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SCADA provides the facility of continuously supervising and controlling the industrial plant or process equipment. The main components of a typical SCADA system include the Master Terminal Unit (MTU), Programmable Logic Controller (PLC), Remote Terminal Unit (RTU), Communication Media, and Human–Machine Interface (HMI).

 MTU is the core of a SCADA system that gathers the information from the distributed RTUs and analyses this information for the control process. The plant performance is evaluated through histogram generation, standard deviation calculation, plotting one parameter with respect to another, and so on. Based on the performance analysis, an operator may decide to monitor any channel more frequently, change the limits, shut down the terminal units, and so on. The software can be designed according to the applications and the type of analysis required. The human operator sometimes cannot find the best operating policy for a plant that will minimise the operating costs. Because of this deficiency caused by the enormous complexity of a typical process plant, the master computer station with a high speed and the programmed intelligence of the digital computer are used to analyse the situation and find out the best policy. The MTU monitors, controls, and coordinates the activities of various RTUs and sends supervisory control commands to the process plant.

 Field devices (RTUs, PLCs, and IEDs) are computer‐based components, that are deployed at a remote site to gather data from sensors and actuators. Each field device may be connected to one (or more) sensors and actuators that are directly connected to physical equipment such as pumps, valves, motors, etc. The main function of such devices is to convert the electrical signals coming from sensors and actuators into digital values in order to be sent to the MTU for further processing and analysis using a communication protocol (e.g. Modbus). On the another hand, they can convert a digital command message, which is received from the MTU, into an electrical signal in order to control actuators that are being supervised and controlled. Even though these field‐level devices, RTUs, PLCs, and IEDs, are intended to be deployed at a remote site, they have different functionalities. RTUs collect data from sensors and send it back to the MTU and then the MTU takes a decision based on the this data and sends a command to the actuators. In addition to the same function of RTUs, PLCS can collect data from sensors and, based on the collected data, can send commands to actuators. That is, PLCs can process the data locally and take the decision without contacting the MTU. IEDs are part of control systems such as transformers, circuit breakers, sensors, etc., and can be controlled via PLCs or RTUs.

 HMI provides an efficient human–machine interface through which the operator can monitor and control the end devices such as sensors and actuators. That is, the information of the current state of the supervised and controlled process can be graphically displayed to the user, and therefore s/he can be updated with alerts, warnings, and urgent messages. In addition, HMI allows the user to entirely interact with the system.

 Historian is a database that is used to store all data gathered from the system, such as measurement and control data, events, alarms, operator's activities, etc. These data are used for historical, auditing, and analysis purposes.