Hi there,
I just realized there's probably a much more straightforward way to do this. In the Control Design & Simulation palette in LabVIEW there is a ramp signal VI. It's under Simulation >> Signal Generation >> Ramp Signal. Since you should have a solid knowledge of the rate your loop is running at you should be able to do some math to set the slope to ramp up at the rate you desire. Do you think that will work for you?