| author | dominicbetts |
|---|---|
| ms.author | dobett |
| ms.service | azure-iot |
| ms.topic | include |
| ms.date | 03/31/2021 |
[!INCLUDE iot-authentication-device-connection-string]
To complete the steps in this article, you need the following resources:
[!INCLUDE iot-central-prerequisites-basic]
-
A development machine with Python installed. Check the Azure IoT Python SDK for current Python version requirements. You can run
python --versionat the command line to check your version. Python is available for a wide variety of operating systems. The instructions in this tutorial assume you're running the python command at the Windows command prompt. -
A local copy of the Microsoft Azure IoT SDK for Python GitHub repository that contains the sample code. Use this link to download a copy of the repository: Download ZIP. Then unzip the file to a suitable location on your local machine.
In the copy of the Microsoft Azure IoT SDK for Python you downloaded previously, open the azure-iot-sdk-python/samples/pnp/temp_controller_with_thermostats.py file in a text editor.
The sample implements the multiple-component Temperature Controller Digital Twin Definition Language model.
When you run the sample to connect to IoT Central, it uses the Device Provisioning Service (DPS) to register the device and generate a connection string. The sample retrieves the DPS connection information it needs from the command-line environment.
The main function:
- Uses DPS to provision the device. The provisioning information includes the model ID. IoT Central uses the model ID to identify or generate the device template for this device. To learn more, see Assign a device to a device template.
- Creates a
Device_clientobject and sets thedtmi:com:example:TemperatureController;2model ID before it opens the connection. - Sends initial property values to IoT Central. It uses the
pnp_helperto create the patches. - Creates listeners for the
getMaxMinReportandrebootcommands. Each thermostat component has its owngetMaxMinReportcommand. - Creates property listener, to listen for writable property updates.
- Starts a loop to send temperature telemetry from the two thermostat components and working set telemetry from the default component every 8 seconds.
async def main():
switch = os.getenv("IOTHUB_DEVICE_SECURITY_TYPE")
if switch == "DPS":
provisioning_host = (
os.getenv("IOTHUB_DEVICE_DPS_ENDPOINT")
if os.getenv("IOTHUB_DEVICE_DPS_ENDPOINT")
else "global.azure-devices-provisioning.net"
)
id_scope = os.getenv("IOTHUB_DEVICE_DPS_ID_SCOPE")
registration_id = os.getenv("IOTHUB_DEVICE_DPS_DEVICE_ID")
symmetric_key = os.getenv("IOTHUB_DEVICE_DPS_DEVICE_KEY")
registration_result = await provision_device(
provisioning_host, id_scope, registration_id, symmetric_key, model_id
)
if registration_result.status == "assigned":
print("Device was assigned")
print(registration_result.registration_state.assigned_hub)
print(registration_result.registration_state.device_id)
device_client = IoTHubDeviceClient.create_from_symmetric_key(
symmetric_key=symmetric_key,
hostname=registration_result.registration_state.assigned_hub,
device_id=registration_result.registration_state.device_id,
product_info=model_id,
)
else:
raise RuntimeError(
"Could not provision device. Aborting Plug and Play device connection."
)
elif switch == "connectionString":
# ...
# Connect the client.
await device_client.connect()
################################################
# Update readable properties from various components
properties_root = pnp_helper.create_reported_properties(serialNumber=serial_number)
properties_thermostat1 = pnp_helper.create_reported_properties(
thermostat_1_component_name, maxTempSinceLastReboot=98.34
)
properties_thermostat2 = pnp_helper.create_reported_properties(
thermostat_2_component_name, maxTempSinceLastReboot=48.92
)
properties_device_info = pnp_helper.create_reported_properties(
device_information_component_name,
swVersion="5.5",
manufacturer="Contoso Device Corporation",
model="Contoso 4762B-turbo",
osName="Mac Os",
processorArchitecture="x86-64",
processorManufacturer="Intel",
totalStorage=1024,
totalMemory=32,
)
property_updates = asyncio.gather(
device_client.patch_twin_reported_properties(properties_root),
device_client.patch_twin_reported_properties(properties_thermostat1),
device_client.patch_twin_reported_properties(properties_thermostat2),
device_client.patch_twin_reported_properties(properties_device_info),
)
################################################
# Get all the listeners running
print("Listening for command requests and property updates")
global THERMOSTAT_1
global THERMOSTAT_2
THERMOSTAT_1 = Thermostat(thermostat_1_component_name, 10)
THERMOSTAT_2 = Thermostat(thermostat_2_component_name, 10)
listeners = asyncio.gather(
execute_command_listener(
device_client, method_name="reboot", user_command_handler=reboot_handler
),
execute_command_listener(
device_client,
thermostat_1_component_name,
method_name="getMaxMinReport",
user_command_handler=max_min_handler,
create_user_response_handler=create_max_min_report_response,
),
execute_command_listener(
device_client,
thermostat_2_component_name,
method_name="getMaxMinReport",
user_command_handler=max_min_handler,
create_user_response_handler=create_max_min_report_response,
),
execute_property_listener(device_client),
)
################################################
# Function to send telemetry every 8 seconds
async def send_telemetry():
print("Sending telemetry from various components")
while True:
curr_temp_ext = random.randrange(10, 50)
THERMOSTAT_1.record(curr_temp_ext)
temperature_msg1 = {"temperature": curr_temp_ext}
await send_telemetry_from_temp_controller(
