MQTT AT commands

The following commands list contains the AT commands used to operate the MQTT client.

MQTT event #XMQTTEVT

The #XMQTTEVT is an unsolicited notification that indicates the event of the MQTT client.

Unsolicited notification

It indicates the event of the MQTT client.

Syntax

#XMQTTEVT=<evt_type>,<result>

  • The <evt_type> value is an integer indicating the type of the event. It can assume the following values:

    • 0 - Connection request.

    • 1 - Disconnection. The MQTT client is disconnected from the MQTT broker once this event is notified.

    • 2 - Message received on a topic the client is subscribed to.

    • 3 - Acknowledgment for the published message with QoS 1.

    • 4 - Confirmation of the reception for the published message with QoS 2.

    • 5 - Release of the published message with QoS 2.

    • 6 - Confirmation to a publish release message with QoS 2.

    • 7 - Reception of the subscribe request.

    • 8 - Reception of the unsubscription request.

    • 9 - Ping response from the MQTT broker.

  • The <result> value is an integer indicating the result of the event. It can assume the following values:

    • 0 - Success.

    • Negative value - Failure. It is the error code indicating the reason for the failure.

MQTT connect #XMQTTCON

The #XMQTTCON command allows you to connect to and disconnect from the MQTT broker.

Set command

The set command allows you to connect to and disconnect from the MQTT broker.

Syntax

AT#XMQTTCON=<op>[,<client_id>,<username>,<password>,<url>,<port>[,<sec_tag>]]

  • The <op> parameter is an integer. It can accept one of the following values:

    • 0 - Disconnect from the MQTT broker.

    • 1 - Connect to the MQTT broker using IP protocol family version 4.

    • 2 - Connect to the MQTT broker using IP protocol family version 6.

  • The <client_id> parameter is a string. It indicates the MQTT Client ID.

  • The <username> parameter is a string. It indicates the MQTT Client username.

  • The <password> parameter is a string. It indicates the MQTT Client password in cleartext.

  • The <url> parameter is a string. It indicates the MQTT broker hostname.

  • The <port> parameter is an unsigned 16-bit integer (0 - 65535). It indicates the MQTT broker port.

  • The <sec_tag> parameter is an integer. It indicates the credential of the security tag used for establishing a secure connection.

Response syntax

#XMQTTEVT: <evt_type>,<result>

  • The <evt_type> value is an integer. When 0, it indicates the acknowledgment of the connection request.

  • The <result> value is an integer. It can assume the following values:

    • 0 - Connection succeded.

    • Negative Value - Error code. It indicates the reason for the failure.

Examples

AT#XMQTTCON=1,"MyMQTT-Client-ID","","","mqtt.server.com",1883
OK
#XMQTTEVT: 0,0

AT#XMQTTCON=0
OK
#XMQTTEVT: 1,0

Read command

The read command shows MQTT client information.

Syntax

AT#XMQTTCON?

Response syntax

#XMQTTCON: <client_id>,<url>,<port>[,<sec_tag>]]

  • The <client_id> value is a string. It indicates the MQTT client ID.

  • The <url> value is a string. It indicates the MQTT broker hostname.

  • The <port> value is an unsigned 16-bit integer (0 - 65535). It indicates the MQTT broker port.

  • The <sec_tag> value is an integer. It indicates the credential of the security tag used for establishing a secure connection.

Examples

AT#XMQTTCON?
#XMQTTCON: "MyMQTT-Client-ID","","","mqtt.server.com",1883
OK

Test command

The test command is not supported.

MQTT subscribe #XMQTTSUB

The #XMQTTSUB command allows you to subscribe to an MQTT topic.

Set command

The set command allows you to subscribe to an MQTT topic.

Syntax

AT#XMQTTSUB=<topic>,<qos>

  • The <topic> parameter is a string. It indicates the topic to be subscribed to.

  • The <qos> parameter is an integer. It indicates the MQTT Quality of Service types. It can accept the following values:

    • 0 - Lowest Quality of Service. No acknowledgment of the reception is needed for the published message.

    • 1 - Medium Quality of Service. If the acknowledgment of the reception is expected for the published message, publishing duplicate messages is permitted.

    • 2 - Highest Quality of Service. The acknowledgment of the reception is expected and the message should be published only once.

Response syntax

#XMQTTEVT: <evt_type>,<result>

  • The <evt_type> value is an integer. It can assume the following values:

    • 2 - Notification that a publish event has been received on a topic the client is subscribed to.

    • 7 - Acknowledgment of the subscribe request.

  • The <result> value is an integer. It can assume the following values:

    • 0 - Value indicating the acknowledgment of the connection request.

    • Negative Value - Error code indicating the reason for the failure.

