Change C-script's parameters during simulation. It doesn't work

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1

Hi everyone!

I have built a generic discrete transfer function in a C-script.

This is the code:

Code declaration:

define u Input(0)

define y Output(0)

define a ParamRealData(0,0)

define b ParamRealData(1,0)

define c ParamRealData(2,0)

define alpha ParamRealData(3,0)

define beta ParamRealData(4,0)

define gamma ParamRealData(5,0)

define K ParamRealData(6,0)

define reset_value ParamRealData(7,0)

define UL Input(1)

define LL Input(2)

define reset Input(3)

double u_prev_1,u_prev_2,y_prev_1,y_prev_2,y_unsat;

Start function:

y=0;

y_prev_1=0;

y_prev_2=0;

u_prev_1=0;

u_prev_2=0;

Output function:

if (reset==0)

{

y_unsat=-(b/a)*y_prev_1-(c/a)y_prev_2+(K/a)((alpha)*u+(beta)u_prev_1+gammau_prev_2);

if (y_unsat < LL)

y = LL;

else if (y_unsat > UL)

y = UL;

else

y=y_unsat;

}

else

{

y=(reset_value/100)*LL;

}

Output(1)=K;

Update function:

y_prev_2=y_prev_1;

u_prev_2=u_prev_1;

y_prev_1=y;

u_prev_1=u;

Basically, it converts a 2nd order discrete transfer function in a Linear difference equation.

I write the parameters in the block mask and the C-script has a discrete sample time. (500e-6s)

I would like to change the gain K during simulation but I noticed that it doesn’t change at all!

Is it possible? How can I solve ?

Thank you everyone!

2

The parameters of a C-Script are not tunable, i.e. cannot be changed during a simulation. You can tell this by the fact that the parameter fields in the dialog are greyed out while a simulation is running.

If you want to change a variable during a simulation, you need to feed it into the C-Script as an input signal.

3

Thank you very much!

I’m solving in the way you suggest… It works!