Entities and mappings
What is an entity?
An entity represents an asset you want to monitor or control. It brings together channels from one or more devices, so your dashboard describes your equipment or process rather than a list of individual sensors.
One device can feed several entities, and one entity can draw from several devices. The mapping is what makes that possible.
Connect inputs and outputs
Open Entities and create or edit an entity. For each input connection, select the device and its input. For an output connection, select the device and its output. Save your changes.
For example, a room entity can use the temperature input from one device and an output from a controller. Each connection must point to the intended device channel — there is no automatic matching by name across devices.
Why mappings matter
Mappings determine which device readings belong to the entity. They are also what makes a reading durable.
In the MQTT processing path, telemetry with no connected input can be received without creating a history event. If the Messages tab has data but a chart does not, verify the mappings before changing anything about the chart.
This is worth stating plainly because the failure is silent and looks like a dashboard problem. The order to check is always the same:
- Does the Messages tab show the reading?
- Is the payload key mapped to an entity input?
- Only then: is the widget configured correctly?
Next: Build a dashboard.