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I can't figure out how to report telemetry to IOTCentral.

I created a Device Template, added a Telemetry measurement, Field Name "freeDiskSpace", Maximum Value 999999999999. Got a device associated with the template. Fired up the device code, but looking at the device in Device Explorer of IOTCentral it only says "Missing Data".

First I tried:

const upd = {};
upd.freeDiskSpace = info.available;
deviceTwin.properties.reported.update(upd, function (err) {

and in the debugger I could see the twin received the data

Got device twin
{ reported:
   { update: [Function: update],
     freeDiskSpace: 468716691456,
     '$version': 4 },

But nothing in IOTCentral.

Then I noticed how they were sending down desired properties:

desired:
 { setCurrent: { value: 0 },

so I tried

const upd = {};
upd.freeDiskSpace = { value: info.available };
deviceTwin.properties.reported.update(upd, function (err) {

but still nothing in IOTCentral.

AshokPeddakotla
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lordbah
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2 Answers2

1

A comment on another question pointed me to https://learn.microsoft.com/en-us/azure/iot-central/howto-connect-nodejs which I had somehow never found in all my searching. The key point is that telemetry is reported as an event, not as a reported property. This is counterintuitive to me because I understand an "event" to be a distinct meaningful incident versus "telemetry" being continuous data. But it works. Code snippet from that link:

  var data = JSON.stringify({
    temperature: temperature,
    humidity: humidity,
    pressure: pressure,
    fanmode: (temperature > 25) ? "1" : "0",
    overheat: (temperature > 35) ? "ER123" : undefined });
  var message = new Message(data);
  client.sendEvent(message, (err, res) =>
lordbah
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0

You should use the Device Property to create your device twin reported property on the IoTCentral, see the following screen snippet:

enter image description here

Roman Kiss
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