That is confusing. You say you need to input 2 sine waves into a 6009 and that to me implies that you are doing a DAQmx Read. Then you say you have a voltmeter to read the output. That implies you are doing a DAQmx Write. If you are really doing a write from the 6009, then on demand is, of course your only choice. As the specs clearly indicate, the output of the 6009 is strictly software timed so you would need to pass a sine wave point by point and then you would have very little control over the frequency. And, again as the specs clearly state, the fastest output rate you could expect is 150Samples/sec.
