How do you differentiate between SCADA, DCS and PLC-based systems?

SCADA-supervisory control and data acquistion systemm

DCS-data control system

PLC-programmable logic controller

scada and dcs are used for monitoring and control

but plc used for control and monitor it by scada or dcs

DCS is combination of multiple PLC and SCADA... DCS is used for complex plant level control and monitoring the data Plc used at unit level control

DCS is used for control a huge elements that need to be controlled and DCS systems can't be monitored as SCADA due to huge number of elements to be controlled

Firstly,

SCADA-supervisory control and data acquistion systemm

DCS-data control system,

PLC-programmable logic controller

scada and dcs are a bit linked to each other they are used to have a whole control on the systems or instruments used in the projects or at site,it is under manual control.by sitting at one place the work can be carried out it can also deduct the errors and solve it where a man can't reach.

where as the plc is a computer based device it uses logics and loops and diagrams.a software is installed and by that work is carried out.

An automation system responsible for the supervision/data-collection of a process is usually connected to a PLC based system.

 

A DCS can be connected to different PLC based systems to gather data.

 

A SCADA system can collect data from DCS installed at different geographical locations.

A SCADA system - Supervisory Control And Data Acquisition - can be a very simple system as long as it contains the basic functionality of supervisory control and data acquisition. A simple example is a PLC that is connected to sensors and actuators that is connected to a computer with SCADA software and an HMI that does the Supervisory Control And Data Acquisition.

DCS ( Distributed Control System) refers more to the distribution of the control and monitor functionalities across a site or multple sites. This could be multiple SCADA systems interconnected and sharing information to become one system.

 

A PLC is simply the controller that gathers information from sensors, sends commands to actuators according to a set of programmable logic rules. PLC's are used in both DCS and SCADA systems.