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In this section, you will find important information relating to the setup and diagnosis of your 819-
GPRS modem. If you are having trouble communicating with the modem, please read this
"Troubleshooting" section in full. If, after reviewing this section, you are still having problems
connecting, call our Technical Support line at: 507-833-8819 for more assistance. Toll charges may
apply.
Helpful Hints
Only assign one device to any given COM port on your system.
The 819-GPRS data modem has a default COM port speed of 115,200 bps. This is the data rate at
which your modem connects to your computer. The modem's COM port speed can be lowered to
300bps or raised to 230,400 bps. Warning: Please ensure your COM port is capable of 230,400 data
rates before changing the modem to this speed. As this setting adjusts the communications speed
that the modem utilizes to speak to the computer, altering this parameter must be performed in a
very specific way, otherwise, you may lose communication with the modem. To alter the default
speed of 115,200 bps, first, connect via your terminal emulation software (settings: 115200bps, 8,
N, 1, Hardware). Now, you may issue the AT+IPR command to query or change the default speed.
After adjusting the port speed, disconnect from the modem and reconnect using the new data rate.
Refer to Table 9.5: Serial Interface Control Commands in Section 9 for more information pertaining
to the AT+IPR command.
Make certain the serial cable is firmly connected to an enabled COM port with no hardware resource
conflicts. Make sure that you have properly added the "MC75 Modem (GPRS)" (or the "Standard
19200 bps Modem") to your system (see Section 3 above). Also, check to see if you have an infrared
(IR) port assigned to your modem's COM 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.
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, such as Hyperterminal. Once the modem is ready to accept
commands, type: ATI and press enter. The product information of the modem should print out on
the screen (for example: SIEMENS, TC65, REVISION 02.000). This will confirm that you are
communicating with the LandCell modem and not some other device connected to or inside the PC.
If the product information 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.
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001-0003-829 Revision 1
Page 34 of 65
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