Why do I receive a warning on bus-capable blocks + matlab function from r2017 and not before?

Hello,

I have an issue regarding the use of Bus combined with Matlab function.

What I want to do is the following:

• use a matlab function block to treat a signal.
• This matlab function outputs a bus (not a mux, because signals can be of differents data types)
• this Bus is send to other buses in the model

The issue is the following: when I use the serach function (ctrl+f), I get the following warning in the command window:

Warning: 'untitled/test/Bus Selector Frame_1' must be connected to a Bus Creator, Bus Selector or a bus capable block.

A possible cause of this error is the use of a bus-capable block (such as Merge or Unit Delay) that in this current situation is

unable to propagate the bus downstream to the block reported in this error. Please see Simulink documentation for further

information on composite (i.e. bus) signals and their proper usage.

I did defined the bus in the properties of the subsystem (InitFcn and LoadFcn), and I did assigned the definition in the bus properties:

The bus signal is effectively defined in the workspace, and the model runs properly (also runs properly after code generation).

(FYI, I do have the same behaviour if I define the bus externally, from the command window, before model opening)

This warning is a big problem for me because I use this a lot of times in my model, and the search function takes 1 day because of this warnings instead of 15min... This behaviour is also observed with the used of function looking for backpropagation properties ending on this matlab function. Therefore using code generation tools, I get the same warning.

The temporary workaround I found is the deactivation of the warning, but I would like to solve the issue once and for all..

What I don't understand is that it is matlab version related: I do not have this issue in r2016b, but I have it using r2017a and r2020b.

You can find attached a model producing this issue.

Thanks for your anwers.

Answer 1

[deRicaud]

If somebody has the same issue, Matlab will correct this in future release. There is apparently no workaround, except deactivating manually the warning with the following line:

warning('off','Simulink:blocks:BusSelectorUnconnected')

Answer 2

[Jonas]

I get no warnings when running your model or searching objects.

Maybe it is related to the fact that you create the Bus object using a block callback function.

Why don't you create a Simulink.Bus object inside your Model Workspace or a linked Data Dictionary to define the structure and its elements there, and then use the Bus object as the data type for the output of the MATLAB function. I am guessing it will avoid the warning you get because the Bus object will be findable at any stage.

[deRicaud]

Do you have a Matlab version newer thant r2016b ?

I would like to keep the bus definition in the subsystem callback because I actually use a mask that generates automatically everything in the subsystem (including the matlab function, bus definition etc...). It would be harder to have this mask updating a separate file, in common with many other blocks, used by multiple matlab users...

What I don't get is that the bus definition is present in the matlab workspace, so it should be accessible at anytime...

Anyway, I have just tried to run the bus definition prior model opening, (i removed the InitFcn and LoadFcn) and I get exactly the same warning... As if the serach function does not look for bus definition..

[Jonas]

I am using 2020b.

Which steps are you taking exactly to 'use the search' function?

1. Just open the model, and press ctrl+f to search for text? Which text do you enter?
2. Or do you use the search function in the Model Explorer? If so, what search query do you use?

[deRicaud]

Hi,

I'm using the first option, and I enter 'test' (without the apostrophes)

[Jonas]

Wait, I do get the warning in the Command Window. The search itself is probably just working quickly because it is a small model.

[deRicaud]

Ha sorry, I forgot to mention that the warning is in the command window. So as you can see it is not much of a problem in this example, but when you multiply this by the number of recursion I have in my model, you end up with a long time for warning displaying, and a command window that grows to hundreds of thousands lines...