Hi St Augustine, This depends on the precision of your square wave and the frequency of the square wave. If the frequency and precision is low, then you can use the digital I/O on the board and control it directly through the NI-DAQ driver.
If you require precision and high frequency, you can use the onboard counters to generate a pulse train. You will then be able to vary the frequency of the pulse trains using a command called "switch cycle" which effectively changes the counter parameters controlling the frequency of the counter. There are several examples of switch cycle depending on your application development environment. How Do I Change The Frequency Output Of My Pulse Train On The Fly? http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/7b1b0427c39fe33086256cee00752133?OpenDocument Hope that helps. Have a good day. Ron
