2023-24 Trimester B - Internet of Things MMI126818-22-B (15 Credits).

RESIT Coursework 1: Combined Specification and Submission Template.

2.2 Google Cloud Node-RED application functionality: 7

3 Code Exports 8

• • The details of each response that is expected for each part of the CW. These are provided as yellow-coloured boxes.

• You must deliver the CW submission within a copy of this current document, using the entries provided.

• Unless specifically stated otherwise, you are required to provide only your own diagrams/screenshots as part of your responses.

• For snippets of JavaScript code, do not use screenshots; copy the textual code content.

• • be spell-checked,

  • be grammatically correct,

• Writing Skills

  • https://www.gcu.ac.uk/aboutgcu/academicschools/cebe/study/ldc/learningresources

IoT Messaging with MQTT

Note: Parts of this question require you to form suitable MQTT topic structures based upon the guidance found within the IoT module Week 4 materials “Organising IoT data for Messaging”. You must create your own example values for the various parts of the topics requested.

1. Provide a syntactically correct JSON data structure that represents an example of the following information relating to a sensor oriented IoT Device. You should create keys and values within the structure as appropriate, including nesting where this improves clarity. You should select appropriate values for any data items included in the description. The required data items are as follows:

2. 1. An ‘inject’ node to initiate a function execution.

   2. A clearly named ‘function’ node that emits the JSON data structure created in part (a) above. The node should have a suitable name. Provide the JavaScript content of the function node below (as text, not a screenshot):

Note: some of the following questions require you to create some MQTT topics. These should be suitably descriptive, using topics with a style taken from the IoT module Week 4 materials “Organising IoT data for Messaging”

3. The IoT Device data structure in Part (a) above is to form the payload for an appropriate message that publishes the status of a specific sensor IoT device via MQTT. You are required to provide a suitable example of an MQTT publishing topic for this device to send this message.
   
   Provide an example of the MQTT topic and then provide a brief narrative explanation of the construction of your topic.

Provide an example of the MQTT payload:

5. A Cloud application sends an MQTT message to an IoT device with the following content for the topic and payload:
   Topic: “org_glasgow_west/HEATER_TYPE_3/id_02312/command”
   Payload: {“night_temperature”: 10, “day_temperature”:17}
   
   Provide a narrative explanation of each part of the Topic and Payload to describe what is being requested and from which device:

End-to-end application utilising IoT Device (PC) and Google Cloud.

• • Receives IoT sensor data and displays this on charts and gauges on a dashboard.

  • Processes the sensor data and outputs the current-status on the dashboard.

IoT device functionality

• Utilises the ‘Sense HAT’ simulator for simulated sensors.

• Regularly sends data as a single message to the Google Cloud application that includes sensor values and timestamp:

  • Sends the current time in Unix timestamp format, as a number.

  • The frequency of sensor data must be restricted to sending one set (both sensors) of data every 10 seconds.

2. Explain how you form the complete Payload message to be sent to the Google Cloud application. This should include the textual JavaScript content (not a screenshot) of any Node-RED ‘function’ node, and the configuration of any other nodes (as screenshots). Add debug output as appropriate to evidence the functionality.

3. Provide the MQTT publishing topic for the IoT device and explain why you have constructed it in the way that you have.

Google Cloud Node-RED application functionality:

• • Displays the following on the dashboard:

    • A clearly labelled chart with Temperature data for the last hour.

    • A text output, representing the outcome of the rules shown in the table below.

  • The two Temperature-related items should be in one dashboard group.

Please deliver the following items. You can include clearly named debug nodes (with screenshot output from the debug panel) to evidence any aspects that you wish to highlight.

All functions must be given clear descriptive names.

9. For each function provided in the Cloud application, provide the function name and the text content of the function (not a screenshot). All code should include a clear set of comments.

10. For all other (non-function) nodes provide screenshots of their configuration. All configurations must be complete. You do not have to include the ‘debug’ nodes.

Code Exports