debug a GSM Modem using AT command

Question

Folks

I have two protoypes (say prototype A and B ). Both the prototypes uses Telit GSM modem . I am using the common SIM to work with both of them.

Problem: If I use the sim with prototype A , AT+CGDCONT, AT#GPRS=1 these commands work perfect . But with Prototype B using the same sim AT+CGDCONT, AT#GPRS=1 don't work . AT+CGDCONT always echos "operation not allowed" .

So is there any way i can debug this issue ?

Thanks Ak

Answer 1

You might want to ramp up the error detail. Try setting:

AT+CMEE=1

Most common GSM Modems with a standard AT Command set will then output proper error codes. I have found often such generic messages are then replaced with much more detailed error codes.

Answer 2

Swap the GSM modems and see if the fault moves with the swap. If it does, dump the faulty modem (i.e. replace it to see if that cures the problem). If not the problem may be with your prototype.

Answer 3

It is difficult to guess the reasons. It could be that module B is faulty.

Even though you think both devices are identical, there are settings that might make them different. I remember Telit have commands like AT#SELINT and you have to check whether those settings are the same for both modules. There are a couple of other settings like this which persists after power cycles. If you don't know how to track those differences, you can always format the modules.

Go to Roundsolutions Download section and download the firmware for the module and burn them in using the tools in the same website. After that is done, you will be sure that they are really identical.