Tutorial: Connect an IoT Plug and Play multiple component device applications running on Linux or Windows to IoT Hub

This tutorial shows you how to build a sample IoT Plug and Play device application with components, connect it to your IoT hub, and use the Azure IoT explorer tool to view the information it sends to the hub. The sample application is written in C and is included in the Azure IoT device SDK for C. A solution builder can use the Azure IoT explorer tool to understand the capabilities of an IoT Plug and Play device without the need to view any device code.

Browse code

In this tutorial, you:

  • Download the sample code.
  • Build the sample code.
  • Run the sample device application and validate that it connects to your IoT hub.
  • Review the source code.

Prerequisites

Before you continue, make sure you've set up your environment, including your IoT hub.

You can complete this tutorial on Linux or Windows. The shell commands in this tutorial follow the Linux convention for path separators '/', if you're following along on Windows be sure to swap these separators for '\'.

The prerequisites differ by operating system:

Linux

This tutorial assumes you're using Ubuntu Linux. The steps in this tutorial were tested using Ubuntu 18.04.

To complete this tutorial on Linux, install the following software on your local Linux environment:

Install GCC, Git, cmake, and all the required dependencies using the apt-get command:

sudo apt-get update
sudo apt-get install -y git cmake build-essential curl libcurl4-openssl-dev libssl-dev uuid-dev

Verify the version of cmake is above 2.8.12 and the version of GCC is above 4.4.7.

cmake --version
gcc --version

Windows

To complete this tutorial on Windows, install the following software on your local Windows environment:

Download the code

If you completed the Tutorial: Connect a sample IoT Plug and Play device application running on Linux or Windows to IoT Hub (C) you've already downloaded the code.

In this tutorial, you prepare a development environment you can use to clone and build the Azure IoT Hub Device C SDK.

Open a command prompt in a folder of your choice. Execute the following command to clone the Azure IoT C SDKs and Libraries GitHub repository into this location:

git clone https://github.com/Azure/azure-iot-sdk-c.git
cd azure-iot-sdk-c
git submodule update --init

You should expect this operation to take several minutes to complete.

Build and run the code

You can build and run the code using Visual Studio or cmake at the command line.

Use Visual Studio

  1. Open the root folder of the cloned repository. After a couple of seconds, the CMake support in Visual Studio creates all you need to run and debug the project.

  2. When Visual Studio is ready, in Solution Explorer, navigate to the sample iothub_client/samples/pnp/pnp_temperature_controller/.

  3. Right-click on the pnp_temperature_controller.c file and select Add Debug Configuration. Select Default.

  4. Visual Studio opens the launch.vs.json file. Edit this file as shown in the following snippet to set the required environment variables. You made a note of the scope ID and enrollment primary key when you completed Set up your environment for the IoT Plug and Play quickstarts and tutorials:

    {
      "version": "0.2.1",
      "defaults": {},
      "configurations": [
        {
          "type": "default",
          "project": "iothub_client\\samples\\pnp\\pnp_temperature_controller\\pnp_temperature_controller.c",
          "projectTarget": "",
          "name": "pnp_temperature_controller.c",
          "env": {
            "IOTHUB_DEVICE_SECURITY_TYPE": "DPS",
            "IOTHUB_DEVICE_DPS_ID_SCOPE": "<Your ID scope>",
            "IOTHUB_DEVICE_DPS_DEVICE_ID": "my-pnp-device",
            "IOTHUB_DEVICE_DPS_DEVICE_KEY": "<Your enrollment primary key>"
          }
        }
      ]
    }
    
  5. Right-click on the pnp_temperature_controller.c file and select Set as Startup Item.

  6. To trace the code execution in Visual Studio, add a breakpoint to the main function in the pnp_temperature_controller.c file.

  7. You can now run and debug the sample from the Debug menu.

The device is now ready to receive commands and property updates, and has started sending telemetry data to the hub. Keep the sample running as you complete the next steps.

Use cmake at the command line

To build the sample:

  1. Create a cmake subfolder in the root folder of the cloned device SDK, and navigate to that folder:

    cd azure-iot-sdk-c
    mkdir cmake
    cd cmake
    
  2. Run the following commands to generate and build the project files for SDK and samples:

    cmake ..
    cmake --build .
    

In Set up your environment, you created four environment variables to configure the sample to use the Device Provisioning Service (DPS) to connect to your IoT hub:

  • IOTHUB_DEVICE_SECURITY_TYPE with the value DPS
  • IOTHUB_DEVICE_DPS_ID_SCOPE with the DPS ID scope.
  • IOTHUB_DEVICE_DPS_DEVICE_ID with the value my-pnp-device.
  • IOTHUB_DEVICE_DPS_DEVICE_KEY with the enrollment primary key.
  • IOTHUB_DEVICE_DPS_ENDPOINT with the value global.azure-devices-provisioning.net.

To learn more about the sample configuration, see the sample readme.

