Temperature sensor data visualisation with Node-RED: Difference between revisions

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== Subscribing to MQTT ==
* To subscribe to MQTT we need the '''mqtt in'' node.
* Find the mqtt in node and drag it onto the '''Flow 1'''
* You will notice that the node has both a blue circle and a red triangle.
* The red triangle indicates that the node requires further configuration before it will work
[[File:Screen Shot 2022-04-13 at 6.13.51 am.png | 900px]]
== Configuring the mqtt in node ==
* Double click on the mqtt in node.
* In Properties > Server > select '''Add new mqtt-broker'''
* Click on the '''Edit button''' to the right - which looks like a pencil
[[File:Screen Shot 2022-04-13 at 6.19.00 am.png | 900px]]
* Enter the following details:
** Properties > Name > '''pycom-temperature-1'''
** Connection > Server > '''au1.cloud.thethings.network'''
** Connection > Port > '''1883'''
** Leave all other details as shown in the example below.
[[File:Screen Shot 2022-04-13 at 6.25.12 am.png | 900px]]

Revision as of 20:26, 12 April 2022

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.

Subscribing to MQTT

  • To subscribe to MQTT we need the 'mqtt in node.
  • Find the mqtt in node and drag it onto the Flow 1
  • You will notice that the node has both a blue circle and a red triangle.
  • The red triangle indicates that the node requires further configuration before it will work

Configuring the mqtt in node

  • Double click on the mqtt in node.
  • In Properties > Server > select Add new mqtt-broker
  • Click on the Edit button to the right - which looks like a pencil

  • Enter the following details:
    • Properties > Name > pycom-temperature-1
    • Connection > Server > au1.cloud.thethings.network
    • Connection > Port > 1883
    • Leave all other details as shown in the example below.

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