#AzureIoT – Read and Write 📝 Twin Properties for an ☁️ Azure IoT Edge Module

Hi !

In my previous post I wrote about the libraries that we will use to access to Twin Properties in an Azure IoT Edge Module. Let’s go for it.

Configuration

We will use 3 main settings to read and write Twin information

# connect using IoTHub connection string and device id with the module identity name
IOTHUB_CONNECTION_STRING = "IoT Hub Connection String"
DEVICE_ID = 'Device Id'
MODULE_ID = 'Module Id'

Read Twin Properties

Let’s read twin properties with a couple of lines

# read twin
iothub_registry_manager = IoTHubRegistryManager(IOTHUB_CONNECTION_STRING)
module_twin = iothub_registry_manager.get_module_twin(DEVICE_ID, MODULE_ID)
twin_properties = "{0}".format(module_twin.properties) 
print ( twin_properties )

Update Twin Properties

And, if we need to update this, similar code.

iothub_registry_manager = IoTHubRegistryManager(IOTHUB_CONNECTION_STRING)
module_twin = iothub_registry_manager.get_module_twin(DEVICE_ID, MODULE_ID)
twin_original = "{0}".format(module_twin.properties) 

# Update twin
twin_patch = Twin()
twin_patch.properties = TwinProperties(desired={"doorState": 0, "doorStateSource": "python test app"})
updated_module_twin = iothub_registry_manager.update_module_twin(DEVICE_ID, MODULE_ID, twin_patch, module_twin.etag)

# display changes
twin_updated = "{0}".format(updated_module_twin .properties) 
print (f" original: {twin_original} ")
print (f" updated: {twin_updated} ")

Conclusion

Once you find the right libraries and code sample, read and update Twin Properties is easy. Now I’m ready to write a couple of Azure Functions that will interact with my Azure IoT Edge Modules Twin Properties !

References

• Get started with device twins
• Understand and use module twins in IoT Hub

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