How to control simulink executing plural steps by matlab script ?

Hi there, My simulink model need to be paused several times during the simulation for some external commands. I want to execute the model programmatically. "set_param("",SimulationCommand, 'step')" seems can be a solution. But I want to move plural steps, how to realise it with matlab script? As the step has an optimal value, so I can't change the step's value. For ex. step is 0.02s, the model should be paused each 30s then be resumed. Thanks a lot.