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View and Access Signal Logging Data

You can view logged signal data during simulation using the Simulation Data Inspector, or for paused or stopped simulations, using other visualization interfaces. See Decide How to Visualize Simulation Data.

Alternatively, you can access signal logging data programmatically, using MATLAB® commands.

Tip

If you do not see logging data for a signal that you marked in the model for signal logging, check the logging configuration. Use the Signal Logging Selector to enable logging for a signal whose logging is overridden. For details, see View the Signal Logging Configuration and Override Signal Logging Settings.

Signal Logging Object

The software saves signal logging data in a Simulink.SimulationData.Dataset object, which is a MATLAB workspace variable. The default name of the signal logging variable is logsout. You can change the variable name using the text box next to the Signal logging parameter in the Configuration Parameters dialog box.

You can specify whether you want the data for individual signals in a dataset to use MATLAB timeseries or timetable elements by setting the Dataset signal format configuration parameter. For details, see Dataset signal format.

Releases earlier than R2016a also supported a ModelDataLogs format. For details, see Convert Data to Dataset Format.

To search for specific elements in a Dataset object, use the find function. To return the names of the Dataset object elements, use the getElementNames function.

Tip

To call a function on each specified MATLAB timeseries object, you can use the Simulink.SimulationData.forEachTimeseries function. For example, you can use this function to make it easy to resample every element of a structure of timeseries objects obtained by logging a bus signal.

Access Data Programmatically

Open Live Script

Access a Simulink.SimulationData.Dataset object and its elements.

Simulate the model sldemo_clutch, which models a rotating clutch system. Then, access the Dataset object sldemo_clutch_output, which contains the signal logging data. For more information about the model, see Building a Clutch Lock-Up Model.

sim("sldemo_clutch");
sldemo_clutch_output
sldemo_clutch_output = 
Simulink.SimulationData.Dataset 'sldemo_clutch_output' with 10 elements

                         Name          BlockPath                         
                         ____________  _________________________________ 
    1  [1x1 Signal]      Fn            sldemo_clutch/Clutch Pedal       
    2  [1x1 Signal]      Tin           sldemo_clutch/Engine Torque      
    3  [1x1 Signal]      LockedFlag    sldemo_clutch/Friction Mode Logic
    4  [1x1 Signal]      LockupFlag    sldemo_clutch/Friction Mode Logic
    5  [1x1 Signal]      UnlockFlag    sldemo_clutch/Friction Mode Logic
    6  [1x1 Signal]      Tfmaxk        sldemo_clutch/Friction Model     
    7  [1x1 Signal]      Tfmaxs        sldemo_clutch/Friction Model     
    8  [1x1 Signal]      ShaftSpeed    sldemo_clutch/Locked             
    9  [1x1 Signal]      EngineSpeed   sldemo_clutch/Unlocked           
   10  [1x1 Signal]      VehicleSpeed  sldemo_clutch/Unlocked           

  - Use braces { } to access, modify, or add elements using index.

To access Dataset object elements, you can use indexing with curly braces. For example, access the Tin element of the signal logging Dataset object using the index 2.

el2 = sldemo_clutch_output{2}
el2 = 
  Simulink.SimulationData.Signal
  Package: Simulink.SimulationData

  Properties:
              Name: 'Tin'
    PropagatedName: ''
         BlockPath: [1x1 Simulink.SimulationData.BlockPath]
          PortType: 'outport'
         PortIndex: 1
            Values: [1x1 timeseries]


  Methods, Superclasses

The signal data is stored in the Values property of the Simulink.SimulationData.Signal object as a timeseries object. The time values are in the Time property of the timeseries object. The signal values are in the Data property.

el2.Values
  timeseries

  Common Properties:
            Name: 'Tin'
            Time: [387x1 double]
        TimeInfo: tsdata.timemetadata
            Data: [387x1 double]
        DataInfo: tsdata.datametadata

Handling Spaces and Newlines in Logged Names

This example shows three signals that illustrate how signal logging names:

  • A signal with a name that contains a space

  • A signal with a name that contains a newline

  • An unnamed signal that originates on a block with a name that contains a newline

Simulate the model and then look at the signal logging results in the logsout variable. You can see that the names in the Dataset object use a space where the signal name contained a space and a newline where the name contained a newline. The unnamed signal has an empty character array as its name.

logsout
logsout = 

Simulink.SimulationData.Dataset 'logsout' with 3 elements

                         Name  BlockPath                              
                         ____  ______________________________________ 
    1  [1x1 Signal]      x y   ex_signal_names_with_spaces/Sine Wave 
    2  [1x1 Signal]      a b   ex_signal_names_with_spaces/Sine Wave1
    3  [1x1 Signal]      ''    ex_signal_names_with_spaces/Sine Wave2

  - Use braces { } to access, modify, or add elements using index.

You can access a signal with a name that contains a space by name or by index. Include the space in the name you pass to the getElement function. To access a signal with a name that contains a newline, use the index.

>> logsout{2}

ans = 

  Simulink.SimulationData.Signal
  Package: Simulink.SimulationData

  Properties:
              Name: 'a↵b'
    PropagatedName: ''
         BlockPath: [1×1 Simulink.SimulationData.BlockPath]
          PortType: 'outport'
         PortIndex: 1
            Values: [1×1 timeseries]

Access Logged Signal Data in ModelDataLogs Format

Before R2016a, you could log signals in ModelDataLogs format. Starting in R2016a, you cannot log data in the ModelDataLogs format. Signal logging uses the Dataset format.

If you have already logged signal data in the ModelDataLogs format, you can use the convertToDataset function to update the signal logging data to use Dataset format. For more information, see Migrate Legacy Code That Uses ModelDataLogs.

See Also

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