Modbus is widely used in the fields of factory automation and plant automation because its specifications are open to the public, free to use and relatively easy to implement. Therefore, Modbus is the most common serial communication protocol for connecting industrial equipment.

Modbus is based on serial communication and has two transmission modes, Modbus ASCII and Modbus RTU. The physical layer of Modbus often uses the RS-485 standard. By combining the RL78 microcontroller (MCU) with sample programs and RS-485 transceiver products, you can easily implement slave devices that communicate using Modbus ASCII or Modbus RTU. The RL78 microcontroller has industry-leading low power operation, making it ideal for simple functions such as low power operation, I/O control, temperature and humidity measurement.

System Benefits

  • Modbus ASCII/RTU enables 1: N connection and communication with a maximum transmission distance of 500m by using RS-485 for the physical layer
  • Modbus can manage the environment in a factory by acquiring the illuminance, air quality, temperature, and humidity information to control the equipment and air vents
System Block Diagram

Modbus ASCII/RTU Slave Board

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