I want to apply an input (ramp) voltage which varies from 0 - 30 V to Schmitt Trigger and I want to get an output voltage from 0 - 30V.
Furthermore I want to have low threshold voltage at 0 V and high threshold voltage at 30 V.
Can someone help/guide me in this regard?
What is the highest output provided by the Schmitt Trigger?
Schmidt triggers don't work like that. Their most important difference from other circuits is that their threshold voltage is NOT zero. That's why I can't tell you how to get a Schmidt trigger to trigger at zero volts.