If Dennis has already answered your question, than you can disregard
this message. I got the sense that your question wasn't about the
"sample-and-hold" circuitry built into DAQ cards capable of
simultaneous sampling, but actually was a software question about
tracking and holding peak (or maximum) values that are coming in
through an analog input. If this is the case, please provide a little
more information about your program, and I'm sure we can help you out.
Chris