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MichaelBalzer

Option to log scaled data when using "DAQmx Configure Logging"

Status: New

As far as I can tell, DAQmx Configure Logging only allows for raw data and scaling information to be saved as part of a DAQmx task. This is great for throughput and disk space considerations, but a problem arises when using DIAdem to analyse the TDMS files with raw + scaling info - it is incredibly slow for large files (~500MB).

 

Some basic tests show it's around 10 times slower to process raw + scale TDMS files (stored as I16s) vs. already scaled TDMS files (stored as SGLs). DIAdem crawls when trying to generate calculation previews, zoom in and out of graphs, and so on.

 

It'd be great if the DAQmx logging provided the option to log scaled data (in the user's preferred datatype), and an option to not include the scaling information in the TDMS metadata.




Certified LabVIEW Architect
Unless otherwise stated, all code snippets and examples provided
by me are "as is", and are free to use and modify without attribution.
2 Comments
crossrulz
Knight of NI

I'm not understanding your problem.  Whenever I use the DAQmx Logging, it stores the data as DBLs.  Perhaps it is because you are reading the raw ADC value instead of the scaled data.


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MichaelBalzer
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I'm using the DAQmx Configure Logging VI to setup DAQmx logging, and the help has a note stating it logs raw + scale to the TDMS file. To do the actual DAQ and logging, I use the Analog 1D Wfm NChan NSamp instance of DAQmx Read (Log and read is set for DAQmx Configure Logging). Did I miss an option to log scaled DBLs?

 

Note that when reading data back from the files I get DBL waveforms, as the TDMS VIs apply the scaling transparently. I want DAQmx logging to be able to log the as values which have already been scaled.




Certified LabVIEW Architect
Unless otherwise stated, all code snippets and examples provided
by me are "as is", and are free to use and modify without attribution.