MATLAB: How to use Dwork vectors in the S-Function Builder in Simulink 6.0 (R14)

builderdworks-functionsimulinkvector

I would like to use Dwork vectors in the S-Function Builder in Simulink 6.0 (R14).

Best Answer

Dwork vectors are not supported in the S-Function Builder.

Execute 'sfundemos' as a starting point to manually write S-Functions.

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MATLAB: How to specify the identifier of the DWork vector when writing an S-function in Simulink 6.4 (R2006a) such that on code generation it is accessed via its identifier and not as a field of the DWork structure

This bug has been fixed in Release 2006b (R2006b). For previous product releases, read below for any possible workarounds:

A DWork vector can contain state information that is particularly useful when you have multiple instances of an S-function in your model. The advantage of using DWork vectors to store state information is that Simulink will allocate memory, assign values, and de-allocate memory. You do not have to interact with pointers, and the DWork vectors become part of the SimStruct structure and can be accessed anywhere in the code.

A DWork vector can be accessed in two ways:

1. Accessed via the identifier assigned to it

/* Exported block states */
real_T mySignal;                            /* '<Root>/S-Function' */

2. Accessed as a field in the DWork structure.

/* Block states (auto storage) */
D_Work_modelname modelname_DWork;

When the DWork vector identifier is a field in the DWork structure, it may be accessed as follows:

/* states (dwork) */
modelname_DWork.mySignal = 0.0F;

In order to access the DWork vector by its identifier directly, you must set the storage class to "ExportedGlobal" in the workspace or in the S-function. The two ways you can achieve this functionality are:

a. The DWork vector can be named after a signal in the MATLAB workspace. For example, the following code creates a Simulink signal and sets its storage class.

mySignal = Simulink.Signal;
mySignal.RTWInfo.StorageClass='ExportedGlobal'

In your S-function, use the following macros in the callback mdlInitializeSizes

ssSetNumDWork(S, 1);
ssSetDWorkWidth                (S, 0, 1);
ssSetDWorkDataType(S, 0, SS_SINGLE);
ssSetDWorkRTWIdentifier(S, 0, "mySignal");

NOTE: The macros are not intended for use outside the callback mdlInitializeSizes.

b. Alternatively, you can set the identifier for your DWork vector directly in your S-function. For more information, refer the following S-function demo:

 sfcndemo_sfun_rtwdwork.mdl

MATLAB: How to view model dependencies using Simulink 6.0 (R14)

This enhancement has been incorporated in Release 2007a (R2007a). For previous product releases, read below for any possible workarounds:

This feature has been added in Simulnik 6.6 (R2007a). You can generate a model manifest using Tools -> Model Dependencies -> Generate Manifest.

If you are using a previous version, to view the model dependencies on MATLAB files you can do the following:

1. Open the Matlab profiler using the editor menu Tools -> Open profiler

2. In the "Run this code" field in the Profiler, enter the SIM command with your model's name as follows

sim('vdp')

3. Run the profiler by pressing the button "Start Profiling"

4. After the profiling is finished, enter the following commands at MATLAB prompt to view the model dependencies on MATLAB files

stats = profile('info')
stats.FunctionTable.CompleteName

The ability to view model dependecies on C-files does not exist in Simulink.

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Related Solutions

MATLAB: How to specify the identifier of the DWork vector when writing an S-function in Simulink 6.4 (R2006a) such that on code generation it is accessed via its identifier and not as a field of the DWork structure

MATLAB: How to view model dependencies using Simulink 6.0 (R14)

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