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ai acquisition external trigger rate in windows 2000/xp

I'm doing repetitive measurements of the type described in the nidaq example DAQsingleBufExtTrig.C:

iStatus = DAQ_Rate(dSampRate, iUnits, &iSampTB, &uSampInt);
iStatus = DAQ_Start(iDevice, iChan, iGain, piBuffer, ulCount, iSampTB, uSampInt);
while ((iDAQstopped != 1) && (iStatus == 0))
iStatus = DAQ_Check(iDevice, &iDAQstopped, &ulRetrieved);

When using a 100 Hz external trigger, the above code can be repeated at nearly 100 Hz on our various ni hardware (PCI E-series and a DAQCard-1200) under windows 95/98/me, using appropriate parameters. Under Windows 2000 but otherwise identical conditions, the best rep rate I can do is in the low 40s. I wouldn't have been too surprised if the roles of (2000/xp)
and (9x/me) were switched, but as it is I don't know why this is happening. Any ideas are welcome.
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Hello;

As you are reconfigure the hardware at each end of the buffer, you will become system dependent. The maximum speed that you can go will vary from machine to machine even.

The way to go about that, is to set up a retriggerable Analog Input operation, which is hardware controlled. By doing that, you will become completely system independent, and will be able to run your application in any sort of machine/OS.

I'm attaching a ANSI C example that does the trick.
Hope this helps.
Filipe A.
Applications Engineer
National Instruments
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Thanks for your response. I am already aware of the "SimulateRetriggerScan_Eseries" code, and maybe that would solve the problem of being able to acquire every single trigger regardless of machine/OS. It isn't an option in this specific case, as there are actually many more data input/output operations than just this one. Perhaps this should have been mentioned in the beginning, but I was trying to simplify the statement of the problem. In any case, my requirements are not so stringent as to require every acquisition.

I'm trying to find the minimum time required to do the hardware configuration, and I want to know why, on a given machine, it is smaller in Windows 98 than in Windows 2000/xp.
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