There?s a great <a href="http://digital.ni.com/public.nsf/allkb/4D1435DF82EF494186256D8A006DD6D4?OpenDocument" target="_blank"> KnowledgeBase (KB)</a> that covers the explanation
in more depth, but basically the sample clock (scan clock) is controlling the time
between one sample on channel 0 and the next sample on channel 0, regardless of
how many channels you?re sampling on. The convert clock (channel clock) is a clock
that is responsible for latching every sample of every channel, so it will be
faster than the sample clock for multiple channels. The diagram in the KB above should help make sense of the
two. Feel free to post back to the community if you have further questions.