Hello Om,
The RFSA Acquire IQ Data in Blocks VI uses the RFSA driver not the 5660 driver. The RFSA VIs require the 5661 = 5600 and 5142. Both of these devices are DAQmx devices. However the 5660 = 5600 and 5620, where the 5620 is only a Traditional DAQ device. You only have to associate a digitizer with the 5600 if you use it with the 5142 and the RFSG driver. The behavior you are seeing is expected.
All of the examples you can run will start with ni5660 and perhaps the ni5660 Fetch IQ Data will work for you.
Regards,
Jesse O.
Applications Engineering
National Instruments
Jesse O. | National Instruments R&D