A Guide for Learning Ladder Logic Online For Dummies

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If you wish to become an expert in the world of programmable logic controllers or PLCs, you are in the right place. The main problem with each beginning is the overwhelming amount of information that you can find both online and in books. 

Therefore, you should find a guide that will briefly explain to you the idea between PLCs, ladder logic, and everything that comes with it. That way, you will be able to determine whether it is something you wish to pursue or not.

Generally, programmable logic controllers are small computers used in industries that feature modular components that can handle automated processes. 

They are most common in industrial plants and factories to handle pumps, control motors, circuit breakers, fans, lights, and other machinery.

It is important to check here so that you can understand everything about automation industry. 

The simplest way to understand what you will get with the PLC is by starting from the very beginning.

A Brief History of PLCs

Industrial automation is not something that entered the scene a few years ago. It was something that existed even before PLCs entered the market.

In the middle of the previous century, automation used electromechanical relay circuits, which were highly complicated and problematic to troubleshoot.

The main problem is that a single, simple automation process required plenty of space, wires, and relays, which was highly expensive and caused severe downtimes. 

Of course, even today, people are using electromagnetic relays for various applications and purposes, but they became obsolete for controlling the automation processes after PLC entered the scene.

The first PLC appeared in 1968 with an idea to replace expensive and problematic relay circuits. The main goal was to adapt the similar concepts technicians and engineers used beforehand, which is why they created ladder logic that used similar methods as relay logic.

From the very start, programmable logic controllers started using ladder logic as the way to replace the control circuit schematics. 

It meant that technicians and engineers could easily transit from relay circuits to PLC controlling and programming, which was an effective way to reduce the training expenses.

Ladder logic uses simple control circuit schematics in which you can find both input and output sources. Input sources can include proximity sensors, pushbuttons, and switches, and you can see them on the left side, while the right side is reserved for outputs.

The first controllers had limited features and options, as well as speed and memory capabilities. However, as time went by, things significantly improved. 

However, the existence of PLCs allowed us to simplify industrial automation and create intricate designs that required expensive equipment back in the day.

How Does PLC Operate?

We can easily describe a PLC as a small industrial computer that features components that will help you control a wide array of automated processes. Therefore, you should know that controllers are affecting most modern automation processes that are happening all around us.

Of course, each PLC comes with essential components such as processor, inputs, and outputs. Generally, you should know that controllers are convincing and sophisticated computers. 

They operate by taking the input, performing logic on it throughout the CPU, and as a result, it leads to an output response based on the programming.

One of the most famous examples of how controllers function is by analyzing the appliance most of us have in our homes: dishwasher. Keep in mind that they come with a microprocessor that will function similarly to controllers.

Generally, you will find inputs at the dishwasher as well as outputs and in the middle a processor or CPU. Inputs include the buttons on the front, the door switch, the water sensors, and many more.

On the other hand, outputs include the heat elements, water valves as well as pumps. So we press the input, the processor uses particular programming to activate the sound outputs. 

It is the simplest example that will explain to you the idea of programmable logic controllers and their functions.

Analog and Discrete Input and Output

When it comes to inputs and outputs, you should know that they could be discrete and analog. Generally, discrete signals are the ones that can only be turned on or off, depending on the programming.

Remember that we are talking about the most common and purest form of inputs and outputs. You can also use the analog I/O, but it is not something that we can explain by using the same dishwasher example as above.

Analog signals are not affected only by open/closed or on/off possibilities. Still, you will be able to measure the input so that you can determine the particular effect of an output. 


PAC or Programmable Automation Controller is the term that appeared on the market at the beginning of new millennia. The main goal was to differentiate it from the typical PLC and create a more powerful, advanced, and more flexible solution for controlling automated tasks.

The typical disagreement is about differences between a PLC and PAC, even though most people are using it interchangeably within the industry. Of course, we can provide you differences between PLCs and PACs, and the idea is profoundly minimalistic and straightforward.

PACs are excellent choices for complex systems that use processes that PLC cannot handle at once. Of course, if you are handling simple processes, it is much better to use PLCs because they are more effective and will provide you less downtime.

The Common PLC Applications

  • Wind Turbine Operation – For instance, wind turbines are more efficient and with less downtime since they are, using PLCs. Remember that turbines must use proper and accurate information about wind conditions so that you can operate safely and use it for the overall turbine protection. Therefore, PLC will convert the signals from the wind speed by using direction sensors, and as a result, control the wind turbines. At the same time, PLCs are ordinary for creating statistical data and analysis that will simulate and predict potential failures before they happen. 
  • Smart Factories – You have probably heard about the idea that the industrial internet of things is taking primate in the world of manufacturing. Therefore, factories have achieved significant production and efficiency improvement. Today, you can find factories that operate by using advanced robotics, intelligent automation, as well as other devices that will handle the automation process. Even though the technology is rapidly changing, PLC is still a critical factor in the manufacturing world, and it operates as the central processor for all real-time decisions. For instance, PLC can send data for sensor performance that you can connect to a cloud so that you can get a picture of productivity and efficiency whenever you decide to do it by using a mobile device.

As soon as you enter this link: https://onlineplcsupport.com/ladder-logic-tutorial-studio-5000, you will be able to learn about the importance of learning the ladder logic. 

  • Cement Manufacturing – In the process of cement manufacturing, PLC is highly crucial because it controls the processes that involve mixing various compounds and raw materials within the kiln. By implementing a controller, you will be able to ensure both the quantity and quality of raw materials throughout the process so that you can get the best possible result. 
  • Glass Production – Finally, the production of glass started implementing programmable logic controllers to handle every single step of the procedure. We are talking about controlling the processing of flat glasses, material ratio, and other steps that are crucial for reaching perfection.

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