SCADA system consists of following components
1.Man Machine Interface (MMI):
Man Machine Interface is process and display units from where the data is process and displayed to the operator for monitoring and control by human. It is also called Human Machine Interface.
2.Remote Terminal Units (RTU):
Remote Terminal Units are located at the process side of the plant. They are connected to the sensors in process and data is converted from sensor signal to digital data and sends to the Supervisory control. In simple, RTU is a micro controller and located at the remote side of the process system their objective is to collect data from process side and deliver to Supervisory control
3.Programmable Logic Controller (PLCs):
PLCs are more versatile than RTUs and does the job of RTUs and also control the process when command receive from supervisory control.
These are the software protocols used for transferring the data from the supervisory control to RTU and vise-versa.
This is the master controller of the System which receives the data from RTUs and PLCs,monitors the data, process the data display data to operator via HMI or MMI and gives command signal to RTUs and PLCs to carry out certain operation.