PLC Coding in 2019: Beginner’s Guide and Introduction to Programmable Logic Controller

If you are interested in learning more about the Programmable automated controller or Programmable logic controller but don’t know where or when to start, this article might be what you need, a PLC programming for beginners guide. In this article, we will talk about the introduction to PLC and PAC, the history, how they work and their components.

After reading this, you will be able to understand, know, and identify the primary components of a PAC and a PLC system, have a basic understanding of the function and purpose of programmable logic and automated controller. So, without further ado, let’s jump right into the introduction of PLC and PAC.


PLC or programmable logic controller is industrial computers with modular components that are designed to automate a customized controlling process. PLCs are sometimes used in industrial plants and factories to control the machine, pumps, fans, circuit breakers, motors, and other machinery. To further understand the purpose of programmable controllers, we need to look at the history of the PLC and PAC.


Industrial and factory automation began long before PLCs was even thought of. During the 1900s or the start of the industrial revolution, automation was customarily done by intricate electromechanical relay circuits. But the number of wires, relays, and space that is needed to make even simple automation was challenging.

Hundreds, if not thousands of relays are necessary to run and automate a factory process. And if there’s something in the logic circuitry are needed to be changed, that would be a big problem. On a basic level, the electromechanical relays work by magnetically opens or close the electrical contacts when the circuit coils of the relays are energized.

They are essential devices and still plays a big part in the automation of industrial machinery. At the start of 1968, the first programmable logic controller was first introduced to replace the complicated relay circuits in the factory and industrial plants.

The PLC and PAC were designed to make sure that the programmers, technicians, and plant engineers that are already familiar with the process can easily program the system with their logic and control schematics. Since its conception, the programmable controllers have been programmed using a series of ladder logic that is designed to copy the control circuits schematics of the older automation system.

The ladder diagram looks like a central control circuit where the power flows from left to right through the closed contacts that energize a relay coil.

To know more about PAC, visit

Ladder logic sample

As you all know, ladder logic is like a simple control circuitry schematic where the input sources like the push-button, switches or the proximity sensors are shown on the left side, and the outputs are displayed on the right side. The ability of the PLC and PAC to program difficult and intricate automated processes using an intuitive interface like a ladder logic made the change from relay logic to a programmable logic controller much more straightforward for programmers, technicians, … Read More

Continue Reading →