Via decomposition into logical elements, modularization and modern software techniques, each program is structured, increasing its re-usability, reducing errors and increasing programming and user efficiency. This includes the graphical languages Ladder Diagram (LD) and Functional Block Diagram (FBD), and the textual languages Instruction List (IL) and Structured Text (ST), as well as the Sequential Function Chart (SFC) language, used to structure the internal organization of a program. IEC 61131-3 defines, as a minimum set, the basic programming elements, syntactic and semantic rules for the most commonly used programming languages.
Yet all pieces adhere to a common structure and work together harmoniously. A standard programming interface allows people with different backgrounds and skills to create different elements of a program during different stages of the software life-cycle: specification, design, implementation, testing, installation and maintenance. It harmonizes the way people design and operate industrial controls by standardizing the programming interface. The third part provides the only global standard for industrial control programming. IEC 61131-3: Programming Languages - providing the basis for PLCopen Specifies equipment requirements and related tests for programmable controllers (PLC's) and their associated peripherals. IEC 61131-2: Equipment requirements and tests It consists of the following parts:Ĭontains the definitions and identifies the principal characteristics relevant to the selection and application of programmable controllers and their associated peripherals. The International Standard IEC 61131 provides a complete collection of standards on programmable controllers and their associated peripherals.