If you have been wanting to start a career in the industrial automation business and have been looking for basic Programmable Logic Controller or PLC training, but you’re not sure where to start, this is your lucky day. In this article, we will take a closer look at how beginners can start with PLC training.
After you read this article, there is a big chance that you will be able to know the primary components of a Programmable Logic Controller system and will have all the necessary information and understanding of the function and purpose of this technology. After reading this article, you can begin learning PLC programming. It will tackle issues like Rslogix 5000 training, processors and ladder logic. So, without further ado, let us jump right into it.
PLC or Programmable Logic Controllers are small computers used in industrial settings that have modular components carefully designed to automate the customized control process. This technology is usually used in industrial plants and factories to control pumps, fans, circuit breakers, lights and other types of machinery. To know the purpose of this technology, let us take a closer look at the history of Programmable Logic Controllers.
Automation in the industrial world began long before PLC even existed. From the early to mid-90s, industrial automation was done using a very complicated set of electromechanical relay circuits. But the amount of wires, space and relays needed to make simple automation was a big problem. Hundreds, if not thousands of relays, are necessary to operate an automated factory process. And imagine the horror if there is a logical circuit that needs to be changed.
Note: On the basic level, the electromechanical relay functions by closing the electrical contacts or magnetically opening it when the relay’s coil is being energized. These devices are beneficial and still an essential part of industrial automation. In 1968, the very first PLC was created to replace very complicated relay circuits in factories and industrial plants.
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This technology was designed to be an easy programmable for technicians and engineers that already knew about control schematics and relay logic. Since its conception, Programmable Logic Controllers have been using ladder logic, which was designed to imitate control circuit schematics. Its ladder diagrams look like a control circuit where the power is free-flowing from left to right via closed contacts to energize its relay coil.
Example of LL system
As you can see, the LL system looks like a simple control circuit program where the import sources like proximity sensors, push-buttons and switches are shown on the left side and the output sources are shown at the right side of the schematics.
The ability of this program is a very complicated automation process with an instinctive interface like the ladder logic made the complex transition from relay LL to Programmable Controllers, which is much simpler for a lot of businesses. But the first Programmable Controller was limited in the memory and speed capabilities; they usually improved quickly for the past few years. The presence of this technology helped the implementation and design of industrial automation a lot simpler.
How does it work?
It can be described as a small computer used in industrial settings with modular components that are designed to automate the control process. The Programmable Logic Controller is behind in almost all modern automation in an industrial environment.
There are a lot of components that make up a PLC, but usually, they can be grouped into three categories: Central Processing Unit or processors, the Inputs and Outputs. They are a compelling yet complex computer. However, we can describe its functions in simple terms. It takes inputs, helps perform logic on the CPU’s inputs and turns off or on outputs that are based on the logic.
The central processing unit will monitor the status of its data like the proximity sensor off, switch on, or valve 40 percent open. The CPU then takes the information it receives from inputs and performs logic on these inputs. The central processing unit also operates the logic’s outputs like open the valve or turn off the motors.
Flowchart of PLC functions
Let us use a typical example to illustrate how PLC works, your very own dishwasher. A lot of this appliance has microprocessors with the same function as your standard PLC. It has an input, an output, and a central processing unit. Most of these inputs would be the front buttons, the door switch and the water sensor. Most of this appliance’s outputs will be the heat elements, the pumps and the water valves.
Now let us take a closer look at how the dishwasher uses different components. Note that the CPU is the brain of the dishwasher that was programmed to make the decisions. That’s just like a Programmable Logic Controller processor, which makes a logical decision that is based on an input status.
What is a CPU? Click here to know more.
Analog and discreet Input and Output
Inputs and outputs usually are abbreviated I/O. Using the dishwasher as an example, we treated all input and output as a digital or discrete signal. A discreet signal is a signal that is either on or off. It is the simplest and most common type of Input and Output.
Although there are some analog Input and Output in the dishwasher control system, we want to make it as simple as possible. With these analog signals, instead of having only open and closed or on and off possibilities, you may have a percentage, Ampere, Celsius, Fahrenheit or other measuring units that you can use to measure the input or driving as an output.
Now, you have a better understanding and knowledge of what PLC technology is all about its history and how they work. You can now start learning about different components of this technology and how it can help with every business in every industry. PLC is considered as one of the most critical technology in every factory or industrial plant. That is why knowing all its components and how they work is very important to make sure that all the machines in the workplace are working correctly.