A Complete Guide of Understanding the Different Types of PLC

In the world of industrial automation, Programmable Logic Controllers (PLCs) play a central role in ensuring processes run smoothly and efficiently. But not all PLCs are the same. In fact, choosing the right type of PLC depends on your application needs, budget, and the complexity of the task. If you're wondering about the types of PLC, their classification, and which PLC name is most suited for your setup, you're in the right place.

In this blog, we’ll break down the different types of PLC, how they are classified, and answer common questions like how many types of PLC are there or what are the 3 types of PLC you should know.

What is a PLC?

Before diving into the classification of PLC, let’s quickly review what a PLC is.

A Programmable Logic Controller is an industrial digital computer designed to control manufacturing processes such as assembly lines, robotic devices, or any activity that requires high-reliability control and ease of programming. PLCs are built to withstand harsh industrial environments and can be reprogrammed to adapt to changes in operations.

How Many Types of PLC Are There?

One of the most frequently asked questions by engineers, students, and automation professionals is:
"How many types of PLC are there?"

The answer can vary depending on the classification method. Generally, PLCs can be classified based on:

1. Size and Capacity
2. Hardware Configuration
3. Application Area

Let’s explore each in detail.

Classification of PLC Based on Size and Capacity

This is one of the most practical and common ways to classify PLCs.

1. Compact PLC (Fixed PLC)

Also known as integrated PLCs, these are small, cost-effective units with a fixed number of input/output (I/O) modules.

Best For: Simple automation tasks like small machinery, HVAC, or lighting control.

Popular PLC Names: Allen Bradley MicroLogix, Siemens LOGO!

2. Modular PLC

Unlike compact PLCs, modular PLCs allow users to add or remove I/O modules depending on the requirement. They offer better flexibility and scalability.

Best For: Medium to large industrial systems like conveyor belts, process industries, and manufacturing lines.

Popular PLC Names: Siemens S7-300, Mitsubishi FX3U, Allen Bradley CompactLogix

3. Rack-Mounted PLC

These are high-end, powerful PLCs where all modules are mounted on racks. They can control large and complex automation systems across plants.

Best For: Large-scale automation projects, SCADA integrations, or multi-unit industrial processes.

Popular PLC Names: Allen Bradley ControlLogix, Siemens S7-400

3 Types of PLC You Must Know

If you're looking for a quick overview, here are 3 types of PLC that every automation professional should be aware of:

Classification of PLC Based on Hardware Configuration

Besides size, another way to categorize different types of PLC is by how they are built:

1. Central Processing Unit (CPU): The brain of the PLC, responsible for executing control instructions.
   
2. Input/Output Modules: Interface to sensors and actuators.
   
3. Power Supply Module: Provides necessary power to the system.
4. Communication Module: Enables PLCs to talk to other devices or networks.
   

Depending on how these components are arranged or integrated, PLCs can be called:

1. Integrated PLCs (all components in one unit)
2. Distributed PLCs (components spread over a network)
   

Classification of PLC Based on Applications

PLCs can also be grouped based on the nature of the industry or application they serve:

1. Industrial PLCs – Used in heavy manufacturing, automotive, chemical, or textile sectors.
   
2. Building Automation PLCs – For HVAC, elevators, lighting control, and energy systems.
3. Safety PLCs – Designed to meet strict safety requirements in hazardous environments.
   

Common PLC Names in the Market

If you're researching for actual PLC names that match the types discussed above, here are some of the most trusted ones:

Each of these models fits into a different use case depending on your control requirements.

Which PLC Type is Right for You?

When choosing a PLC, ask yourself:

Compact PLCs are great for simple, one-task applications.
Modular PLCs offer flexibility and are future-proof.
Rack-mounted PLCs are robust for large-scale integrations.

Conclusion: Choosing from the Different Types of PLC

Understanding the types of PLC and their classification helps you make informed decisions when building or upgrading an automation system. Whether you're starting small with a compact PLC or managing a large industrial line with a rack-mounted system, there’s a PLC to match your needs.

To recap:

1. There are different types of PLC based on size, hardware, and application.
   
2. The main 3 types of PLC are Compact, Modular, and Rack-mounted.
3. Top PLC names include Siemens, Allen Bradley, Mitsubishi, and Schneider.
   

Looking for expert help in choosing or sourcing the right PLC? Connect with Anadi Automation, your reliable partner for PLCs, HMIs, drives, and complete industrial automation solutions.

Frequently Asked Questions

Q1. How many types of PLC are there?

There are generally 3 main types of PLC: Compact, Modular, and Rack-mounted. However, classifications can vary based on hardware, size, and application.

Q2. What are the different types of PLC used in industry?

Compact for simple tasks, modular for flexible medium systems, and rack-mounted for large-scale complex automation.

Q3. Which PLC brand is best?

Top-performing brands include Siemens, Allen Bradley, Mitsubishi, Omron, and Schneider Electric. The best brand depends on your specific application and support needs.

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