I want to control the switching on and off of an LED with a digital output, and this by generating a rectangular signal in this output to control the duration of the high state and the low state and the period.
And what is your exact question? As you have probably seen from the other posts on this subject, the dio is software timed so you can only write true/false values to the DAQmx Write with wait statements to control the duration.
As noted above you can only do software timed Digital Output with USB-6008. Frequency and control of digital output is done based on your call of DAQmx Write vi.
