PLC Blok Diagram | Programmable Logic Controller

You will understand the operating principle of the PLC from the PLC block diagram. PLC stands for Programmable Logic Controller. Nowadays, PLC is becoming more and more popular in industries for automation purposes. PLC replaced the analog control system by introducing the digital control system to the industry.
There are many advantages of the API or programmable logic controller, which is why it is widely used. The main advantages of PLC are

1. Industrial automation using a very efficient PLC.
2. They work very quickly.
3. Additional advanced tasks can be performed using the API.
4. Easy to use and very good experience.
5. Automated control is also a big advantage of PLC


PLC block diagram

Here is a typical block diagram of the PLC below. From the diagram below, you can understand the overall concept and the working procedure of the programmable logic controller.


Main parts of PLC

As you can see in the figure above, the automaton is made up of three main parts,

1. CPU or central processing unit
2. Input module and output module
3. Programming device

Typically, a microcontroller or microprocessor is used in the programmable logic controller and they are programmed by an external computer. After installing the appropriate program, the controller operates.

PLC working procedure

Now, let's discuss each block of programmable logic control circuits that will help you understand the operating principle of the controller.

CPU (Central Processing Unit)

It is the main part of the automaton. It processes all the instructions necessary for the operation of the circuit. First, we store the program or instruction in memory. During the operating time, the CPU takes control of the input module then processes and finally gives the output to the output module.

Memory

It is a storage device that stores all data, programs and instructions.

Programming device

It is the device on which the program or instruction is written, then using this device, the program or instruction is stored in the memory of the PLC. The programming device can be a computer, a laptop, etc.

Input and output module

The CPU or microprocessor can operate on a 5V DC power supply and can provide a very low output current. However, the input devices or the sensor may not work with the same voltage as 5V DC. Thus, to interface the input devices and sensors of the real world with the microprocessor, the input module is used. Here, the input module always gives an input signal of 5 V DC to the CPU.

Another important point is that the microprocessor can only work with the digital signal but that all input devices or the sensor may not produce a digital signal. In fact, most sensors create an analog signal. Another important function of the input module to convert the analog signal to digital signal.

The microprocessor or processor can supply a very small amount of current (in a few mA) at 5 V DC at the output. It is therefore not possible to control the loads directly with the microprocessor. Here, the output module has solved this problem.

Power source

The power circuit provides power to all peripherals such as the processor, memory, input module, and output module. Generally, the controller operates with a power supply up to 24 V DC.