# structured text

> one of the five languages supported by the IEC 61131-3 standard, designed for programmable logic controllers (PLCs)

**Wikidata**: [Q1753738](https://www.wikidata.org/wiki/Q1753738)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Structured_text)  
**Source**: https://4ort.xyz/entity/structured-text

## Summary
Structured text is one of the five programming languages supported by the IEC 61131-3 standard, specifically designed for programming industrial control systems like programmable logic controllers (PLCs). It resembles Pascal and uses a high-level, structured text format that allows engineers to create complex control algorithms in a human-readable format.

## Key Facts
- Structured text is one of the five languages standardized in IEC 61131-3 for industrial automation
- Designed specifically for programming programmable logic controllers (PLCs) and industrial control systems
- Resembles the Pascal programming language in syntax and structure
- Also known as ST, STX, Texte structure, Texte structuré, Structured Control Language, SCL, and Техно ST
- Has a freebase ID of /m/09c4gw and Microsoft Academic ID of 2778720807
- Available in 10 Wikipedia languages (ar, de, en, es, fr, ja, ko, pt, ru, uk)
- Has 11 sitelinks across different language versions of Wikipedia

## FAQs
### Q: What is structured text used for?
A: Structured text is used for programming industrial control systems, particularly programmable logic controllers (PLCs), as part of the IEC 61131-3 standard. It allows engineers to implement complex control algorithms in a high-level, structured format similar to Pascal.

### Q: How does structured text compare to other PLC programming languages?
A: Structured text is one of five languages in the IEC 61131-3 standard, alongside ladder diagram, function block diagram, sequential function chart, and structured text. It is distinguished by its textual, code-based approach as opposed to graphical languages like ladder diagram.

### Q: What programming languages is structured text based on?
A: Structured text resembles the Pascal programming language in syntax and structure, using similar control structures and data types. This makes it familiar to engineers with experience in traditional programming languages.

### Q: What are the main applications of structured text?
A: Structured text is primarily used in industrial automation and control systems, including manufacturing processes, power generation, building automation, and other applications requiring complex control logic implemented in PLCs.

## Why It Matters
Structured text plays a crucial role in industrial automation by providing engineers with a high-level programming option for PLCs that bridges the gap between graphical programming languages like ladder diagram and traditional programming languages. It enables the implementation of complex algorithms and mathematical operations that would be cumbersome to represent in graphical formats. By standardizing structured text as part of IEC 61131-3, the industrial automation industry gained a unified approach to PLC programming, facilitating code portability between different manufacturers' equipment and improving maintainability of industrial control systems. This has reduced learning curves for engineers and increased the efficiency of industrial automation projects worldwide.

## Notable For
- Being one of the five standardized languages in the IEC 61131-3 international standard for industrial controllers
- Its Pascal-like syntax that provides a familiar programming model for engineers with traditional programming backgrounds
- Its ability to represent complex algorithms and mathematical operations in industrial control systems
- Its inclusion in the standardized portfolio alongside graphical programming languages like ladder diagram
- Its adoption across multiple manufacturers' PLC platforms through the IEC 61131-3 standard

## Body
### Overview
Structured text is one of the five programming languages defined in the IEC 61131-3 international standard for programmable logic controllers. It was developed as part of a standardization effort to unify PLC programming approaches across different manufacturers' platforms. The language provides a high-level, structured text-based alternative to graphical programming methods.

### Technical Characteristics
- Syntax resembles the Pascal programming language
- Uses structured programming constructs including IF-THEN-ELSE statements, CASE statements, and loops (FOR, WHILE, REPEAT)
- Supports complex mathematical operations and algorithmic implementations
- Uses common programming language elements like variables, constants, expressions, and statements
- Can include comments for improved code readability and maintenance

### Standardization
- Officially defined in IEC 61131-3 standard
- Part of the international standard for programmable controllers
- Standardized through International Electrotechnical Commission (IEC)
- Enables code portability between different PLC manufacturers' platforms
- Represents one of five standardized PLC programming languages in the IEC 61131-3 suite

### Implementation and Usage
- Used in industrial automation and control systems
- Particularly suitable for applications requiring complex algorithms
- Common in manufacturing processes, power generation, and building automation
- Often combined with other IEC 61131-3 languages in single projects
- Supported by major PLC manufacturers in their programming environments

### International Availability
- Available in 10 Wikipedia language editions
- Has documentation in Arabic, German, English, Spanish, French, Japanese, Korean, Portuguese, Russian, and Ukrainian
- Referenced with freebase ID /m/09c4gw
- Previously indexed with Microsoft Academic ID 2778720807
- Has 11 sitelinks across different language editions

## References

1. Freebase Data Dumps. 2013