2. Loading Models

You can use the LabVIEW Control Design Assistant to load linear time-invariant, or .lti, files into the LabVIEW SignalExpress environment. A .lti file stores control design linear time-invariant models.

Complete the following steps to load a sample model in the LabVIEW SignalExpress environment.

1. Click the Add Step button, shown below, to open the Add Step menu.
   
   
   
   A step is a configurable function that acquires, generates, analyzes, loads, or stores signals and system data. Steps process input data and produce output data. You can configure the operation of steps by specifying values in the configuration view, or Step Setup tab, for each step. You create projects by adding steps to the Project View.
2. Select Control Design»Import/Export Model»Load Control Design Model to add a Load Control Design Model step to the Project View. The Step Setup tab for the Load Control Design Model step appears.

   Tip  When you move the cursor over a step in the Add Step menu, a description of that step appears in the help window at the bottom of the Add Step menu.

3. In the Step Setup tab, click the Browse button, shown below, next to the File name text box and navigate to the National Instruments\Control Design Assistant\Examples directory.
   
   
4. Double-click the cdmodel.lti data file to load the model.
   
   The cdmodel.lti file contains an open-loop model.
5. Click Record 0 in the Information in file table.
   
   The Information in file table displays information about the loaded model. For example, the model in the cdmodel.lti file is a zero-pole-gain SISO model.
6. Click the Data View tab to display the Data View.
7. In the Project View, right-click the Imported: 0 output and select Rename from the shortcut menu to give the signal a more intuitive name. Change the name of this output to Model Data.
   
   You can create a probe to obtain information about a signal. In the Project View, right-click the Model Data output and select Probe from the shortcut menu to create the probe. Notice that the probe displays information about the output, including which step you used to generate the output. Close the probe.
8. Click the Model Data output of the Load Control Design Model step and drag it from the Project View to the Data View to display a diagram of the model.
9. Right-click the Data View and select Model Type»State-Space from the shortcut menu to view the model as a state-space model. Right-click the Data View again and select Model Type»Zeros and Poles to view the model as a zero-pole-gain model.

   Note  Changing the model type in this way does not convert the model type as the Type Conversion step does. Only the display changes to show the model as a different type.

10. Select File»Save Project As and save this project as My Sample Project.seproj to an easily accessible location. A .seproj file is a LabVIEW SignalExpress project, which refers to the LabVIEW SignalExpress environment in which the Control Design Assistant resides.