WiFi MQTT Publish

Publish messages to message queuing telemetry transport (MQTT) broker

• Library:

• Simulink Support Package for Arduino Hardware / WiFi

• 

Description

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.

The WiFi MQTT Publish block supports these hardware boards.

• Arduino MKR WiFi 1010

• Arduino MKR 1000

• Arduino Nano 33 IoT

• ESP32-WROOM (Arduino Compatible)

• ESP32-WROVER (Arduino Compatible)

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 (Simulink Support Package for Raspberry Pi Hardware).

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