The IEC 61131-3 programming languages features for industrial control systems

With the advancements in the field of science and technology; the hardware as well as the software (programming) techniques have also been advanced to meet the market requirements. The IEC 61131-3 is the third part of IEC 61131 standard; it is a standard for programming Industrial Control Systems like Programmable Logic Controller (PLC) etc. The IEC 61131- 3 specifies the syntax and semantics of two textual languages, Instruction List (IL) and Structured Text (ST), and two graphical languages, Ladder Diagram (LD) and Function Block Diagram (FBD) and one Sequential Function Chart (SFC). The program can be composed of single or multiple modules implemented in any of these languages, where the each language has its own dedicated editor. In this paper, we are going to discuss the available programming languages of the IEC 61131-3 standard and their features that can help us to select the appropriate language for industrial control system as per requirements. In the past, different manufacturers had different programming concepts and methodology which led to incompatibility between systems and make the system less reliable. It also used to consume a lot of time and effort in programming and maintaining the Industrial Control Systems. This IEC standard provides a common manufacturer independent programming language which is flexible and reusable within a project and it can also be used as a library in another programs.