PCI 6602 support in NI-DAQ 7.0 buggy ?

[josswern]

after having managed to do buffered period measurment
with 2 counters on a PCI6602 (see http://exchange.ni.com/servlet/Redirect?id=10279483 )
it seems to be impossible to do the same with 3,4 or more counters of this board.
mostly, the program causes error -10455 (no DMA available) and subsequently causes a GPF, or even crashes the whole system (win2000).
now I wonder if this is a general problem due to DMA limitations, or specific to NI-DAQ 7.0 together with this board ?
thanks
werner

[josswern]

ok, just to answer my own question 😉 - this is what I found out by trial&error and RTFM, respectively:
- DMA works for up to 3 counters simultaneously, at up to 400 KHz/counter
- more than 3 counters only work in interrupt mode, up to 8..10 KHz/counter, depending on # of counters.
this applies to a 1 GHz pentium, running win2000.