Basics of PLC & SCADA Course| Industrial Automation Training | Livewire Karur

Within a short span of time, automation practices have become integral to the overall process in industries. And everyone knows the importance of PLC and SCADA in automation. But what do they actually do? How do they operate? There is a dearth of information regarding these devices and through this article, we at Livewire Karur, Tamil Nadu, aim to help you understand the basics and the importance of PLC and SCADA training.

What is PLC?

A PLC or a Programmable Logic Controller is primarily a logic controlling device which helps in controlling several functions in an industrial system. The major function of this device to continuously be in touch with the input devices and to make important decisions based on the custom program with respect to the condition of input devices.

A microprocessor is present in the PLC which contains the program written in computer language. This program is further transferred to the device using a cable. The program is stored in the non-volatile memory of a PLC. For user convenience, a visual programming language named Ladder programming was created to program the PLC in particular.

The main advantage of PLC is its capacity to change and replicate particular operations while gathering or sending important information. Another advantage of a PLC is its modularity. The user has the option to choose between various input and output devices which best fits their needs.

What is inside a PLC?

basics of plc by Livewire Karur

PLC consists of five major sections — Input/Output section, the Central Processing Unit, programming device, power supply and memory. The input section comprises of mostly switches or sensors. And the Output section comprises of either a lamp or a solenoid or a motor. The functioning of these devices is dependent on the input signals. CPU acts as the brain of the system. The required output is formed here by processing the input. The logic of the system is present in the programming device as a piece of code. The power supply as the name suggests is to power the entire system which helps to power up the input and output devices. And finally, the memory section where the logic part is stored in one part of the memory and the other part consists of the input and output signals.

How does a PLC Operate?

basics of PLC

It consists of four important steps:

  • Input Scan
  • Program Scan
  • Output Scan
  • Housekeeping

The state of the input coming into the system is continuously monitored with the help of input scan. Some of the examples are switches, pushbuttons, sensors etc.

The custom made loaded program is executed to carry out its functions in the program scan.

The output ports are controlled depending upon the input coming in. Mainly involves energizing or de-energizing of output devices. Some of the output devices are solenoids, motors, actuators etc. Housekeeping involves performing internal diagnostics based on communication with programming devices.

Programming Languages used to program a PLC

Some of the most common programming languages are:

  • Ladder Diagram (LD)
  • Sequential Function Charts (SFC)
  • Function Block Diagram (FBD)
  • Instruction List (IL)
  • Structured Text (ST)


Everyone knows SCADA stands Supervisory Control and Data Acquisition. But what does it actually do? What is its advantage? We will be covering these topics in this article. SCADA has become the frontrunner in automation devices in industries. Along with PLC, it is by far the most prominent automation device. And thereby the increase in demand for industrial automation courses.

SCADA helps to monitor all the industrial processes from a central location. It can either be a local or a remote location. In some recent cases, SCADA devices could monitor real-time data coming in and process it. These devices have the ability to directly interact with many other devices with the help of the Human Machine Interface software. It is also a type of auditory device since it logs everything into the system.

Evolution of SCADA

SCADA systems first came into existence in the 1980s. The concept of networking was still coming up at the time and each SCADA system was independent with no connectivity to other systems. This generation of SCADA systems is monolithic systems.

The second generation of SCADA systems consists of distributed systems. In this architecture, multiple stations were connected via LAN which helped to share the information received through the SCADA systems. This reduced the overall cost of the system. But the drawback was security since the people were unsure about networking protocols

The networked SCADA systems were the third generation. In this case, the SCADA systems communicate with each other via a Process Control Network( PCN). In this case, more than one LAN can be present in a single system. It was more cost effective than the earlier generation.

With the emergence of cloud computing and the Internet of Things, it too became a part of SCADA architecture. SCADA systems can now report the present condition in almost real time and with the help of cloud capabilities process complex algorithms. Livewire Karur also provides seperate courses for these new technologies in addition to PLC SCADA training.

Architectural Components of SCADA

basics of SCADA by Livewire Karur

SCADA systems generally consist of:

  • Supervisory Computers: The acts as the core of the system. It involves the computer and software responsible for communicating with the field connection controllers and also involves the HMI software
  • Remote Terminal Unit(RTU): They connect to the sensors and actuators in the process and are present in the network in connection with supervisory computer systems.
  • Programmable Logic Controller(PLC): These are similar to RTU’s but the difference is that PLC’s are more economical, versatile and flexible.
  • Communication Infrastructure: This helps to connect the Supervisory system to the PLC’s and RTU’s. It might contain an industry standard or manufacturer preferred protocols.
  • Human Machine Interface(HMI): It is the GUI part of the SCADA system. In this, all the plant information will be available in a schematic manner to the operating personnel.

The complexity of the SCADA system is relative to its purpose. It can control an incredibly complex system or an easy system. I hope now, you have an understanding of what SCADA is.

PLC SCADA Training by Livewire Karur

PLC and SCADA is a vast topic and we have only seen a brief introduction to it. The PLC and SCADA training by Livewire Karur, Tamil Nadu provides you with a chance to fully grasp and understand it. For those who are trying to get into a career in industrial automation, this is the best platform for you to learn PLC SCADA automation. Our coursework also involves an industrial project which helps the students to apply the things learnt in the course. Livewire Karur’s PLC SCADA course primarily focuses on the employability factor.

There are many who are sceptical about the scope of these devices in the future. If you are one among them, try reading this interesting article about the scope of industrial automation by Livewire Trivandrum. You don’t need to think twice about joining this highly useful PLC SCADA classroom training program by Livewire Karur.

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