gated DAQ

[S.Klumpp]

Dear all,
I have a TTL-Pulse that indicates that the voltage on my analog input channels are valid signals.
I like to configure my PCI-6024E DAQ-Board in the way that it only aquires Data when the TTL-Signal is high!
Because I can't filter the signals in the PC because of the great amount of pulses (app. 500-3000) per second. LabVIEW is too slow for this.
My questions are:
1.) Is the PCI-6024E even capable of this or do I need a more advanced DAQ-Board (which one?)?
2.) Is there a possiblity in LabVIEW to filter approximately 200000 datapoints per second without overrun of the PCI-6024E-Buffer ?

Thanks for your help in advance !!

Stephan

[Filipe A.]

Hello;

See the answer for both of your questions:

1) The board you have there is capable of doing that task. You just need to configure the DAQ task to do a digital triggered Analog Input task. You can even find an example on how to do that in Labview at Search Examples->I/O Interfaces->Data Acquisition->Triggered Acquisition.

2) You can set the AI Read to read that many points, and use the array created as the filter input. That will speed things up, however, the time the filter will execute is system dependent, meaning that we can precise how long it would take.

Hope this helps.
Filipe A.
Applications Engineer
National Instruments

[S.Klumpp]

Hi Filipe,

thank you for your answer!
I figured out how I can gate my siganl with a digital gate! I'm using a TTL-Signal on PFI0 which is high for 10 microseconds. During this time I have two valid Signals on two analog channels (ACH0 and ACH1). So far I can aquire the Signal on ACH0 correct, but for the Signal on ACH1 the board is to slow to get the Siganl right.
So far I'm using the "Clock Config.VI" with a sample rate of 200k per second. I tried 400k and more, also, and signal improves but it is far from good.
Well, I don't think this is good for the DAQ-Board, because it is not made for this sample rate.
What do you mean with filtering the input with the array?
I'm using a multithreadtred programm on a dual-pentium III 550MHz machine! But if I
try to compare every value of the TTL-Signal (if I aquire it on analog channel) if it is higher than a given value, then LabView slows down and my buffer overruns and overwrites values.
Is there a better method than using "greater as" function with case-knote ?

Thank you for your reply in advance!

Stephan