Modbus is a very effective serial communications protocol, which is published by Modicon in 1979, the company later converted to Schneider Electrical . This module is basically used in programmable logic controllers (PLCs). Soon after its release, Modbus has become the simplest and most robust de facto communication protocol in industrial automation.
The major advantages making Modbus the default communication protocol for a wide spectrum of industries are;
It is custom developed to be compliant with all standards industrial applications.
Modbus is open source without royalty free, to be acquired and customised by anyone.
So easy to deploy and maintain.
Not much restrictions on vendors and users.
What Modbus does?
Modbus helps in enabling effective communication and data acquisition in an industrial network with many devices interconnected to the same network. A classic example for such data communication can be a system which measures the temperature and humidity in a plant and then communicating that result to a computer. Modbus is now mostly used to a supervisory computer which has a remote terminal unit (RTU) in a typical supervisory control and data acquisition (SCADA) system.
Building Modbus application unit
To build a Modbus application data unit, the users need to first initiate a Modbus transaction modality. This is a function which informs a server as to what kind of action to be performed. This works in a Master to Slave mode as when the Master sends a message to Slave, this function cold field informs the server on what action to be performed next. There are also options to define multiple actions simultaneously.
The Modbus messages on serial connections are constructed in such a way that it allows the receivers to detect the beginning and end of the message easily. Usually, to identify the start of a message, a colon sign ‘:’ is used. If you are planning to install Modbus, then a bit more intensive research about its functionality is high advised.