First, t is a counting engine which generate values from 0 to 1. This is what the help says about t: A curve equation is defined in terms of the parameter " t ". ?" t " varies from 0 to 1. ? The variables (x, y z) or (r, theta, z) or (rho, theta, phi) should be defined in terms of the " t " parameter. ? As the " t " parameter continuously varies from 0 to 1, output values obtained from x, y and z variables are plotted to create the output curve shape.
The relations editor which opens for curve from equation creation also gives some examples, the heart of which is picking the right coordinate system, Cartesian, Cylindrical or Spherical with the appropriate units. The following is an example of a sine wave equation based on a Cartesian CS: X = T*P (Where P is the Period); Y=A*SIN*(360*T) (Where A is the Amplitude).
*Also see the Relations Chapter in the Fundamentals Guide for a listing of all mathematical functions. And you need to set up values for P and A earlier in the relations section before stating the equation.
As far as SV and EV are concerned, this is probably in the context of the equation. So, in the above example for the value of Y where t*360 is a full circle of the sine wave, it starts by default at 0 and ends at 0. If you wrote it t*270, it would start at 0 and end at 270. So, specifying end values might be a way of getting it to start at 90 and end at 360 or 540 or any other non-default start and end points. A little Algebra should get you the answers to the rest of your questions.
I'm new to Creo, but used Pro/E back in Ver. 20 and some WF releases.
I have a defined model PARameter and would like to use it as an end value for the variable 't' when creating a Datum Curve by Equation.
Before I would set the range with 0