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6 Solving Problems
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MultiModemZPX User Guide
The Modem Cannot Connect When Answering
The default DTR Control command (&D2) inhibits autoanswer. To enable au-
toanswer, change DTR Control to &D0, and make sure &Q0, &Q5, or &Q6 is
also set. For more information, see the &D command in Chapter 4. For informa-
tion on changing the modem’s default configuration, see “Step 5: Install and
Configure Your Software” in Chapter 2.
Autoanswer might be disabled. Turn on autoanswer in your communications
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
If you are using a slow transfer protocol, such as Xmodem, try Zmodem 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.
If you are downloading a compressed file with MNP 5 hardware compression
enabled, try disabling data compression. The transfer may be marginally slower
with data compression enabled, because hardware data compression cannot
compress a file already compressed by an archiving program.
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 V.92 or
the V.90 protocol, depending on which one the ISP’s modem is using. If your ISP
uses the V.90 protocol, the maximum speed you will be able to upload at is
33,600 bps. Check with your ISP to see which protocols it supports.
Are you trying to send a file to another client modem? If so, then your maximum
possible connect speed is 33,600 bps. You can upload at speeds greater than 33,600
bps only when connected to an ISP that supports the V.92 protocol.
Try entering the I11 command in online mode or the &V command in command
mode to display information about the last connection, making a screen print of
the connection statistics, and checking for parameters that might be unacceptable.
Data Is Being Lost
If you are using data compression, set the serial port baud rate to two to six times
the data rate.
Make sure the flow control method you selected in your software matches the
method selected in the modem (see AT commands &K and \Q.)
Enter the I11 command in online mode or the &V command in command mode
to display information about the last connection. Then make a screen print of the
connection statistics, and look for unacceptable parameters.