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5 Different Types Of PLC Programming Languages Commonly Used in Industry

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What are the Most Popular PLC Programming Languages

Today, I am going to introduce you to different types of programming languages defined for Programmable Logic Controller (PLC).

These languages are useful for designing and implementing sequential control of the programmable logic in the automation system.

Let’s study, what are those most used and common PLC programming languages.

5 Different Types of PLC Programming Languages

Based on the ‘International Electrotechnical Commission(IEC)‘ standard, PLC programming languages are classified into five main standards.

  1. Ladder diagram (LD)
  2. Instruction List (IL)
  3. Structured Text (ST)
  4. Function Block Diagram (FBD)
  5. Sequential Function Charts (SFC)

These languages are accepted internationally. Among all of them, mostly Ladder diagram (LD) programming language is used in the industry.

PLC Programming Language Classification Chart

Let’s dive into each PLC programming Langauge one by one.

1. Ladder diagram (LD)

Ladder diagram is the universal programming language of PLC. It has a short abbreviation as LD and also known as Ladder Logic. It is used with programmable logic controllers. And it is one of the oldest programming languages for PLC.

In the ladder diagram, the programming language use to create the program to control the PLC system is known as Ladder Diagram Language or Ladder Logic Language.

Generally, the Ladder Diagram is most popular all over the world (including India). This language is easy to learn by using a logic gate and some important programming rules.

Advantage of Ladder Diagram (LD):

  • LD is simple logic construction and more reliable than an electronic circuit controller.
  • Easy to learn and read the program.
  • Every programming symbol performs specific actions.
  • It having good representation for discrete logic.
  •  Easy to troubleshoot.
  • Shut down the power without the switch (i.e. hardware devices).

To learn more about Ladder Digram, and its basics parts, check this tutorial.

2. Instruction List (IL)

Instruction List (IL) is another type of PLC programming language. It uses the mnemonic code. So the syntax of this programming language is easy to remember. In general, AB PLC brand works on the Instruction List (IL) programming language.

In an earlier article, I have mentioned different PLC brands and their software. AB PLC is one of the standard PLC brands.

Advantages of IL:

  • It has a high execution speed.
  • It takes less memory as compared to other programming languages.

3. Structured Text (ST)

Structured Text PLC language is shortly denoted by the ‘ST’ and ‘STX‘. It uses high-level programming language syntax. The syntax of ST is similar to the syntax of a high-level programming language with loops, variables, conditions, and operators.

Advantages of ST:

  • ST is very easier to understand for both novice and experienced programmers.
  • Because of its standard coding format, it is easy to edit and modify program written in ST language.

4. Function Block Diagram (FBD)

Function block diagram (FBD) is a popular and easy way to write a program like a Ladder Diagram. FBD is represented like box which consists of a number of lines of code for putting different programming functions.

It is a graphical language for programming logic controller. So, it makes your job easy to describe a system.

5. Sequential Function Charts (SFC)

Sequential function charts (SFC) is also a graphical programming language. It is not a textbase. It has become a popular method of accurately specifying sequential control requirements. The benefit of SFC is easy to understand. Because you can visualize what is happening and when it is happening in the procedure of the code.

The main function of SFC is only the active parts of the code are executed. Due to this, it makes easier to troubleshoot and to change the code if problems occur.

Final Thought:

This is all about different types of PLC programming languages commonly used. And you can use those programming languages while developing PLC based on an Automation project.

If you are confused and not sure which programming language you should learn for PLC, go with Ladder Diagram. It is easy to start with a compact PLC or modular PLC.

What’s your experience working on PLC programming? Please share your opinion by comment below.

Happy PLC Programming!

22 thoughts on “5 Different Types Of PLC Programming Languages Commonly Used in Industry”

    • Hello, Hamza Mohamed!

      It’s my pleasure to share the information.

      I didn’t get work on all PLC languages. But, mostly the Ladder Diagram(LD) and Function Block Diagram (FBD) language are used for all kinds of PLC controller.

      Reply
  1. I am also working in siemens plc like S7 300 and 1200 plc and abb drives etc ..i have more interested to develop new programming and modifications etc….

    Reply
  2. Thank you.

    I get more knowledge on your web page. I like to learn about plc.

    I have more interested to develop new programming and modifications etc. If you have any pdf files about plc have to send my mail id. It is used to increase my potential.

    Reply
    • Hie, Nisanka

      I am very glad to saw your feedback about the ‘DipsLab’ and your interest in PLC.

      I am always ready to help the PLC learner like you. But, I have no any kinds of stuff (pdf) related to the PLC.

      You can refer these PLC tutorials where I shared in Dipslab.

      Reply
    • Hie Tamer,

      I am very much glad to see your interest for learning PLC, you can easily learn Ladder Diagram Language of PLC Programming at your home.

      First things that, you should know about Logic Gate (apart from electronic). In the earlier tutorial, I explained the Logic Gate ‘how does it use in the programming language? in detail and many more helpful tutorials for the learning.

      You can learn and practice by using the free software version of the Delta PLC.

      Reply
    • Hie Tamer,

      I am very much glad to see your interest for PLC learning. You can easily learn the Ladder Diagram PLC programming language.

      First things that, you should know about the Logic Gate (part of the Electronic) for learning and writing PLC programming. In the earlier tutorial, I explained Logic Gate and many more useful tutorials in detail.

      If you refer step to step PLC tutorials, hopefully, it will be very helpful to you. And by using the free version of the Delta PLC software, you can try it.

      Reply
    • Hi Abhay,

      I am working on a Ladder diagram (LD) programming language, not using the ST or SFC programming languages. If I get any information stuff related to both languages, surely I will share it.

      If you are interested to learn LD programming, I can assist you.

      Reply

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