06-15-2015 04:30 PM
Thanks for replying.
The data acquisition program we are using has two blocks. One block uses DAQmx to collect the image information. The other one uses high-speed digitizer (NI-SCOPE) to collect the time informaiton. The TDMS file is used inside the digitizer block. Could I ask another question? Does NI-SCOPE have the similar function, for the digitizer part?
06-15-2015 04:32 PM
High speed direct logging to TDMS is only supported by DAQmx driver calls. You'll have to read the data and store it using the TDMS primatives.
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06-15-2015 04:49 PM
Thanks for replying.
After we get data from the NI-Scope, they are put into a queue, and the TDMS accept data after dequeue. We also need to do a little bit on-line analysis after dequeue, which is parallel to the TDMS data recording. So this is not a direct case? High speed direct logging to TDMS will be much faster than this way?
06-16-2015 07:38 AM
@zz_candy_fan wrote:
High speed direct logging to TDMS will be much faster than this way?
I have not done any speed test. But NI claims that by using the DAQmx logging that the speed is faster than performing a read, and then a TDMS write. I've heard some at NI claim this opens a DMA channel from the hardware to the disk drive, and "doesn't involve the CPU". I'm not certain that particular NI person knew what they were saying but my take away was, that it is about as fast as you can get.
That being said TDMS in general is very fast for writing data, and even using the read DAQmx, then write TDMS should be pretty quick. It's on reading TDMS data that can be slow depending on how efficiently it was written.
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06-16-2015 10:00 AM
Thank you very much. As a beginner, I should learn more on Labview and do more test to find the answer. Thanks for your suggestions.
06-16-2015 10:13 AM
We were all beginners once, feel free to ask questions. At the end of this document is some free training if you are interested.
https://decibel.ni.com/content/docs/DOC-40451
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