get Peak amplitude of variable sine wave

Hello,

I am trying to get the peak amplitude of variable sine wave (varied from peak 310 to 150 )in matlab simulinjk using MinMax Running Resettable block but the output of this block is always 310 without any sense of the reduction of the amplitude during running time. Please can you help me in this problem or give me another way to detect the peak of variable sine wave amplitude in Matlab simulink.

Thank you

George