MATLAB: How to write the C S-Function in order to have non-virtual bus (with different data types inside) as input in Simulink 6.6 (R2007a)

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I would like to write my own C S-function which inputs are non-virtual bus. I do not succeed. If I generate the S-function with RTW that works. I would like to know if this can be done manually.

Best Answer

The ability to use buses as input or output of an Hand-written C MEX S-function is not available in Simulink 6.6 (R2007a) as mentioned in the documentaiton :

 <http://www.mathworks.com/access/helpdesk/help/toolbox/simulink/index.html?/access/helpdesk/help/toolbox/simulink/sfg/brgo03i-5.html>

To work around this, you can use Legacy Code Tool to import existing C code by looking at the following demo 'Calling Legacy Functions with Structure Arguments Using Buses'. You can open this demo by typing the following on MATLAB Command Prompt:

sldemo_lct_bus_script

Related Solutions

MATLAB: Simulink performance regarding virtual and non-virtual buses

Non-virtual buses allocates the memory for the inputs as compare to virtual buses which are just graphical representation and doesn't allocate any extra memory.

So if you are using large number of non-virtual buses in the model with complex hierarchy, it may affect the simulation time. It is completely depends on complexity of model and non-virtual buses in the model.

MATLAB: How to input and output Bus signals to and from an S-function created using the S-function builder in Simulink 7.3 (R2009a)

The documentation explaining how to connect bus signals to the S-Function Builder block has been omitted in Simulink 7.3 (R2009a). A link to download an updated version of the documentation section titled "Writing S-Function in C" is provided below.

To connect a bus signal to the Input or Output port of the S-Function Builder follow these steps:

1. Create a bus object in the MATLAB workspace. This can be done from interactively using the Simulink Bus Editor, or from the command line by typing:

a = Simulink.Bus

More information about bus objects can be found at this link:

 <http://www.mathworks.com/help/simulink/ug/using-bus-objects.html>

2. In the S-Function block, go to the "Data Properties" tab and add an Input port.

3. You will notice that the input port has two properties related to bus signals, "Bus" and "Bus Name". Set the "Bus" property to "on" and the "Bus Name" to the bus object created in the MATLAB workspace.

4. You can repeat the same operations for other input and output ports.

It is now possible to access the bus elements in the Outputs, Continuous Derivatives and Discrete Update section of the S-Function Builder.

An example model using bus signals with the S-Function Builder can be reached in MATLAB 7.7 (R2009a) by executing this command:

sfbuilder_bususage

Best Answer

Related Solutions

MATLAB: Simulink performance regarding virtual and non-virtual buses

MATLAB: How to input and output Bus signals to and from an S-function created using the S-function builder in Simulink 7.3 (R2009a)

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