To run the sample:

  1. From the cmake folder, navigate to the folder that contains the executable file and run it:

    # Bash
    cd iothub_client/samples/pnp/pnp_temperature_controller/
    ./pnp_temperature_controller
    
    REM Windows
    cd iothub_client\samples\pnp\pnp_temperature_controller\Debug
    pnp_temperature_controller.exe
    

The device is now ready to receive commands and property updates, and has started sending telemetry data to the hub. Keep the sample running as you complete the next steps.

Use the Azure IoT explorer to validate the code

After the device client sample starts, use the Azure IoT explorer tool to verify it's working.

  1. Open Azure IoT explorer.

  2. On the IoT hubs page, if you haven't already added a connection to your IoT hub, select + Add connection. Enter the connection string for the IoT hub you created previously and select Save.

  3. On the IoT Plug and Play Settings page, select + Add > Local folder and select the local models folder where you saved your model files.

  4. On the IoT hubs page, click on the name of the hub you want to work with. You see a list of devices registered to the IoT hub.

  5. Click on the Device ID of the device you created previously.

  6. The menu on the left shows the different types of information available for the device.

  7. Select IoT Plug and Play components to view the model information for your device.

  8. You can view the different components of the device. The default component and any additional ones. Select a component to work with.

  9. Select the Telemetry page and then select Start to view the telemetry data the device is sending for this component.

  10. Select the Properties (read-only) page to view the read-only properties reported for this component.

  11. Select the Properties (writable) page to view the writable properties you can update for this component.

  12. Select a property by it's name, enter a new value for it, and select Update desired value.

  13. To see the new value show up select the Refresh button.

  14. Select the Commands page to view all the commands for this component.

  15. Select the command you want to test set the parameter if any. Select Send command to call the command on the device. You can see your device respond to the command in the command prompt window where the sample code is running.

Review the code

This sample implements an IoT Plug and Play temperature controller device. This sample implements a model with multiple components. The Digital Twins definition language (DTDL) model file for the temperature device defines the telemetry, properties, and commands the device implements.

IoT Plug and Play helper functions

For this sample, the code uses some helper functions from the /common folder:

pnp_device_client_ll contains the connect method for IoT Plug and Play with the model-id included as a parameter: PnP_CreateDeviceClientLLHandle.

pnp_protocol: contains the IoT Plug and Play helper functions:

  • PnP_CreateReportedProperty
  • PnP_CreateReportedPropertyWithStatus
  • PnP_ParseCommandName
  • PnP_CreateTelemetryMessageHandle
  • PnP_ProcessTwinData
  • PnP_CopyPayloadToString
  • PnP_CreateDeviceClientLLHandle_ViaDps

These helper functions are generic enough to use in your own project. This sample uses them in the three files that correspond to each component in the model:

  • pnp_deviceinfo_component
  • pnp_temperature_controller
  • pnp_thermostat_component

For example, in the pnp_deviceinfo_component file, the SendReportedPropertyForDeviceInformation function uses two of the helper functions:

if ((jsonToSend = PnP_CreateReportedProperty(componentName, propertyName, propertyValue)) == NULL)
{
    LogError("Unable to build reported property response for propertyName=%s, propertyValue=%s", propertyName, propertyValue);
}
else
{
    const char* jsonToSendStr = STRING_c_str(jsonToSend);
    size_t jsonToSendStrLen = strlen(jsonToSendStr);

    if ((iothubClientResult = IoTHubDeviceClient_LL_SendReportedState(deviceClientLL, (const unsigned char*)jsonToSendStr, jsonToSendStrLen, NULL, NULL)) != IOTHUB_CLIENT_OK)
    {
        LogError("Unable to send reported state for property=%s, error=%d", propertyName, iothubClientResult);
    }
    else
    {
        LogInfo("Sending device information property to IoTHub.  propertyName=%s, propertyValue=%s", propertyName, propertyValue);
    }
}

Each component in the sample follows this pattern.

Code flow

The main function initializes the connection and sends the model ID:

deviceClient = CreateDeviceClientAndAllocateComponents();

The code uses PnP_CreateDeviceClientLLHandle to connect to the IoT hub, set modelId as an option, and set up the device method and device twin callback handlers for direct methods and device twin updates:

g_pnpDeviceConfiguration.deviceMethodCallback = PnP_TempControlComponent_DeviceMethodCallback;
g_pnpDeviceConfiguration.deviceTwinCallback = PnP_TempControlComponent_DeviceTwinCallback;
g_pnpDeviceConfiguration.modelId = g_temperatureControllerModelId;
...

deviceClient = PnP_CreateDeviceClientLLHandle(&g_pnpDeviceConfiguration);

&g_pnpDeviceConfiguration also contains the connection information. The environment variable IOTHUB_DEVICE_SECURITY_TYPE determines whether the sample uses a connection string or the device provisioning service to connect to the IoT hub.

When the device sends a model ID, it becomes an IoT Plug and Play device.

