Programmable Logic Controller (PLC) is a computing device used to monitor electromechanical processes while Supervisory Control and Data Acquisition (SCADA) is also a computer-based system used to collect and analyze real-time data.
It is a type of industrial control system used for the monitoring and control of industrial facilities and industrial infrastructure.
Both are used in manufacturing environments and usually used in combination but are still very different.
PLCs have been designed to control complex industrial processes, including machinery and motors. They are easy to program and completely scalable to the requirements of an operation. They are basically upgraded over the old relays and timers which were commonly used to operate industrial machinery, but PLCs can perform tasks which are much more complex.
SCADA is a control mechanism for tracking and operating processes in plants. It is usually computer software, and one of its main functions is to act as a gateway to the industrial machines or Human-Machine Interface (HMI). In simple words, it enables users to monitor equipment: incoming information, enter commands and make programming changes.
Sometimes these systems are used together with PLCs and other instruments.
The data from PLCs and Remote Terminal Units (RTUs) is transmitted to the system and commands are inserted into the HMI to change the processes that they control.
Difference between PLC and SCADA
PLC is a state-controlled device that controls the process output through the ladder diagram program.
The address is used to define each component involved in the PLC.
SCADA is the software for tracking, managing and collecting data from field instruments, sometimes from remote locations.
PLC and SCADA are something entirely different. There is nothing between them to compare.
PLC is a robust industrial computer and is very simple to operate. They can easily handle several inputs and outputs and can run only through codes which are provided to it. The PLC hardware is built with harsh industrial conditions, modularity specifications and scalability in mind.
Some important brands of PLCs include Allen Bradley, Siemens and Omron.
Most applications of PLC include:
SCADA is an implementation system for control, monitoring and automation. It is a program for setting up industrial automation and monitoring system for inspecting remote units at a plant and taking control of whether there is anything wrong using monitoring computers connected to equipment in plants. The most important function of SCADA is to act as a Human Machine Interface (HMI).
SCADA can typically be linked to PLC through software drivers that read data over serial or Ethernet in a specified format using industrial communication networks like Modbus. The SCADA uses these data for various functions, such as HMI monitor & control, historical documentation of process operations and reports.
In common with the PLC, the SCADA systems are also designed for modularity and scalability. Some of the software used for SCADA system used in the industries is R.S View, Wonderware and Win CC.