SM5100B-D Shield Stops Responding To Serial Commands

Wireless & IoT
1

I’m working on a large project Using Fez-Cobra, Netduino and Arduino Boards to do prototyping, I’m also using Sparkfun GSM Shields as part of the project, so far 4 of the 7 Shields I have, have at some point simply stopped responding to any Serial Port Messages, even “AT” messages simply time out.

Has anyone else seen anything like this.

This has happened whether I’ve been stacking the unit’s using only USB power, Using USB and Dedicated Power, not stacked but simply wired together etc. the code is simple, open the Serial port, send a few commands such as “AT”, “AT+CGACT=0,1” etc in an effort to check for connections and open a GPRS connection.

After debugging stopping the debugger and starting it up again for some reason the 4 units mentioned simply stopped sending back responses, and I assume are no longer functioning…

2

Belatu,

Did you ever resolve this?

I am also looking to use this shield with the panda or netduino board.

3

Hi Sam,

Yes we eventually found out that the issue was the number of entries in the PLMN/Roaming list on the Sim, as long as this list has less than 50 Entries it’s fine, but the moment it exceeds 50 it breaks the DM5100B.

It took getting the Actual Sim card manufacturers involved to finally track down the issue.

We are now using Sims specifically meant for tracking devices etc which have much smaller roaming lists than Vodacoms standard 72+