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Autonomous pumping stations with LoRaWAN telemetry

Robust local pump control with level float switches and remote supervision without network coverage or SIM cards.

Runs on: ESP32 PLC 14 / 38AR — Arduino sketches (.ino).

The application

A sanitation operator needed to supervise scattered pumping stations, some more than an hour away and without data coverage. Each station runs autonomously on an ESP32 PLC: a state machine driven by level float switches, alternation between two pumps to even out wear, and automatic failover on pump failure. Telemetry travels over LoRaWAN in 4-byte frames, and the hourly re-join acts as a communications watchdog.

Architecture

• Float switches and contactors → ESP32 PLC digital inputs
• 4-20 mA level probe → analog input (10 bits in the frame)
• State machine with alternation and failover (100 ms FreeRTOS task)
• LoRaWAN OTAA telemetry every 60 s (RN2xx3 module, EU868)
• LoRaWAN gateway → supervision backend

Bill of materials

• ESP32 PLC 14 / 38AR — Industrial Shields controller
• RN2xx3 LoRa module + 868 MHz antenna — telemetry without SIM cards
• Level float switches (3 pcs) — minimum, maximum and overflow
• 4-20 mA level probe — continuous tank level measurement
• Contactors with auxiliary contact + thermal relay — pump control and diagnostics

What is in the pack

• dual-pump-control-lorawan-38ar.ino
• freertos-multitasking-rejoin.ino
• level-sensor-4-20ma.ino
• lorawan-telemetry-bitpacking.ino
• pump-state-machine-float-switches.ino
• Bill of materials + README