Temperature sensor data visualisation with Node-RED
Overview
This lesson assumes that a temperature sensor is sending data to The Things Network. In this lesson we will use the MQTT protocol to subscribe to data transmission events. We will create a program in Node-RED to subscribe to the data transmissions and to graph the data coming from the sensor using the in-built Dashboard function in Node-RED.
Learning Objectives
- Learn how to subscribe to a MQTT using the Node-RED MQTT-in node
- Learn how to extract specific sensor data using the Node-RED function node.
- Learn how to create a Dashboard in Node-RED to monitor live data.
Subscribe to MQTT
Open Node-RED
- Click on the Raspberry Pi main drop down menu.
- Select Programming > Node-RED
- Node-RED will automatically open the Terminal on the Raspberry Pi.
- It takes approximately ten seconds for Node-RED to initialise itself.
- To actually use Node-RED you need to open the web browser on the Raspberry Pi.
- Click on the default web browser.
- In the search bar enter localhost:1880
- Localhost is the address of the local or host machine.
- In this example the host address is 192.168.1.168, but your computer will have a different address.
- The number at the end of the URL (1880) is the port number for the Node-RED application.
- Different ports are assigned to different applications using HTTP protocols.
- Note - if you are using UFW (uncomplicated firewall) you may need to open this port otherwise Node-RED will not work.
