MODBUS Protocol is a messaging structure developed by Modicon in 1979, used to establish master-slave/client-server communication between intelligent devices. It is a de facto standard, truly open and the most widely used network protocol in the industrial manufacturing environment. It is literally implemented by hundreds of vendors on thousands of different devices in order to transfer discrete/analog I/O and register data between control devices. It’s really a lingua franca or common denominator between different manufacturers. One report called it the “de facto standard in multi-vendor integration”.