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iot-hub-csharp-csharp-module-twin-getstarted.md

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title description author ms.service services ms.devlang ms.topic ms.date ms.author ms.custom
Get started w/ Azure IoT Hub module identity & module twin (.NET)
Learn how to create module identity and update module twin using IoT SDKs for .NET.
chrissie926
iot-hub
iot-hub
csharp
conceptual
08/07/2019
menchi
amqp, devx-track-csharp

Get started with IoT Hub module identity and module twin (.NET)

[!INCLUDE iot-hub-selector-module-twin-getstarted]

Note

Module identities and module twins are similar to Azure IoT Hub device identity and device twin, but provide finer granularity. While Azure IoT Hub device identity and device twin enable the back-end application to configure a device and provide visibility on the device's conditions, a module identity and module twin provide these capabilities for individual components of a device. On capable devices with multiple components, such as operating system based devices or firmware devices, module identities and module twins allow for isolated configuration and conditions for each component.

At the end of this tutorial, you have two .NET console apps:

  • CreateIdentities. This app creates a device identity, a module identity, and associated security key to connect your device and module clients.

  • UpdateModuleTwinReportedProperties. This app sends updated module twin reported properties to your IoT hub.

Note

For information about the Azure IoT SDKs that you can use to build both applications to run on devices, and your solution back end, see Azure IoT SDKs.

Prerequisites

  • Visual Studio.

  • An active Azure account. If you don't have an account, you can create a free account in just a couple of minutes.

Create a hub

[!INCLUDE iot-hub-include-create-hub]

Get the IoT hub connection string

[!INCLUDE iot-hub-howto-module-twin-shared-access-policy-text]

[!INCLUDE iot-hub-include-find-registryrw-connection-string]

[!INCLUDE iot-hub-get-started-create-module-identity-csharp]

Update the module twin using .NET device SDK

In this section, you create a .NET console app on your simulated device that updates the module twin reported properties.

Before you begin, get your module connection string. Sign in to the Azure portal. Navigate to your hub and select IoT Devices. Find myFirstDevice. Select myFirstDevice to open it, and then select myFirstModule to open it. In Module Identity Details, copy the Connection string (primary key) when needed in the following procedure.

Azure portal module detail

  1. In Visual Studio, add a new project to your solution by selecting File > New > Project. In Create a new project, select Console App (.NET Framework), and select Next.

  2. Name the project UpdateModuleTwinReportedProperties. For Solution, select Add to solution. Make sure the .NET Framework version is 4.6.1 or later.

    Create a Visual Studio project

  3. Select Create to create your project.

  4. In Visual Studio, open Tools > NuGet Package Manager > Manage NuGet Packages for Solution. Select the Browse tab.

  5. Search for and select Microsoft.Azure.Devices.Client, and then select Install.

    Screenshot that shows the "Microsoft.Azure.Devices.Client" selected and the "Install" button highlighted.

  6. Add the following using statements at the top of the Program.cs file:

    using Microsoft.Azure.Devices.Client;
using Microsoft.Azure.Devices.Shared;
using System.Threading.Tasks;
using Newtonsoft.Json;

  7. Add the following fields to the Program class. Replace the placeholder value with the module connection string.

    private const string ModuleConnectionString = "<Your module connection string>";
private static ModuleClient Client = null;
static void ConnectionStatusChangeHandler(ConnectionStatus status, 
  ConnectionStatusChangeReason reason)
{
    Console.WriteLine("Connection Status Changed to {0}; the reason is {1}", 
      status, reason);
}

  8. Add the following method OnDesiredPropertyChanged to the Program class:

    private static async Task OnDesiredPropertyChanged(TwinCollection desiredProperties, 
  object userContext)
    {
        Console.WriteLine("desired property change:");
        Console.WriteLine(JsonConvert.SerializeObject(desiredProperties));
        Console.WriteLine("Sending current time as reported property");
        TwinCollection reportedProperties = new TwinCollection
        {
            ["DateTimeLastDesiredPropertyChangeReceived"] = DateTime.Now
        };

        await Client.UpdateReportedPropertiesAsync(reportedProperties).ConfigureAwait(false);
    }

  9. Add the following lines to the Main method:

    static void Main(string[] args)
{
    Microsoft.Azure.Devices.Client.TransportType transport = 
      Microsoft.Azure.Devices.Client.TransportType.Amqp;

    try
    {
        Client = 
          ModuleClient.CreateFromConnectionString(ModuleConnectionString, transport);
        Client.SetConnectionStatusChangesHandler(ConnectionStatusChangeHandler);
        Client.SetDesiredPropertyUpdateCallbackAsync(OnDesiredPropertyChanged, null).Wait();

        Console.WriteLine("Retrieving twin");
        var twinTask = Client.GetTwinAsync();
        twinTask.Wait();
        var twin = twinTask.Result;
        Console.WriteLine(JsonConvert.SerializeObject(twin.Properties)); 

        Console.WriteLine("Sending app start time as reported property");
        TwinCollection reportedProperties = new TwinCollection();
        reportedProperties["DateTimeLastAppLaunch"] = DateTime.Now;

        Client.UpdateReportedPropertiesAsync(reportedProperties);
    }
    catch (AggregateException ex)
    {
        Console.WriteLine("Error in sample: {0}", ex);
    }

    Console.WriteLine("Waiting for Events.  Press enter to exit...");
    Console.ReadLine();
    Client.CloseAsync().Wait();
}

    This code sample shows you how to retrieve the module twin and update reported properties with AMQP protocol. In public preview, we only support AMQP for module twin operations.

  10. Optionally, you can add these statements to the Main method to send an event to IoT Hub from your module. Place these lines below the try catch block.

    Byte[] bytes = new Byte[2];
bytes[0] = 0;
bytes[1] = 1;
var sendEventsTask = Client.SendEventAsync(new Message(bytes));
sendEventsTask.Wait();
Console.WriteLine("Event sent to IoT Hub.");

Run the apps

You can now run the apps.

  1. In Visual Studio, in Solution Explorer, right-click your solution, and then select Set StartUp projects.

  2. Under Common Properties, select Startup Project.

  3. Select Multiple startup projects, and then select Start as the action for the apps, and OK to accept your changes.

  4. Press F5 to start the apps.

Next steps

To continue getting started with IoT Hub and to explore other IoT scenarios, see: