code: def p24_pulse_train(n_samples=100):
      
      samples = (np.arange(n_samples, dtype="uint32") % 2)*(2**24)
      samples[-1] = 0
      DigitalOutputTask("Dev1/port0/line24", samples).StartAndWait()
docs: Sends a pulse train of on-off in Dev1/port0/line24.
  
      This function creates a task, starts it and waits until it is over.
      Uses expt_settings.external_clock_line as a clock.
  
      n_samples - number of on off samples.