Find reason for this warning msg: Variable 'hws' originally saved as a handle cannot be instantiated as an object and will be read in as a uint32.

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Hainan Wang 2020-7-9

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/562487-find-reason-for-this-warning-msg-variable-hws-originally-saved-as-a-handle-cannot-be-instantiated

评论： Steven Lord 2020-7-10

load_system('input_check')
hws = get_param('input_check', 'modelworkspace');
hws.DataSource = 'MAT-File';
hws.FileName = 'slx_input_check_pars.mat';
hws.reload; % Line 66 
% sim('input_check')
close_system('input_check')

I am loading some parameters to model workspace of Simulink model 'input_check', code is shown above, run the code get a warning msg as,

Warning: Variable 'hws' originally saved as a handle cannot be instantiated as an object and will be read in as a uint32.

> In run_idp (line 66)

line 66 is marked in the code, % Line 66

I am worried about whether this property woud cause error later so want to know what causes this warning. Isn't 'reload' a valid function?

https://www.mathworks.com/help/simulink/slref/simulink.modelworkspace.html

Another example from: https://www.mathworks.com/help/simulink/ug/change-model-workspace-data.html

hws = get_param(bdroot, 'modelworkspace');
hws.DataSource = 'MAT-File';
hws.FileName = 'params';
hws.assignin('pitch', -10);
hws.assignin('roll', 30);
hws.assignin('yaw', -2);
hws.saveToSource;
hws.assignin('roll', 35);
hws.reload;

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Fangjun Jiang 2020-7-9

can you step through the code line by line and run get(hws) before the warning appears?

Hainan Wang 2020-7-9

编辑：Hainan Wang 2020-7-9

在 MATLAB Online 中打开

load_system('input_check')
hws = get_param('input_check', 'modelworkspace');
hws.DataSource = 'MAT-File';
hws.FileName = 'slx_input_check_pars.mat';
hws % get(hws)
hws.reload; % Line 66 % reload variable from an external file to model workspace
% sim('input_check')
close_system('input_check')

Hi,

If I type get(hws) before warning appears, that pops out an error msg:Error using run_idp ()

Cannot get/set MATLABCode property for workspace unless data source is 'MATLAB

Code'.

Instead I type hws before warning appears(shown in code), here is the result shown in cmd window:

hws = 
Simulink.ModelWorkspace
    DataSource: 'MAT-File'
      FileName: 'slx_input_check_pars.mat'
Warning: Variable 'hws' originally saved as a handle cannot be instantiated as an
object and will be read in as a uint32. 
> In run_idp (line 66) 

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Answer 1

Fangjun Jiang 2020-7-10

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/562487-find-reason-for-this-warning-msg-variable-hws-originally-saved-as-a-handle-cannot-be-instantiated#answer_464042

My suspect is that there is a variable also called 'hws' in the .mat file. It was the handle of an object. For example, the handle of certain graphical object appear to be the value of an integer. It was saved to the .mat file by accident.

The object no longer exists. Thus, when you reload the .mat file to the model workspace. The error message appears.

Check the content of your .mat file. Attach it here if possible. Also indicate your MATLAB version.

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Hainan Wang 2020-7-10

Hi,

My matlab version is 20a.

Your answer solved my question perfectly! I loaded slx_input_check_pars.mat file to base workspace and indeed as you said, there is 'hws' saved as a unit32.

Steven Lord 2020-7-10

What does whos -file when run with the name of your MAT-file show should be the class of hws? Likely the definition of that class no longer exists or is no longer on your MATLAB path.

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