Projects / Measurements, sensors and data acquisition
Wireless sensor network for BMS, HVAC and dispatching: up to 32 sensors per base station, LoRa radio, battery power, discrete input, battery diagnostics and Modbus RTU output.
The task was to make an applied wireless system for buildings and engineering infrastructure. The sensors had to work from batteries, be configurable without a laptop, and pass data into an existing control system over RS-485 / Modbus RTU.
A system consisting of a base station and autonomous sensors was developed. The base station receives radio packets, stores current node states and provides data to the upper level through Modbus RTU. Sensors measure parameters, transmit battery and link diagnostics, and then return to sleep.
Project materials
Engineering context
The system must not depend on a cloud service, Wi-Fi, a mobile application or a subscription.
Operation requires DIP-switch settings for addresses, intervals and channels without a special configurator.
The radio link has to work inside buildings and industrial rooms.
The upper level should see the data as ordinary Modbus registers.
Work done
Base-station plus up-to-32-sensor architecture.
Base-module electronics with STM32, RS-485 and radio channel.
Low-power wireless sensor electronics.
Migration from NRF24 to LoRa 868 MHz.
Support for DS18B20, NTC and a discrete input.
Modbus RTU slave and register map.
DIP-switch settings for addresses, baud rates, intervals and frequency channels.
Schematics, PCB files, BOM, Gerber, iBOM and instructions.
Details
The base station continuously listens to the radio channel, receives packets from sensors, validates the data and stores it in a Modbus register map. This simplifies integration with PLC, BMS and SCADA systems.
A sensor wakes up periodically, measures temperature or a discrete-input state, sends a short packet and returns to sleep. Together with the measured value, it transmits battery state, link quality and service diagnostics.
The system is suitable for monitoring rooms, entrance zones, ventilation chambers, warehouses, production areas, leak sensors, float switches, alarm signals and temporary surveys without cable installation.
Contact
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