What is a PLC? (90 sec)

RealPars

6 Apr 201501:39

Summary

TLDRThis video explains the basics of a Programmable Logic Controller (PLC), highlighting its key components: Input, CPU, and Output. Using an example of a motor controlled by a push button, it demonstrates how a PLC processes input signals, runs them through the CPU, and delivers the output to control devices like motors. The video also touches on the importance of programming the PLC to perform specific tasks, such as turning a motor on or off with the press of a button. Viewers are encouraged to subscribe for more educational content.

Takeaways

🤖 A Programmable Logic Controller (PLC) is a special type of computer used to control industrial processes in fields like petroleum, steel, and automotive.
🖥️ Every PLC consists of three main parts: Input, CPU, and Output.
🔘 In an example with a motor and push button, the goal is to turn the motor on when the button is pressed and turn it off when pressed again.
📝 To achieve this, a program must be written and downloaded to the PLC's CPU.
⚙️ The input (button) sends an electrical signal to the PLC, which passes it to the CPU for processing.
🔄 The CPU cannot directly process raw electrical signals, so the input is converted into a format the CPU can handle.
📡 After processing, the CPU sends the output signal, which is converted back to an electrical signal to control the motor.
🔁 When the button is pressed again, the same process repeats, turning the motor off.
🎮 This process is similar to how a power button on a TV remote works.
📢 The video encourages viewers to subscribe for more educational content.

Q & A

What is a Programmable Logic Controller (PLC)?
-A Programmable Logic Controller (PLC) is a special type of computer designed to control industrial processes such as those in petroleum, steel, or automotive industries.
What are the three main components of a PLC?
-The three main components of a PLC are the Input, CPU, and Output.
What is the function of a PLC in the motor and push button example?
-In the motor and push button example, the PLC controls the motor by turning it on when the button is pressed and turning it off when the button is pressed again, similar to the power button on a TV remote.
What is the purpose of writing a program for the PLC?
-The purpose of writing a program is to instruct the PLC how to process the input signal (button press) and control the output (motor operation) based on the program logic.
Why does the input signal need to be converted before being sent to the CPU?
-The input signal needs to be converted into a format the CPU can process because the CPU cannot handle raw electrical signals directly.
What happens when the button is pressed in the described system?
-When the button is pressed, an electrical signal is sent to the PLC. The input component converts this signal, which is then processed by the CPU. The CPU sends instructions to the output, which turns on the motor.
What happens when the button is pressed again?
-When the button is pressed again, the same process repeats, and the motor is turned off.
How is the output signal processed to control the motor?
-The output component of the PLC converts the processed data back into a raw electrical signal and applies it to the motor, either turning it on or off based on the logic.
Why does the PLC need to convert signals at both the input and output stages?
-The PLC converts signals at the input stage so the CPU can process them, and at the output stage to send the appropriate electrical signals to control devices like the motor.
How does the example in the script compare to the power button on a TV remote?
-The motor and push button system in the example functions similarly to a TV remote's power button, where pressing the button alternately turns the motor (or TV) on or off.

Outlines

00:00

🤖 Introduction to Programmable Logic Controllers (PLCs)

This paragraph introduces PLCs, explaining that they are specialized computers used in various industries like petroleum, steel, and automotive. The main components of a PLC include the input, CPU, and output. The example of controlling an electric motor with a push button is provided to explain how PLCs work. When the button is pressed, the motor turns on, and pressing it again turns it off. This behavior is likened to the power button on a TV remote.

💻 Writing the PLC Program and Hardware Setup

This section describes the process of programming a PLC to control an electric motor. A program is written on a computer and downloaded to the PLC's CPU. The input, in this case, a switch, is connected to the input module, while the motor is connected to the output module. When the button is pressed, an electrical signal is sent to the PLC, initiating the process.

