Devices

A device is a piece of equipment (a sensor or an actuator) that has credentials to connect to the broker. Menu: Device Management → Devices.

The device list

Columns: Name (with a Gateway badge for gateways), Serial, Device type, Tags, Status, Connection (online/offline), Last Seen, and the creation and modification times. Available:

• Search by Name, Serial, Tag, or ID. For tags, a,b means either (OR) and a+b means all (AND).
• Filters for status, kind (regular device or gateway), and device type.
• The Display button to choose columns, remembered per list in your browser.
• Create device and Upload CSV (CSV format).
• Export settings JSON, Export settings CSV, and Import settings for bulk device settings (Configuration files).

Creating a device

Field	Rule
Name	Required.
Device key	Optional, 16 to 128 ASCII characters without spaces. Empty means a random key is generated. Used as the MQTT password.
Serial	Optional. A MAC address or serial number. Unique inside the workspace. Also used to match sensors behind a gateway.
Gateway mode	When on, this device is a gateway. A gateway may not have a gateway.
Intermediary gateways	Shown only when gateway mode is off. Pick the gateways that send data on behalf of this device.
Device type	Chooses a type and version; an attribute form appears according to the version schema (Device Types).
Tags, Group, Metadata	Optional.

The device key is shown only once

After saving, the device key is shown once (it is stored as an argon2id hash and cannot be viewed again). If you lose it, choose Generate new key (random) or Set own key on the detail page. The old key stops working immediately.

Device detail

The side menu of the detail page:

Section	Contents
Configuration	The Configuration tab (name, serial, tags, gateway mode, status, ID, device key, delete), Metadata, Device type, and Gateway.
Connections	Connected channels and their type; connect or disconnect.
Credentials	MQTT code examples with the ID and topic filled in automatically.
Groups	Groups that contain the device.
Telemetry	The latest value of each metric, its time, and a 24-hour trend.
Last messages	The most recent raw payload per subtopic, including config/reported and command results.
Device settings	Remote configuration for supported models (Remote device configuration).
Rules on device	Rules that run on the device (Rules on Device).
Firmware	OTA status and updates (OTA).
Alarms	Alarms related to this device.
Access	Roles and direct policies on the device.
Journals	Change history (created, changed, key changed, connections, and so on).

The Telemetry tab.

The Last messages tab.

The Credentials tab.

Online status and Last Seen

• Last Seen is recorded from every message the broker receives from the device, including messages that are not stored.
• Online/offline is derived from the MQTT session. Celestian records when the device last connected and disconnected.
• For sensors behind a gateway, the status is derived from the data the gateway sends on their behalf (shown as Online via gateway), because the sensors do not connect themselves.

Credentials and security

• MQTT: username = device ID, password = device key.
• A disabled device is refused by the broker. Deleting a device deletes its connections.
• Key changes are recorded in Journals without storing the key value.
• An MQTT client that is currently connected with the old credentials is only refused when it reconnects.

Device installation guide: Connecting devices (MQTT).