What is Modbus?

Modbus is a serial communications protocol originally published by Modicon (now Schneider Electric) in 1979 for use with its programmable logic controllers (PLCs). It is a de facto standard, truly open and the most widely used network protocol in the industrial manufacturing environment. It is a simple master-slave protocol, meaning that one device (the master) sends requests to one or more other devices (the slaves) and receives responses.

The Modbus protocol defines the format for data sent over the network, as well as the procedures used for sending and receiving data. It includes a set of function codes that specify the type of operation to be performed, such as reading or writing data from a specific location in a device’s memory. The Modbus protocol is built on a client-server architecture, in which the master device acts as the client and the slave devices act as servers.

Modbus is typically used in industrial settings to read and write data from sensors and other devices, such as temperature, humidity, and pressure sensors, flow meters, and other types of process control equipment. It can be used over a variety of physical communication media, including serial links (RS-232, RS-485) and TCP/IP networks.

The Modbus Organization is a non-profit organization that maintains the Modbus protocol and provides information and resources for users. They work to promote the protocol, provide education and training, and offer testing and certification services. They also provide technical support and assistance to users of the protocol, as well as maintain a registry of Modbus-enabled products. The organization also has a responsibility to provide the latest version of the specification, maintain a list of vendors and their products, and handle any disputes that may arise between vendors.