how to stop pattern search simulation?

Hello, im trying to tune PID parameters that control frequency response in two area system (Power system) using pattern search method. my objective function was an m file using sim command that calls simulink file. once main file is simulated, the simulation takes place perfectly. but it doesnt seems to stop. i used default options only. im not sure which option to change for stopping the simulation. please help me.

[Ibrahim Cukdar]

Can you send the M file with the objective function