PLC vs SCADA | Difference between PLC and SCADA

This page compares PLC vs SCADA and mentions difference between PLC and SCADA including their basics. The terms PLC and SCADA stands for Programmable Logic Controller and Supervisory Control And Data Acquisition respectively.


Siemens PLC

Following are the features of PLC.
• It is a hardware or a controller or a device which is programmed and installed in a panel.
• It is special computer which is used to control machines and electromechanical processes in the industries.
• There are different types of PLCs based its applications of use. Figure-1 depicts PLC from Siemens. The other popular vendor is ABB.


SCADA system

Following are the features of SCADA.
• It is computer system which collects and analyzes real time data with the help of sensors.
• The system is used for monitoring and control operations of a plant or equipments.
• The SCADA system is composed of three main systems viz. MTU (Master Terminal Unit), RTU (Remote Terminal Units) & Human Machine Interface (HMI).
• It is monitoring software installed on the PC which is used to monitor and control PLC.

Difference between PLC and SCADA

Following table summarize Difference between PLC and SCADA.

Features PLC SCADA
What is it? It is a solid state device which controls the output of the process through the program given in ladder diagrams. It is a software. It is used to monitor, control and acquire data from field devices even from remote locations.
Input/Output Input and output are represented in normal open (NO), normal close (NC) and coil contacts. Input and output are represented in images.
Component/Object Each component involved are defined using address. Each object is defined using name.

Conclusion: In order to understand difference between PLC and SCADA one has to read following topics on PLC and SCADA; SCADA tutorial >>, advantages of SCADA >>, What is PLC >> and PLC modem SoC >>.

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