Multifunction DAQ
Reduce the size of a file created by "write to waveform"
Solved!
Hi
I'm using labview 2012 and I'm having trouble with the size of the tdms file generated by the "Write to waveform" function. The data comes in real-time from 16 channels of a NI USB-6343 X series and is composed by the voltage aquired from a on the Y-axis with the Absolute Time on the X-axis(Waveform format). The file size easily reaches a Gb order in a few hours. Is there a way to reduce this file size? Any configuration on the component?
Thanks for the Help.
Best Regards
Marcelo Nobre
Yes actually, there is a better way. Instead of using the Write to Measurement File express VI, try adding the integrated DAQmx logging to your DAQmx task (before the task is started):
This method will write the raw unscaled binary data to the file (2 bytes per sample since it is a 16-bit DAQ card) with scaling information in the header of the file. In the example you have posted, you are writing data which is already scaled to the file (8 byte double per sample). So making this change you'd expect to reduce your file size by ~4x.
If you'd like you can compress the files after you have finished writing to them to get further reduction in size, but there isn't support for doing this while you are currently writing to the tdms file. Also, you'll need to decompress the file before you can access the data in the .tdms file. You can probably get good results with something as simple as putting the logged data into a .zip file.
Best Regards,
Marcelonobre wrote:...i can´t use the "Write to Measurement File express VI" features like spliting the file when they reach an specific number of samples. Is there a way to do this with the DAQmx logging?
Use a DAQmx Read property node. You can choose Logging->Samples Per File.
