Modbus protocol, despite the passage of time (was developed in the Modicon company in 1980) continues to be standard in most industrial controllers (PLC) and is widely used in industrial automation systems. Modbus can works in two modes, ASCII and RTU, and the use is compatible with RS232 interface (RS422, RS485, modems, etc.) In recent years, great popularity gaining also Modbus TCP / IP -Modbus protocol implementation based on TCP / IP Ethernet network. With the significant decline in prices microcontroller interface RS232 and Ethernet, Modbus recently started to be frequently used in embedded systems. This site is intended to assist in implementing the Modbus in embedded systems.