Device twins and state

A twin is a JSON document for each device with two parts:

• desired: what you want (set from the console, your apps or rules)
• reported: what the device says it is doing

When they differ, the device receives a delta with only the fields that need to change.

1. 1App sets desirede.g. setpoint -20 °C
2. 2Device gets the deltaon .../twin/update/delta
3. 3Device applies itand reports its new state
4. 4Twin in synchistory keeps every version

#Topics

Named twins (several documents per device, for example config and firmware) are supported. Devices already written for a shadow-style topic layout keep working: those topics are answered by the twin too.

#From your application

curl -X POST https://<your-endpoint>/v1/things/store-hyd-01-freezer-1/twin \
  -H "Authorization: Bearer $TOKEN" -H "Content-Type: application/json" \
  -d '{"state": {"desired": {"setpoint_c": -20, "report_interval_s": 300}}}'

#Tips

• Keep twins small: configuration and status, not telemetry history.
• Have the device report its full state after it reconnects, so the twin is right after a power cut.
• Each update has a version; send the version you read to avoid overwriting someone else's change.