ladder logic

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ladder logic

(programming)
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 ...
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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.
Graphical

 ladder logic
 function block diagram
 sequential function chart


 Textual

 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   |
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References in periodicals archive ?
He explains new terms and concepts associated with the ControlLogix Platform and RSLogix 5000 software, including the ControlLogix hardware, RSLogix 5000 software features and basic navigation, RSLogix 5000 project organization, understanding I/O addressing, performing an I/O configuration for digital and analog modules, understanding tag structure, creating tags, setting up a communications path, creating a new RSLogix 5000 project, understanding basic ladder programming and relay ladder instructions, editing, adding documentation, and downloading and monitoring the RSLogix 5000 project to the modular ControlLogix or CompactLogix controller.
The UT35A and UT32A have a fixed control scan period of 200 ms and 300 steps for ladder programming, compared with the three control scan periods and 500 steps in the high-end UT55A and UT52A models.
The product features are: The right functionality at half the price: The UT35A and UT32A have a fixed control scan period of 200 ms and 300 steps for ladder programming, compared with the three control scan periods and 500 steps in the high-end UT55A and UT52A models.
WindLDR software provides intuitive ladder programming, online editing and simulation mode.