How to send any type of parameters in update-function to output-function in simulink s-function?

I try to show 'ax' in output, so I send 'ax' to output by adding it to the state vector 'x'.

But, it is not a good idea when the size of 'ax' vector is increasing. It will increase computation time because dim. of state increases.

global 'ax' doesn't work at all.

any suggestions?

function sys=mdlUpdate(t,x,u)

dt = 0.01;

Td = u;

% Numerical Integration

x_prev = x(1);

x(1) = x(1) + Td*dt; % Euler integration

ax = (x(1)-x_prev)/dt;

x(2) = ax;

sys = [x(1) x(2)];

function sys=mdlOutputs(t,x,u)

ax = x(2);

sys = [x(1) ax];

Answer 1

[Pavan Sahith]

Hello,

I understand you are trying to pass a parameter ‘ax’ in the update function to output function of the Simulink S-function block.

As a workaround you can try “ssSetUserData” and “ssGetUserData” functions which uses the S-function’s user data.

Please refer to this sample code to understand the use of “ssSetUserData” and “ssGetUserData” function.

%In update-function you can use these 
% Retrieve 'ax' from the userdata field 
% ‘gcb’- get current block.    
userdata = ssGetUserData(gcb);  % Get user data 
ax = userdata.ax;  % Access 'ax' from the user data 

% Update 'ax' in the user data 
userdata.ax = ax;  % Update 'ax' in user data 
ssSetUserData(gcb, userdata);  % Set user data 

% sample output-function can be like this   
function sys = mdlOutputs(t, x, u) 
    % Retrieve 'ax' from the userdata field 
    userdata = ssGetUserData(gcb);  % Get user data 
    ax = userdata.ax;  % Access 'ax' from the user data 
    sys = [x(1); ax];
end

Please refer to the MathWorks documentation links to know more about

“ssSetUserData” - https://in.mathworks.com/help/simulink/sfg/sssetuserdata.html

“ssGetUserData” -https://in.mathworks.com/help/simulink/sfg/ssgetuserdata.html

Hope it helps.