I created an Azure IoT Central application with a gateway and 4 downstream devices. I have a PLC that gather the information from 4 machines. The data from the PLC is sent to an edge database. I have an IoT Edge module that is doing the aggregation and I would like to send the data as a downstream device, so not on the Module output stream. Basically, what I want is to see the data in the correct downstream device in IoT Central. How can I do that?

Hello @Cédric Melançon , so the custom iot edge module is aggregating data from the PLC/four machines and this aggregated data has to arrive in the cloud as being sent by the actual devices (with their own device registration). It seems you want to set up an edge gateway that does Identity translation . I have not seen any out-of-the-box configuration solution for this. You will have to program this yourself. A starting point could this example .

How can IoT Edge Module send data as a downstream device to Azure IoT Central

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Sander van de Velde | MVP 32,736 Reputation points MVP

2020-12-01T16:20:55.62+00:00

Hello @Cédric Melançon ,

so the custom iot edge module is aggregating data from the PLC/four machines and this aggregated data has to arrive in the cloud as being sent by the actual devices (with their own device registration).

It seems you want to set up an edge gateway that does Identity translation.

I have not seen any out-of-the-box configuration solution for this.

You will have to program this yourself. A starting point could this example.
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2 people found this answer helpful.
Cédric Melançon 126 Reputation points

2020-12-01T17:36:14.807+00:00

Is it compatible with Azure IoT Central. I don't have the connection string of the IoT Hub.

So if I understand well, I use the IoT Edge SDK for the aggregation and all and the device SDK for the communication with the IoT Central? Am I right?

Thank you

Cédric Melançon 126 Reputation points

2020-12-01T17:45:41.92+00:00

Also, when I want to attach my device to the gateway in IoT Central, I get the following error:

Invalid relationship for instanceof dtmi:x3tpblntie:v2 between devices <gateway device ID> and <device ID> with relationshipType undefined

Any idea of what I did wrong?

Sander van de Velde | MVP 32,736 Reputation points MVP

2020-12-01T20:19:55.143+00:00

You need separate security credentials for the devices.

With the SDK, you create a connection to IoT central for one or more devices.

Off-topic: Never use an IoT Hub outside Azure. That key is to be kept in the cloud.

Cédric Melançon 126 Reputation points

2020-12-01T20:25:00.033+00:00

How can I create one connection to IoT Central for many devices? Is there a documentation somewhere?

Sander van de Velde | MVP 32,736 Reputation points MVP

2020-12-01T20:30:48.45+00:00

Building an identity translation solution is very delicate due to handling multiple device identities.

Adding IoT Central to the equation makes it even more complex.

Please try to code a custom IoT Central device first. Then migrate that code into a container.

Please accept an answer if correct. Original posters help the community find answers faster by identifying the correct answer.

Sander van de Velde | MVP 32,736 Reputation points MVP

2020-12-01T20:49:48.647+00:00

Identity translation is something that can be done with a regular IoTHub.

IoT Central has support for another use-case of Azure IoT Edge, a transparent Gateway with downstream devices:

I suggest contacting Microsoft support for a more in-depth example.

Sander van de Velde | MVP 32,736 Reputation points MVP

2020-12-28T23:06:50.18+00:00

IoT Central supports the concept of child devices related to an edge device.

This is the Transparent Edge Gateway solution.

If you are interested in the Identity translation solution, this is a good starting point.

Unfortunately, there are not that many examples. I have not come across an example with IoT Central involved.

On the other hand, if you are able to write eg. a C# sample app, you just need to change that into an IoT edge module:

For Identity translation, you do not have to case about a child-parent relationship.

The telemetry coming from a DeviceClient is automatically rerouted to the EdgeHub.
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