SCADA System

Supervisory Control And Data Acquisition

Generally a computer control system that has the ability to monitor programs and collect data. It can be used in industrial programs, infrastructure or equipment.

System Components

A SCADA system will include the following subsystems:

A human machine interface (HMI) is a device that displays the status of a program and allows the operator to monitor and control the program.

（A monitoring system (computer) can collect data and submit commands to monitor the program.

Remote terminal control system (abbreviated as RTU) connects many sensors used in the program and sends digital information to the monitoring system after data acquisition.

Programmable logic controllers (programmable logic controller, abbreviated as PLC) are also commonly used as field devices because of their low price and wide range of applications, replacing the RTUs with special functions.

The communication network provides a conduit for data transmission between the monitoring system and the RTU (or PLC).

System Concept

The term SCADA refers to a centralized system that monitors and controls all equipment, or a combination of many systems scattered throughout a region (as small as a factory or as large as a country). Most of the control is carried out by a Remote Terminal Control Unit (RTU) or PLC, and the main system is generally only controlled at the system monitoring level. For example, in a system where a PLC controls the flow of cooling water in a process, a SCADA system allows the operator to change the target value of the flow rate, set warning conditions to be displayed and recorded (e.g., flow rate too low, temperature too high.) The PLC or RTU will control the flow rate or temperature using teach-back control, while the SCADA monitors the overall performance of the system.