RE: serial_lte_modem stops responding when you send an empty line

Georgi Valkov — Fri, 24 Jul 2020 15:46:24 GMT

Thank you very much, Didrik!

The ping works now.

RE: serial_lte_modem stops responding when you send an empty line

Didrik Rokhaug — Fri, 24 Jul 2020 08:00:05 GMT

Hi, and sorry for your bad experience with the serial_lte_modem.

[quote user=""]Unlike the AT client sample which simply works with PuTTY out of the box, for the serial_lte_modem you need to configure PuTTY, Terminal, Keyboard to CR LF.[/quote]

Yes, as explained in the documentation: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.3.0/nrf/applications/serial_lte_modem/README.html#terminal-connection

You can, however, change the terminating character by setting either of the following options to "y" in the prj.conf file:

- CONFIG_SLM_NULL_TERMINATION

- CONFIG_SLM_CR_TERMINATION

- CONFIG_SLM_LF_TERMINATION

- CONFIG_SLM_CR_LF_TERMINATION (default)

[quote user=""]hen it will accept commands until you send an empty line. Once you do that, it will not replay to any further commands until you power cycle the board.[/quote]

This is, unfortunately, a known issue we are working on resolving. For now, don't send empty lines, or commands terminated by an interleaving sequence of carriage-returns and linefeeds. I.e. an "\r\r\r\r\n\n\n\n" ending is ok because the carriage-returns and linefeeds are not "mixed", while "\r\n\r" is not ok.

[quote user=""]On top of that I cannot send PING or connect to anything, even though my Thingy:91 is registered to an NB-IoT network, and has a valid and enabled IP address context. What is the proper syntax of those proprietary AT commands? There is no description on the Infocenter for AT commands, so I used whatever scarce resources there are on the serial_lte_modem page.[/quote]

As the example adds more AT commands that are handled by the application, and not the modem, the AT command documentation in the infocenter is not the right place to look. That documentation only describes the commands supported by the modem. Instead, the added AT commands are documented in the sample documentation. We are aware that the sample documentation is a bit lacking, and are working on improving that.

As for why your commands are not working, it looks to me like you have done everything correctly, except for missing double-quotes around the strings. I.e. the #XPING command should be

AT#XPING="httpstorm.com",32,1000,4,1000

Best regards,

Didrik