System Implementation Details

The system is built around an ESP32 microcontroller acting as the main controller and protocol bridge.

Modbus RTU Interface

  • Modbus RTU communication is implemented via RS‑485, using transceivers such as MAX485, SP485, or SN65HVD1781
  • Supports Modbus RTU master read/write operations
  • Fully compatible with PLCs and industrial Modbus devices used in real‑world applications

Network Connectivity

  • Wi‑Fi: used for cloud communication and remote monitoring
  • Ethernet: implemented via LAN8720A PHY, providing reliable wired connectivity for industrial environments
  • All collected Modbus data is transmitted using the MQTT protocol

Data can be monitored through:

  • Smartphone applications
  • PC / laptop tools (including custom C#‑based applications)

Software Platform

  • Firmware developed using the Arduino IDE
  • Modular structure allowing easy expansion and customization
  • Proven stable in continuous operation with PLCs in deployed applications

Thermal Management

When operating, the board temperature typically reaches 45–55°C, which is acceptable for the selected components. To ensure thermal stability, the board is equipped with:

  • A 5V cooling fan
  • Heat sink activated when the temperature rises

Power and Electrical Characteristics

  • Input voltage: 7–40 V (AC or DC)
  • Power consumption: < 2 W
  • Over‑current protection: 100 mA fuse
  • Over‑voltage protection: TVS diode (6.8 V)

Modbus RTU Specifications

  • RS‑485 baud rates: 1200, 2400, 4800, 9600, … up to 115200 bps, and up to 512000 bps
  • Maximum number of slaves: up to 32 devices on a single bus

Ethernet (LAN8720A) Specifications

  • Bandwidth: 10 / 100 Mbps
  • Operating temperature: –40°C to +85°C
  • Ethernet isolation: HanRun HR911105A transformer

Open Hardware & Availability

  • Altium schematic files and sample source code (Modbus RTU read/write, Wi‑Fi/Ethernet communication, MQTT data transmission) are available and can be shared with interested developers.
  • PCB layout (Altium) files can be provided upon a small donation (e.g. “a cup of coffee” support).
  • Demo boards are available and ready to ship upon request.

Contact & Demo