User`s guide

3 Working with Real-Time Workshop

3-20

To configure data logging, you use the Data Import/Export pane of the

Configuration Parameters dialog. The process is the same as configuring a

Simulink model to save output to the MATLAB workspace. In addition,

however, for each workspace return variable you define and enable,

Real-Time Workshop defines a parallel MAT-file variable. For example, if you

save simulation time to the variable

tout, your generated program logs the

same data to a variable named

rt_tout. You can change the prefix rt_ to a

suffix (

_rt), or eliminate it entirely. You do this from the Interface tab of the

Real-Time Workshop configuration dialog.

Note Simulink enables you to log signal data from anywhere in a model via

the

Log signal data option in the Signal Properties dialog (accessed via

context menu by right-clicking on signal lines). Real-Time Workshop does

not incorporate this method of signal logging in generated code. To log

signals in generated code, you must either use the

Data Import/Export

options described below or include To File or To Workspace blocks in your

model.

In this tutorial, you modify the

f14rtw model such that the generated

program saves the simulation time and system outputs to the file

f14rtw.mat. Then you load the data into the MATLAB workspace and plot

simulation time against one of the outputs.

Part 1: Data Logging During Simulation

To use the data logging feature,

1 With the model f14rtw open, select Configuration Parameters from the

Simulation menu (or type Ctrl+E).

2 Select the Data Import/Export tab of the Configuration Parameters

dialog. Its

Save to workspace section lets you specify which outport data

is to be saved to the workspace and what variable names to use for it.

3 Select the Time option. This tells Simulink to save time step data during

simulation as a variable named

tout. You can enter a different name to

distinguish different simulation runs (for example using different step

sizes), but allow the name to default for this exercise. Selecting

Time