Dear Customer,
For continous data acquisitions, we can find lots of example in LabVIEW
i.e. Cont. Acq&Graph Voltage-Int Clk.vi from NI example finder
For finite data acquisitions, it depends on how you design your program
i.e. Acquisitions will be take twice a second, you may ask user inputing how long should the acquisition running (60 seconds)
then you will get the # of samples, and you design a while loop which may loop twice a second, and stop after 120 iterations.
With Case structure of LabVIEW, you can swtich the 2 modes with a Boolean control on front panel.
-ChinaSupport
John L.