How to change the amplitude of the block Sin wave function during different instants within a simulation?

Hi,

I need to use the sin wave function block, but I need to set diferents amplitudes over the simulation time. Let's see...for the first 50 seconds of simulation I need an amplitude (variable "dp") of 1000, then when the simulation reach the 200 seconds I need an amplitude of 2000 for example. How can I manage to update this value during the simulation since it's not coming from a input port?