How to declare a global variable in a large Simulink model?

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In c-code to declare a global variable is very easy. But I found that it was not so easy in a large Simulink model with several subsystems.
I used a Memory block with a Memory_Read block followed by a GOTO block. Then use FROM blocks at places where this variable was used as input signal (and Memory_Write block to update).
Problems came when this variable was needed (as output) inside an inner level of a subsystem. This variable name would not be recognized there even after adding an input port on the subsystem (unnecessarily) to "feed in" a signal with this name. The only thing I could do was to name an output with this name. When generating code, I found that RTW added a suffix to this name (an operation known as "mangle", meaning that Simulink thinks that it is a diiferent variable so gives it a different name). How to tell Simulink that it is a global variable and not to change its name?
I searched Matlab Help but did not find any advices. My solution was to manually edit the generated code, but was unhappy with the solution. Please help. Thanks!

Answers (4)

Kaustubha Govind
Kaustubha Govind on 10 Nov 2011
It appears that what you need is a Data Store Memory block. You can use the Data Store Read and Data Store Write blocks to read/write to it respectively. You can also customize how this data is represented in generated code bu changing the storage class, as described here.
Kaustubha Govind
Kaustubha Govind on 14 Nov 2011
You need to connect your chart output to a Data Store Write block (, not a Memory Write block. Could you try if this fixes the issue?

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Kyon on 9 Apr 2016
how can i make the output of a block or a subsystem a global variable to write to blocks and Matlab function function blocks?

Ricardo A. Baila
Ricardo A. Baila on 12 Apr 2016
I don't know if it could be simply this, but did you declare the goto's visibility as global?

Foad Sojoodi Farimani
Foad Sojoodi Farimani on 20 Feb 2019
This is strange because in Scilab-xcos and Scicoslab-scicos one can write a script in the context including some global variables :
Annotation 2019-02-20 104116.jpg


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