Get timestamp from the JSON payload

BERNARD Thomas 166

Is it possible the override the timestamp of the telemetry payload ?

When I check raw data from my device in IOT Central application, I see 2 timestamp:

The first (timestamp) is provided by my device on its telemetry payload, but it is not used by the application
The second (_timestamp) is automatically added by the IOT Central application (I think this is the data reception timestamp)

I want to use only my device's timestamp in the application, because this is the only real accurate value.

Is there anybody who know how to do that ?

Thanks in advance for the help !

Thomas

Sander van de Velde 16,046 Reputation points MVP

2022-02-01T17:31:02.98+00:00

Hello @BERNARD Thomas ,

so you connected a device to Azure IoT Central. Great.

Just to be sure I understand the question, you have designed a device template with the fields "Global_0_85894" and "Global_0_85880" as Telemetry type? Did you also define a timestamp field as Telemetry type matching "timestamp" (and with schema datetime)?

If so, is the timestamp telemetry not showing the right date and time?
Roman Kiss 2,021 Reputation points

2022-02-01T19:17:51.357+00:00

Hi Thomas,

In your case, when your IoT Central App is based on the device timestamp, you can use a message property iothub-creation-time-utc for sending a device timestamp.

Note, that this timestamp will be in the raw data as an _eventcreationtime property and it is acceptable by IoT Central App features.

Thanks
Roman
BERNARD Thomas 166 Reputation points

2022-02-07T08:25:10.083+00:00

Thanks to all your answers !

I tried 2 versions of JSON payloads, but no one works.

Remember that I am sending data through MQTT. That's why I tried to use "creation-time" instead of "iothub-creation-time-utc". As described here:
https://learn.microsoft.com/en-us/azure/iot-hub/iot-hub-mqtt-5-reference

Any other suggestion ?

Thanks again !

Thomas

Accepted answer

Roman Kiss 2,021 Reputation points

2022-02-07T11:04:12.57+00:00
Hi Thomas,

The following is my example for sending a telemetry data (using the current protocol MQTT version 3.1.1) to the IoT Central App:

device3, modelId=dtmi:com:example:TemperatureController;2
topic:

devices/device3/messages/events/$.ct=application%2Fjson&$.ce=utf-8&iothub-creation-time-utc=2022-02-07T09:29:05.681Z

payload:

{ "workingSet":38.36 }

IoT Central App, Raw data:

Thanks
Roman
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4 people found this answer helpful.
BERNARD Thomas 166 Reputation points

2022-02-07T14:09:06.787+00:00

Thanks a lot Roman, this is exactly what I need. Everything works fine now !

Have a nice day,

Thomas
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