IoT Plug and Play support for Azure IoT Edge devices in IoT Central

In a previous blog, I already gave an introduction about the benefits of IoT Plug and Play (IPnP).

IoT Plug and Play enables solution builders to integrate IoT devices with their solutions without any manual configuration.

It introduces a model as a public description of a device. This device model advertises the capabilities of the logic on your IoT device like telemetry, properties, and commands. These elements are bundled as an interface. These interfaces are described using the Digital Twins Definition Language (DTDL).

Implementing IPnP in your solution is not that hard. The Azure IoT Device SDKs have you covered. Just interact with the cloud as usual. Only, when setting up the connection, the device exposes a ModelId. This id is compared with public models available in a repository so the actual model can be restored.

Azure IoT Central supports the capability models using the concept of device templates.

Next to direct-internet-connected devices, Azure IoT also support this concept of edge compute:

The way Azure IoT Edge devices are connected to the cloud differs quite a lot.

Azure IoT Edge devices lack the support for a ModelId. So there is no direct reference to any model is a model repository. But each type of edge device comes with a Deployment Manifest, describing the logic to be rolled out on the edge device and related settings.

These differences have an impact on how to implement IoT Plug and Play device templates.

Let’s see how to get started with IPnP for edge devices in IoT Central.

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IoT Plug and Play, modeling IoT Central devices

If you have built an IoT Device yourself and are finally able to send telemetry to the cloud, you should be familiar with the scenario where you have to repeat the hard work of describing the messages all again on ingestion.

IoT Devices expose D2C telemetry and it can also support C2D communication. This interface is most of the time unique for that device. To be able to get insights from a device you have to be able to react to its interface.

Wouldn’t it be nice if a device was able to provide metadata about its interface once it connects to the cloud? This way, the incoming D2C telemetry could automatically result in e.g. a full user interface. And all C2D output could be represented by pre-configured input controls.

With IoT Plug and Play this is all possible:

IoT Plug and Play enables solution builders to integrate smart devices with their solutions without any manual configuration. At the core of IoT Plug and Play, is a device model that a device uses to advertise its capabilities to an IoT Plug and Play-enabled application

https://docs.microsoft.com/en-us/azure/iot-pnp/overview-iot-plug-and-play

Microsoft provides a way to describe the interface of a device and annotate every feature.

To experience how this works, we will look at the best example: Azure IoT Central.

This SaaS IoT Dashboard makes perfect use of the ability how devices can expose their meta-model.

Let’s see how.

Azure IoT Central bridge for The Things Network

During the last The Thing Conference back in January in Amsterdam, The Netherlands, I spoke with the team of Tektelic. I got this smart room sensor from them to experiment with:

This sensor works with Lora and has some neat features. The sensor reads eg. temperature and humidity of the room it is placed in, but it also has a few other sensors. One of these is a magnetic switch.

It’s this sensor I am interested in. I want to see if a door is left open (and maybe putting a big, loud horn next to it…):

Today, I decided to connect this module to Azure IoT Central. For this, we use the Azure IoT Central Bridge.

I already blogged about this bridge where I connected to the Partical cloud. This time, I show how to connect to The Things Network cloud:

These are the steps we have to execute when connecting:

1. Connect the Tektelic Room sensor to The Things Network
2. Convert the byte array with data into a JSON message
3. Setup an IoT Central App
4. Setup the IoT Central Bridge
5. Modify the bridge so it can handle TTN messages
6. Setup a TTN webhook integration to the bridge
7. Create a Device capability model for our room sensor
8. See the influx of telemetry in IoT Central

Yes, there are a lot of small steps to perform. But I did the heavy lifting for you so it should be easy to follow.

Let’s see how to detect if a kitchen door is left open…