5 years, 9 months ago.

Why is the C030-N211 board running with a wrong AT Command but not without it?

Hello everyone,

I've got a problem with the C030-N211 NB-IoT board. I'm trying to implement a simple ping pong with the board as the device and a local UDP server.

I am using a 1NCE SIM card and the mbedOS library, especially the ATCmdParser, to work with the AT commands.

The tests of my implementation have been successful and I was able to communicate with the server and vice versa using the following AT command:

//initalizing network settings
at->send("AT+NPIN=0,\"12345\""); 
at->send("AT+CFUN=1");
at->send("AT+CFDCONT=1,\"IP\",\"iot.1nce.net\"");
at->send("AT+NBAND=8");
at->send("AT+COPS=1,2,\"26201\",7");

//checking if connection has been established
at->send("AT+CEREG?");
at->send("AT+COPS=?");

//creating a socket and sending a UDP message
at->send("AT+NSOCR=\"DGRAM\",17,19019,1");
at->send("AT+NSOST=0,\"10.11.12.13\",1912,4,\"70696E67\"");

This was successful and I was able to send and receive messages. But when cleaning up my code I realized that I had a spelling mistake in the third AT command ("AT+CFDCONT" instead of "AT+CGDCONT"). I corrected this and tested the implementation once again and realized that it was not working anymore.

After multiple test, e.g. sending absolut nonsense as an AT command, I came to the conclusion that a "wrong" command is required between CFUN and NBAND to get the code to work which is kind of strange behavior.

Does anyone have an idea what I am doing wrong or where this behavior may come from?

If some more informations, e.g. code, are needed I will try to give them if requested.

Greetings

Sebastian