Loading Structure from base workspace to embedded matlab

Does anyone know how to load a structure from base workspace to embedded matlab ?

The structure itself is a combination of constants and sub-structures containing more constants and all I really want is all this information to be made available in the embedded matlab function scope.

Cheers !

[Kaustubha Govind]

Have you tried making it a parameter of the Embedded MATLAB block?

[Robbo]

I have but I get an error message implying that it cannot accept a structure as an input, only constants/bus objects..etc if that makes any sense ?

Answer 1

[Arnaud Miege]

You need to define the scope of the structure as a parameter, not an input (which is the default). Here's a simple example. In the base workspace, I have defined:

s = struct;
s.a = 1;
s.b = 2;

and then I have a MATLAB Function block (previously called Embedded MATLAB Function):

function y = fcn(u,s)
%#codegen
y = s.a * u + s.b;

and s is defined as a parameter in the Model Explorer and it works fine. See Working with Structures and Bus Signals in the documentation.

HTH,

Arnaud

[Arnaud Miege]

PS: Support for non-tunable MATLAB structure parameters in Embedded MATLAB Function blocks was introduced in R2008a and support for tunable MATLAB structure parameters in R2010a. See the release notes for more details:

http://www.mathworks.com/help/toolbox/simulink/rn/brh2esz-1.html#brj84ed-1

http://www.mathworks.com/help/toolbox/simulink/rn/bsawhtd.html#bsawlji

[Robbo]

Thanks Arnaud for the reply. I tried your example and it worked ! But when I tried it with my structure, which has 50 elements of which 3 are arrays, I get an error sayin

"MATLAB function interface error : Unable to map dialog parameter 1 of s-function 'sf_sfun' in mymodel/.../myblock/ SFunction to a run-time parameter. This parameter is an unsupported variable class such as a string, structure, cell or an unsupported data type"

[Robbo]

- mymodel and myblock are the names of my overall model and MATLAB function respectively

[Arnaud Miege]

Have a look at the restrictions when using structures:

http://www.mathworks.com/help/toolbox/eml/ug/bsvdbhz.html

It may be that your structure violates some of those restrictions.

[Robbo]

I see, as soon as I deleted the arrays in my structures it worked. Thank you

[Gilles]

It works like a charm !

Answer 2

[Fangjun Jiang]

From the documentation, "The Embedded MATLAB Function block accepts inputs of any type that Simulink supports, including fixed-point and enumerated types. For more information, see Data Types Supported by Simulink in the Simulink documentation."

Looking further, structure data is not supported by Simulink. I guess you have to flatten your structure data then.

[Robbo]

Oh I see, thank you very much. I was thinking of converting my structure into a bus object and tried the busCreate functionality which I assumed would turn a given MATLAB structure into a bus. I could then route this bus into the embedded matlab function as input, however I was unsuccessful again and obtained 2-3 error messages.