waveform data is a 2D array containing all information about a waveform's pulses and c-bits to be sent to the generator. This data structure is partially used in the full data clusters. channel data is the value that controls to which channels the waveform should be sent. waveform string returns the translated bit stream ready for sending to the generator.
you should normally have no need to use this VI directly, as it is called by higher level VIs.