problem of getting data from Simulink to Workspace with Matlab Fcn block

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Sonny 2011-7-20

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Hello,

I'm trying to convert the hexadecimal numbers to ascii strings and pass it from Simulink to Workspace. To do that I used a Matlab Fcn block : function y = fcn(u) %#eml eml.extrinsic('assignin'); eml.extrinsic('strcat'); eml.extrinsic('plot');

Temp5 = ConvertToAscii(u(1),u(2),u(3),u(4));
assignin('base','Str_Digits',Temp5);
y = u(1);

So, when I click on the button 'Start simulation' in Simulink, I can see the output value change every time steps. However, when I launch a m file, I can only see the output after that m file execution finished. How to resolve this problem?

Thank you,

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Kaustubha Govind 2011-7-20

Do you mean that at the end of simulation, only the last value of 'Temp5' is available, and you really want it to be an array of strings?

Sonny 2011-7-21

Indeed, I would like to visualize the evolution of the variable during the simulation. But here it's not possible, I only get the result at the end of the execution of m.file. However, if I don't stop the simulation after that, I can see the value change. So only during the execution of the script that I can't get the values

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Answer 1

Fangjun Jiang 2011-7-21

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在 MATLAB Online 中打开

Your MATLAB Fcn block is also executed at every simulation step. Your statement assignin('base','Str_Digits',Temp5); over-write the variable "Str_Digits" in base workspace. Are you saying that you only saw one value of "Str_Digits"? Try to add the following line after that statement. Maybe you will see the value got updated continuously in the command window.

evalin('base','Str_Digits')

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Sonny 2011-7-21

Indeed when I put it in the Fcn block, I get the value updated continuously in the command window. Of course in the command windows it could be annoying when executing a script, but it's already better than having nothing at all. Thank you

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Answer 2

Rick Rosson 2011-7-21

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Simulink does not support character or string data types. I would recommend that you do these calculations in MATLAB instead. If the data is being generated by a Simulink model, then you can simply pass the data from Simulink to the MATLAB Workspace using the "To Workspace" block, and then process the data using the "StopFcn" Callback Function.

There is no real advantage in trying to do this task with the MATLAB Function Block, and as you have discovered, there are many disadvantages in this case.

HTH.