Real-Time Windows Target

Entering Signal and Triggering Properties

Data is saved to the MATLAB workspace through a Simulink Scope block. Signal and triggering properties need to be set only when running a real-time application. If you are running a simulation, you can skip this procedure.

After you create a Simulink model and add a Scope block, you can enter the signal and triggering properties for logging to the MATLAB workspace. This procedure uses the Simulink model rtwin_model.mdl as an example and assumes you have already loaded that model:

1. In the Simulink window, and from the Tools menu, click External Mode Control Panel.

1. The External Mode control Panel dialog box opens.

2. Click the Signal & Triggering button.

1. The External Signal & Triggering dialog box opens.

3. Click the Select all button. From the Source list, choose manual. From the Mode list, choose normal.

1. The X under Signal selection designates that a signal has been tagged for data collection, and T designates that the signal has been tagged as a trigger signal.

4. In the Duration box, enter the number of sample points in a data buffer. For example, if you have a sample rate of 1000 samples/second and a stop time of 10 seconds, you could enter

• 10000
  

1. Note The Duration value is related to the Limit data points to last value in the Scope parameters dialog box. The smaller of either value limits the number of sample points saved to the MATLAB workspace. We recommend that you do not select the Limit data points to last check box, and use the Duration value to set the number of sample points saved.

   To clear the Limit data points to last check box, see Entering Scope Parameters.

   The Duration value specifies the number of contiguous points of data to be collected in each buffer of data. We recommend that you enter a Duration value equal to the total number of sample points that you need to collect rather then relying on a series of buffers to be continuous.

   If you enter a value less than the total number of sample points, you will lose sample points during the time needed to transfer values from the data buffer to the MATLAB workspace. The Real-Time Windows Target ensures that points are continuous only within one buffer. Between buffers, due to transfer time, some samples will be omitted.

   We also recommend setting the time axis for Simulink Scope blocks equal to the sample interval (in seconds) times the number of points in each data buffer. This setting will display one buffer of data across the entire Simulink Scope plot.

   The Signal & Triggering dialog box will look similar to the figure below.
   
   

5. Do one of the following:
• Click Apply to apply the changes to your model and leave the dialog box open.
• Click Close to apply the changes to your model and close the Simulation Parameters dialog box.

1. Note You must click the Apply or Close button on the Signal and Triggering dialog box for the changes you made to take effect. Generally it is not necessary to rebuild your real-time application.

Entering Scope Parameters

Plotting Logged Signal Data