# ladder logic

> programming language that represents a program by a graphical diagram based on the circuit diagrams of relay logic hardware; used to develop software for programmable logic controllers used in industrial control applications

**Wikidata**: [Q1411875](https://www.wikidata.org/wiki/Q1411875)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Ladder_logic)  
**Source**: https://4ort.xyz/entity/ladder-logic

## Summary
Ladder logic is a programming language that represents a program as a graphical diagram modeled on the circuit diagrams of relay logic hardware. It is a visual programming language commonly used to develop software for programmable logic controllers (PLCs) in industrial control applications.

## Key Facts
- Ladder logic is a programming language that represents a program by a graphical diagram based on the circuit diagrams of relay logic hardware.
- It is used to develop software for programmable logic controllers (PLCs) used in industrial control applications.
- Instance of: programming language.
- Programming paradigm: visual programming language.
- Wikipedia title: "Ladder logic" (sitelink_count: 24).
- Common media/image resource: https://commons.wikimedia.org/wiki/Special:FilePath/Ladder_diagram.png (Commons category: Ladder diagrams).
- Aliases include: Lenguaje de programación LADDER; Lenguaje de programacion LADDER; Diagrama de contactos; Diagrama de escalera; Ladder Diagram; Schéma à relais; Schéma à contact; Langage à contacts; Schéma à contacts; LD.
- Wikipedia language editions listed: ar, be, commons, de, en, es, eu, fi, fr, id.
- Freebase identifier: /m/0hjbh (reference/publication date: 2013-10-28).
- Microsoft Academic (discontinued) identifier: 44986683.
- Quora topic entry: "Ladder-Logic".

## FAQs
### Q: What is ladder logic used for?
A: Ladder logic is used to develop software for programmable logic controllers (PLCs) that control equipment and processes in industrial control applications.

### Q: How does ladder logic represent a program?
A: Ladder logic represents a program as a graphical diagram modeled on relay logic circuit diagrams, using visual elements rather than textual source code.

### Q: Is ladder logic a visual programming language?
A: Yes. Ladder logic is classified as a visual programming language because it encodes programs in graphical diagram form.

## Why It Matters
Ladder logic matters because it provides a direct, diagram-based way to express control logic for industrial systems. By modeling programs on the familiar schematic forms of relay logic hardware, ladder logic enables control engineers and technicians to translate physical relay-based control concepts into software that runs on programmable logic controllers (PLCs). PLCs are central elements in industrial automation, and ladder logic is one of the established languages for creating their control programs. As a visual programming paradigm, ladder logic emphasizes circuit-like diagrams rather than text, which supports inspection, troubleshooting, and maintenance in settings where hardware wiring diagrams and relay logic are common reference points. Its role in PLC software development links traditional relay-control practices to modern automated control systems used across industrial applications.

## Notable For
- Representing control programs as graphical diagrams directly based on relay logic circuit diagrams.
- Being a visual programming language specifically used for PLC software development in industrial control.
- Wide recognition and multilingual coverage on Wikipedia (title "Ladder logic", sitelink_count: 24; editions in multiple languages).
- Presence in reference and indexing systems (Freebase ID /m/0hjbh; Microsoft Academic ID 44986683).
- Commonly associated media and documentation under the Commons category "Ladder diagrams".

## Body
### Definition
- Ladder logic is defined as a programming language that represents a program by a graphical diagram based on the circuit diagrams of relay logic hardware.
- It is used to develop software for programmable logic controllers (PLCs) in industrial control applications.

### Representation and Diagram Basis
- The program structure uses graphical elements that mirror relay logic circuit diagrams.
- Diagrams used in ladder logic are often referred to as ladder diagrams (Commons category: Ladder diagrams).
- An example image resource: https://commons.wikimedia.org/wiki/Special:FilePath/Ladder_diagram.png

### Primary Use and Applications
- Primary application is PLC software development.
- Target domain: industrial control applications where PLCs manage machines and processes.

### Classification and Paradigm
- Instance of: programming language.
- Programming paradigm: visual programming language.

### Names and Aliases
- Common English name: Ladder logic.
- Other aliases and translations: Lenguaje de programación LADDER; Lenguaje de programacion LADDER; Diagrama de contactos; Diagrama de escalera; Ladder Diagram; Schéma à relais; Schéma à contact; Langage à contacts; Schéma à contacts; LD.

### Identifiers and References
- Wikipedia title: Ladder logic (sitelink_count: 24).
- Freebase ID: /m/0hjbh (reference date 2013-10-28).
- Microsoft Academic ID (discontinued): 44986683.
- Quora topic: Ladder-Logic.

### Language Coverage and Media
- Wikipedia language editions listed: ar, be, commons, de, en, es, eu, fi, fr, id.
- Commons media category: Ladder diagrams; representative image available at the provided Commons file path.

## References

1. Freebase Data Dumps. 2013
2. Quora
3. [OpenAlex](https://docs.openalex.org/download-snapshot/snapshot-data-format)