⚡ Signal Processing by the CPU

Here, the paragraph explains that the raw electrical signal sent from the input must be converted into a format the CPU can understand. Since the CPU operates as a computer system, it cannot directly process raw electrical signals. Once the data is processed by the CPU, the output converts it back into an electrical signal to operate the motor.

🔁 Repeated Process to Turn Off the Motor

The final part describes the repeating process. When the button is pressed again, the PLC repeats the same steps, resulting in the motor being turned off. This shows the simplicity and efficiency of using PLCs to automate such processes.

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Mindmap

Keywords

💡Programmable Logic Controller (PLC)

A PLC is a specialized computer used to control industrial processes such as those in petroleum, steel, or automotive industries. It is the central component in the video, as the process of controlling the motor relies on programming the PLC. The PLC receives input, processes data, and sends output to manage devices like motors.

💡Input

The input refers to the signals or data received by the PLC from external devices, like a push button. In the context of the video, the input is the electrical signal sent when the push button is pressed. This signal is essential for the PLC to know what action to take.

💡CPU

The CPU (Central Processing Unit) is the brain of the PLC, responsible for processing input data. In the video, the CPU processes the signal from the input (the push button) and decides whether to turn the motor on or off. It plays a crucial role in interpreting signals and controlling outputs.

💡Output

The output in a PLC system is the action that occurs as a result of processing the input. In the video, the output is the electrical signal that turns the motor on or off. This signal is sent after the CPU processes the input, ensuring the motor responds as programmed.

💡Electrical Signal

An electrical signal is the form of communication between devices like the push button and the PLC. When the button is pressed, it sends an electrical signal to the PLC's input, which then processes this signal through the CPU. This signal controls the motor's operation in the video.

💡Motor

The motor is the device being controlled by the PLC in the video. The PLC is programmed to turn the motor on or off based on the input from the push button. It illustrates the practical application of PLCs in industrial settings for controlling machinery.

💡Push Button

The push button serves as the user interface or input device for controlling the motor in the video. When pressed, it sends an electrical signal to the PLC, which processes the signal and determines whether to turn the motor on or off. This interaction mimics everyday devices like TV remotes.

💡Raw Electrical Signal

A raw electrical signal is the unprocessed form of the signal generated by the push button. The PLC input receives this signal but cannot directly use it, so it must be converted into a format the CPU can process. This distinction highlights the PLC's need to handle both raw and processed data.

💡Download Program

Downloading a program refers to transferring the software that controls the motor from a computer to the PLC’s CPU. The video explains that once the program is written, it must be uploaded to the PLC for it to function. This step is essential for automating processes in industrial systems.

💡TV Remote

The TV remote is used as an analogy to explain how the push button controls the motor. Just as pressing the power button on a remote toggles the TV on and off, pressing the button in the video toggles the motor's power. This comparison simplifies the concept of a PLC for viewers by relating it to everyday experiences.

Highlights

A Programmable Logic Controller (PLC) is a specialized computer programmed to control industrial processes such as petroleum, steel, or automotive.

Every PLC consists of three main parts: Input, CPU, and Output.

The function of turning a motor on or off using a button is similar to the power button on a TV remote.

A program must be written on a computer and then downloaded to the PLC's CPU to control the process.

The input, such as a button, sends an electrical signal to the PLC, which must be converted to a format that the CPU can process.

The CPU processes the input signal and sends the result to the output.

The output converts the processed data back into an electrical signal to control external devices, such as turning a motor on or off.

When the button is pressed, the PLC receives the signal and turns the motor on.

When the button is pressed again, the PLC repeats the process and turns the motor off.

The CPU cannot process raw electrical signals directly; they must first be converted into a compatible format.

PLC technology is critical in automating processes in industries such as petroleum, steel, and automotive.

The key components in this process are the electrical signals, input processing, CPU computations, and output actions.

The PLC system helps industries control complex machinery with simple input mechanisms, like buttons or switches.

The process demonstrates how simple electrical inputs can automate machinery using programming logic.

This video provides a basic introduction to PLC functions and operations in an industrial context.