Rich,
The other option from National Instruments is to get separate low-cost E series boards. However, they do not have all the bells and whistles of the Arb boards, such as the NI 5401. Both can handle an external update clock, which is one method of handling retriggering. This method involves using a counter to wait for a trigger, and then generate a pulse train that would act as the update clock. However, the 5401 can handle retriggering in other ways, whereas that is the only way for precise timing with an E series board. In addition, the 5401 can give you smooth waveforms without the glitches that an E series board could possibly have when changing waveforms, as the specifications note. Also, the 5401 allows for creating staging lists for the wavef
orms and smooth frequency hops and sweeps.
You can find out more about these boards in the http://www.ni.com/catalog pages or the http://www.ni.com/support pages.
Regards,
Geneva L.
Applications Engineer
National Instruments
http://www.ni.com/support