With the callback handlers in place, the device reacts to twin updates and direct method calls:

  • For the device twin callback, the PnP_TempControlComponent_DeviceTwinCallback calls the PnP_ProcessTwinData function to process the data. PnP_ProcessTwinData uses the visitor pattern to parse the JSON and then visit each property, calling PnP_TempControlComponent_ApplicationPropertyCallback on each element.

  • For the commands callback, the PnP_TempControlComponent_DeviceMethodCallback function uses the helper function to parse the command and component names:

    PnP_ParseCommandName(methodName, &componentName, &componentNameSize, &pnpCommandName);
    

    The PnP_TempControlComponent_DeviceMethodCallback function then calls the command on the component:

    LogInfo("Received PnP command for component=%.*s, command=%s", (int)componentNameSize, componentName, pnpCommandName);
    if (strncmp((const char*)componentName, g_thermostatComponent1Name, g_thermostatComponent1Size) == 0)
    {
        result = PnP_ThermostatComponent_ProcessCommand(g_thermostatHandle1, pnpCommandName, rootValue, response, responseSize);
    }
    else if (strncmp((const char*)componentName, g_thermostatComponent2Name, g_thermostatComponent2Size) == 0)
    {
        result = PnP_ThermostatComponent_ProcessCommand(g_thermostatHandle2, pnpCommandName, rootValue, response, responseSize);
    }
    else
    {
        LogError("PnP component=%.*s is not supported by TemperatureController", (int)componentNameSize, componentName);
        result = PNP_STATUS_NOT_FOUND;
    }
    

The main function initializes the read-only properties sent to the IoT hub:

PnP_TempControlComponent_ReportSerialNumber_Property(deviceClient);
PnP_DeviceInfoComponent_Report_All_Properties(g_deviceInfoComponentName, deviceClient);
PnP_TempControlComponent_Report_MaxTempSinceLastReboot_Property(g_thermostatHandle1, deviceClient);
PnP_TempControlComponent_Report_MaxTempSinceLastReboot_Property(g_thermostatHandle2, deviceClient);

The main function enters a loop to update event and telemetry data for each component:

while (true)
{
    PnP_TempControlComponent_SendWorkingSet(deviceClient);
    PnP_ThermostatComponent_SendTelemetry(g_thermostatHandle1, deviceClient);
    PnP_ThermostatComponent_SendTelemetry(g_thermostatHandle2, deviceClient);
}

The PnP_ThermostatComponent_SendTelemetry function shows you how to use the PNP_THERMOSTAT_COMPONENT struct. The sample uses this struct to store information about the two thermostats in the temperature controller. The code uses the PnP_CreateTelemetryMessageHandle function to prepare the message and send it:

messageHandle = PnP_CreateTelemetryMessageHandle(pnpThermostatComponent->componentName, temperatureStringBuffer);
...
iothubResult = IoTHubDeviceClient_LL_SendEventAsync(deviceClientLL, messageHandle, NULL, NULL);

The main function finally destroys the different components and closes the connection to the hub.

This tutorial shows you how to build a sample IoT Plug and Play device application with components, connect it to your IoT hub, and use the Azure IoT explorer tool to view the information it sends to the hub. The sample application is written in C# and is included in the Azure IoT device SDK for C#. A solution builder can use the Azure IoT explorer tool to understand the capabilities of an IoT Plug and Play device without the need to view any device code.

Browse code

In this tutorial, you:

  • Download the sample code.
  • Build the sample code.
  • Run the sample device application and validate that it connects to your IoT hub.
  • Review the source code.

Prerequisites

Before you continue, make sure you've set up your environment, including your IoT hub.

To complete this tutorial on Windows, install the following software on your local Windows environment:

Clone the SDK repository with the sample code

If you completed Tutorial: Connect a sample IoT Plug and Play device application running on Windows to IoT Hub (C#), you've already cloned the repository.

Clone the samples from the Azure IoT Samples for C# GitHub repository. Open a command prompt in a folder of your choice. Run the following command to clone the Microsoft Azure IoT samples for .NET GitHub repository:

git clone https://github.com/Azure-Samples/azure-iot-samples-csharp.git

Run the sample device

In this quickstart, you use a sample temperature controller device that's written in C# as the IoT Plug and Play device. To run the sample device:

  1. Open the azure-iot-samples-csharp\iot-hub\Samples\device\PnpDeviceSamples\TemperatureController\TemperatureController.csproj project file in Visual Studio 2019.

  2. In Visual Studio, navigate to Project > TemperatureController Properties > Debug. Then add the following environment variables to the project:

    Name Value
    IOTHUB_DEVICE_SECURITY_TYPE DPS
    IOTHUB_DEVICE_DPS_ENDPOINT global.azure-devices-provisioning.net
    IOTHUB_DEVICE_DPS_ID_SCOPE The value you made a note of when you completed Set up your environment
    IOTHUB_DEVICE_DPS_DEVICE_ID my-pnp-device
    IOTHUB_DEVICE_DPS_DEVICE_KEY The value you made a note of when you completed Set up your environment
  3. You can now build the sample in Visual Studio and run it in debug mode.

