Changes:
var url = ‘http://api.thingspeak.com/channels/40743/feed/last.json’;

// Get the angle (convert to radians)
var angle = radians(Number(weather.field1));
// Get the wind speed
var windmag = Number(weather.field1);

Here is a quick reminder on how to access a Channel’s last entry via the ThingSpeak API.
URL:
http://api.thingspeak.com/channels/(channel_id)/feed/last.json

Reponse:
{“created_at”:””,”entry_id”:(entry_id)”field1″:””,”field2″:””,”field3″:””,”field4″:””,”field5″:””,”field6″:””,”field7″:””,”field8″:””}

Parsing JSON with jQuery

jQuery makes it so easy to make web-service and API calls

Are you using ThingSpeak to capture and save your IoT device data points? Ever felt constrained by the 8 field channels limit?

I was.

A Simple Solution

Hmm, what to do?

While you are limited to 8 data fields, a channel is not constrained by it’s own channel data. So the answer is right there…just add another channel and you get another group of 8 data fields. Since the additional data fields can be accessed from any of the master channel’s “plug-in” webpages, you have just doubled the number of entries in a single record, from 8 to 16. There is really no limit to how many channels that can be added, scaling the data set upward by 8 fields for each channel added.

Note the nested jQuery “$.getJSON” to retrieve the ThingSpeak channel data. All processing needs to be performed inside the inner nest in order to keep the values in scope.

Conclusion

Scalable ThingSpeak data sets. This short post should serve as a reference…a reminder of just how simple and obvious it is to expand your sensor data beyond the 8-field limit imposed on a ThingSpeak channel.

Getting Started with ThingSpeak
Introduction to ThingSpeak and overview of its basic workflow

MATLAB Analysis and Visualization
Explore and transform data, visualize data in MATLAB plots

TweetControl App
http://se.mathworks.com/help/thingspeak/tweetcontrol-app.html?requestedDomain=www.mathworks.com&requestedDomain=www.mathworks.com

Create a TweetControl

Link a ThingHTTP request to a Twitter hashtag.

Sign into ThingSpeak.

Select Apps > TweetControl.

Click New TweetControl.

Check the Anonymous TweetControl box to enable anyone to trigger this TweetControl.

Twitter Account: Enter a Twitter username to tie the control to one specific Twitter user.

Trigger: Enter the trigger word preceded by a hashtag. For example, #turnlightson.

ThingHTTP Action: Select a ThingHTTP to run.

Save the TweetControl.