Why Root-Level Inport didn't inherit the sample time?

Hi guys,

I want to build a fixed-step discrete time model, which will be referenced later in a larger model. To simplify the issue, let's say it's just a direct-through, including only one input port connected to one output port.

Because the model doesn't restricted to any specific sample time, I set the solver pane as following.

Before I actually reference it to the real larger model, I want to do a quick test using base workspace variables. Here is the settings of the Data Import/Export pane.

And here is how I constructed my test signal.

    t = (0 : 0.1 : 10)';
    u = rand(size(t));

After I ran the model, I found that the output signal y has fewer samples than the input signal x. This is due to the fact that it has a default sample time (0.2).

 >> whos
   Name        Size            Bytes  Class     Attributes

   t         101x1               808  double              
   u         101x1               808  double              
   y          51x1               408  double

How can I make the model inherit the sample time of the external test signal correctly?

Thanks!