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Response Time PS 4224

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Response Time PS 4224

Postby Armin_T. » Tue Mar 29, 2011 10:55 am

Hello,

I am using PicoScope 4224 with LabView10 to measure and record short pulses. The record length of each pulse is 10 µs and the Samplerate is 10 MSamples/s.
I am using rapid block mode and tried different numbers of captures before sending them to the PC.
I managed to get a record without skipped pulses up to a pulse-repetitionrate of approx. 30Hz. Above this frequency some pulses are skipped. I would like to record these pulses up to a repetition rate of 400Hz.
In my opionion they are skipped, because LabView is still waiting for the scope-data of the pulse before. I also figured out that there is almost no time difference between the transfer of 1 Sample an 1000 Samples, so I guess my problem is the minimum response time of the scope.
How long does it take to measure and transfer these pulses (100 Samples each) to a pc with PS 4224?
Would a more expensive USB-Scope of yours have a shorter response time?

Thanks for your help.
Regards,
Armin
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Re: Response Time PS 4224

Postby Chris » Fri Apr 01, 2011 2:47 pm

You should easily be able to do this.

It's withing the capabilities of block mode, without needing to use memory segmentation of rapid block mode.

Have you tried using the ps4000ExampleBlock.vi in the PS4000 SDK, downloadable from the Pico Website

http://www.picotech.com/software.html

You are correct that there will be almost no difference in retrieving 1 or 1000 samples, due to the USB overhead.
Chris
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Re: Response Time PS 4224

Postby Armin_T. » Mon Apr 04, 2011 8:19 am

Thanks for your answer,

I already tried the example VIs. I added a "write to spreadsheet" function to the ps4000ExampleBlock.vi to see, how many captures of a pulse train with 400Hz are saved in the spreadsheet. It is about 30 recorded captures per second, so 370 captures per second are skipped.
Has the setup-time of the driver anything to do with this limitation? Or is it possible to avoid the setup time between getting the captures?

Regards,
Armin
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Re: Response Time PS 4224

Postby Chris » Thu Apr 14, 2011 10:15 am

The SetDataBuffers section only needs to be done once, and can be carried out outside of the RunBlock / GetData loop.
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