ladder logic

Also found in: Wikipedia.

ladder logic

Source code formatted in two columns with conditions on the left that lead to outputs on the right:

if (c1) s1 else if (c2) s2 else if (c3) s3 ...
This article is provided by FOLDOC - Free Online Dictionary of Computing (

IEC 61131

A family of programming languages for programmable logic controllers (PLCs). Of the three graphical and two textual languages, ladder logic (see example below) was the first language and widely used. IEC 61131 was previously known as IEC 1131. See PLC.

 ladder logic
 function block diagram
 sequential function chart


 structured text
 instruction list

The following example of ladder logic shows how logical AND and OR gates are diagrammed. In this case, x = a AND (b OR c).

   ---[ ]-----|--[ ]--|-----( )---
       a      |   b   |      x
              |       |
              |--[ ]--|
              |   c   |
Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
References in periodicals archive ?
The update allows engineers to pick the best software tool for their specific application; to mix and match several software tools to build control and IIoT solutions on one platform; and to leverage existing employee knowledge in IEC 61131-3 programming methods, including ladder logic. OPTO 22,
The PLCs can be programmed by using several programming languages under the international standard IEC 61131-3, such as Ladder Logic Diagram (LLD), Function Block Diagram (FBD), Structured Text (ST), Instruction List (IL) etc.
Now, you could be a ladder logic programmer, a flowchart programmer or a structured text programmer; frankly, the IIoT really doesn't care what language or environment you use to write your control programs, as long as it can get access to the data in your control tags.
The contacts have to be checked in ladder logic for healthiness and safety measures .In order to increase the performance of the system, all less critical sensors are replaced with dual sensors through ladder logic.
Sample programs are available on AMCI's website and can be easily incorporated into new or existing ladder logic programs, making adding the module to your system a quick and efficient process.
These PLCs are generally programmed with ladder logic or function-block programming languages.
Centralized low cost control of field devices in a factory using ladder logic functions.
Users can also program it directly from a PLC if they are familiar with ladder logic. Users can deploy the robot for pharmaceutical packaging, since it is rated IP65 (protection against particles and resistance to water).
Customers use the Studio 5000 Logix Designer front-end interface with Add-On-Instructions (AOI's) and Add-On-Profile (AOP) software to communicate with and configure the robot controller as the ladder logic programming is translated into robot code.
Hoehn, "Ladder Logic & Programmable Controllers: Using Ladder Diagrams with PLC's for Machine Tools & Industrial Processes.", Frederick Hoehn; 1st edition (April 20, 2014), ASIN: B00JU79TAQ, pp.
A program editor optimized for the four languages this system uses is detailed then, and a detailed description of the languages themselves: programming languages for ladder logic (LAD), function block diagrams (FBD), statement lists (STL), and structured control (SCL).
* Conversion of Logic Manager Ladder logic to Functional Logic Diagrams in the FSC Blue system;