Can I control Simulink's simulation interval?

Can I control Simulink's simulation interval? I thought it would be set by the sample time in the model parameters, (i.e.), Solver: [Type = Fixed step, Solver = discrete (no continuous states), Fixed step size]. But it appears to be completely independent, (as seen by the output of the Clock block).

I am doing sample by sample processing and do not need the higher rate of the simulation interval.

[Kaustubha Govind]

I'm not sure I understand your question. Could you elaborate on do not need the higher rate of the simulation interval". What is the selected fixed-step size, and what is the Clock showing you?

[cr]

From what I understand, you mean to say you see simulation step sizes to be different from what you set them to be for a fixed step discrete solver. Thats weird, attach your model for inspection.