How to Format Raw Sensor Data into JSON Objects Using Node-RED


In the realm of IoT, the ability to efficiently process and format raw sensor data is crucial. Node-RED, a versatile programming tool, offers a user-friendly interface for handling such data. 

This blog will guide you through the process of transforming raw sensor data into structured JSON objects using Node-RED, enhancing the data's usability for IoT applications.

Getting Started in Node-RED

Before diving into data formatting, ensure that Node-RED is set up and running on your system. Node-RED's flow-based programming model makes it an ideal platform for connecting IoT devices and processing data streams. If you're new to Node-RED, you can find installation instructions and a wealth of resources on their official website.

How to Inject Raw Data into Node-RED

Using the 'Inject' Node: Start by dragging an 'inject' node onto the canvas. This node is used to input raw data, simulating sensor input in this case. Configure the node to inject the type of data your sensor would typically produce, such as numerical temperature readings.

Understanding Data Structure: Connect the 'inject' node to a 'debug' node to understand the structure of the data. Deploy the flow and inject data to see how Node-RED represents the sensor data.

How to Inspect Data with the Debug Node

The 'debug' node is a powerful tool for inspecting data within Node-RED. It allows you to view the data structure and content, which is crucial for proper formatting. Use the 'debug' node to examine the properties of the message object, including 'payload', 'topic', and '_msgid'.

Understanding and Manipulating Message Objects

Node-RED uses message objects to pass data between nodes. The message object typically contains a 'payload' property, which holds the actual data. Understanding how to access and manipulate this object is key to formatting your sensor data effectively.

Formatting Sensor Data with the Change Node

Introduction to the 'Change' Node: The 'change' node is used to modify the properties of a message object. It's particularly useful for transforming raw data into a more structured format.

Using JSONata for Data Transformation: JSONata is a powerful query and transformation language for JSON data. Use JSONata expressions in the 'change' node to perform operations like unit conversion (e.g., Celsius to Fahrenheit) on the sensor data.

Enhancing Data with Additional Properties

Adding Metadata:  Metadata like 'timestamp' and 'type' can be crucial for data analysis. Use the 'change' node to add these properties to your message object, ensuring that each piece of data is properly contextualized.

Implementing Conditional Logic: Conditional properties, such as 'alert' based on specific sensor readings, can be added using JSONata's conditional expressions. This allows you to flag data that requires immediate attention.

Advanced JSON Object Manipulation

As your IoT application grows, you might need to represent more complex data structures. Learn how to structure nested JSON objects to represent your sensor data effectively. This might involve grouping multiple sensor readings together or formatting the data to be compatible with other systems or databases.


Formatting raw sensor data into structured JSON objects is a fundamental skill in IoT. Node-RED, with its intuitive interface and powerful nodes, simplifies this process, allowing you to focus on building and optimizing your IoT solutions. By following the steps outlined in this blog, you can transform your raw sensor data into structured, actionable information.

For a visual guide on formatting sensor data in Node-RED, watch this informative video.

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For those starting their journey in IoT, Prescient Designer offers an even more intuitive interface. Enhancing Node-RED's capabilities, it simplifies the creation, deployment, and management of IoT solutions. Its drag-and-drop functionality and visualization tools make working with JSON in Node-RED straightforward, particularly for beginners.


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