The Wavedac component is created using a VDAC component and a DMA block. The 8 bit VDAC can take values from 0 to FF(255) which will be passed with the help of the DMA clocked at the rate your require. This is how the waveform is generated. I hope this explains what is the significance of the values you give. You have an option to draw the waveform you need in the component.
Thanks a lot, VSRS!
That was really helpful.