I want to store my encorder rpm values as my test data to do parameter optimization, in 0.001 descreate time. Any one who can explain the procedure?

As in this video.

https://in.mathworks.com/videos/estimating-dc-motor-parameters-97057.html

Here, it is loading some test data how can I take those test data using an encoder. I can get the encoder readings. But how can i store the data in 0.001s.