Samples to read and Rate (Hz) USB 6009

[Saille]

Hi everyone, and sorry because my english is not very good.

I’m running tests waveforms charge and discharge of a capacitor, and I want to collect data for a week without interruptions.

How do I define: Samples to ReadandRate (Hz)?

Thanks

[crossrulz]

Rate is how often you want to take a sample.  This is only valid when you are NOT using single sample acquisitions (ie, reading continuously or N samples).  The units are really Samples/second.  So by setting the rate to 1000, you will take 1000 samples every second, or 1 sample every 1ms.

Samples to Read on the DAQmx Read is simple how many samples you want to get from the DAQ buffer.

[Saille]

Thank  crossrulz..

butfor my test, what is the best value for a long time? 1000?

Thank very much

[johnsold]

I have used the USB-6009 for long term tests (battery discharge) lasting more than a month.

The rate depends on how fast you need to get data. if one charge/discharge cycle takes an hour, taking readings once every ten seconds is probably fast enough. If a charge/discharge cycle lasts 10 ms, then 1 kHz is probably too slow.

Most important is to be sure that all the power saving options that the OS might use to shut down the USB port are disabled. Next most important is to read and save the data fast enough that you do not get any buffer overflow errors. 

But we cannot give you specific answers on the sample rate because we do not know the timing of your charge/discharge cycle.

Lynn

[Saille]

Thank you very much.. jonhsond

Thank you very much.. crossrulz