The official Modbus specification can be found at. The Master can also write information to the Slaves. In a standard Modbus network, there is one Master and up to 247 Slaves, each with a unique Slave Address from 1 to 247. The simplest setup would be a single serial cable connecting the serial ports on two devices, a Master and a Slave. Modbus is transmitted over serial lines between devices. Versions of the Modbus protocol exist for serial lines (Modbus RTU and Modbus ASCII) and for Ethernet (Modbus TCP). Modbus is often used to connect a supervisory computer with a remote terminal unit (RTU) in supervisory control and data acquisition (SCADA) systems. It is used widely by many manufacturers throughout many industries.Modbus is typically used to transmit signals from instrumentation and control devices back to a main controller or data gathering system, for example a system that measures temperature and humidity and communicates the results to a computer.
It has become a standard communications protocol in industry, and is now the most commonly available means of connecting industrial electronic devices. Modbus is used in monitoring to communicate between intelligent devices, sensors or instruments and to monitor field devices using computer and HMI. Modbus is an open protocol, meaning that it’s free for manufacturers to communicate between electronics devices. In simple terms, it is a method used for transmitting information over serial lines between electronic devices. Modbus is a serial communication protocol developed by Modicon in 1979. Let us start with some basics understanding of Modbus Protocol: What is Modbus Protocol?
In this user guide, we will explore some basic concept of Modbus protocol, Interfacing of RS485 Module with ESP32 board, MAX485 TTL To RS485 Module and finally will prepare simple code to read the data over ESP32 serial port using SoftwareSerial Library.
This tutorial, we will learn how to handle Modbus RTU RS485 Protocol with ESP32 board using Arduino IDE.