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Import ladder diagram into a Simulink subsystem



mdlname = plcimportladder(filename)generates a Simulink® representation of the ladder diagram in the L5X file created using Rockwell Automation® IDEs such as RSLogix™ 5000 and Studio 5000.

[mdlname,mdllib,genbusscript] = plcimportladder(filename,Name,Value)generates a Simulink representation of the ladder diagram in the L5X file with properties specified using one or more Name,Value pair arguments.


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Simulate, test, and validate your .L5X ladder diagram files by importing your ladder diagram files into Simulink®. Use the plcimportladder function to import your ladder diagram files into Simulink. Simulink PLC Coder™ supports only import of ladder diagram files created by using Rockwell Automation® RSLogix 5000® and Studio 5000 ® integrated development environments (IDEs).

Ladder Diagram Description

The ladder diagram in the simple_timer.L5X file controls a motor by using an input switch Switch_A and a timer Motor_timer. This ladder diagram was created using the Studio 5000 IDE.


Light1, Light2, and Motor are the outputs of this ladder diagram.

Import Ladder Diagram

Before using the plcimportladder function to import your ladder diagram files into Simulink:

  • Verify that your .L5X ladder diagram file has no errors by compiling the file in the Rockwell Automation IDE.

  • Verify that the .L5X ladder diagram file uses blocks that are supported by Simulink PLC Coder. For a list of supported blocks at the MATLAB® command line, enter:


To import the simple_timer.L5X ladder diagram file into Simulink, use the plcimportladder function.


The ladder diagram is imported into Simulink and a simple_timer.slx file is created. The current folder also contains a simple_timer_value.mat file that loads the initial values for Motor_timer into the model data store memory. The data store memory also contains state information of elements of the ladder diagram. This state information is updated by the model during simulation.

During the ladder diagram import, Simulink PLC Coder:

  • Imports rung comments. For example, rung two of simple_timer.L5X has the comment Motor On Delay Timer. This comment also appears in the Simulink model as well.

  • Imports Add On Instruction (AOI) with mixed-order arguments, while preserving the order of the arguments. This order argument is preserved during ladder diagram code generation as well.

Imported Ladder Diagram Structure

The simple_timer.L5X ladder diagram file is located in Controller simple_timer > MainTask > MainProgram > MainRoutine.


The simple_timer.slx ladder diagram is located in simple_timer > MainTask > MainProgram > _Logic. This structure is similar to the structure in the Rockwell Automation IDE.


Verify Imported Ladder Diagram

To verify the imported ladder diagram:

  • Open the simple_timer.slx model. Open the simple_timer block, double-click Controller Tags and set Switch_A to Input Symbol and Motor to Output Symbol. Click OK.

  • Add a Signal Editor block. Open the Signal Editor block interface and set the File Name to verify_ladder.mat. Click OK.

  • Add a Cast to Boolean block between the Signal Editor block and Switch_A.

  • Add a Scope block and connect the Switch_A and Motor signals to this block.

  • Open the Scope block and click the Run button.

This image shows the Scope block output for the model simulation. The Motor output turns on three seconds after Switch_A is turned on and turns off as soon as Switch_A is turned off.

Input Arguments

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Specifies the name of the ladder file to read. Depending on the location of your file, you can either specify the name of the file or provide the full or relative path. name.

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: [mdlName,mdlLib,genBusScript] = plcimportladder('sampleLadder.L5X','OpenModel','on','TopAOI','sampleAOI')

At the end of import process, the model is hidden by default. To keep the model open at the end of import, set the value of OpenModel to on.

Specify the function blocks that is to be imported. The software imports it into a ladder diagram 'runner' block.

Output Arguments

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Specifies the name of the generated Simulink model.

Specifies the name of the generated Simulink model library.

Specifies the name of the generated bus script.

Version History

Introduced in R2018a