Steve,
With a 60Hz trigger you will have 16.67 milliseconds to complete your analog output operation of 100 points. What is probably happening is these 100 points are taking longer than this amount of time and the output operation is not completed in time to be set up to receive the next trigger.
Normally 100 points would not be a problem; however, I cannot verify this with LabVIEW 5.1 because I don't have it installed as it is quite an older version. We are currently up to version 7.0 and a number of significant improvements have been made to both LabVIEW and our new NI-DAQ 7.0 driver. Especially in regard to retriggerable operations in NI-DAQ 7.0 which has made it incredibly easy.
I found the retriggerable_AO_easy_5.vi you are referring to on
our website. This is the first time I have seen this particular example for a retriggerable operation and not what I would expect. Placing AO Start in the while loop, as well as AO Wait, will slow down the loop and is probably the reason you are being limited to a low number of samples. I would definitely recommend, at the very least, the advanced example if you wish to exceed 100 points per cycle. In order to run the advanced example you will probably have to upgrade your NI-DAQ driver. Try version 6.9.3. However, I would definitely recommend an upgrade to LabVIEW 7.0 and NI-DAQ 7.0.
Regards,
Justin Britten
Applications Engineer
National Instruments