Unsolicited notification

If the MQTT client successfully subscribes to a topic, the following unsolicited notification indicates that a message from the topic is received:

#XMQTTMSG: <topic_length>,<message_length><CR><LF>
<topic_received><CR><LF>
<message>

  • The <topic_length> value is an integer. It indicates the length of the <topic_received> field.

  • The <message_length> parameter is an integer. It indicates the length of the <message> field.

  • The <topic_received> value is a string. It indicates the topic that receives the message.

  • The <message> value can be a string or a HEX. It contains the message received from a topic.

Examples

AT#XMQTTSUB="nrf91/slm/mqtt/topic0",0
OK
#XMQTTEVT: 7,0

AT#XMQTTSUB="nrf91/slm/mqtt/topic1",1
OK
#XMQTTEVT: 7,0

AT#XMQTTSUB="nrf91/slm/mqtt/topic2",2
OK
#XMQTTEVT: 7,0

Read command

The read command is not supported.

Test command

The test command is not supported.

MQTT unsubscribe #XMQTTUNSUB

The #XMQTTUNSUB command allows you to unsubscribe from an MQTT topic.

Set command

The set command allows you to unsubscribe from an MQTT topic.

Syntax

AT#XMQTTUNSUB=<topic>

  • The <topic> parameter is a string. It indicates the topic to unsubscribe from.

Response syntax

#XMQTTEVT: <evt_type>,<result>

  • The <evt_type> value is an integer. When 8, it acknowledges the reception of the unsubscription request.

  • The <result> value is an integer. It can assume the following values:

    • 0 - Value indicating the successful unsubscription.

    • Negative Value - Error code indicating the reason for the failure.

Examples

AT#XMQTTUNSUB="nrf91/slm/mqtt/topic0"
OK
#XMQTTEVT: 8,0

Read command

The read command is not supported.

Test command

The test command is not supported.

MQTT publish #XMQTTPUB

The #XMQTTPUB command allows you to publish messages on MQTT topics.

Set command

The set command allows you to publish messages on MQTT topics.

Syntax

AT#XMQTTPUB=<topic>[,<msg>[,<qos>[,<retain>]]]

  • The <topic> parameter is a string. It indicates the topic on which data is published.

  • The <msg> parameter is a string. It contains the payload on the topic being published. The max NET_IPV4_MTU is 576 bytes. When this parameter is not specified, SLM enters slm_data_mode.

  • The <qos> parameter is an integer. It indicates the MQTT Quality of Service types. It can accept the following values:

    • 0 - Lowest Quality of Service (default value). No acknowledgment of the reception is needed for the published message.

    • 1 - Medium Quality of Service. If the acknowledgment of the reception is expected for the published message, publishing duplicate messages is permitted.

    • 2 - Highest Quality of Service. The acknowledgment of the reception is expected and the message should be published only once.

  • The <retain> parameter is an integer. Default value is 0. When 1, it indicates that the broker should store the message persistently.

Response syntax

#XMQTTEVT: <evt_type>,<result>

  • The <evt_type> value is an integer. It can assume the following values:

    • 3 - Acknowledgment for the published message with QoS 1.

    • 4 - Reception confirmation for the published message with QoS 2. It is notified when PUBREC is received from the broker.

    • 5 - Release of the published message with QoS 2.

    • 6 - Confirmation (PUBREL) to a publish release message with QoS 2. It is notified when PUBREL is received from the broker.

  • The <result> value is an integer. It can assume the following values:

    • 0 - Value indicating the acknowledgment of the connection request.

    • Negative Value - Error code indicating the reason for the failure.

Examples

AT#XMQTTPUB="nrf91/slm/mqtt/topic0","Test message with QoS 0",0,0
OK
#XMQTTMSG: 21,23
nrf91/slm/mqtt/topic0
Test message with QoS 0
#XMQTTEVT: 2,0

AT#XMQTTPUB="nrf91/slm/mqtt/topic0"
{"msg":"Test Json publish"}
#XMQTTMSG: 21,27
nrf91/slm/mqtt/topic0
{"msg":"Test Json publish"}
#XMQTTEVT: 2,0
+++
OK

AT#XMQTTPUB="nrf91/slm/mqtt/topic1","Test message with QoS 1",1,0
OK
#XMQTTEVT: 3,0
#XMQTTMSG: 21,23
nrf91/slm/mqtt/topic1
Test message with QoS 1
#XMQTTEVT: 2,0

AT#XMQTTPUB="nrf91/slm/mqtt/topic2","Test message with QoS 2",2,0
OK
#XMQTTEVT: 4,0
#XMQTTEVT: 6,0
#XMQTTMSG: 21,23
nrf91/slm/mqtt/topic2Test message with QoS 2
#XMQTTEVT: 2,0

Read command

The read command is not supported.

Test command

The test command is not supported.