User's Guide

The Operational View SB300 Series
Page 66 Proprietary and Confidential 2110059 Rev 1.0
8.3. General Communication Problems
Problem Description Suggestions
Fails to respond to AT
command.
Verify that you are using the correct COM port and communication
parameters (speed, data bits, parity, etc.)
Verify the serial cable connections.
Verify the modem is powered on and allow for 10 seconds initialization
time.
Try typing the command ATE1Q0. This will enable the modem echo
of your keystrokes (in following commands) and disable the quiet mode
(suppression of return codes).
Try typing AT&F. This restores factory defaults.
Try resetting the modem.
Data is intermittently lost
during the connection.
Ensure that proper flow control is being used at all connections.
If UDP is used, remember that data loss is inherent in the design.
Implement a positive acknowledge and timeout scheme at the
application level with re-transmissions as needed.
If the connection is CSC mode, try setting a slower data rate (register
S37).
8.4. CDPD Problems
This table lists problems specifically related to CDPD use.
Problem Description Suggestions
Fails to lock onto a CDPD
channel.
Make sure that the antenna is connected correctly.
Check that you are in the CDPD coverage area, or that your immediate
location is not preventing the radio/modem from receiving a signal, e.g.,
you are in an area of weak signal strength.
Fails to register on a CDPD
channel.
Make sure the NEI and side designator are configured correctly.
Make sure you are using the correct registration mode (auto or manual)
and are issuing the registration command if using manual registration.
If ATH1 was issued, the modem will not resume auto-registration until
the modem is reset or the command AT+WS173=1 is issued to re-
enable auto-registration.
Check that the correct NEI is being used (Active or Auto-register NEI
Indices) and the SPNI table. An incorrect value will prevent registration
even in areas with strong signals. Erase the SPNI table if necessary.
Check with your CDPD service provider to confirm that your account is
activated. You may need to reset your credentials.
Registers but data transfer
fails.
Check that the host serial cable is properly attached.
There may be a flow control problem.
Slow response from the
CDPD network.
The CDPD network may be congested with heavy use. No user action
can alleviate this problem. Retry your connection later.