Chapter 3 – Troubleshooting
Multi-Tech Systems, Inc. MultiModem® GPRS with USB User Guide 35
Whenever I send the # commands, I receive an error.
• You must enable the stack before the modem will accept the # commands.
• ‘AT+WOPEN=1’ will enable the stack and ‘AT#VVERSION’ will display the version of the stack.
• If you receive an error when sending ‘AT+WOPEN=1’, then you may not have the stack present on the
modem.
How do I know if I have the stack?
• Use the ‘AT+WOPEN=1’ command. If it returns an error, then the stack may not be present in the
modem.
How do I make a GPRS connection using the stack?
• Send: AT#GPRSMODE=1 (sets the modem to GPRS mode)
AT#APNSERV=”APN” (sets the APN for the modem to connect)
AT+CGATT=1 (attaches the modem to the GPRS network)
AT+CGREG=1 (registers the modem onto the GPRS network)
AT#CONNECTIONSTART (to start the connection)
AT#CONNECTIONSTOP (to stop the connection)
I have T-Mobile. When I try to establish a GPRS connection using the stack, the modem doesn’t connect.
It seems like the modem gets reset.
• Check the firmware version: ‘AT+CGMR’.
• Version 640b had a bug that caused the modem to reset when using a non-authenticated account.
Authenticated accounts such as AT&T and Cingular work OK. Firmware version 641a fixes this issue.
• You will have to send the modem in for a firmware upgrade. Send it to the attention of the MultiTech
Repairs Department. Include a letter stating the problem and that you need the version 641a firmware.
How do I make a connection to my ISP using the stack?
Make sure you have CSD service.
Send: AT#GPRSMODE=0 (sets the modem to GSM mode)
AT#DIALN1=”ISP’s access #”
AT#DIALSELECT=1
AT#ISPUN=”username”
AT#ISPPW=”password”
AT#CONNECTIONSTART
AT#CONNECTIONSTOP
I can’t use the stack to connect to the GPRS network. I keep getting CME errors.
• Check the CME error number in the AT Command Reference Guide.
• Make sure the modem is attached and registered with the ‘AT+CGATT?’ and ‘AT+CGREG?’
commands.
• Make sure the APN is correct with ‘AT#APNSERV?’.
Can I ping the modem when I have a connection established with the stack?
• Yes, but you must be connected to an APN or server that provides public IP address and is not blocked
by a firewall.
Can I ping out using the stack?
• Yes, but you must have the firmware version 641a or higher.
• The command is ‘AT#PINGREMOTE=”<address to ping>”’ and ‘AT#PING’ to start the ping.
• You must have a connection established with the stack in order to use the ping commands.
•
Does the stack support UDP?
• Yes, but only on the firmware version 641a and above.