HW triggered buffered event counting sync/async

[Vlad_R]

I am using 6602 board to do buffered event counting. The counting is HW triggered from RTSI bus to sync with other operations. I encountered a wierd problem: the whole operation is held up until the first event occurs. So instead of being sync'ed to the rest of the operations the event counting is sync'ed to the first event. Not only that, if there were no events, it will report -10920 at the end of the operation as if the event rate was too high, while in fact it was too low(zero). If I use synchronous counting, there is no problem, but I do not really want to use it since the events are coming in bursts and the rate may exceed the 1/4 of the max timebase.

I am using NI-DAQ 6.9.3 and VC++ 6 under Win95.

[Sarah Thompson]

Vlad R,
Take a look at this KnowledgeBase entry. It gives some troubleshooting ideas about the -10920 error you are receiving.

http://digital.ni.com/public.nsf/websearch/8FB9091CB9BB452B8525642000554799?OpenDocument

Have a great day!

[Vlad_R]

I did read it, but I think it doesn't apply here. The article describes the situation when there are so many samples to be recorded that it overloads the card-to-memory channel. In my case this data rate depends on the gate signal. My gate signal is the same in both sync and async mode, but the results are quite different. Plus, I do not understand how I can overload the memory channel when there is a total of zero samples recorded.