WiFi MQTT Publish

Publish messages to message queuing telemetry transport (MQTT) broker

Since R2022b

• 

Libraries:
Simulink Support Package for Arduino Hardware / WiFi

Description

Add-On Required: This feature requires the Simulink Support Package for Arduino Hardware add-on.

Use the WiFi MQTT Publish block to publish messages from your publisher (hardware) to the MQTT broker on the topic you specify in the Topic parameter.

Note

The WiFi MQTT Publish block supports MQTT over TCP/IP sockets only.

Supported Arduino Boards

The WiFi MQTT Publish block supports these Arduino^® boards.

• Arduino MKR WiFi 1010

• Arduino MKR 1000

• Arduino Nano 33 IoT

• Arduino compatible ESP32 – WROOM board

• Arduino compatible ESP32 – WROVER board

• Arduino UNO R4 Wi-Fi^®

• Arduino compatible Raspberry Pi^® Pico W

Examples

Publish and Subscribe to Messages on ThingSpeak Using MQTT Blocks on Arduino

Use the WiFi MQTT Publish and WiFi MQTT Subscribe blocks from the Simulink® Support Package for Arduino® Hardware to publish to and receive messages from MQTT broker to Arduino board. In this example, ThingSpeak™ is the MQTT broker and Arduino board is the MQTT client.

• Open Model

Securely Publish and Subscribe to Messages on Mosquitto Broker Using Arduino Hardware

Learn how to securely exchange messages between Arduino and a Mosquitto™ broker using MQTT blocks in Simulink^®.

• Open Model

Ports

Input

message — Message to publish

scalar

Specify the message you want the publisher to publish to the MQTT broker as an array of ASCII characters of type uint8.

Data Types: uint8

Output

status — Status code from MQTT broker

0 | 1

The block outputs the status code issued by the MQTT broker in response to the publish request. If the broker accepts the message for publishing, the block outputs 1 at this port. The block outputs 0 when the broker rejects the message. The broker can reject a message for various reasons, such as an incorrect user name or password or if the message requires a protocol version that the broker cannot accept.

Data Types: int8

Parameters

Broker service — MQTT broker service provider

ThingSpeak (default) | Other

Select the MQTT broker service provider that receives, filters, and sends messages to the clients.

• ThingSpeak — When you specify this option, the MQTT access to your channels is handled by a ThingSpeak™ MQTT broker. To create an MQTT device, follow the steps in Create a ThingSpeak MQTT Device (ThingSpeak).

• Other — Specify this option when the MQTT access to your channels is handled by other MQTT public brokers such as HiveMQ^®, Mosquitto, and so on.

Configure the same MQTT broker properties as in the MQTT properties.

Topic — Routing information for MQTT broker

channels/<channelID>/publish (default) | any valid topic name

Specify a topic that the publisher uses to filter messages. A topic can have a maximum of 128 characters. For information on topics and their structure, see Topics in MQTT.

Retain message — Option to send message to new subscribers

off (default) | on

Control how the MQTT broker handles new subscriptions.

• on — When a new subscription is made to a topic, the broker identifies the message in its database with the matching topic name and sends the message immediately.

  Note

  The MQTT broker retains only the last published message related to the specified topic.

• off — When a new subscription is made to a topic, the subscriber must wait until the publisher sends the next message.

Dependencies

To enable this parameter, set Broker Service to Other.

Update interval (seconds) — Rate of publishing message(s)

60 (default) | scalar

Enter the time interval in seconds to publish message(s) to the MQTT broker.

Print diagnostic messages — Print MQTT broker response on serial port

off (default) | on

Select this option to print the response from the MQTT broker on the Arduino serial port for each publish request.

Version History

Introduced in R2022b