TDMS Advanced Open Function

LabVIEW 2018 Help

Edition Date: March 2018
Part Number: 371361R-01
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Owning Palette: Advanced TDMS VIs and Functions

Requires: Base Development System

Copyright: (c) 2018 National Instruments. All rights reserved.

Opens a .tdms file for reading or writing in the byte order of the host computer. You also can use this function to create a new file or replace an existing file. Unlike the TDMS Open function, the TDMS Advanced Open function does not create a .tdms_index file. If you use this function to open an existing .tdms file that has a corresponding .tdms_index file, this function removes the .tdms_index file.

Details  Examples

file path specifies the absolute path to the file you want to open. If you use this function to create a new file, the file extension of the filename you specify in file path must be .tdms. Otherwise, this function automatically appends .tdms to the filename you specify. If you use this function to open or update an existing file, you do not have to ensure that the file extension is .tdms.
operation specifies the operation to perform.

0open (default)—Opens a .tdms file to write to.
1open or create—Creates a new .tdms file or opens an existing .tdms file to configure.
2create or replace—Creates a new .tdms file or replaces an existing .tdms file.
3create—Creates a new .tdms file.
4open (read-only)—Opens a read-only version of the .tdms file.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
disable buffering? (Windows) specifies whether LabVIEW opens, creates, or replaces a .tdms file without system buffering. The default is TRUE, which means this function disables system buffering. If the value is TRUE, the size of data to read or write must be a multiple of the sector size of the hard disk. Disabling system buffering can speed up data transfers in certain situations. If you have a small amount of data to transfer, you might not notice a difference if you disable buffering. To read or write a data file to a Redundant Array of Independent Disks (RAID), consider opening the file without buffering to speed up data transfers. To read the same set of data repeatedly from the computer, consider enabling buffering.
enable asynchronous? (Windows) specifies whether to enable asynchronous reads or writes for the .tdms file. Set the value to TRUE if you want to use the TDMS Advanced Asynchronous I/O or TDMS Advanced Data Reference I/O functions. Set the value to FALSE if you want to use the TDMS Advanced Synchronous I/O functions. The default is TRUE.
tdms file out returns a TDMS file reference to the .tdms file on which you performed the operation.
sector size returns the sector size of the hard disk. (macOS/Linux/RT targets) sector size is not supported and returns a value of zero.
Note  Traditionally, the sector size of hard disks is 512 bytes. In recent years, the sector size is 4096 bytes for large hard disks and RAID arrays.
error out contains error information. This output provides standard error out functionality.

TDMS Advanced Open Details

The byte order, or endian format, specifies whether LabVIEW represents numeric values in memory from most significant byte to least significant byte or vice versa.

Note  Use this function to open a .tdms file with a file format version of 2.0. To open a version 1.0 file, use the TDMS Open function.


Refer to the following VIs for examples of using the TDMS Advanced Open function:

  • TDMS Advanced Asynchronous Write VI: labview\examples\File IO\TDMS\Advanced Read and Write\Asynchronous Read and Write
  • TDMS Advanced Basic Asynchronous Read VI: labview\examples\File IO\TDMS\Advanced Read and Write\Asynchronous Read and Write


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