Hi Hoat Le,
The Buffer Selector is used to select the signal data associated with a specified iteration in a series of iterations.
The parameter Selection is set by default to 0 (the indexing for iterations starts at 0). If the parameter Selection is set to Iterations – 1 (using Script mode) the component will forward the signal data associated with the final iteration of the series. For example if Iterations = 5 (within Layout Parameters/Signals), the Buffer Selector will forward the signal data associated with the 5th iteration of the CW laser.