| Alarm / warning |
two condition levels computed on the node. alarm_level: 0 normal, 1 warning, 2 alarm |
| Bridge |
the part of Mosquitto on the gateway that forwards status and settings messages between the local broker and Celestian |
| Celestian |
the IoT platform that receives, stores, and displays Sentinel data |
cfg_ver |
the version number of the server’s config message, reported back by the node. Counterparts: rules_ver, sources_ver, profiles_ver, tgroups_ver |
Channel (ch) |
one quantity in a Modbus profile (e.g. v voltage); one channel produces one metric per device |
confirm_s |
temporary application: the set runs for N seconds and reverts to the old set unless confirmed |
| Direct / gateway mode |
the node connects anonymously to the gateway; or the node logs in to Celestian itself |
| Dormant |
a valid rule or source that is waiting for a metric or profile that does not exist yet |
| DS18B20 |
a 1-Wire temperature sensor; bound to a slot by ROM ID |
| Flag |
a volatile boolean variable f1…f4 for rules |
| Gateway DC |
one per data center; the rack LAN router, local broker, NTP, OTA server, and bridge to Celestian |
| Hysteresis |
the difference between the start and end thresholds so a condition does not flicker |
history |
the gateway component that stores telemetry and events on disk and sends them to Celestian |
| LWT |
the MQTT last-will message; the broker publishes offline status if the node disappears |
| MAC |
the node’s Ethernet address; Sentinel’s identity in all topics and the Serial in Celestian |
| Metric |
one named value that is sent (rack_top, voltage, alarm_level) |
| OTA |
firmware update over the network |
| PCF8574 |
an I2C I/O expander for four touch buttons and four outputs |
| Profile |
the register map of one Modbus device type |
| PZEM-004T |
a single-phase AC power measurement module (UART) |
q |
the sequence number of SenFlat v2 telemetry messages, persistent, for dropping duplicates |
| Retained |
an MQTT message stored by the broker and delivered to new subscribers |
| ROM ID |
the unique 64-bit address of a 1-Wire sensor |
| Rules |
condition → action logic that runs on the node |
| SenFlat |
a compact flat JSON format (v1, v2); SenML is the standard format of RFC 8428 |
| Slot |
a fixed sensor position: t1…t4, d1…d4, o1…o4 |
Source (sources) |
one installation of a Modbus device that references a profile |
| Telemetry group |
a set of metrics with the same send schedule and thresholds |
ts |
a SenFlat v2 marker: 1 if the node clock is NTP-synchronized |
