Ramana,
National Instruments has an example available in the Developer Zone for the creation of a Swept Sine Wave in LabVIEW. I have attached the example below. You should be able to combine this example with either Gen Mult Volt Updates-Int Clk.vi (NI-DAQmx) or Generate N Updates.vi (Traditional NI-DAQ), both of which are available in LabVIEW (Gen Mult Volt Updates-Int Clk.vi is not available in LabVIEW 6.1 or earlier), to accomplish your task.
Good luck with your application.
Spencer S.
