Get started with IoT Hub module identity and module twin using the portal and .NET device


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.

In this tutorial, you will learn:

  • How to create a module identity in the portal.

  • How to use a .NET device SDK to update the module twin from your device.


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.


  • 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

This section describes how to create an IoT hub using the Azure portal.

  1. Sign in to the Azure portal.

  2. From the Azure homepage, select the + Create a resource button, and then enter IoT Hub in the Search the Marketplace field.

  3. Select IoT Hub from the search results, and then select Create.

  4. On the Basics tab, complete the fields as follows:

    • Subscription: Select the subscription to use for your hub.

    • Resource Group: Select a resource group or create a new one. To create a new one, select Create new and fill in the name you want to use. To use an existing resource group, select that resource group. For more information, see Manage Azure Resource Manager resource groups.

    • Region: Select the region in which you want your hub to be located. Select the location closest to you.

    • IoT Hub Name: Enter a name for your hub. This name must be globally unique. If the name you enter is available, a green check mark appears.


    Because the IoT hub will be publicly discoverable as a DNS endpoint, be sure to avoid entering any sensitive or personally identifiable information when you name it.

    Create a hub in the Azure portal

  5. Select Next: Size and scale to continue creating your hub.

    Set the size and scale for a new hub using the Azure portal

    This screen allows you to set the following values:

    • Pricing and scale tier: Your selected tier. You can choose from several tiers, depending on how many features you want and how many messages you send through your solution per day. The free tier is intended for testing and evaluation. It allows 500 devices to be connected to the hub and up to 8,000 messages per day. Each Azure subscription can create one IoT hub in the free tier.

    • IoT Hub units: The number of messages allowed per unit per day depends on your hub's pricing tier. For example, if you want the hub to support ingress of 700,000 messages, you choose two S1 tier units. For details about the other tier options, see Choosing the right IoT Hub tier.

    • Advanced Settings > Device-to-cloud partitions: This property relates the device-to-cloud messages to the number of simultaneous readers of the messages. Most hubs need only four partitions.

  6. For this article, accept the default choices, and then select Review + create to review your choices. You see something similar to this screen.

    Review information for creating the new hub

  7. Select Create to create your new hub. Creating the hub takes a few minutes.

Register a new device in the hub

In this section, you create a device identity in the identity registry in your IoT hub. A device cannot connect to a hub unless it has an entry in the identity registry. For more information, see the IoT Hub developer guide.

  1. In your IoT hub navigation menu, open IoT Devices, then select New to add a device in your IoT hub.

    Create device identity in portal

  2. In Create a device, provide a name for your new device, such as myDeviceId, and select Save. This action creates a device identity for your IoT hub.

    Add a new device


    The device ID may be visible in the logs collected for customer support and troubleshooting, so make sure to avoid any sensitive information while naming it.

  3. After the device is created, open the device from the list in the IoT devices pane. Copy the Primary Connection String to use later.

    Device connection string


The IoT Hub identity registry only stores device identities to enable secure access to the IoT hub. It stores device IDs and keys to use as security credentials, and an enabled/disabled flag that you can use to disable access for an individual device. If your application needs to store other device-specific metadata, it should use an application-specific store. For more information, see IoT Hub developer guide.

Create a module identity in the portal

Within one device identity, you can create up to 20 module identities. To add an identity, follow these steps:

  1. For the device you created in the previous section, choose Add Module Identity to create your first module identity.

  2. Enter the name myFirstModule. Save your module identity.

    Add module identity

    Your new module identity appears at the bottom of the screen. Select it to see module identity details.

    See module identity details

Save the Connect string - primary key. You use it in the next section to you set up your module on the device.

Update the module twin using .NET device SDK

You've successfully created the module identity in your IoT Hub. Let's try to communicate to the cloud from your simulated device. Once a module identity is created, a module twin is implicitly created in IoT Hub. In this section, you will create a .NET console app on your simulated device that updates the module twin reported properties.

Create a Visual Studio project

To create an app that updates the module twin reported properties, follow these steps:

  1. In Visual Studio, select Create a new project, then choose Console App (.NET Framework), and select Next.

  2. In Configure your new project, enter UpdateModuleTwinReportedProperties as the Project name. Select Create to continue.

    Configure your a visual studio project

Install the latest Azure IoT Hub .NET device SDK

Module identity and module twin is in public preview. It's only available in the IoT Hub pre-release device SDKs. To install it, follow these steps:

  1. In Visual Studio, open Tools > NuGet Package Manager > Manage NuGet Packages for Solution.

  2. Select Browse, and then select Include prerelease. Search for Microsoft.Azure.Devices.Client. Select the latest version and install.

    Install Azure IoT Hub .NET service SDK preview

    Now you have access to all the module features.

Get your module connection string

You need the module connection string for your console app. Follow these steps:

  1. Sign in to the Azure portal.

  2. Navigate to your IoT hub and select IoT Devices. Open myFirstDevice and you see that myFirstModule was successfully created.

  3. Select myFirstModule under Module Identities. In Module Identity Details, copy the Connection string (primary key).

    Azure portal module detail

Create UpdateModuleTwinReportedProperties console app

To create your app, follow these steps:

  1. Add the following using statements at the top of the Program.cs file:
using Microsoft.Azure.Devices.Client;
using Microsoft.Azure.Devices.Shared;
using Newtonsoft.Json;
  1. 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;
  1. 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("Sending current time as reported property");
        TwinCollection reportedProperties = new TwinCollection
            ["DateTimeLastDesiredPropertyChangeReceived"] = DateTime.Now

        await Client.UpdateReportedPropertiesAsync(reportedProperties).ConfigureAwait(false);
  1. Finally, replace the Main method with the following code:
static void Main(string[] args)
    Microsoft.Azure.Devices.Client.TransportType transport = Microsoft.Azure.Devices.Client.TransportType.Amqp;

        Client = ModuleClient.CreateFromConnectionString(ModuleConnectionString, transport);
        Client.SetDesiredPropertyUpdateCallbackAsync(OnDesiredPropertyChanged, null).Wait();

        Console.WriteLine("Retrieving twin");
        var twinTask = Client.GetTwinAsync();
        var twin = twinTask.Result;

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

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

    Console.WriteLine("Waiting for Events.  Press enter to exit...");

private static void ConnectionStatusChangeHandler(ConnectionStatus status, ConnectionStatusChangeReason reason)
    Console.WriteLine($"Status {status} changed: {reason}");

You can build and run this app by using F5.

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.

Next steps

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