How to send one array element at a time to a subsystem every 0.5 seconds in Simulink?

Hi all, I'm working on a Simulink model where a MATLAB Function block outputs an array of control commands (the command array is generated once at the start of simulation). I’d like to send one command at a time from this array to a subsystem input, with a rate of 2 Hz (i.e., one value every 0.5 seconds).

What’s the best way to implement this?

Thanks in advance!

[Mathieu NOE]

Unbuffer

[Ben Navon]

@Mathieu NOE I'm getting this error from the Unbuffer block:

Error:Error in 'go2_pp/Unbuffer': All sample times must be discrete. No continuous or constant sample times are allowed.

[Mathieu NOE]

as it says , you can only use this block with fixed sampling rates

Answer 1

[Fangjun Jiang]

Nothing special. Use a Counter block (free-running or limited) in combination with the model solver setting to provide the step (every 0.5 second). Feed it to this function.

function y = fcn(u)
persistent cmd
N=10;
if isempty(cmd)
    cmd=zeros(N,1);
end
if u==0
    cmd=10*(1:N);
    y=0;
elseif u>=N
    y=cmd(N);
else
    y=cmd(u);
end
end

[Ben Navon]

Thanks for your response! I'm not sure I fully understand the architecture you're recommending.

What exactly should I feed into your function? Where should the function's output be connected?

For context, here is my current model:

• The MATLAB Function block (which generates the commands vector) is inside an Enabled Subsystem.
• I'm using a Counter block with a 0.5 [s] sample time (default 16-bit).
• The Rate Transition block has its output port sample time set to 0.5 [s].
• My simulation duration is 60 seconds.

Model solver settings:

Also, I'm getting this error from the Unbuffer block:

Error:Error in 'go2_pp/Unbuffer': All sample times must be discrete. No continuous or constant sample times are allowed.

[Fangjun Jiang]

Feed the Counter block to the MATLAB Function block input.

The function output is the "one array element at a time".