  4. You see messages saying that the device has sent some information and reported itself online. These messages indicate that the device has begun sending telemetry data to the hub, and is now ready to receive commands and property updates. Don't close this instance of Visual Studio, you need it to confirm the service sample is working.

Use Azure IoT explorer to validate the code

After the device client sample starts, use the Azure IoT explorer tool to verify it's working.

  1. Open Azure IoT explorer.

  2. On the IoT hubs page, if you haven't already added a connection to your IoT hub, select + Add connection. Enter the connection string for the IoT hub you created previously and select Save.

  3. On the IoT Plug and Play Settings page, select + Add > Local folder and select the local models folder where you saved your model files.

  4. On the IoT hubs page, click on the name of the hub you want to work with. You see a list of devices registered to the IoT hub.

  5. Click on the Device ID of the device you created previously.

  6. The menu on the left shows the different types of information available for the device.

  7. Select IoT Plug and Play components to view the model information for your device.

  8. You can view the different components of the device. The default component and any additional ones. Select a component to work with.

  9. Select the Telemetry page and then select Start to view the telemetry data the device is sending for this component.

  10. Select the Properties (read-only) page to view the read-only properties reported for this component.

  11. Select the Properties (writable) page to view the writable properties you can update for this component.

  12. Select a property by it's name, enter a new value for it, and select Update desired value.

  13. To see the new value show up select the Refresh button.

  14. Select the Commands page to view all the commands for this component.

  15. Select the command you want to test set the parameter if any. Select Send command to call the command on the device. You can see your device respond to the command in the command prompt window where the sample code is running.

Review the code

This sample implements an IoT Plug and Play temperature controller device. The model this sample implements uses multiple components. The Digital Twins definition language (DTDL) model file for the temperature device defines the telemetry, properties, and commands the device implements.

The device code connects to your IoT hub using the standard CreateFromConnectionString method. The device sends the model ID of the DTDL model it implements in the connection request. A device that sends a model ID is an IoT Plug and Play device:

private static DeviceClient InitializeDeviceClient(string hostname, IAuthenticationMethod authenticationMethod)
{
    var options = new ClientOptions
    {
        ModelId = ModelId,
    };

    var deviceClient = DeviceClient.Create(hostname, authenticationMethod, TransportType.Mqtt, options);
    deviceClient.SetConnectionStatusChangesHandler((status, reason) =>
    {
        s_logger.LogDebug($"Connection status change registered - status={status}, reason={reason}.");
    });

    return deviceClient;
}

The model ID is stored in the code as shown in the following snippet:

private const string ModelId = "dtmi:com:example:TemperatureController;1";

After the device connects to your IoT hub, the code registers the command handlers. The reboot command is defined in the default component. The getMaxMinReport command is defined in each of the two thermostat components:

await _deviceClient.SetMethodHandlerAsync("reboot", HandleRebootCommandAsync, _deviceClient, cancellationToken);
await _deviceClient.SetMethodHandlerAsync("thermostat1*getMaxMinReport", HandleMaxMinReportCommandAsync, Thermostat1, cancellationToken);
await _deviceClient.SetMethodHandlerAsync("thermostat2*getMaxMinReport", HandleMaxMinReportCommandAsync, Thermostat2, cancellationToken);

There are separate handlers for the desired property updates on the two thermostat components:

_desiredPropertyUpdateCallbacks.Add(Thermostat1, TargetTemperatureUpdateCallbackAsync);
_desiredPropertyUpdateCallbacks.Add(Thermostat2, TargetTemperatureUpdateCallbackAsync);

The sample code sends telemetry from each thermostat component:

await SendTemperatureAsync(Thermostat1, cancellationToken);
await SendTemperatureAsync(Thermostat2, cancellationToken);

The SendTemperatureTelemetryAsync method uses the PnpHhelper class to create messages for each component:

using Message msg = PnpHelper.CreateIothubMessageUtf8(telemetryName, JsonConvert.SerializeObject(currentTemperature), componentName);

The PnpHelper class contains other sample methods that you can use with a multiple component model.

Use the Azure IoT explorer tool to view the telemetry and properties from the two thermostat components:

Multiple component device in Azure IoT explorer

You can also use the Azure IoT explorer tool to call commands in either of the two thermostat components, or in the default component.

This tutorial shows you how to build a multiple component sample IoT Plug and Play device application, connect it to your IoT hub, and use the Azure CLI to view the telemetry it sends. The sample application is written in Java and is included in the Azure IoT device SDK for Java. A solution builder can use the Azure CLI to understand the capabilities of an IoT Plug and Play device without the need to view any device code.

This tutorial shows you how to build a sample IoT Plug and Play device application with components, connect it to your IoT hub, and use the Azure IoT explorer tool to view the information it sends to the hub. The sample application is written in Java and is included in the Azure IoT device SDK for Java. A solution builder can use the Azure IoT explorer tool to understand the capabilities of an IoT Plug and Play device without the need to view any device code.

