PLC is a Hardware to read the sensor (physical signal), solve the algorithm and gives the controlled output., whereas SCADA is the software which can be interfaced to PLC, to read and present the information in graphical, animated form or make a log. For example: Controlling the LEVEL is done by PLC and infographics of the level with information about it (level, critical levels, alarms etc.) from last 3 years or more is done by SCADA.
is a solid-state 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.
is a software. Used to monitor, control and acquire data from field devices even from remote locations.
2. I/p & O/p are represented in images.
3. Each object is defined using the name.