What is PLC Programming? Types & How It Works?

The short-form PLC stands for programmable logic controllers, which are used in industrial automation. The controlling method can be anything from simple switches to more complex control units or structures. This programming was implemented in the late 1960s to enable industrial automation. It was mainly developed and formulated to control the manufacturing activities of the factories’ processes.

Learning about PLC is an exciting subject if you are interested in technical fields. This post will explain the basics of PLC.

What is PLC Programming?

PLC programming (or programmable controller programming) is an industrial control systems. It is used to identify input devices and perform decision-based tasks to control customer output machines. And it is an important activity that helps control the output device to get the result based on the customer’s need and demand.

PLC programming can include a textual, graphical or other interface to represent logic. The correct command will be executed. PLC software is available for download in the PLC hardware that supports the type of PLC programming. Generally, the manufacturer of the PLC device or the hardware manufacturer allows the user enter and install UAC (or the user application code) in their device. This programming allows HMIs (Human Machine Interfaces) to display the variables in the device. After the program is downloaded to the PLC, it is ready for installation.

Types and types of programming languages for PLCs

PLC programming can be completed using one of the five major PLCs programming languagesThese are listed below.

1. Instructions List

It is a text-based PLC programming language, which works in the same way as the assembly language. It uses the codes of AND and OR, LD, as well as many other codes that can be used on PLC machines. This language is used to program a device that can interpret the instructions.

2. Structured Text

Structured text is also a PLC programming languages that is used to execute complex tasks. It is one the most powerful programming languages like C and Pascal. It can combine mathematical functions with algorithms with repetitive activities. These codes can contain statements that semicolons may separate.

3. Function Block Diagrams

Function block diagrams can be used to represent the graphical-based PLC programming language. The diagram represents the relations between the input and output commands.

4. Ladder Logic

It was a type of PLC programming language based on relay logic. It is used mainly in the switches and mechanical relays to control the functions or processes. It uses the internal logic system for all other machines that require electrical signals to remain active.

5. Sequential Function Diagrams

Sequential function charts are used to perform the given action. This can be determined based on the time taken. It uses the transition method to complete the task according to the predefined scenarios. The transition refers to the set of instructions used to automate various processes.

Types of PLCs

Due to their size and structure, the PLC (programmable logic controllers) can come in a variety of types.

  • The compact PLC can also be used. It is controlled by the manufacturer or user.
  • The modular PLC can be described as a PLC that contains the many I/O devices the user requires. These units can be assembled together to make a custom machine for monitoring input and output.

Each language has its own advantages and disadvantages. The programmer decides which use scenario to use. Thus, the programmers are more likely to switch any PLC programming languages depending on the customer’s need and project demand.

How does a PLC work?

The programmable logic control first gathers information from the connected devices. These devices are usually input devices or sensors. After that, they process the command or information. Once the command is processed, it triggers the result according to the programmed parameters.

The PLC device can also monitor temperature and run the program automatically. It can also turn on and off the processes. PLC programming is one of the most robust technologies used in industry.

In PLC hardware, essential components are the CPUThe I/O unit, rack and power unit. The CPU is the brain of the PLC system. It handles all the heavy tasks and runs the system at a rapid pace. The I/O units are the sensors that gather feedback from the PLC.

Here the processor’s output work is performed by the device. The rack is the bridge or pillar that connects I/O unit and CPU. This ensures that communication between these two hardware remains stable.

So the first scanning takes place, then it performs an internal check, and finally, the scan input takes effect. Once the scanning process is complete, it will then perform an internal check. Finally, the scan input takes place. It then displays the output in the form mechanical motion.

PLC Programming is Used for Industrial Automation

PLC programming is industrial programming. It installs in the PLC hardware and monitors the input and output processes. So that machine can decide on the preprogrammed code stored in the PLC’s memory unit. This industrial programming allows humans to make faster and more efficient decisions. It is now used in many industries, where PLC machines perform several tasks efficiently.


PLC programming is an industrial program that automates industrial machines. Thus, I hope it’s clear to you what PLC programming is, how it works, and its programming languages. We also covered some terms that will help strengthen your understanding about PLC programming.

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