How do I receive the message when I subscribe to a topic using "MQTT in Matlab"?

Question

Sven Fießer 2018-6-2

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/403718-how-do-i-receive-the-message-when-i-subscribe-to-a-topic-using-mqtt-in-matlab

回答： Shubham 2023-8-28

Hello!

Right now I am using the toolbox "MQTT for Matlab". Pubishing messages works fine. But when I'm subscribing to any topic I can't get the content of the message. The "MessageCount" goes up for every message I'm publishing to that topic but Matlab isn't showing me any content at all for my subscription.

The code I used: myMQTT = mqtt('tcp://broker.hivemq.com'); mySub = subscribe(myMQTT,'testtopic')

Sven

3 个评论
显示 1更早的评论隐藏 1更早的评论

eman karim 2019-7-20

Hello, I have the same problem .. Have you reached a solution?

Eman

Faraz Azmi 2020-5-15

编辑：Faraz Azmi 2020-5-15

when i do message = read(mySub) , it says there are no messages waiting to be read. the message count stays 0 everytime but i do have data being published under the topic. what can i do about solving this. i asked this question in MATLAB answers but no answers yet, can u please help.

link to my question which contains screenshots

https://in.mathworks.com/matlabcentral/answers/524900-read-function-in-mqtt-says-there-are-no-messages-waiting-to-be-read

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Shubham 2023-8-28

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/403718-how-do-i-receive-the-message-when-i-subscribe-to-a-topic-using-mqtt-in-matlab#answer_1295012

Hi Sven,

In MATLAB, you can use the read() function to retrieve messages from different MQTT subscriptions. Additionally, when subscribing to a topic, you can assign a callback function that will be triggered whenever a message is received. This allows you to obtain real-time messages from multiple topics and perform actions on them.

Read here to know more about declaring and assigning callback functions while subscribing to a topic.