has some good suggestions.
Note that any time you import data but not as a time series, then it has to effectively be constant data, such as for a constant block or as initialization for a memory block.
If you are thinking in terms of "Well, first row the first time, second row the second time", then you are thinking of discrete simulation instead of continuous simulation, and if you are doing that, then you might as well do a timeseries in which the first column is the discrete step times.
