Bring the text file into excel and add a third column for z and fill it with zero's and save back out as a text file, then you can insert a curve thru xyz points using the text file.

I want to do is to animate a plotting curve, like the curves in Matlab. Or curves with y-t coordinate similar to the curves in Solidworks simulation module.

This kind of curve does not look like what I want, I need curves in terms of t function.

How about Excel file which can be read in to SW

otherwise, you need a macro to read the txt file