Simulink model error: Brace indexing is not supported for variables of this type.

I'm not sure why I'm getting this error with Simulink. I thought perhaps it was related to "local" vs. "scoped" variables (local having [] and scoped {}), but that doesn't appear to be the case. One challenge is that the Diagnostic Viewer doesn't give me a link to where in the model the error comes from, and the only description is: Brace indexing is not supported for variables of this type.

Answer 1

[Shadaab Siddiqie]

From my understanding you are getting an error in your Simulink. This error message may stem from an uncaught syntax error in your reference design plugin file (plugin_rd.m). For example, if the 'CustomConstraints' property of the hdlcoder.referencedesign class is specified as a char array:

hRD.CustomConstraints = 'myConstraints.xdc';

instead of a cell array:

hRD.CustomConstraints = {'myConstraints.xdc'};

Starting from R2020a, validation for this property was added, so it will now properly error out. You can see this by running the following code in the latest release:

>> hRD = ZedBoard.vivado_base_2018_1.plugin_rd;
>> hRD.validateReferenceDesign;

which will error out with the message:

Invalid property value for property "CustomConstraints". 
Value must be a cell array of character vectors, for example, hRD.CustomConstraints = {'abc.xyz'}.

[Dave Hall]

Thanks, @Shadaab Siddiqie. I will look further, but so far, I don't see any places where I've coded character arrays vs. cell arrays and I don't appear to be using plugin_rd anywhere. In fact, this was a small Simulink code that was working previously and mysteriously started producing this error. I'm in the process of re-writing the code to see if that avoids the problem. Very frustrating, though.

Also, I tried running it under 2021a to see if that gave me better error checking, but I got the same "Brace indexing is not supported for variables of this type." error with no link.

[Dave Hall]

@Shadaab Siddiqie, quick update: I re-wrote the module, and the problem has disappeared. Not sure what this error was, but I've avoided it for now. Moving on. Thanks for your help.