Instruction List is one of the 5 languages supported by the IEC 61131-3

IEC 61131-3

IEC 61131-3 is the third part of the open international standard IEC 61131 for programmable logic controllers, and was first published in December 1993 by the IEC...

 standard. It is designed for programmable logic controller

Programmable logic controller

A programmable logic controller or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or light fixtures. PLCs are used in many industries and machines...

s (PLCs). It is a low level language

Low-level programming language

In computer science, a low-level programming language is a programming language that provides little or no abstraction from a computer's instruction set architecture. Generally this refers to either machine code or assembly language...

 and resembles assembly

Assembly language

An assembly language is a low-level programming language for computers, microprocessors, microcontrollers, and other programmable devices. It implements a symbolic representation of the machine codes and other constants needed to program a given CPU architecture...

. All of the languages share IEC61131 Common Elements. The variables and function call are defined by the common elements so different languages can be used in the same program.

Program control (control flow

Control flow

In computer science, control flow refers to the order in which the individual statements, instructions, or function calls of an imperative or a declarative program are executed or evaluated....

) is achieved by jump instructions and function calls (subroutines with optional parameters).

The file format has now been standardized to XML

XML

Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....

 by PLCopen.

Example

LD Speed
GT 1000
JMPCN VOLTS_OK
LD Volts
VOLTS_OK LD 1
ST %Q75

Variations

Siemens PLC instruction list language is known as "Statement List" or "STL" in English, and "Anweisungs-Liste" or "AWL" in German, Italian and Spanish. The user of a Simatic development package may choose between German and International mnemonics to represent instructions. For example "A" for "AND" or "U" for "UND", "I" for "Input" or "E" for "Eingang".

External links

• Instruction List – Commands of Instruction List