delay in Simulink Matlab function block

Hi,

I want to do something very simple, but since I've failed to find a way, I turn to you :-)

I use a Matlab function block in a Simulink model.

I have an input (PumpOn) which switches on, and off (0-1) When it switches on, I want to wait (delay), then change the output to AirExDCInvO2.

I want to keep that output for the same time (delay), then set the output back to zero.

The time I want to wait, is simulated time, not real time.

The model should keep simulating, while the delay is active.

I have tried to use pause, but I think it only pauses simulation. I have tried a timer, but timer is not supported in the Matlab fcn code generation.

The code from the matlab function block is shown below.

Thanks for reading :-)

Hans

function y = InvalidO2Control(PumpOn, delay, AirExDCInvO2)

y = 0;

if PumpOn == 1 %pump is switched on

pause(delay) % Let the pump run for a while, before doing anything

y = AirExDCInvO2; % set the output (open valve)

pause(delay) % let the valve be open for a while, while pump is still running

y = 0; % close the valve ( pump continues to run)

end

end

Answer 1

[Fangjun Jiang]

It looks like the Delay block in Simulink could meet your need.

[Hans Jensen]

Hi,

I am not sure, that I can. The delay has to be executed inside the Matlab fcn block.

I have added some comments to the code above, so you can see what I want to do.

[Fangjun Jiang]

Keep in mind that MATLAB Function block is just like any other Simulink block. It is running at every simulation step. What you need is to have a persistent variable to serve as the timer/counter and then decide the output based on the timer/counter value.

[Fangjun Jiang]

Or, if you have the Stateflow toolbox, use absolute time temporal logic

web(fullfile(docroot, 'stateflow/examples/using-absolute-time-temporal-logic.html'))