Using a Weidmueller UC 20 Controller as Azure IoT Edge child device

Azure IoT Edge is a powerful solution for your edge computing needs. It can collect telemetry, make local decisions, and send data to the cloud. This works great if an internet connection is available. If the connection is temporarily broken, everything still works. The telemetry is temporarily persisted so no data is lost.

An edge gateway can also act as a transparent gateway:

Here, child devices are made part of the local routing mechanism of the edge. The child devices are configured to send their telemetry to the edge device. From there, the same telemetry is sent to the cloud as if it’s sent by the child device itself.

The main advantages are:

  1. If no internet connection is available, the child telemetry is stored on the edge until the connection is restored. The child devices have no notion of the edge gateway, hence ‘transparent’
  2. The logic running on the edge is able to access the telemetry coming from child devices so this can be used and combined with other data to take local decisions

This architecture is also known as downstream devices.

I already wrote a blog on this topic previously. In there, some test apps stole the show.

Now, let’s see this in action with an actual industrial device. We also check out sending telemetry back:

We will be working with a Weidmueller UC20, an automation controller.

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Expanding Raspberry PI I/O using I²C on Azure IoT Edge

The GPIO of a Raspberry gives you the opportunity to interact with the physical world using digital pins and various IO busses like SPI and I²C.

In the past, in this blog, I already demonstrated how to access the GPIO of a Raspberry Pi.

In the last few months, I spent my spare time building a beerlift:

The beerlift is capable to serve multiple bottles of beer so each bottle has its bottle holder:

The bottle holder contains a switch to detect a bottle being placed or being removed. It also contains a LED so it can visualize if a bottle is placed or removed or eg. advertised.

I wanted to support up to sixteen bottles (so 32 switches and LEDs) which exceed the GPIO pin limitation of a Raspberry Pi.

Therefore, I bought myself a couple of MCP23017 I/O Expanders. This device offers sixteen digital inputs or outputs over a serial interface. I went for the I2C version:

Let’s see how we can use them in an Azure IoT Edge solution.

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Sending IoT Hub telemetry to a Blazor Web App

For those who are interested in software development for the web using the C# programming language, Blazor is a viable alternative for building progressive websites as compared to Asp.Net Core / Angular / JavaScript.

Blazor lets you build interactive web UIs using C# instead of JavaScript. Blazor apps are composed of reusable web UI components implemented using C#, HTML, and CSS. Both client and server code is written in C#, allowing you to share code and libraries.

In the past, I already implemented Blazor on the Edge, including message routing.

Now, let’s see how we can integrate a Blazor website with telemetry coming from an Azure IoT Hub in the cloud.

For this to happen, we need this architecture:

So, the moving parts are:

  • An IoT Hub with message routing enabled
  • Azure Function with IoT Hub / EventHub trigger
  • Server-side Blazor website with API Controller integration

Let’s see how this is set up.

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