Ublox SARA-R4 Series User Manual (English)

To Next Page

To Previous Page

SARA-R4/N4 series-AT Commands Manual

UBX-17003787 - R09



24MQTT

Page 247 of 307

24MQTT

The MQ Telemetry Transport (MQTT) protocol specifies a simple and lightweight messaging protocol,

designed for constrained devices and low-bandwidth, high-latency, or unreliable networks. An MQTT client

uses publish and subscribe methods to interact over a TCP connection with an MQTT message broker

(henceforth referred to as an MQTT server). The u-blox modules can be configured to operate as an MQTT

client.

To publish or subscribe, the MQTT client must first establish a TCP connection to an MQTT server.

The MQTT protocol specifies case-sensitive Topics, with Topic Names containing Topic Level separators "/" to

which messages will be published. For example, a message of "78 Fahrenheit or 25 Celsius" could be published

to the Topic Name of "/heat/sensor/SD/bldg5/DelMarConfRm". MQTT clients subscribe to Topic Filters to

determine if the client receives messages published to a given Topic name.

The Topic Filters may exactly specify a Topic Name or may contain either of the following wildcards:

• '+' - (Single level wildcard) applies to a single Topic Level

• '#' - (Multi-level wildcard) applies to potentially many Topic Levels (and must be the last character specified

in a Topic Filter);

'#' can be specified on its own or following a topic level separator ('/'). For example, the Topic Filter, "/heat/

sensor/SD/#", would receive any messages published to the "/heat/sensor/SD/bldg5/DelMarConfRm" Topic

Name.

MQTT specification states that Topic Filters starting with either wildcard will not match any Topic Name

that starts with "$".

The MQTT protocol also specifies a Quality of Service (QoS) level to be applied to message transactions:

• 0 - At most once delivery [default]

• 1 - At least once delivery

• 2 - Exactly once delivery

The MQTT protocol also allows an MQTT client to create a Will message, which the MQTT remote server

will store and only publish (to the Topic name specified as the Will Topic name) when the MQTT client gets

disconnected from the MQTT server, but not if the MQTT client explicitly sends a disconnect command.

24.1MQTT profile configuration +UMQTT

+UMQTT

SARA-R410M-02B SARA-R410M-52B SARA-R412MModules

SARA-N4

Syntax PIN required Settings saved Can be aborted Response time Error referenceAttributes

full No No No - MQTT Error

24.1.1Description

Configures or reads the parameter value of an MQTT client profile. Issue a set command for each <op_code>

parameter to set all of the parameters in an MQTT client profile.

24.1.2Syntax

Type Syntax Response Example

Generic syntax

Set AT+UMQTT=<op_code>[,

<param1>[,<param2>]]

+UMQTT: <op_code>,<result>

AT+UMQTT=12,1

+UMQTT: 12,1

MQTT unique client ID

Set AT+UMQTT=0,<client_id> +UMQTT: 0,<result>

AT+UMQTT=0,"352753090041680"

+UMQTT: 0,1

MQTT local TCP port number

Other manuals for Ublox SARA-R4 Series

System Integration Manual157 pages

Need help?

Do you have a question about the Ublox SARA-R4 Series and is the answer not in the manual?

Ublox SARA-R4 Series Specifications

General

Operating Temperature	-40°C to +85°C
Category	Cellular Module
Technology	LTE Cat M1, LTE Cat NB1
Frequency Bands	B1, B2, B3, B4, B5, B8, B12, B13, B18, B19, B20, B25, B26, B28, B39
Interfaces	UART, USB, I2C, GPIO
Protocols	TCP/IP, UDP, HTTP, HTTPS, MQTT, LWM2M
Security	TLS/SSL, DTLS, Secure Boot
Certifications	GCF, PTCRB, CE, FCC, IC