# Multifunction DAQ

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## PXI-4462 sample rate set

Hi!

How can I determine available sample rate for this board? What mean "181.9 uS/s increment" in the datasheet?

Jury

Message 1 of 9
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## Re: PXI-4462 sample rate set

Hi Jury,

I'm assuming you're looking at the 4462 spec sheet?

Your available sample rates range from 1 kS/s to 204.8 kS/s.  181.1 uS/s is the smallest amount you can increment your sample rate.

Thanks for the question,

Lisa

Applications Engineer
National Instruments
Message 2 of 9
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## Re: PXI-4462 sample rate set

Hi Lisa!

If 181.9 uS/s mean that available sample rate is:

1000 Hz

1181.9 Hz

1363.8 Hz

... and so on.

Jury

Message 3 of 9
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## Re: PXI-4462 sample rate set

Hi Jury,

The 181.9 uS/s means 181.9 microSamples/second.  Thus, your available rates are [1000, 1.0001819, 1.0003638...] Hz.

Thanks,

Lisa

Applications Engineer
National Instruments
Message 4 of 9
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## Re: PXI-4462 sample rate set

Hi Lisa!

Is the value 1 kHz and 181.9 microSamples/second precise?

We planed to use PXI-6653 10 MHz oscillator, disciplined by the PXI-6682 GPS for precise time sync. I must know perecise SampleRate if I want to calculate time of the Sample as [SampleNumber]/[SampleRate] with GPS accuracy for long-time record (about 10^4 and more seconds).

Can you say me, how can I calculate the increment of 181.9 microSample/second?

Usually, the sample rate can be obtained as some inner frequency divided on the integer number.

Jury

Message 5 of 9
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## Re: PXI-4462 sample rate set

Hello Jury,

Please find this information in the general DSA manual under Timing and Synchronization, then Sample Rate and Update Rate, Accuracy and Coercion.

Calculating the coerced rate depends a lot on your individual system set up.

Feel free to let me know if you have any specific questions.

Lisa

Applications Engineer
National Instruments
Message 6 of 9
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## Re: PXI-4462 sample rate set

Hi Lisa,

Did you manage to configure and test the system?

I also would like to obtain precise disciplined clock using PXI-6653 and PXI-6682. I was wondering if you could give me some guidelines about timing and synchronization aspects in LabVIEW. I know right now how to configure the DSAs using DAQmx and how to trigger DSAs using niSync however it is of great unknown how to route the signals between PXI-6682 and PXI-6653 and how to send the timebase from PXI-6653 to DSAs via backplane. I have PXI-4495 as well as 4472 in two different chassis. I also started a separated topic here since this seems to be quite complex issue.

--

Łukasz

Message 7 of 9
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## Re: PXI-4462 sample rate set

lukko,

TylerK provided some great advice in your other thread regarding clock disciplining your multiple remote chassis.  However, you may not actually be able to synchronize your PXI-4495 with your PXI-4472 in one chassis.  The PXI-4472 only supports synchronization by sharing the oversample clock over the backplane PXI star trigger lines.  In your case this would be generated via DDS on the PXI-6653 and routed to the star trigger lines.  The PXI-4495 doesn't have star trigger lines available because it is a hybrid-slot compatible module.  PXI-4495 modules are synchronized by sharing the 10 MHz backplane clock and generating their own oversample clock on board via DDS with a 100 MHz crystal oscillator.  You can still trigger the acquisition from the two cards together, but you may not be able to discipline the clocks together in a single chassis.

Regards,

Jared R.
Precision DC Product Support Engineer
National Instruments
Message 8 of 9
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Hi Jared,