Generate Simulink PLC Coder Ladder Diagram Code from Stateflow Chart

Note

Ladder diagram generation from Stateflow® charts will be removed in a future release. To generate ladder diagrams, use Simulink® models instead. To create Simulink models compatible with ladder logic generation, do one of the following:

  • Use the blocks from the PLC Ladder library to create a model that is compatible with ladder diagram generation. To open the PLC Ladder library, type plcladderlib at the MATLAB command prompt.

  • Import ladder logic from a L5X file with the plcimportladder function.

To generate ladder logic from the Simulink models, use these functions: plcgeneratecode and plcgeneraterunnertb

This example shows how to:

  • Generate code from a Stateflow chart that you can view as Ladder Diagram in your IDE.

  • Generate test bench for validation of the Ladder Diagram code in your IDE.

For the complete Ladder Diagram code generation workflow, see Ladder Diagram Generation Workflow.

Stateflow Chart and Ladder Logic Diagram

The figure shows a Stateflow chart that implements three-aspect logic, a decision logic for many railway signaling applications.

The chart consists of five states: Init, Fault, Red, Yellow, and Green. Based on the input to the chart, transitions to any of these states can take place. For instance, the state Red becomes active in the following scenarios:

  • Initialization and power up: The previous state is Init and the condition Power_Up is true.

  • Fault rectification: The previous state is Fault and the condition VLDHealthy & FaultRectified is true.

  • Transitions from other colors: The previous state is Green or Yellow, the conditions that allow transition to Red are true, and the conditions that allow transition to another color or to the Fault state are false.

  • Staying red: The previous state is Red and the conditions that allow transition to another state are false.

The figure shows a portion of the Ladder Diagram code generated from the chart when viewed in the CODESYS 3.5 IDE. The Ladder Diagram consists of contacts (normally open and normally closed) and coils (normal, set, and reset).

You can map elements of the original Stateflow chart to these coils and contacts. For instance, the coil Red_new corresponds to the update of the state Red in the Stateflow chart. For the coil to receive power, one of the following must be true:

  • Initialization and power up: The normally open contacts Init and Power_Up must be closed.

  • Fault rectification: The normally open contacts Fault and T_1_1_trans must be closed. The contact T_1_1_trans represents the transition condition VLDHealthy & FaultRectified in the chart.

  • Transitions from other colors: The normally open contact Green must be closed and the following must be true:

    • The normally open contact T_2_3_trans must be closed. This contact corresponds to the chart condition that must be true for transition to the Red state.

    • The normally closed contacts T_2_1_trans and T_2_2_trans must stay closed. These contacts correspond to the chart condition that must be false for transition to the Red state. If the conditions are true, the contacts open and the coil no longer receives power.

  • Staying red: The normally open contact Red must be closed, and the normally closed contacts T_4_1_trans and T_4_2_trans must stay closed. These contacts correspond to the chart conditions that must be false for the Red state to continue to be active. If the conditions are true, the contacts open and the coil no longer receives power.

Generate Ladder Diagram from Chart

To generate Ladder Diagram code from the model plcdemo_ladder_three_aspect:

  1. Open the model.

  2. Open the PLC Coder app. Click the PLC Code tab.

  3. Specify the target IDE for which to generate the Ladder Diagram code.

    Click Settings. Specify a supported IDE for the option Target IDE. See IDEs Supported for Ladder Diagram Code Generation. Click OK.

  4. Right-click the chart and select PLC Code > Generate Ladder Logic for Chart.

If code generation is successful, in the subfolder plcsrc of the current working folder, you see the file ModelName.xml. You import this file to your IDE and view the Ladder Diagram. For the CODESYS 3.5 IDE, see Import Ladder Diagram Code to CODESYS 3.5 IDE and Validate Diagram.

You can also use the function plcgenerateladder to generate Ladder Diagram code from a Stateflow chart.

Generate Ladder Diagram Along with Test Bench

You can generate a test bench to validate the generated Ladder Diagram code. You import the code together with the test bench in your IDE and validate the Ladder Diagram against the original Stateflow chart using the test bench. To generate test bench along with the Ladder Diagram code:

  1. Open the PLC Coder app. Click the PLC Code tab.

  2. Click Settings. Select the option Generate Testbench for Subsystem.

  3. Right-click the chart and select PLC Code > Generate Ladder Logic for Chart.

The test benches use the inputs to the original Stateflow chart. Therefore, you can create test harnesses for the original chart and reuse them for validation of the Ladder Diagram code.

You can also use the function plcgenerateladder to generate test benches.

After generating the Ladder Diagram code and the test benches, you can import them to your IDE. For the CODESYS 3.5 IDE, see Import Ladder Diagram Code to CODESYS 3.5 IDE and Validate Diagram.

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