5 Most Popular PLC programming languages nowdays

PLC programming languages are used to program the automation devices within the industrial field.

The controllers that are used in industrial automation need to be programmed to perform certain tasks like moving products or sorting them.

In industrial automation, devices are connected through PLCs that are programmed using the software.

There are five programming languages for PLC that are divided into two main sections, text-based and graphical.

Text-based: Instruction list, Structured text

Graphical : Ladder logic(LLD), Function block diagram(FBD), Sequential Function chart(SFC)

PLC Programming languages

PLC Programming languages

PLC programming languages :

The two common methods for PLC programming languages are ladder logic and block diagram.

All these languages are defined by the international standard for PLC programming languages and concepts. (IEC 61131-3)

The standard explains the format, syntax, and display for the five PLC languages available.

Each language is used and best suited for certain types of applications.

How to read, write, assemble ladder logic. Ladder logic is one of the languages used to develop software for programmable logic controllers, PLCs used in industrial control applications.

A PLC programmer is the person responsible for coming up with the logic needed and programming the controller to solve the required task.

These are the processes normally a PLC will carry PLC(Programmable logic controller) is multiple inputs and output digital computer used for automation of electromechanical processes. out during one cycle.computers. From computer, binary or pseudocode will be

Downloaded to PLC through Ethernet, RS-232, RS-485 or RS-422 cable.

PLCs are programmed using the application software on personal

Step 4-: Write outputs (Above four steps are repeated again and again)

Step 3-: Process logics/instructions.

Step 2-: Read inputs and store values.

Step 1-: Self-diagnosis.

Instruction List(IL) Programming :

IL make use of an important concept – STACK

ANB – ‘AND’ the last two variables in stack

ORB – ‘OR’ the last two variables in stack

LD A- Put A back to memory

LD A- Store A to stack

IL is similar to mnemonic programming languages

Structured Text Programming :

Similar to the high-level languages, such as Basic or C

Example – Average of 5 numbers

F9:10 := 0;
WHILE (N6:0 < 5) DO
F9:10 := F9:10 + F9:[N6:0];
N6:0 := N6:0 + 1;

Functional Block Programming :

It is a graphical dataflow programming method

Functional Block diagram

Ladder Logic Programming :

Each program statement is a line called the rung with inputs to the left and the output to the right.


Execution starts from the top rung, down to the last rung.

It is a graphical programming language evolved from electrical relay circuit

Sequential Function chart :

SFC is based on GRAFCET (GRAphe Fonctionnel de Commande Etapses/Transitions) [itself based binary petri nets]

Sequential Function Charts (SFCs) is a graphical technique for writing concurrent control programs Directed links between steps and transitions. Transitions with associated logic conditions Steps with associated actions

Main components of SFC are: Sequential Function Charts (SFCs) is a graphical technique for writing concurrent control programs

Leave a Comment