Watching Data Values with Debuggers :: Debugging and Testing (Stateflow®)

Stateflow^®

Watching Data Values with Debuggers

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Watching Data in the Stateflow^® Debugger Watching Stateflow^® Data in the MATLAB^® Command Window

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Watching Data in the Stateflow^® Debugger

Watching Stateflow^® Data in the MATLAB^® Command Window

Watching Data in the Stateflow^® Debugger

The Browse Data pull-down menu in the Stateflow^® Debugger lets you display selected data in the bottom output display pane of the Stateflow Debugger during simulation, after a breakpoint is reached. The Debugger can filter the display between:

Watched data and all data
Watched data in the currently executing chart and watched data for all charts in a model

Note You designate Stateflow data to be watched data by enabling the property Watch in Stateflow^® Debugger, as described in Properties You Can Set in the Value Attributes Pane.

The following example displays All Data (All Charts) for two executing charts, Chart1 and Chart2, in a simulating model. Each chart has its own data value: x1 and x2, respectively.

The data for each chart is headed by its owning object. Each displayed object (chart, state, data, and so on) is accompanied by a unique identifier in the form (#id(xx:yy:zz)), which is used in linking the listed object to its appearance in the Stateflow chart.

Note Fixed-point data appears with two values: the quantized integer value (stored integer) and the scaled real-world (actual) value. For more information, see Using Fixed-Point Data in Stateflow^® Charts.

Watching Stateflow^® Data in the MATLAB^® Command Window

When simulation reaches a breakpoint, you can view the values of Stateflow data in the MATLAB^® Command Window. In the following example, a default transition calls an Embedded MATLAB™ function with a breakpoint set at the last executable line of the function:

When simulation reaches the breakpoint, you can display Stateflow data in the MATLAB Command Window. Assuming you want to watch the data variable vals from the previous example, follow these steps:

At the MATLAB prompt, press Enter.
A debug>> prompt appears.

Enter the MATLAB command whos to view the data that is visible at the current scope.

debug>> whos
  Name        Size               Bytes  Class       
                                                    
  vals        4x1                   32  double array
  len         1x1                    8  double array
  stdev       1x1                    8  double array
  mean        1x1                    8  double array
  invals      4x1                   32  double array

Grand total is 5 data in scope

debug>>

Enter the name of data array vals at the prompt to display its value.
```
debug>> vals
 
	vals =

     2
     3
     4
     5

debug>> 
```
Enter vals(2:3) to view the values of a submatrix of the array.
```
debug>> vals (2:3)

ans =

     3
     4

debug>>
```

The Command Line Debugger provides these commands during simulation:

Command	Description
`dbstep`	Advance to next executable line of code.
`dbstep [in/out]`	When debugging Embedded MATLAB functions: `dbstep [in]` advances to the next executable line of code. If that line contains a call to another function, execution continues to the first executable line of the function. `dbstep [out]` executes the rest of the function and stops just after leaving the function.
`dbcont`	Continue execution to next breakpoint.
`dbquit` (`ctrl-c)`	Stop simulation of the model. Press Enter after this command to return to the command prompt.
`help`	Display help for command-line debugging.
`print` var ...or... var	Display the value of the variable var.
var (i)	Display the value of the ith element of the vector or matrix var.
var (i:j)	Display the value of a submatrix of the vector or matrix var.
`save`	Saves all variables to the specified file. Follows the syntax of the MATLAB `save` command. To retrieve variables in the MATLAB base workspace, use the `load` command after simulation has ended.
`whos`	Display the size and class (type) of all variables in the scope of the halted Embedded MATLAB function.

You can issue any other MATLAB command at the debug>> prompt but the results are executed in the Stateflow workspace. For example, you can issue the MATLAB command plot(var) to plot the values of the variable var.

To issue a command in the MATLAB base workspace at the debug>> prompt, use the evalin command with the first argument 'base' followed by the second argument command string, for example, evalin('base','whos').

Note To return to the MATLAB base workspace, use the dbquit command.

Debugging Cyclic Behavior

Monitoring Test Points in Stateflow^® Charts