nRF9151 SLM app + socket (open/send/receive/close)

[bojan]

Hello, guys 

I have nRF9151-dk running Serial LTE Modem (SLM) app on it and want to test the ability of working with sockets (open socket, send/receive data, close the socket...).

I'm following the flow of AT commands from here, but when it comes to connecting to the server with 

AT#XCONNECT="google.com",80

modem responds with ERROR after some time. 

FYI, prior to start working with sockets, the following AT commands are used to set modem device to full functionality:

Set to flight mode
AT+CFUN=4
Sets the device to full functionality. Active modes depend on the%XSYSTEMMODE setting
AT+CFUN=1

AT+CEREG? returns +CEREG: 1,5 (Registered to network, roaming) and only then I start with AT commands from here for socket open/send/receive/close...

Am I missing something in the flow of events? Do I need to somehow tell the modem the details about my SIM card as well?

Thanks in advance for your time and efforts. 

Sincerely,
Bojan.

[Håkon Alseth]

Hi,

 

modem responds with ERROR after some time. 

After a while (depending on the server you're connecting to), it is common that the peer disconnects due to a timeout if no communication is exchanged.

Is that what is happening here? Can you share a full log?

 

Kind regards,

Håkon

[bojan]

What I meant by 

Håkon Alseth said:

modem responds with ERROR after some time. 

is that I'm unable to establish a connection with the server. The connection is not broken due to the inactivity, it seems that the connection is not established at all. Here is the log:

[Håkon Alseth]

Hi,

 

You are getting an error as the socket does not exist. You should create the socket first, as shown in the documentation:

https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/applications/serial_lte_modem/doc/slm_testing.html#tcp-ip-at-commands

 

If you are connecting to a website, it might be beneficial to use the http specific at commands:

https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/applications/serial_lte_modem/doc/HTTPC_AT_commands.html

 

Kind regards,

Håkon

[bojan]

Hello, Håkon Alseth 

I forgot to add this socket opening step in my log, but it is not about it. Here is the log with the opening socket step included. Again, I'm unable to connect to HTTP server.

[Håkon Alseth]

Hi,

 

Thank you for sharing these details.

I see that you have PPP enabled, and I initially tested without. Sorry for this.

 

When adding PPP, I see the same problem. If you issue AT#XPPP=0, the socket connection will work. I will report this internally as a bug.

 

Kind regards,

Håkon

[bojan]

It works after

AT#XPPP=0

command, Håkon Alseth . Thanks for the support!

[Håkon Alseth]

Glad to hear you got it working. Happy to help!

As mentioned, I reported this internally as a bug.

 

Kind regards,

Håkon