The 5610 and the 5600 come with their respective Arbitrary waveform generators and digitizers. The 5610 with the 5441 for example is a package called the PXI-5671. The 5661 is the 5600 with a 5142. Do you have the generator and the digitizer? Also, these products are for radio frequency, all the way up to 2.7 Ghz. In order to output digital pulses you would need to modulate those pulses and output them on the upconverter, downconvert them and then demodulate them on the downconvertor again.
National Instruments provides a toolkit called the Modulation toolkit. If you have the modulation toolkit there are plenty of examples that you can use. There are plenty of digital modulation schemes, FSK being one of those. If you go to C:\Program Files\National Instruments\LabVIEW 8.5\examples\Modulation\RFSG examples, you should see an FSK example in there and you can modulate your digital signal the way you want to.
Hope that helps.
Regards,
Raajit L
National Instruments
