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picolog sampling rate

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picolog sampling rate

Postby rogerd » Fri Jul 06, 2007 8:41 pm

When I set picolog to real time continuous, 1 msec sample interval, and 1 reading/sample in one channel, it takes about 3 milliseconds to record a sample. If I set it for two channels, it takes about 10 milliceconds to record a sample.

What must I do to get actual real time sampling? And why is the number of samples limited to 1000000 when they are being stored in the computer?

I am using the 3424 oscilloscope with a Mac Pro running XP Pro with a Boot Camp partition. It will read and write 20 MB/sec to a hard drive through the USB port that I am using with the 3424.

Where is the delay?
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Postby ziko » Mon Jul 09, 2007 8:34 am

Hi and thank you for your post.

You are using real time continuous mode which relies on the PC or OS to dictate the timing and hence you will not be guaranteed to get 1ms/S due to overheads within the operating system. Since you are using the 3424 you can use streaming mode, where this time you are not restricted by the OS overheads and since the scope has its own memory and clock you will get your desired times.

The number of samples is limited to 1,000,000 per channel in one PLW file, if you have more samples it will create another PLW file automatically with a number denoted at the end. So if you wish to view the information at a later date you would load more then one PLW file.

Hope this answers your questions.

Kind regards
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picolog sampling rate

Postby rogerd » Mon Jul 09, 2007 10:12 pm

Is the operating system overhead slowing down the 1 ms sampling rate specific for an Intel Mac with XP Pro, or is it generally true for PCs?
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Postby ziko » Tue Jul 10, 2007 8:12 am

No this in general to any PC.
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Postby Guest » Mon Mar 16, 2009 6:29 pm

I am having the same problem.

I want to use my ADC24 (USB) to sample at a time resolution of 2ms. I was getting samples every 6-10 milliseconds using "real time continuous".


I have attempted switching to streaming, but the software will not let me enter a value lower than 61ms in the scan time box, and won't let me set conversion time to less than 60ms. I have PicoLog r 5.20.3, and am running Windows XP if that matters.
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Postby Robin » Wed Mar 18, 2009 2:29 pm

Hi

See http://www.picotech.com/precision-data-acquisition.html

The minimum sampling period of the ADC-24 is 60 mS.

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