An
Introduction To SCADA (Supervisory Control And Data Acquisition) For
Beginners // On photo Monitor iFIX By ServiTecno via FlickR
Control and Supervision
It is impossible to keep control and supervision on all industrial activities manually. Some automated tool is required which can control, supervise, collect data, analyses data and generate reports. A unique solution is introduced to meet all this demand is SCADA system.SCADA stands for supervisory control and data acquisition. It is an industrial control system where a computer system monitoring and controlling a process.
Another term is there, Distributed Control System (DCS). Usually there is a confusion between the concept of these two.
A SCADA system usually refers to a system that coordinates, but does not control processes in real time, but DCS do that. SCADA systems often have Distributed Control System (DCS) components.
Components of SCADA
1. Human Machine Interface (HMI)
It is an interface which presents process data to a human operator, and through this, the human operator monitors and controls the process.2. Supervisory (computer) system
It gathers data on the process and sending commands (or control) to the process.3. Remote Terminal Units (RTUs)
It connect to sensors in the process, converting sensor signals to digital data and sending digital data to the supervisory system.4. Programmable Logic Controller (PLCs)
It is used as field devices because they are more economical, versatile, flexible, and configurable than special-purpose RTUs.5. Communication infrastructure
It provides connectivity to the supervisory system to the Remote Terminal Units.SCADA System Concept
The term SCADA usually refers to centralized systems which monitor and control entire sites, or complexes of systems spread out over large areas (anything between an industrial plant and a country).
Most control actions are performed automatically by Remote Terminal Units (RTUs) or by programmable logic controllers (PLCs).
Host control functions
are usually restricted to basic overriding or supervisory level
intervention. For example, a PLC may control the flow of cooling water
through part of an industrial process, but the SCADA system may allow
operators to change the set points for the flow, and enable alarm
conditions, such as loss of flow and high temperature, to be displayed
and recorded.The feedback control loop passes through the RTU or PLC, while the SCADA system monitors the overall performance of the loop.
A simple SCADA system with single computer