Execute subsystem in Simulink if condition is met for 5 seconds?

I have a subsystem that I want executed in Simulink when a variable, RC_flag, is equal to 0 for 5 seconds. I have RC_flag updating at each Simulink time step, and I have Elapsed Real Time block to output the elapsed real time since the start of the simulation (different than the Simulink time step). How do I combine these two variables to execute my subsystem when RC_flag = 0 for 5 seconds?

Answer 1

[Fangjun Jiang]

Do an equal comparison (==) between RC_flag and zero, generate this int_flag. Feed int_flag to an Integrator. If the output of the Integrator is greater than 5, then execute the subsystem.

Enable the external reset of the Integrator block. Use the int_flag and specify "falling" edge to reset the Integrator. Any change of the int_flag during the 5 seconds will reset the Integrator block.

[Andrew Poissant]

Works like a charm, great idea!

[Alberto Boñal Bravo]

Hi Fangjun, what do you mean by specifying falling edge to reset the integrator? How do you that? Thank you!

[Fangjun Jiang]

double click the Integrator block to open the dialog. You will see the option.

[Alberto Boñal Bravo]

Thank you!