S-Function Block and Masking Parameters

I have created an S-function (Level2) and included a callback function in its 'OpenFcn' under Block Properties. This callback reads an xls file and assigns data read to the S-Function parameters (variables). I would like perform the following items: 1) Display the data read at respective Mask Parameters of the S-Function block 2) Based on the data read, change the number of input and output port of the S-function block. (Example, if suppose there are 3 rows of data in the xls, the number of input ports will be 3). Any help or ideas on this would be greatly appreciated.

Atit

Answer 1

[Kaustubha Govind]

To set the number of inputs/outputs based on parameter values, you can add code such as the following to your setup function:

block.NumInputPorts  = block.DialogPrm(1).Data;
block.NumOutputPorts = block.DialogPrm(2).Data;

You can display the value of the parameters using block.DialogPrm(idx).Data

[Atit]

Thanks Kaustubha. I will have try your suggestions and see if that's what I was looking for. Else, I will have to re-frame my question :).

Otherwise, I have few other queries as well specifically on S-functions.

1) What does this datatype int_T corresponds to? If I have a value lets say as 203.65 and its typecasted as (int_T)203.65, then what should be outcome? Does this rounds and fixes it? (i.e. it may possibly become 203?) I am having some challenges dealing with this and similar datatypes used on of the S-functions. This is peculiar, as it doesn't imply if its similar to int32_T (!!).

2) Does this function mxGetPr returns pointer to a pointer as in C? (i.e. **ptr)? If this so, can we use this interchangebly? Some of my queries including the above once could have resolved if there is simple ways to debug an S-functions (without any other third party tool/Software), but I don't to debug them. Still figuring out.... Regard Atit

[Kaustubha Govind]

1. AFAIK, int_T is defined as int32_T on 32-bit machines and int64_T on 64-bit machines. It is used to maintain platform independence (see What are the real_T and int_T datatypes referenced in the Simulink template CMEX S-function?)
2. You must use mxGetPr only for double arrays (default type in MATLAB) only. This returns a double-pointer as documented.

There is no built-in debugger for S-functions because they are essentially shared libraries (DLLs) with a predefined format - the binary format itself depends on the MEX compiler that is used and is not MATLAB-specific. This is why we recommend debugging with your C compiler tools.