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NI LabVIEW 2009 introduces major enhancements to the TDMS file I/O format to optimize write performance. With new support for interleaved data, the option to bypass the Windows OS buffer, and the ability to stream raw integers, you can now stream data to disk up to four times faster than in previous versions of LabVIEW, reaching speeds of up to 400 MB/s.
NI made the new improvements to the TDMS File I/O API within the existing VIs, so you do not need to modify your programs. However, to optimize your write speeds, you can use a new input in the File Open VI to bypass the Windows OS buffer. Also, you can use a new VI on the TDMS File I/O palette, the TDMS Create Scaling Information VI, to store the raw unscaled data to the TDMS channels. It stores the scaling information in the properties of that channel.
There are two main benefits to integrating file I/O in the driver. First, you can now use a single VI, found on the DAQ palette, to log all your acquisition channels to disk, making it the simplest way to perform file I/O. All you need is a data acquisition task/channel input and a file path.
Second, when you enable TDMS data logging, NI-DAQmx can stream data directly from the device buffer to the hard disk. NI-DAQmx improves performance and reduces the disk footprint by writing raw data, including the scaling information, to the TDMS file separately for use when you read the TDMS file. With the new Configure Logging VI, you can achieve file writing speeds up to 1.2 GB/s, making it the fastest way to stream data to disk in LabVIEW.
