Paradyne COMSPHERE 3911 Installation And Operation Manual page 225

Symptom
The modem does not accept or
echo back AT commands.
3910-A2-GN32-40
Table B-4
Modem — DTE Connection
Verify that the cable between the Async port of the DTE and the
modem is a standard RS-232 cable. (Null modem cables, also known
as crossover cables, do not work in this application.)
Verify that the Command Character Echo configuration option is
enabled. Refer to DTE Dialer in Chapter 5, DCP Configuration.
Verify that the DTE Dialer Type configuration option is set to AT. Refer
to DTE Dialer in Chapter 5, DCP Configuration.
Verify that the Result Codes configuration option is enabled. Refer to
DTE Dialer in Chapter 5, DCP Configuration.
Reload the Async Dial factory configuration area to guarantee that all
configuration options are returned to their proper setting.
Make sure that all AT commands are terminated with a carriage return.
Verify that the Carriage Return Character configuration option matches
what is used by the DTE. Refer to DTE Dialer in Chapter 5, DCP
Configuration.
Verify that the DTE has a valid character format. Valid format consists
of 8 data bits with no parity or 7 data bits with even, odd, mark or
space parity.
Verify that the DTE's data rate is supported by the modem. Refer to the
Async DTE Rate configuration option in DTE Interface in Chapter 5,
DCP Configuration.
If using a PC, verify that the modem is attached to the correct
communications port.
September 1998
Action
Troubleshooting
B-3