In 1993, the IEC released the first version of the IEC 61131. It is an international programming standard that provides a common set of programming languages for programmable logic controllers (PLCs), simplifying the development of industrial control systems. The standard defines four main programming languages, which are Ladder Diagram (LD), Function Block Diagram (FBD), Structured Text (ST), and Sequential Function Chart (SFC).
Ladder Diagram (LD) is a graphical language that is based on the electrical wiring diagrams used in relay-based control systems. It is easy to understand and has a low learning curve, making it a popular choice for beginners. Function Block Diagram (FBD) is another graphical language that uses function blocks to represent the different functions of a system. It is useful for complex systems and can be easily reused.
Structured Text (ST) is a high-level programming language that is similar to the C programming language. It is useful for complex mathematical calculations and is easy to read and write. Sequential Function Chart (SFC) is a graphical language that is used to represent complex systems that involve multiple states and transitions. It is useful for designing and documenting the behavior of a system and can be easily modified.
The IEC 61131-3 standard also defines a common set of programming tools and methodologies, which allows engineers and technicians to develop and maintain industrial control systems efficiently. These tools include editors, compilers, and debuggers, which simplify the development process and improve the reliability and safety of the control system.
Over the next few weeks, we will be taking a deeper dive into each of these programming languages and showing their relative strengths. Follow us on social media so you don’t miss out.
