What is MODBUS TCP?

Modbus is a serial communications protocol using RS485 originally published by Modicon in 1979 for use with its programmable logic controllers (PLCs). Modbus is typically use within industrial environments and building management applications. Modbus is an open protocol and a method for transmitting information over serial lines between electronic devices. The Modbus messaging protocol defines the rules for organising and interpreting the data independent of the data transmission method. The device requesting the information is called the Modbus Master and the devices supplying information are known as Modbus Slaves. In a typical Modbus network, there is one Master but can be up to 247 Slaves, each with their own unique Slave Address (1 to 247). The Modbus Master can also write information to the Slaves.