PLC is a controller but SCADA monitor sytem with spisfic control over regions(most of time SCADA used in electrcal distrbution systems )

Basically, the application layer differs, so their role differs.

PLC is one (there are several) option to implement a control system. SCADA is more high-level. It observes the system under the control of the PLC, and it shows this behavior to the user through a wed-based interface. Of course it also supports a dual-channel connection to allows users to also interfere on the system whenever convenient. Hope that helps!

A PLC (Programmable Logic Controller) is is an Industrial Computer (It is a hardware)that performs discrete or sequential logic in a company environment.

SCADA is a computer software that interfaces with PLCs and other industrial control devices to give equipment operators an interface with equipment (Human Machine Interface/HMI) and to collect data from equipment for analysis and record keeping.

PLC :

1. It is a solid state device. It controls the output of the process through the program given in Ladder diagrams.

2.I/p & O/p are represented in NO,NC and coil contacts.

3.Each component involved are defined using Address.

SCADA:

1. It is a software. Used to monitor,control and acquire data from field devices even from remote locations.

2. I/p & O/p are represnted in images.

3. Each object is defined using name.

SCADA is usually associated with process control (water treatment, steel manufacture, chemical etc.), whereas PLC is more of a digital logic control geared towards machines. There really is no hard line as you could argue they are all machine controls of some sort.

The PLC performs the primary control of the technological process. It contains a processor, input / output interfaces for data achizition from sensors and provides commands to the process.

If PLC or PLC group supervision is desired, they are integrated into the SCADA using various communication protocols (Modbus, Profibus, etc.). From the SCADA level, you can set different references for PLC-led processes, or implement global optimization algorithms. In addition, the history of processes can be stored in SCADA, statistical reports, etc. can be stored.

A SCADA is basically a PLC added with minimal Graphical User Interface. A PLC is specifically used for emergency shutdown or trip applications. PLC does not include graphical user interface and analog I/O inorder to reduce the scan time.

The PLC is part of the SCADA. The PLC aims to control a part of the process. While in the scada is formed by PLCs (also PAC, DCS and RTU), networks, operator interfaces, computers and software. All these elements are harmonically integrated. The function of the SCADA are control, supervision, data acquisition among others. In the following links you can find more information:

https://controlreal.com/es/dcs-o-plc-o-pac-o-rtu/

https://controlreal.com/en/interfaz-de-operacion/