Log and View Data with the Stateflow API

This example shows how to log and view logged data from the command line.

Logging data can help you debug issues with chart design or analyze data from your simulation. By using the command-line API, you can analyze large sets of data by creating scripts that log data, display the data in MATLAB, or export the data to Excel. For more information on the Stateflow application programming interface, see Overview of the Stateflow API.

Log Chart Signals

To enable logging for a state or data object, get a handle to the object and set its LoggingInfo.DataLogging property to true.

1. Load the model:

load_system("sf_yoyo");

2. Access the Stateflow.State object that corresponds to the state ReelMoving:

reelMoving = find(sfroot,"-isa","Stateflow.State", ...
    Name="ReelMoving");

3. Access the Stateflow.Data object that corresponds to the output data ReelState:

reelState = find(sfroot,"-isa","Stateflow.Data", ...
    Name="ReelState");

4. Enable logging for the state ReelMoving and the output data ReelState:

reelMoving.LoggingInfo.DataLogging = true;
reelState.LoggingInfo.DataLogging = true;

5. Enable custom naming and change the logging name of the state ReelMoving to Reel Moving Log:

reelMoving.LoggingInfo.NameMode = "Custom";
reelMoving.LoggingInfo.LoggingName = "Reel Moving Log";

6. Run the model:

sim("sf_yoyo.slx");

View Logged Data in the MATLAB Workspace

To access the data logged during simulation, use the get function. For example, get the data for the ReelMoving state and the ReelState output data by entering:

reelMovingLog = get(logsout,"Reel Moving Log")

reelMovingLog = 
  Stateflow.SimulationData.State
  Package: Stateflow.SimulationData

  Properties:
         Name: 'Reel Moving Log'
    BlockPath: [1×1 Simulink.SimulationData.BlockPath]
       Values: [1×1 timeseries]


  Methods, Superclasses

reelStateLog  = get(logsout,"ReelState")

reelStateLog = 
  Stateflow.SimulationData.Data
  Package: Stateflow.SimulationData

  Properties:
         Name: 'ReelState'
    BlockPath: [1×1 Simulink.SimulationData.BlockPath]
       Values: [1×1 timeseries]


  Methods, Superclasses

To access the logged data and time of each logged element, use the Values.Data and Values.Time properties. Arrange the logged data as a table by entering:

T1 = table(reelMovingLog.Values.Time,reelMovingLog.Values.Data);
T1.Properties.VariableNames = ["Time","Data"]

T1=121×2 table
     Time     Data
    ______    ____

         0     0  
     5.025     1  
     5.275     0  
     10.16     1  
     10.66     0  
     15.03     1  
     15.53     0  
    20.124     1  
    20.624     0  
    24.992     1  
    25.492     0  
    30.084     1  
    30.584     0  
    34.951     1  
    35.451     0  
    40.041     1  
      ⋮

T2 = table(reelStateLog.Values.Time,reelStateLog.Values.Data);
T2.Properties.VariableNames = ["Time","Data"]

T2=122×2 table
       Time       Data
    __________    ____

             0      0 
    3.1554e-30      0 
         5.025      1 
         5.275      0 
         10.16     -1 
         10.66      0 
         15.03      1 
         15.53      0 
        20.124     -1 
        20.624      0 
        24.992      1 
        25.492      0 
        30.084     -1 
        30.584      0 
        34.951      1 
        35.451      0 
      ⋮

View the logged data in a figure window by using the plot function:

X = reelStateLog.Values.Time;
Y = reelStateLog.Values.Data;

plot(X,Y,"-o")
xlabel("Time")
ylabel("Data")
set(gcf,"position",[100,100,1000,400])

The signal logging object records a data point every time that the Stateflow chart writes to the data, even if the data does not change value. For example, in the table T2, the first two entries contain a value of 0. These entries correspond to when the chart initializes the output data ReelState at time 0 and when a default transition sets ReelState at time 3.1554e-30.