Browse code

In this tutorial, you:

  • Download the sample code.
  • Build the sample code.
  • Run the sample device application and validate that it connects to your IoT hub.
  • Review the source code.

Prerequisites

Before you continue, make sure you've set up your environment, including your IoT hub.

To complete this tutorial on Windows, install the following software on your local Windows environment:

Download the code

If you completed Tutorial: Connect a sample IoT Plug and Play device application running on Windows to IoT Hub (Java), you've already cloned the repository.

Open a command prompt in the directory of your choice. Execute the following command to clone the Azure IoT Java SDKs and Libraries GitHub repository into this location:

git clone https://github.com/Azure/azure-iot-sdk-java.git

Expect this operation to take several minutes to complete.

Build the code

On Windows, navigate to the root folder of the cloned Java SDK repository. Run the following command to build the dependencies:

mvn install -T 2C -DskipTests

Run the device sample

In Set up your environment, you created four environment variables to configure the sample to use the Device Provisioning Service (DPS) to connect to your IoT hub:

  • IOTHUB_DEVICE_SECURITY_TYPE with the value DPS
  • IOTHUB_DEVICE_DPS_ID_SCOPE with the DPS ID scope.
  • IOTHUB_DEVICE_DPS_DEVICE_ID with the value my-pnp-device.
  • IOTHUB_DEVICE_DPS_DEVICE_KEY with the enrollment primary key.
  • IOTHUB_DEVICE_DPS_ENDPOINT with the value global.azure-devices-provisioning.net.

To run the sample application, navigate to the \device\iot-device-samples\pnp-device-sample\temperature-controller-device-sample folder and run the following command:

mvn exec:java -Dexec.mainClass="samples.com.microsoft.azure.sdk.iot.device.TemperatureController"

The device is now ready to receive commands and property updates, and has started sending telemetry data to the hub. Keep the sample running as you complete the next steps.

Use Azure IoT explorer to validate the code

After the device client sample starts, use the Azure IoT explorer tool to verify it's working.

  1. Open Azure IoT explorer.

  2. On the IoT hubs page, if you haven't already added a connection to your IoT hub, select + Add connection. Enter the connection string for the IoT hub you created previously and select Save.

  3. On the IoT Plug and Play Settings page, select + Add > Local folder and select the local models folder where you saved your model files.

  4. On the IoT hubs page, click on the name of the hub you want to work with. You see a list of devices registered to the IoT hub.

  5. Click on the Device ID of the device you created previously.

  6. The menu on the left shows the different types of information available for the device.

  7. Select IoT Plug and Play components to view the model information for your device.

  8. You can view the different components of the device. The default component and any additional ones. Select a component to work with.

  9. Select the Telemetry page and then select Start to view the telemetry data the device is sending for this component.

  10. Select the Properties (read-only) page to view the read-only properties reported for this component.

  11. Select the Properties (writable) page to view the writable properties you can update for this component.

  12. Select a property by it's name, enter a new value for it, and select Update desired value.

  13. To see the new value show up select the Refresh button.

  14. Select the Commands page to view all the commands for this component.

  15. Select the command you want to test set the parameter if any. Select Send command to call the command on the device. You can see your device respond to the command in the command prompt window where the sample code is running.

Review the code

This sample implements an IoT Plug and Play temperature controller device. The model this sample implements uses multiple components. The Digital Twins definition language (DTDL) model file for the temperature device defines the telemetry, properties, and commands the device implements.

The device code uses the standard DeviceClient class to connect to your IoT hub. The device sends the model ID of the DTDL model it implements in the connection request. A device that sends a model ID is an IoT Plug and Play device:

private static void initializeDeviceClient() throws URISyntaxException, IOException {
    ClientOptions options = new ClientOptions();
    options.setModelId(MODEL_ID);
    deviceClient = new DeviceClient(deviceConnectionString, protocol, options);

    deviceClient.registerConnectionStatusChangeCallback((status, statusChangeReason, throwable, callbackContext) -> {
        log.debug("Connection status change registered: status={}, reason={}", status, statusChangeReason);

        if (throwable != null) {
            log.debug("The connection status change was caused by the following Throwable: {}", throwable.getMessage());
            throwable.printStackTrace();
        }
    }, deviceClient);

    deviceClient.open();
}

The model ID is stored in the code as shown in the following snippet:

private static final String MODEL_ID = "dtmi:com:example:Thermostat;1";

After the device connects to your IoT hub, the code registers the command handlers.

deviceClient.subscribeToDeviceMethod(new MethodCallback(), null, new MethodIotHubEventCallback(), null);

