Hello,
In order to measure the distance between 2 pulses with Scope, you will need to measure both signals and then take the time delay between the 2 channels. We actually have an example in the example Finder that allows you to take this measurement and it is called niScope EX Measurement Library.vi. In this VI, it uses the scope function of reading several different types of measurements which include Time delay. Along with this, the block diagram explains how it implements this code and I would highly suggest walking through the code to understand it better.
Jim St
National Instruments
RF Product Support Engineer