Using Historical Data from Sensors in Arduino Cloud | Arduino Blog

Historical data can be essential to making your electronics and Arduino project work how you want them to. Data retention is one of the features that changes depending on which level of Arduino Cloud account you have. Here’s everything you need to know, so you can choose exactly the right Arduino Cloud plan.

Data or Variables?

When you add variables to your Things, the Arduino Cloud automatically generates sketches that include them.

Hang on though. Aren’t we here to talk about data retention?

Indeed we are. When we say “variables”, this is the term used to describe the data you send to your Arduino Cloud. It sounds a bit technical, but consider the word. “Variable” actually makes more sense than “data”, which is kinda woolly.

Variables are information that changes or, you guessed it, varies. Temperature, for example. If you have a temperature sensor sending data to the Cloud, it’s a variable. Because the value of the data (the temperature) is always changing/varying. 

So in your sketch it’s known as a variable. The different data retention options in the Arduino Cloud plans tell you how long the Cloud will store a record of those variables for you.

Historical Data Options

Each Arduino Cloud plan offers a different length of time for how long you retain sensor data, depending on your needs.

If you’re running a home automation to turn the lights on when it drops dark, your system is working with (pretty much) real-time data. So 24 hours of sensor information is perfectly adequate. It’s not like you’ll be turning a lamp on or off based on yesterday’s ambient light levels.

A weather station might work a bit differently though. If you’re measuring the temperature or rainfall or daylight hours, you may want to build a comparison to see how the weather is changing. In this case, an Arduino Cloud Entry plan would give you 15 days of data, allowing you to monitor and record recent changes in your weather station’s variables.

Historical data for an IoT greenhouse, or maybe an aquarium or terrarium, would be much more important. Maybe it’s even an industrial project that’s monitoring equipment for predictive maintenance needs. In these cases, being able to look back at your variables over previous weeks and months could be essential. In that case, you’d go Maker or Maker Plus, so you can build dashboards with detailed histories of your measurements.

It’s very possible that you don’t even know how much historical data will be useful to your project at first. You start on the free tier, decide that it’d be useful to have legacy information, and go up through the Entry plan and eventually settle on Maker. The project leads the way, until it’s delivering everything you need.

Putting Historical Data to Use in Arduino Cloud

Arduino Cloud is really clever when it comes to the data generated by sensors and used as variables. For example, you can specify how often new data is sent to your Arduino Cloud.

Let’s say you’re monitoring Wi-Fi signal strength at the bottom of the garden, where a project (weather station, let’s say) is installed. If this is a solar and/or battery powered device, power consumption becomes essential. By changing the data sampling interval from updating a variable on Arduino Cloud every second to updating once a minute, you can extend battery life by a huge amount. The device is only operating a fraction of the time it was before, and the information is just as useful.

Combined with 15 days or three months of historical data, you can build a detailed picture of Wi-Fi performance that lets you keep everything running perfectly. Or, if you need to find out when and why your signal has been dropping, the story is right there in your Arduino Cloud dashboard.

Choosing the Right Arduino Cloud Plan

So for all these reasons, you can see why different amounts of data retention are available in the Arduino Cloud plans. It’s not that all projects benefit from as much retention as possible. As we discussed, even some complex, elaborate projects barely need any. Others, which might be simple signal strength monitoring or rainfall measurement, need to know what was happening months ago.

You have the choice, because the different Arduino Cloud plans offer different historical data options for different needs. If in doubt for what your project needs to work as intended, start on the free plan and work up from there.

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