There are separate handlers for the desired property updates on the two thermostat components:

deviceClient.startDeviceTwin(new TwinIotHubEventCallback(), null, new GenericPropertyUpdateCallback(), null);
Map<Property, Pair<TwinPropertyCallBack, Object>> desiredPropertyUpdateCallback = Stream.of(
        new AbstractMap.SimpleEntry<Property, Pair<TwinPropertyCallBack, Object>>(
                new Property(THERMOSTAT_1, null),
                new Pair<>(new TargetTemperatureUpdateCallback(), THERMOSTAT_1)),
        new AbstractMap.SimpleEntry<Property, Pair<TwinPropertyCallBack, Object>>(
                new Property(THERMOSTAT_2, null),
                new Pair<>(new TargetTemperatureUpdateCallback(), THERMOSTAT_2))
).collect(Collectors.toMap(AbstractMap.SimpleEntry::getKey, AbstractMap.SimpleEntry::getValue));

deviceClient.subscribeToTwinDesiredProperties(desiredPropertyUpdateCallback);

The sample code sends telemetry from each thermostat component:

sendTemperatureReading(THERMOSTAT_1);
sendTemperatureReading(THERMOSTAT_2);

The sendTemperatureReading method uses the PnpHhelper class to create messages for each component:

Message message = PnpHelper.createIotHubMessageUtf8(telemetryName, currentTemperature, componentName);

The PnpHelper class contains other sample methods that you can use with a multiple component model.

Use the Azure IoT explorer tool to view the telemetry and properties from the two thermostat components:

Multiple component device in Azure IoT explorer

You can also use the Azure IoT explorer tool to call commands in either of the two thermostat components, or in the default component.

This tutorial shows you how to build a sample IoT Plug and Play device application with components, connect it to your IoT hub, and use the Azure IoT explorer tool to view the information it sends to the hub. The sample application is written for Node.js and is included in the Azure IoT Hub Device SDK for Node.js. A solution builder can use the Azure IoT explorer tool to understand the capabilities of an IoT Plug and Play device without the need to view any device code.

Browse code

In this tutorial, you:

  • Download the sample code.
  • Run the sample device application and validate that it connects to your IoT hub.
  • Review the source code.

Prerequisites

Before you continue, make sure you've set up your environment, including your IoT hub.

To complete this tutorial, you need Node.js on your development machine. You can download the latest recommended version for multiple platforms from nodejs.org.

You can verify the current version of Node.js on your development machine using the following command:

node --version

Download the code

If you completed Tutorial: Connect a sample IoT Plug and Play device application running on Windows to IoT Hub (Node), you've already cloned the repository.

Open a command prompt in the directory of your choice. Execute the following command to clone the Microsoft Azure IoT SDK for Node.js GitHub repository into this location:

git clone https://github.com/Azure/azure-iot-sdk-node

Install required libraries

You use the device SDK to build the included sample code. The application you build simulates a Plug and Play device with multiple components that connects to an IoT hub. The application sends telemetry and properties and receives commands.

  1. In a local terminal window, go to the folder of your cloned repository and navigate to the /azure-iot-sdk-node/device/samples/pnp folder. Then run the following command to install the required libraries:
npm install

This will install the relevant npm files required to run the samples in the folder.

Review the code

Navigate to the azure-iot-sdk-node\device\samples\pnp folder.

The azure-iot-sdk-node\device\samples\pnp folder contains the sample code for the IoT Plug and Play temperature controller device.

The code in the pnpTemperatureController.js file implements an IoT Plug and Play temperature controller device. The model this sample implements uses multiple components. The Digital Twins definition language (DTDL) model file for the temperature device defines the telemetry, properties, and commands the device implements.

Open the pnpTemperatureController.js file in a code editor of your choice. The sample code shows how to:

  • Define the modelId which is the DTMI for the device that's being implemented. This DTMI is user-defined and must match the DTMI of the temperature controller DTDL model.

  • Implement the components defined in the temperature controller DTDL model. The components in a real temperature controller should implement these two interfaces. These two interfaces are already published in a central repository. In this sample, the two interfaces are:

    • Thermostat
    • Device information developed by Azure
  • Define component names. This sample has two thermostats and one device information component.

  • Define command name. These are the commands the device responds to.

  • Define the serialNumber constant. The serialNumber is fixed any given device.

  • Define the command handlers.

  • Define the functions to send command responses.

  • Define helper functions to log command requests.

  • Define a helper function to create the properties.

  • Define a listener for property updates.

  • Define a function to send telemetry from this device. Both thermostats and the default component send telemetry. This function receives the component name as parameter.

  • Define a main function that:

    • Uses the device SDK to create a device client and connect to your IoT hub. The device supplies the modelId so that IoT Hub can identify the device as an IoT Plug and Play device.

    • Starts listening for command requests using the onDeviceMethod function. The function sets up a listener for command requests from the service:

      • The device DTDL defines the reboot and getMaxMinReport commands.
      • The commandHandler function defines how the device responds to a command.
    • Starts sending telemetry by using setInterval and sendTelemetry.

