LandCell CDM819u User manual - page 17
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port. Disable it if you are not using this function. Often, an IR port can interfere with the COM
port even after you successfully connect. Device Manager may indicate that there is no conflict
between the two, but disabling the IR port may still help.
If your system's COM port appears to be locked, you may have to shut down and reboot your
system.
Do not use "Disable Call Waiting" (commonly referred to as *70) when configuring Dialing
Properties.
Make certain that you are using the proper RS-232 serial cable. For most applications, you must
use a straight-through RS-232 serial cable. For certain types of equipment, you may be required
to use a null modem cable. For more information on this, refer to the FAQ section 7.11 "When Do
I Need A Null Modem Cable?".
6.2 Diagnosing COM Port Problems Using HyperTerminal
If you are experiencing problems connecting to the cellular network, you can verify if the issue is
between the computer and the modem or between the modem and the cellular network. To test,
open your terminal emulation software as described in the "Using Terminal Emulation Software
To Talk To The Modem" section 3.0 above. Once the modem is ready to accept commands, type:
AT+GSN and press enter. The ESN of the modem should print out on the screen in the following
format “+GSN: 45262036”. This will confirm that you are communicating with the Land-
Cellular modem and not some other device connected to or inside the PC. If the ESN does not
print out, please confirm that you have selected the COM port that the modem is attached to, and
not some other port, internal modems typically show up as COM3.
To test the link between your modem and the cellular network try to call your cell phone. Type
in: AT+CDV
This command will perform a voice call similar to the type a standard home phone would make
and if your modem has been activated correctly your cell phone should ring and display the
number of the modem. Answer the incoming call on your cell phone and then hang-up your cell
phone. If you are properly communicating with the modem using the steps above and still cannot
connect through the cellular network, here are a few items to check:
•
Call the phone number of the modem. If the phone number is not active, the cellular
service will inform you of this.
•
Confirm that the ESN on the Label matches the ESN in the module with AT+GSN This
will print out the ESN of the Modem in Hex format, +GSN: 45263F2A. This rarely
happens, but if the numbers do not match, the wrong ESN may be in your Account.
•
Contact your cellular provider and make certain that the Electronic Serial Number (ESN)
of the modem is active in their system.
•
Check the signal strength reaching the modem using the following command: AT+CSQ?
A typical reply is +CSQ? 19,99.The signal strength ranges from 0 to 31, the higher the
number the better the signal. See also the FAQ for more information on "No Carrier"
issues.
•
Issue the command: AT+CSS? to verify that the modem is registered onto a cell tower. If
the return from the modem is: 2,Z,99999 then the modem is not registered. It may take up
to 15 seconds or so after power-up to register on the network. Once registered a typical
response will be +CSS?: 1,A,4152 where 1 is the band class, 1=800 MHz, 2=1900 MHz,
A-F is the band (Z indicates not registered on network), 4152 is the SID, i.e. the cell
tower ID, (99999 indicates not registered on network).