I am unable to connect MQTT client using Thingspeak in MATLAB.

Question

Anam Amjad 2022-7-5

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1754175-i-am-unable-to-connect-mqtt-client-using-thingspeak-in-matlab

评论： Anam Amjad ，2022-7-6

Here is my piece of code, I am following the steps of the tutorial https://www.mathworks.com/help/icomm/ug/get-started-with-mqtt.html

clientID = "client id";
userName = "user name";
password = "password";
rootCert = "Path";
brokerAddress = "ssl://mqtt3.thingspeak.com";
port = 8883;
mqClient = mqttclient(brokerAddress, Port = port, ClientID = clientID,...
    Username = userName, Password = password, CARootCertificate = rootCert);

upon reaching the mqClient, the following error occurs

ThingSpeakMQTT
Error: File: ThingSpeakMQTT.m 
Incorrect use of '=' operator. To assign a value to a variable, use '='. 
To compare values for equality, use '=='.

Please someone guide me on this.

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Geoff Hayes 2022-7-6

@Anam Amjad - you are using R2022a which Create MQTT client connected to broker suggests when this functionality was introduced? (I'm not entirely sure of this though...) Note that https://www.mathworks.com/matlabcentral/answers/1753160-incorrect-use-of-operator-to-assign-a-value-to-a-variable-use-to-compare-values-for-equal had a similar error but the way you have written the above code seems to be correct (and identical to that from the link you posted).

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Answer 1

Vinod 2022-7-6

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1754175-i-am-unable-to-connect-mqtt-client-using-thingspeak-in-matlab#answer_1001075

I believe you are using an older version of MATLAB. You need to use MATLAB R2022a or newer and have a license to the Industrial Communication Toolbox to use the syntax you have in the example.