    • Uses the helperCreateReportedPropertiesPatch function to create the properties and the updateComponentReportedProperties to update the properties.

    • Uses desiredPropertyPatchListener to listen for property updates.

    • Disables all the listeners and tasks, and exits the loop when you press Q or q.

In Set up your environment, you created four environment variables to configure the sample to use the Device Provisioning Service (DPS) to connect to your IoT hub:

  • IOTHUB_DEVICE_SECURITY_TYPE with the value DPS
  • IOTHUB_DEVICE_DPS_ID_SCOPE with the DPS ID scope.
  • IOTHUB_DEVICE_DPS_DEVICE_ID with the value my-pnp-device.
  • IOTHUB_DEVICE_DPS_DEVICE_KEY with the enrollment primary key.
  • IOTHUB_DEVICE_DPS_ENDPOINT with the value global.azure-devices-provisioning.net.

To learn more about the sample configuration, see the sample readme.

Now that you've seen the code, use the following command to run the sample:

node pnpTemperatureController.js

You see the following output, indicating the device has begun sending telemetry data to the hub, and is now ready to receive commands and property updates.

Device confirmation messages

Keep the sample running as you complete the next steps.

Use Azure IoT explorer to validate the code

After the device client sample starts, use the Azure IoT explorer tool to verify it's working.

  1. Open Azure IoT explorer.

  2. On the IoT hubs page, if you haven't already added a connection to your IoT hub, select + Add connection. Enter the connection string for the IoT hub you created previously and select Save.

  3. On the IoT Plug and Play Settings page, select + Add > Local folder and select the local models folder where you saved your model files.

  4. On the IoT hubs page, click on the name of the hub you want to work with. You see a list of devices registered to the IoT hub.

  5. Click on the Device ID of the device you created previously.

  6. The menu on the left shows the different types of information available for the device.

  7. Select IoT Plug and Play components to view the model information for your device.

  8. You can view the different components of the device. The default component and any additional ones. Select a component to work with.

  9. Select the Telemetry page and then select Start to view the telemetry data the device is sending for this component.

  10. Select the Properties (read-only) page to view the read-only properties reported for this component.

  11. Select the Properties (writable) page to view the writable properties you can update for this component.

  12. Select a property by it's name, enter a new value for it, and select Update desired value.

  13. To see the new value show up select the Refresh button.

  14. Select the Commands page to view all the commands for this component.

  15. Select the command you want to test set the parameter if any. Select Send command to call the command on the device. You can see your device respond to the command in the command prompt window where the sample code is running.

This tutorial shows you how to build a sample IoT Plug and Play device application with components, connect it to your IoT hub, and use the Azure IoT explorer tool to view the information it sends to the hub. The sample application is written in Python and is included in the Azure IoT device SDK for Python. A solution builder can use the Azure IoT explorer tool to understand the capabilities of an IoT Plug and Play device without the need to view any device code.

Browse code

In this tutorial, you:

  • Download the sample code.
  • Run the sample device application and validate that it connects to your IoT hub.
  • Review the source code.

Prerequisites

Before you continue, make sure you've set up your environment, including your IoT hub.

To complete this tutorial, you need Python 3.7 on your development machine. You can download the latest recommended version for multiple platforms from python.org. You can check your Python version with the following command:

python --version

You can download the latest recommended version for multiple platforms from python.org.

Download the code

The azure-iot-device package is published as a PIP.

In your local python environment install the package as follows:

pip install azure-iot-device

If you completed Tutorial: Connect a sample IoT Plug and Play device application running on Windows to IoT Hub (Python), you've already cloned the repository.

Clone the Python SDK IoT repository:

git clone https://github.com/Azure/azure-iot-sdk-python

Review the code

This sample implements an IoT Plug and Play temperature controller device. The model this sample implements uses multiple components. The Digital Twins definition language (DTDL) model file for the temperature device defines the telemetry, properties, and commands the device implements.

The azure-iot-sdk-python\azure-iot-device\samples\pnp folder contains the sample code for the IoT Plug and Play device. The files for the temperature controller sample are:

  • temp_controller_with_thermostats.py
  • pnp_helper.py

Temperature controller has multiple components and a default component, based on the temperature controller DTDL model.

Open the temp_controller_with_thermostats.py file in an editor of your choice. The code in this file:

  1. Imports pnp_helper.py to get access to helper methods.

  2. Defines two digital twin model identifiers (DTMIs) that uniquely represent two different interfaces, defined in the DTDL model. The components in a real temperature controller should implement these two interfaces. These two interfaces are already published in a central repository. These DTMIs must be known to the user and vary dependent on the scenario of device implementation. For the current sample, these two interfaces represent:

    • A thermostat
    • Device information developed by Azure.
  3. Defines the DTMI model_id for the device that's being implemented. The DTMI is user-defined and must match the DTMI in the DTDL model file.

  4. Defines the names given to the components in the DTDL file. There are two thermostats in the DTDL and one device information component. A constant called serial_number is also defined in the default component. A serial_number can't change for a device.

