How to Learn Industrial Automation?

The Modicon Company invented the first PLC, which is known as Snyder Company, called Sequence Controller. In 1969, model 084 was named Morley, Morley, is the mother of PLC, but it was not marketed commercially. In 1973, Michael Greenberg invented the PLC commercially with 184 models. The automation system is an important part of industrial controlling applications, and most newly graduated engineers think about how to learn industrial automation. These are discussed below.

What is the History of PLC?

PLC is a programmable logic controller. PLC is a device through which other devices can be easily controlled, in some cases, it acts as an alternative to a microcontroller. The difference between a microcontroller and a PLC is that the microcontroller needs to be programmed, but the work can be done very quickly with the PLC ladder diagram. There are different types of PLCs in the market, and some of them are significant PLCs.

  • Siemens
  • Delta
  • ABB
  • Mitsubishi
  • LS
  • Omron
  • Allen Bradley
  • Panasonic
  • Beckhoff
  • Snyder

PLC Working Process

PLC is a type of microprocessor-based control system with programmable memory that stores various instructions to perform mathematical, logical, timing, sequencing, and other functions. It works like a microcontroller, but the microcontroller’s main difference is that PLC is used in the industry to control high-power control systems. On the other hand, microcontrollers are used to control low-power and exemplary control systems. Depending on the PLC function, the input signal is given in the first step by processing it through its ladder diagram.

What is the reason for PLC?

Most of the industry is using automation systems, for this reason, PLC is used for various reasons, like industrial control systems. The PLC is also used for multiple reasons:

  • The size is small, so it takes less space to control the industry
  • The plant can communicate with the computer
  • Troubleshooting is much easier for the technical person
  • It costs less to design or maintain a relatively complex control system
  • High speed and production are high
  • It takes less human resources

PLC is also widely used for controlling systems in the industry for various reasons. Not only PLC but also HMI, VFD servo drive, etc., are used.

PLC Numbering System

 In addition to the 10 decimal base methods, different numbering systems are used in PLC. For successful programming. It is essential to know the other systems.

Binary number

Each of the binary number systems is called a binary unit or bit for short. The binary is a standard two-number system base, which means there are only two possible values ​​for each number. The value of each bit may only be 0 or 1. A 4-bit group is called a nibble, an 8-bit group is called a byte, and a 16-bit group is called a word.

Its value determines the position of a bit in a byte or word and starts from the right side. The value of the bit number is 0 and 1. If you keep going to the left, the value of the bit will continue to double with each place. The value of bit 1 will be 2, and the importance of bit 2 will be 4.

Hexadecimal number

A hexadecimal number is a 16-number system base which means there are only 16 possible values ​​. Every digit newly represents a number from 0 to 15. This is accomplished by using the letters for values ​​greater than 9, such as 9 above, 10 for A, 11 for B 13 for C 14 for D 15 for E, and 16 for F.

Octal number

 Octal is an 8-number system base which means there will be only 6 possible values ​​for each number. The numbers in the octal system are 0 to 7. When a count in decimals exceeds 9, 19, etc., the count starts again from 0. But with ten digits, the value is increased by one. Thus the calculation in octal resumes counting from zero when it exceeds 7 and the value increases to 10 numbers.

How to learn PLC Programming in detail?

The PLC is a programmable logic controller. Dick Morley invented the first PLC in 1989 for general motors, the first PLC CPU model was 084. For this reason, Dick Morley is also called the mother of PLC.

Definition of Programmable Logic Controller

PLC is a digital computer with which other devices can be easily controlled. Which constantly monitors input device status and relies on custom programs to control output device status. Which is used to automate electromechanical systems. PLC usually consists of a microprocessor that has to be programmed with the help of the computer. The program is written in computer software and it is loaded on plc with the help of a cable.

How does PLC work?

 PLC is a type of microcontroller-based control system. It has a programmable memory. This memory stores a variety of instructions, through which mathematical, logical, timing, sequencing, etc. functions are performed. Microcontrollers, on the other hand, are used to control low-power and fine-control systems.

The input signal will be given in the first step, and it will be processed through the ladder diagram and the desired output signal will be obtained in the second step. This allows other devices to be easily controlled.

What are the essential requirements of PLC?

Used in any machine automation, chemical industry, nuclear power generation plant, home automation, or automated industry. PLC has three main sections: 1. Power supply 2. input/output 3. CPU-central processing unit.


Power supply

Power is required to activate plc. The power supply function is to supply the necessary electricity to the input, output, and CPU. In the case of different PLCs, the required power may be more or less. Many PLCs require 115 volts to 249-volt AC to operate. Most Programmable Logic Controllers have 24 VDC or 220 VAC power supplies.

 Input Devices

It sends the information received from the input devices to different parts of the output devices according to the ladder diagram. Note that the CPU can connect some information of its own according to the diagram with the information obtained from the input device.

The input is usually sent to the central processing unit by the various types of switches, sensors, temperature information, variable voltage, etc. The name of input devices: 1. push switch 2. limit switch 3. toggle switch 4. proximity sensor 5. pressure switch 6. level switch 7. temperature sensor 8. gas sensor etc. Basically, there are two types of input.

  1. Digital input.
  2. Analog input.

 Digital input is again of two types.

  1. PNP (+ 24v input)
  2. NPN (0V input)

Analog input again has four types.

  1. 0v-10v, 14v
  2. mA-20 mA.
  3. RTD (PT-100, PT-300, PT-1000)
  4. TC (K Type, T type)

Analog input/output.

 This input/output is very useful knowledge in the world of sensors. If you don’t know how to set it up and use it, a large part of it will remain unknown. Therefore, the name of the attempt to digitally transform all the objects/feelings in the real world is called an Analog input/output system.

Output devices

The information coming from the central processing is sent to the machine through the relay switch and the machine works accordingly. Depending on the device used in the machine, the relay may not be used. While the machine is working, the information is re-input through sensors and other devices. In this way, the cycle action continues automatically. The name of output devices: 1. Magnetic conductor. 2. Relay. 3. Solenoids. 4. Emergency. 5. Motor. 6. Heater etc.

CPU (Central Processing Unit)

The data coming from the central processing unit and input is sent to different parts of the output device according to the ladder diagram. In addition, the information received from the input device may be connected to some of its information according to the CPU diagram.

 What are the types of PLC programming languages?

Basically, PLC runs or controls machinery based on the PLC programming. PLC programs can be done in different programming languages. There are five types of PLC programming languages.

  • Ladder Image (LD)
  • Sequential function chart (SFC)
  • Instruction List (IL)
  • Function Block Diagram (FBD)
  • Structured text (ST)

Each language is used to write the PLC program, but Ladder Logic programming language is used more as the PLC Programming language due to the ease of writing a program.

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