device_client, temperature_msg1, thermostat_1_component_name
)
curr_temp_int = random.randrange(10, 50) # Current temperature in Celsius
THERMOSTAT_2.record(curr_temp_int)
temperature_msg2 = {"temperature": curr_temp_int}
await send_telemetry_from_temp_controller(
device_client, temperature_msg2, thermostat_2_component_name
)
workingset_msg3 = {"workingSet": random.randrange(1, 100)}
await send_telemetry_from_temp_controller(device_client, workingset_msg3)
send_telemetry_task = asyncio.ensure_future(send_telemetry())
# ...The provision_device function uses DPS to provision the device and register it with IoT Central. The function includes the device model ID, which IoT Central uses to assign a device to a device template, in the provisioning payload:
async def provision_device(provisioning_host, id_scope, registration_id, symmetric_key, model_id):
provisioning_device_client = ProvisioningDeviceClient.create_from_symmetric_key(
provisioning_host=provisioning_host,
registration_id=registration_id,
id_scope=id_scope,
symmetric_key=symmetric_key,
)
provisioning_device_client.provisioning_payload = {"modelId": model_id}
return await provisioning_device_client.register()The execute_command_listener function handles command requests, runs the max_min_handler function when the device receives the getMaxMinReport command for the thermostat components and the reboot_handler function when the device receives the reboot command. It uses the pnp_helper module to build the response:
async def execute_command_listener(
device_client,
component_name=None,
method_name=None,
user_command_handler=None,
create_user_response_handler=None,
):
while True:
if component_name and method_name:
command_name = component_name + "*" + method_name
elif method_name:
command_name = method_name
else:
command_name = None
command_request = await device_client.receive_method_request(command_name)
print("Command request received with payload")
values = command_request.payload
print(values)
if user_command_handler:
await user_command_handler(values)
else:
print("No handler provided to execute")
(response_status, response_payload) = pnp_helper.create_response_payload_with_status(
command_request, method_name, create_user_response=create_user_response_handler
)
command_response = MethodResponse.create_from_method_request(
command_request, response_status, response_payload
)
try:
await device_client.send_method_response(command_response)
except Exception:
print("responding to the {command} command failed".format(command=method_name))The async def execute_property_listener handles writable property updates such as targetTemperature for the thermostat components and generates the JSON response. It uses the pnp_helper module to build the response:
async def execute_property_listener(device_client):
while True:
patch = await device_client.receive_twin_desired_properties_patch() # blocking call
print(patch)
properties_dict = pnp_helper.create_reported_properties_from_desired(patch)
await device_client.patch_twin_reported_properties(properties_dict)The send_telemetry_from_temp_controller function sends the telemetry messages from the thermostat components to IoT Central. It uses the pnp_helper module to build the messages:
async def send_telemetry_from_temp_controller(device_client, telemetry_msg, component_name=None):
msg = pnp_helper.create_telemetry(telemetry_msg, component_name)
await device_client.send_message(msg)
print("Sent message")
print(msg)
await asyncio.sleep(5)[!INCLUDE iot-central-connection-configuration]
To run the sample application, open a command-line environment and navigate to the folder azure-iot-sdk-python-2/samples/pnp folder that contains the temp_controller_with_thermostats.py sample file.
[!INCLUDE iot-central-connection-environment]
Install the required packages:
pip install azure-iot-device
Run the sample:
python temp_controller_with_thermostats.py
The following output shows the device registering and connecting to IoT Central. The sample sends the maxTempSinceLastReboot properties from the two thermostat components before it starts sending telemetry:
Device was assigned
iotc-60a.....azure-devices.net
sample-device-01
Updating pnp properties for root interface
{'serialNumber': 'alohomora'}
Updating pnp properties for thermostat1
{'thermostat1': {'maxTempSinceLastReboot': 98.34, '__t': 'c'}}
Updating pnp properties for thermostat2
{'thermostat2': {'maxTempSinceLastReboot': 48.92, '__t': 'c'}}
Updating pnp properties for deviceInformation
{'deviceInformation': {'swVersion': '5.5', 'manufacturer': 'Contoso Device Corporation', 'model': 'Contoso 4762B-turbo', 'osName': 'Mac Os', 'processorArchitecture': 'x86-64', 'processorManufacturer': 'Intel', 'totalStorage': 1024, 'totalMemory': 32, '__t': 'c'}}
Listening for command requests and property updates
Press Q to quit
Sending telemetry from various components
Sent message
{"temperature": 27}
Sent message
{"temperature": 17}
Sent message
{"workingSet": 13}
[!INCLUDE iot-central-monitor-thermostat]
You can see how the device responds to commands and property updates:
{'thermostat1': {'targetTemperature': 67, '__t': 'c'}, '$version': 2}
the data in the desired properties patch was: {'thermostat1': {'targetTemperature': 67, '__t': 'c'}, '$version': 2}
Values received are :-
{'targetTemperature': 67, '__t': 'c'}
Sent message
...
Command request received with payload
2021-03-31T05:00:00.000Z
Will return the max, min and average temperature from the specified time 2021-03-31T05:00:00.000Z to the current time
Done generating
{"avgTemp": 4.0, "endTime": "2021-03-31T12:29:48.322427", "maxTemp": 18, "minTemp": null, "startTime": "2021-03-31T12:28:28.322381"}