Thingspeak - status 429 with message "Too Many Requests"

Basically, I am getting temperature values and trying to send an email alert whenever the temperature exceeds a specific point.

But however the code runs but yet I am facing an error that says

Error using matlab.internal.webservices.HTTPConnector/copyContentToByteArray (line 373)

The server returned the status 429 with message "Too Many Requests" in response to the request to URL https://api.thingspeak.com/alerts/send.

Error in readContentFromWebService (line 46)

byteArray = copyContentToByteArray(connection);

Error in webwrite (line 139)

[varargout{1:nargout}] = readContentFromWebService(connection, options);

Error in Customer Temperature Email Trigger (line 10)

webwrite(alertUrl , "body", alertBody, "subject", alertSubject, options);

I am also attaching the code.

channelID = 1614947;
alertApiKey = 'PRIVATE_ALERT_API_KEY';
alertUrl="https://api.thingspeak.com/alerts/send";
options = weboptions("HeaderFields", ["ThingSpeak-Alerts-API-Key", alertApiKey ]);
temperature = thingSpeakRead(channelID,'NumDays',30,'Fields',1);
recentvalue = temperature(end)
alertSubject = sprintf("Temperature Alert");
alertBody = sprintf(" The temperature of the customer entering the store is high : ",recentvalue);
    if recentvalue > 32
    webwrite(alertUrl , "body", alertBody, "subject", alertSubject, options);
    end

Basically the other articles tell me that I have to enter a delay or a pause because the free version of thingspeak has limitations. Any idea on what I could do to make sure the code runs with minimal amount of delay?

[Ajay Kumar]

Further update,

I have gone through all the documentation but they do not explicity mention on if we can add delays or pauses or any code to prevent the code from throwing Error 429. Is it possible that the field chart on thingspeak I am plotting my temperature points on is the reason for this?

Source :

Create email alert with HTTP POST - MATLAB - MathWorks India

Answer 1

[Vinod]

Did you read the note on the help page that says "Users are limited to 2 alerts every 30 minutes. The rate limit is applied when the request is made, not when the email is sent. If you exceed the request limit, the API returns the response code 429"?

How often is your MATLAB code executing? If it is more than twice every 30 minutes, it is expected that you will get a 429 code. If your temperature is likely to exceed that limit, one way is to try-catch the call to webwrite so the 429 is handled gracefully by your code.

channelID = 1614947;
alertApiKey = 'YOUR_ALERT_API_KEY';
alertUrl="https://api.thingspeak.com/alerts/send";
options = weboptions("HeaderFields", ["ThingSpeak-Alerts-API-Key", alertApiKey ]);
temperature = thingSpeakRead(channelID,'NumDays',30,'Fields',1);
recentvalue = temperature(end)
alertSubject = sprintf("Temperature Alert");
alertBody = sprintf(" The temperature of the customer entering the store is high : ",recentvalue);
if recentvalue > 32
   try 
      webwrite(alertUrl , "body", alertBody, "subject", alertSubject, options);
   catch
       % Code execution will end up here when a 429 is caught
   end
end

The above solution may be OK for your application, or, you may want more frequent alerts which the above try-catch will skip over. In this case you can use webwrite with a service like www.pushingbox.com and use that service to send the alerts.

[Joseph]

Hi Vinod, I am trying to set up a system to send notifications if my float switches are pressed (indicating the water level in a fish tank is low). My ThingSpeak React and MATLAB analysis worked when I inserted the "try" and "catch" functions are you recommended above, thanks!. However I will probably need more the two email alerts every 30 mins; is this the limit for paid version of ThingSpeak? Is so, how can I webwrite to www.pushingbox.com ?