  5. Defines command handler implementations. These define what the device does when it receives command requests.

  6. Defines functions to create a command response. These define how the device responds with to command requests. You create command response functions if a command needs to send a custom response back to the IoT hub. If a response function for a command isn't provided, a generic response is sent. In this sample, only the getMaxMinReport command has a custom response.

  7. Defines a function to send telemetry from this device. Both the thermostats and the default component send telemetry. This function takes in a optional component name parameter to enable it to identify which component sent the telemetry.

  8. Defines a listener for command requests.

  9. Defines a listener for desired property updates.

  10. Has a main function that:

    • Uses the device SDK to create a device client and connect to your IoT hub. The device sends the model_id so that the IoT hub can identify the device as an IoT Plug and Play device.

    • Uses the create_reported_properties function in the helper file to create the properties. Pass the component name, and the properties as key value pairs to this function.

    • Updates the readable properties for its components by calling patch_twin_reported_properties.

    • Starts listening for command requests using the execute_command_listener function. The function sets up a listener for command requests from the service. When you set up the listener you provide a method_name, user_command_handler, and an optional create_user_response_handler as parameters.

      • The method_name defines the command request. In this sample the model defines the commands reboot, and getMaxMinReport.
      • The user_command_handler function defines what the device should do when it receives a command.
      • The create_user_response_handler function creates a response to be sent to your IoT hub when a command executes successfully. You can view this response in the portal. If this function isn't provided, a generic response is sent to the service.
    • Uses execute_property_listener to listen for property updates.

    • Starts sending telemetry using send_telemetry. The sample code uses a loop to call three telemetry sending functions. Each one is called every eight seconds

    • Disables all the listeners and tasks, and exits the loop when you press Q or q.

In Set up your environment, you created four environment variables to configure the sample to use the Device Provisioning Service (DPS) to connect to your IoT hub:

  • IOTHUB_DEVICE_SECURITY_TYPE with the value DPS
  • IOTHUB_DEVICE_DPS_ID_SCOPE with the DPS ID scope.
  • IOTHUB_DEVICE_DPS_DEVICE_ID with the value my-pnp-device.
  • IOTHUB_DEVICE_DPS_DEVICE_KEY with the enrollment primary key.
  • IOTHUB_DEVICE_DPS_ENDPOINT with the value global.azure-devices-provisioning.net.

To learn more about the sample configuration, see the sample readme.

Use the following command to run the sample:

python temp_controller_with_thermostats.py

The sample device sends telemetry messages every few seconds to your IoT hub.

You see the following output, which indicates the device is sending telemetry data to the hub, and is now ready to receive commands and property updates.

Device confirmation messages

Keep the sample running as you complete the next steps.

Use Azure IoT explorer to validate the code

After the device client sample starts, use the Azure IoT explorer tool to verify it's working.

  1. Open Azure IoT explorer.

  2. On the IoT hubs page, if you haven't already added a connection to your IoT hub, select + Add connection. Enter the connection string for the IoT hub you created previously and select Save.

  3. On the IoT Plug and Play Settings page, select + Add > Local folder and select the local models folder where you saved your model files.

  4. On the IoT hubs page, click on the name of the hub you want to work with. You see a list of devices registered to the IoT hub.

  5. Click on the Device ID of the device you created previously.

  6. The menu on the left shows the different types of information available for the device.

  7. Select IoT Plug and Play components to view the model information for your device.

  8. You can view the different components of the device. The default component and any additional ones. Select a component to work with.

  9. Select the Telemetry page and then select Start to view the telemetry data the device is sending for this component.

  10. Select the Properties (read-only) page to view the read-only properties reported for this component.

  11. Select the Properties (writable) page to view the writable properties you can update for this component.

  12. Select a property by it's name, enter a new value for it, and select Update desired value.

  13. To see the new value show up select the Refresh button.

  14. Select the Commands page to view all the commands for this component.

  15. Select the command you want to test set the parameter if any. Select Send command to call the command on the device. You can see your device respond to the command in the command prompt window where the sample code is running.

Clean up resources

If you plan to continue with additional IoT Plug and Play articles, you can keep and reuse the resources you used in this article. Otherwise, you can delete the resources you created in this article to avoid additional charges.

You can delete both the hub and registered device at once by deleting the entire resource group with the following Azure CLI command. Don't use this command if these resources are sharing a resource group with other resources you want to keep.

az group delete --name <YourResourceGroupName>

To delete just the IoT hub, run the following command using Azure CLI:

az iot hub delete --name <YourIoTHubName>

To delete just the device identity you registered with your IoT hub, run the following command using Azure CLI:

az iot hub device-identity delete --hub-name <YourIoTHubName> --device-id <YourDeviceID>

You may also want to remove the cloned sample files from your development machine.

Next steps

In this tutorial, you've learned how to connect an IoT Plug and Play device with components to an IoT hub. To learn more about IoT Plug and Play device models, see: