A 'presence' is an abstraction on top of a read of an item (passive UHF tag, BLE beacon, Barcode, etc.).
When an item has been read by an i4 Reader, it will become 'present'. An item will remain present until the item is no longer being read by the Smartspot and the 'hold-time' of the item has expired.
Please refer to Presence, holdtime and proximity for an in debt explanation of Presences.
A presence does not contain the raw signal strength (e.g. RSSI), instead, it contains an estimated proximity determined by signal strength. These levels are an estimate of the distance between the Smartspot and the item.
There are three proximity levels:
- Immediate: Item has a strong signal strength.
- Near: Item has a medium signal strength.
- Far: Item has a weak signal strength.
There are three types of presence events:
- Create: When an item has been read for the first time.
- Update: When the proximity level is updated.
- Delete: When the item is currently not being read and the hold-time has expired.