It’s primary purpose was, of course, to exchange data between PLCs and other devices on the production floor. It was developed in 1978 by the engineers at Modicon… originators of the first PLC. Modbus is one of the oldest fieldbuses on the market. While Modbus was previously mainly used on wired serial communication lines, there are also extensions to the standard for wireless communications and TCP/IP networks.

are able to communicate with Modbus, also many intelligent sensors are equipped with a Modbus interface to send their data to host systems. Not only intelligent devices like microcontrollers, PLCs etc. The nice thing of the Modbus standard is the flexibility, but at the same time the easy implementation of it. In a short time hundreds of vendors implemented the Modbus messaging system in their devices and Modbus became the de facto standard for industrial communication networks. The original Modbus interface ran on RS-232, but most later Modbus implementations used RS-485 because it allowed longer distances, higher speeds and the possibility of a true multi-drop network. The physical layer of the Modbus interface was free to choose. It was an open standard that described the messaging structure. Communication between the Modbus nodes was achieved with messages.

It is 1979 when PLC manufacturer Modicon-now a brand of Schneider Electric’s Telemecanique-published the Modbus communication interface for a multidrop network based on a master/client architecture. Modbus has its roots in the late seventies of the previous century. Because of this, Modbus became the first widely accepted fieldbus standard. These standards-like the Modbus interface-emerge because they are good, simple to implement and are therefore adapted by many manufacturers. Not because they are pushed by a large group of vendors or a special standards organisation. Some communication standards just emerge.

Modbus rtu parser