Multi-Tech Systems PN S000408C - Manual (Page 42)

Chapter 7 – Troubleshooting
Multi-Tech Systems, Inc. MT5600BA-V92 User Guide 42
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.)
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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.
The Modem Doesn’t Work with Caller ID
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Caller ID information is transmitted between the first and second rings, so if autoanswer is turned
off (S0=0) or if the modem is set to answer after only one ring (S0=1), the modem will not receive
Caller ID information. Check your initialization string, and if necessary change it to set the modem
to answer after the second ring (S0=2).
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Make sure that you have Caller ID service from your telephone company.