FuelFleet reference stack

Bench test

Pending bench test — stack follows published ultrasonic/Modbus datasheets; not yet end-to-end on Autoconnecto hardware. Validation status.

Fleet dashboard for fuel tank level monitoring. Device type: fuel_tank.

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Telemetry contract

Key	Unit	Notes
fuel_level	%	Tank fill 0–100
fuel_volume_l	L	Derived from strapping table or sensor volume output
temperature	°C	Optional product / ambient probe on some transmitters

Sample data uses realistic bands (not 0–100 random): level mid-band with low-fuel dips, volume scaled to tank size.

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Reference hardware (pending bench test)

Item	Detail
Class	RS485 Modbus RTU ultrasonic level transmitter (diesel / water-compatible per datasheet)
Example SKU	Holykell HK-US series ultrasonic level sensor (Modbus) — verify Holykell published specifications for range, beam angle, and register map for your tank height
Install	Top-of-tank mount; blind zone and beam width per datasheet; strapping table for fuel_volume_l

Status: Pending bench test — map Modbus registers to the keys above per vendor manual.

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Connectivity options

Profile	Edge	Link layer	Status
P1	4G DTU serial tunnel	4G	Pending bench test
P2	ESP32 Modbus master	WiFi	Pending bench test
P4	LTE level sensor with MQTT	4G	BYO if keys match

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Wiring — P1 (4G, cloud Modbus)

flowchart LR
  AC[Autoconnecto]
  GW[fuelgateway MQTT_SERIAL]
  DTU[4G DTU]
  UL[Ultrasonic level Modbus]
  TANK[(Tank)]
  AC --> GW
  GW <-->|MQTT| DTU
  DTU --> UL
  UL --- TANK

Step	Action
1	Mount sensor per manufacturer installation sheet (min/max level, dead band)
2	RS485 to DTU; set baud/slave ID from datasheet
3	Autoconnecto: gateway + child fuel_tank; holding register map → fuel_level, fuel_volume_l, temperature
4	Calibrate % and volume with tank strapping

Same DTU pattern as DR154 Modbus MQTT; register addresses differ per level transmitter manual.

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Wiring — P2 (ESP32 WiFi)

Follow ESP32 Modbus edge; poll level transmitter; publish JSON keys for FuelFleet.

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Autoconnecto checklist

• [ ] Create gateway + child devices linked with parentDeviceId (Sample On demos this topology)
• [ ] Child device type fuel_tank
• [ ] Telemetry keys on the child (fuel_level, fuel_volume_l, temperature)
• [ ] Optional hub health: publish gateway.heartbeat on the gateway token
• [ ] Gateway shows Active from hub heartbeat and/or any active child

Datasheet alignment checklist

• [ ] Level range covers tank height (include blind zone at top/bottom)
• [ ] Modbus scale matches % and liters (some report mm only — scale in edge or cloud map)
• [ ] Material compatibility (diesel, kerosene) per sensor rating
• [ ] Alarm thresholds on dashboard reflect operational low-fuel limits, not sensor FS

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Related

• Tank level widget
• Reference stacks