How do I export a vector to workspace in simulink?

I'm trying to model a household appliance in simulink. When the simulation ends, I need the model to output a vector to the workspace which contains power loads corresponding to simulation times. I've started with trying to implement as simple a model as I can, shown below.

The idea here is to just send simulation time to a function which appends the simulation time to a vector containing all simulation times. Basically, if the simulation stop time is 10, what I want from this model is AllTimes = [1, 2, 3, ... 10].

I've set the model to run an initialization function, which contains the following:

times = [];

The MATLAB function block contains the following:

function times = fcn(currentTime)
   times = [times, currentTime];
times = time;

Simulink complains that:

The issue, as I understand it, is that "time" is declared outside fcn's scope. I've tried the following tweaks to fix this:

function times = fcn(currentTime)
    if ~exist('vect')
        vect = [];
    end
times = currentTime;

function times = fcn(currentTime)
    times = evalin('base', [times, currentTime]);
times = currentTime;

function times = fcn(currentTime)
    assignin('base', times, [times, currentTime])
times = currentTime;

However, none of these have worked.

I also tried importing the function times from the workspace and passing it as an argument to fcn, like so:

function times = fcn(currentTime, times)
    
    times = [times, currentTime];

times = currentTime;

However, this throws the error:

Unfortunately, I have very limited knowledge of MATLAB and even less knowledge of simulink. If anyone has any advice I would very much appreciate help.

[Jim Riggs]

In this second example, I think that the problem may simply be that the output signal "times" has the same name as one of the input signals. Try changing the name of one of these

[Shiloh Greer]

Trying that gave the same bus error as before. Here's my new implementation:

function times = fcn(currentTime, previousTimes)
    
    previousTimes = allTimes;
    
    times = [previousTimes, currentTime];

times = [currentTime, previousTimes];

The InitFcn initializes previousTimes to be an empty vector.

[Jim Riggs]

Your implementation is very confusing to me.

The variable "allTimes" is not defined inside this funtion, and I don't understand what you are trying to accomplish with this statement. Assuming that "previousTimes" is a 1D array (double) and "currentTime" is a scalar double, then the Mux should work.

Inside your function block, it should be a simple as:

function times = fcn(currentTime, previousTimes)
     times = [curentTime, previousTimes];
end

[Shiloh Greer]

I just discovered that exactly what I'm trying to achieve can be done by using the "To Workspace" block and having it export an array. I have switched to that implementation, and have gotten what I needed from it.

Thank you for your help, Jim. I appreciate you being willing to help me out.

[Jim Riggs]

Oops. I was assuming that the block in your diagram with the label "Alltimes" was a "to Workspace" block and that you were simply trying to constuct the desired output vector.

In the future, select all of your blocks, then select "Format / Show Block Name" before you capture screenshots.

Answer 1

[Jim Riggs]

It'a actually very easy. Simulink has a block for combining two signals, called a "mux" block.

Simply combine the two signals together, like so:

[Shiloh Greer]

Hello Jim,

When I try using your solution I get the same error as the last one I put up a screenshot of. Does it matter that the times variable is a vector, and that we're combining a scalar signal with a vector signal?

[Jim Riggs]

The two signals have to be the same type and compatible shape.

You can use a "Data type convert" block to change the type of one signal, and there is a "reshape" block if you need to change the shape.

For more complex shapes (2D or more), you may need to use use a "Vector concatenate" block in place of the Mux.