibits autoanswer. To enable autoanswer, change DTR
Control to &D0, and make sure &Q0, &Q1, &Q5, or &Q6 is also set. For more information, see the
&D command in the AT Command Reference Guide on the CD shipped with your modem. For
information on changing the modem's default configuration, see "Step 3: Install and Configure Your
Software" in Chapter 2.
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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.

File Transfer is Slower Than It Should Be

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You might have an older UART. For best throughput, install a 16550AFN UART or a Multi-Tech ISI
serial port card.
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If you are using a slow transfer protocol, such as Xmodem, try Zmodem or Ymodem/G instead.
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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.
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Are you downloading a compressed file with MNP 5 hardware compression enabled? 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.
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Try entering the &V1 command to display information about the last connection, making a LCD print
of the connection statistics, and checking for parameters that might be unacceptable.

Data is Being Lost

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If you are using data compression and a high speed serial port, set the serial port baud rate to four
times the data rate.
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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.
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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.
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Try entering the &V1 command to display information about the last connection, making a LCD print
of the connection statistics, and checking for parameters that might be unacceptable.

There are Garbage Characters on the Monitor

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Your computer and the remote computer might be set to different word lengths, stop bits, or
parities. If you have connected at 8-N-1, try changing to 7-E-1, or vice-versa, using your
communication software.
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You might be experiencing line noise. Enable error correction, if it is disabled, or hang up and call
again; you might get a better connection the second time.
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At speeds above 2400 bps, the remote modem might not use the same transmission or error
correction standards as your modem. Try connecting at a slower speed or disabling error correction.
(With no error correction, however, line noise can cause garbage characters.)
Multi-Tech Systems, Inc. MT5600BA-V92 User Guide
Chapter 8– Troubleshooting
42