case about nRF9160 serial_lte_modem example MQTT_AT_commands.rst

[peter.min]

Hi,

The customer test routine serial_lte_modem mqtt returns 9,0

What does this state mean?

  * ``9`` - Ping response from the MQTT broker.

Thank you for all your assistance.
Kind regards,
Peter.Min

Thank you for all your assistance.
Kind regards,
Peter.Min

[Didrik Rokhaug]

Hi,

When in an MQTT connection, the broker will close the connection with the client if it hasn't heard from the client for a duration (given by the CONFIG_MQTT_KEEPALIVE Kconfig option).

Therefore, to keep the connection alive if the application hasn't sent any data, the MQTT client library will send an MQTT PING packet. A ping response (PINGRESP) is the reply from the broker, saying that it received the PING, and that the connection is still open.

Best regards,

Didrik

[peter.min]

Hi Didrik Rokhaug,

Thank you for all your assistance.
Kind regards,
Peter.Min