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A Beginner’s Guide on Advanced PLC Programming

If you wish to learn more on programmable logic controllers and you do not know where to start, you can rest assured because we are here to present you a beginner’s guide to PLC programming.

We have to start by saying that programmable logic controllers are industrial computers that feature modular components that are designed to automate customized control processes.

In most cases, industrial plants and factories are using PLCs to control fans, lights, pumps, circuit breakers and another type of automated machinery. If you wish to understand the main idea of programmable logic controller, it is vital to learn more about its historical significance.

You should check out this link: so that you can learn more on PLCs and its programming languages. Industrial automation started back in the middle of the 20th century, and it was done by using electromechanical relay circuits.

That was a hassle for each production because of the number of wires, relays, and space that was necessary to create simple automation. Therefore, thousands of relays were vital so that you can deal with simple factory process. That is something that changed with introduction of PLCs.

You should note that on a basic level, the industry is still using electromechanical relays that were magnetically opening and closing electrical contact as soon as relay reaches some level of energy.

These devices are still useful in specific industries and play significant role in industrial automation. The first PLC entered the market in 1968, and it was designed by plant technicians and engineers so that they can use it without learning new tricks and methodology.

Technicians that were familiar with control schematics and relay logic could easily use and read PLC programs. Since the very beginning, programmable logic controllers used ladder logic programmable language that was used to mimic control circuit schematics.

Have in mind that the ladder diagram appears a combination of circuits that you read from left to right with the primary goal to energize a relay coil.

Ladder logic appears as control circuit schematics that use input sources such as pushbuttons, switches, proximity sensors on the left, while on the right you can see output sources.

This particular programming language can maintain and control complicated automated processes that use an intuitive interface such as ladder logic, which was an excellent transition for engineers, and technicians that used relay logic before that.

Even though first programmable logic controllers featured limited speed and memory capabilities, over the years, it advanced and improved and today, it is a vital component for each industry because it can simplify implementation and design of industrial automation.

If you wish to learn more on history of PLCs, you should check here.

How Do They Work?

We can say that PLCs are small industrial computers that feature the main goal and that is to control automated processes in various industries. They are the brain behind most industrial automation nowadays, and there are numerous components, but we have to categorize them in these three:

  • CPU (Processor)
  • Inputs
  • Outputs

Have in mind that PLCs are powerful and complex computers, but if you wish to describe the function of the programmable logic controller in simple terms, we have to say that it takes inputs, performs logic on them and turns on or off outputs based on specific logic you implemented.

The processor can monitor the status of inputs such as proximity sensor, switch and opening valves. At the same time, it will take information from inputs and perform logic on them. Afterward, it will use the same logic so that it can operate with outputs logic.

If we use the example of the dishwasher, you should have in mind that most of them feature microprocessors that have similar functions as programmable logic controllers. The dishwasher has inputs and outputs as well as CPU so that you can visualize the idea.

When it comes to inputs on the dishwasher, they are controls and buttons you will find on the front as well as door switch and water sensors. On the other hand, outputs are heat elements, water valves and pumps that will deal with things inside.

Analog or Discrete Inputs and Outputs

I/O or inputs and outputs are vital parts of PLCs, and if we continue using dishwasher example, we have mentioned above, the idea is to treat each input and output as a digital or discrete signal.

Have in mind that discrete signals are the ones that could be turned on or off based on the instruction. These are the most common and simplest types of inputs and outputs.

However, they can also be analog, such as on dishwasher program where you have to program everything so that you can deal with washing manually.

Check this link: if you wish to learn how to use ladder logic and implement it into everyday life.

When it comes to analog signals, instead of only on and off possibilities, you will have different types and programs, and whatever you choose you will have to measure input and wait for output so that you can finish with the programming.

Difference between PAC and PLC

If you did not hear about PAC or programmable automation controller, now is the time, because this particular term because popular in 2001 to differentiate original and standard programmable logic controllers from the latest, powerful and technologically advanced controller.

Of course, some experts state that these are similar and even same machines but with additional power and capabilities, but in most cases, terms are interchangeable within the industry.

In case that you use a complex system, it is much better to use PACs, but PLCs are more durable and affordable, so if you have a tight budget and you wish to implement automation controller, then you should consider PLC instead.

The main reason for that is because it uses the modern user interface, it features powerful memory and additional power that makes PACs far more superior than PLCs.

The idea is to determine the automation processes that you wish to implement so that you can decide which one is the best for your preferences and requirements.