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Debugging a MATLAB Function block slows simulation. For maximum simulation speed, disable debugging as described in Enabling and Disabling Debugging.
There are two levels of debugging available when using MATLAB Function blocks, model level debugging and block level debugging.
Disable debugging for an entire model by clearing the Enable debugging/animation check box in the Simulation Target pane in the Configuration Parameters dialog. Disable debugging for an individual MATLAB Function block by clicking Breakpoints > Enable Debugging in the MATLAB Function Block Editor. If Enable Debugging is unavailable, then the Simulation Target pane in the Configuration Parameters dialog is controlling debugging.
In Create Model That Uses MATLAB Function Block, you created an example model with a MATLAB Function block that calculates the mean and standard deviation for a set of input values.
To debug the MATLAB Function in this model:
len = length(vals);
A small red ball appears in the margin of this line, indicating that you have set a breakpoint.
If you get any errors or warnings, make corrections before you try to simulate again. Otherwise, simulation pauses when execution reaches the breakpoint you set. This is indicated by a small green arrow in the left margin.
The execution arrow advances to the next line of stats, which calls the local function avg.
Execution advances to enter the local function avg. Once you are in a local function, you can use the Step or Step In commands to advance execution. If the local function calls another local function, use the Step In icon to enter it. If you want to execute the remaining lines of the local function, use Step Out.
Execution advances to the line after the call to the local function avg.
The plot function executes in MATLAB®:
In the MATLAB Function Block Editor, a green arrow points down under the last line of code, indicating the completion of the function stats.
The computed values of mean and stdev now appear in the Display blocks.
While you simulate a MATLAB Function block, you can use several tools to keep track of variable values in the function.
In the MATLAB Function Block Editor, place the mouse cursor over the variable text and observe the pop-up display.
For example, to watch the variable len during simulation, place the mouse cursor over the text len in the code. The value of len appears adjacent to the cursor, as shown:
You can report the values for a function variable with the Command Line Debugger utility in the MATLAB window during simulation. When you reach a breakpoint, the Command Line Debugger prompt, debug>>, appears. At this prompt, you can see the value of a variable defined for the MATLAB Function block by entering its name:
debug>> stdev 1.1180 debug>>
The Command Line Debugger also provides the following commands during simulation:
Quit debugging and terminate simulation.
Continue execution to next breakpoint.
Quit debugging and terminate simulation.
Advance to next program step after a breakpoint is encountered. Step over or step into/out of a MATLAB local function.
Display help for command line debugging.
Display the value of the variable var in the current scope. If var is a vector or matrix, you can also index into var. For example, var(1,2).
Saves all variables in the current scope to the specified file. Follows the syntax of the MATLAB save command. To retrieve variables to the MATLAB base workspace, use load command after simulation has been ended.
Equivalent to "print <var>" if variable is in the current scope.
Display the variables in the current scope.
Display the size and class (type) of all variables in the current scope.
You can issue any other MATLAB command at the debug>> prompt, but the results are executed in the workspace of the MATLAB Function block. 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'). To return to the MATLAB base workspace, use the dbquit command.
You can display the execution result of a MATLAB Function block line by omitting the terminating semicolon. If you do, execution results for the line are echoed to the MATLAB window during simulation.
The MATLAB Function Block Editor does not display the contents of matrices that have more than two dimensions or more than 200 elements. For matrices that exceed these limits, the MATLAB Function Block Editor displays the shape and base type only.
When you enable debugging, MATLAB Function blocks automatically check input and output data for data range violations when the values enter or leave the blocks.
In the Ports and Data Manager, select the input or output of interest.
The data properties dialog box opens.
In the data properties dialog box, select the General tab and enter a limit range, as described in Setting General Properties.
Use the following tools during a MATLAB Function block debugging session:
|Tool Button||Description||Shortcut Key|
Access this tool from the Editor tab by selecting Build Model > Build.
Check for errors and build a simulation application (if no errors are found) for the model containing this MATLAB Function block.
Access this tool from the Editor tab by selecting Build Model > Update Diagram.
Check for errors based on the latest changes you make to the MATLAB Function block.
Access this tool from the Editor tab by selecting Build Model > Update Ports.
Updates the ports of the MATLAB Function block with the latest changes made to the function argument and return values without closing the MATLAB Function Block Editor.
Start simulation of the model containing the MATLAB Function block. If execution is paused at a breakpoint, continues debugging.
Stop simulation of the model containing the MATLAB Function block. Alternatively, from the Editor tab, select Quit Debugging if execution is paused at a breakpoint.
Access this tool by selecting Breakpoints > Set/Clear.
Set a new breakpoint or clear an existing breakpoint for the selected line of code in the MATLAB Function block. The presence of the text cursor or highlighted text selects the line. A breakpoint indicator appears in the on the selected line.
Alternatively, click the hyphen character (-) next to the line number. A breakpoint indicator appears in place of the hyphen. Click the breakpoint indicator to clear the breakpoint.
Access this tool by selecting Breakpoints > Clear All.
Clear all existing breakpoints in the MATLAB Function block code.
Step through the execution of the next line of code in the MATLAB Function block. This tool steps past function calls and does not enter called functions for line-by-line execution. You can use this tool only after execution has stopped at a breakpoint.
Step through the execution of the next line of code in the MATLAB Function block. If the line calls a local function, step into the first line of the local function. You can use this tool only after execution has stopped at a breakpoint.
Step out of line-by-line execution of the current function or local function. If in a local function, the debugger continues to the line following the call to this local function. You can use this tool only after execution has stopped at a breakpoint.
Continue debugging after a pause, such as stopping at a breakpoint. You can use this tool only after execution has stopped at a breakpoint.
Exit debug mode. You can use this tool only after execution has stopped at a breakpoint.