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Chapter 6 - Troubleshooting
Multi-Tech Systems, Inc. MT5634ZPX User Guide 31
The modem does not respond to commands
• Make sure you are in terminal mode in your data communications program; then type
AT and press Enter. You should get an OK response. If not, reset your modem by
sending it an
ATZ
or
AT&F
command in terminal mode. If using legacy software
(software designed for an older operating system), make sure the initialization string
includes
&F
as the first command to cancel any
leftover
commands that could
interfere with the modem’s operation. For more information on initialization strings,
refer to Chapter 5.
• If you don’t get an
OK
, the problem may still be in the communications software.
Make sure you have properly configured the port in your communications software.
Most legacy (prior to Windows 95) communications programs connect to the COM
port when the software loads and remain connected until the program terminates.
Some programs can disconnect without exiting the program. If this is the case, try
issuing the software’s connection command. If more than one communications
program is open, they may conflict with each other. Make sure all other
communications programs are closed and try to make the connection again.
• If using legacy software, the COM port setting may not match the COM port that
Windows assigned. Compare the COM port setting in your software to the COM port
reported in Windows. To view your modem COM port settings:
• In Windows 95/98, select Start | Settings | Control
Panel |Modems, and then Diagnostics.
• In Windows NT, select Start | Settings | Control Panel |Modems. Click
Properties.
• In Windows 2000, click Start | Settings | Control Panel |Modem and
Phone Options | Properties.
• Another expansion card (such as a sound card) may be using the same COM port,
memory address, or interrupt request (IRQ) as your modem. See Chapter 3 for
information on verifying the configuration for your operating system. Look for
conflicts with other devices installed on your computer. Resources are assigned at
power up by thecomputer’s BIOS. If the resources assigned to the MultiModemZPX
conflict with the resources of another device, the resources of the second device
have to be changed. Select the port the conflicting device is on and change it to
resolve the conflict. If you need to change switches or jumpers on the conflicting
device, refer to the device’s documentation.
• If you have another MultiModemZPX, install it and try to make a connection.
The modem dials but cannot make a connection
Several reasons why the MultiModemZPX fails to make a connection include:
• Lack of a physical connection to the telephone line.
• A wrong dial tone.
• A busy signal.
• A wrong number.
• No modem at the other end.
• A faulty modem, computer, or software at the other end.
• Incompatibility between modems.
Narrow the list of possibilities by using extended result codes. If you disabled the
modem’s extended result codes, enable them by entering ATV1X4 in a terminal
window and press Enter. When you dial again, the modem reports the call’s
progress.