Owning Palette: TDM Streaming VIs and Functions
Requires: Base Development System. This topic might not match its corresponding palette in LabVIEW depending on your operating system, licensed product(s), and target.
Use the Advanced TDMS VIs and functions to perform advanced file I/O operations, such as asynchronous reads and writes, on .tdms files. You can use these VIs and functions to read data from an existing .tdms file, write data to a new .tdms file, or replace subsets of data in an existing .tdms file. You also can use these VIs and functions to convert the file format version of a .tdms file or to create scaling information for unscaled data.
| Note Use the standard TDMS VIs and functions when the features of the Advanced TDMS VIs and functions are not necessary. Incorrect use of the Advanced TDMS VIs and functions might result in a corrupt .tdms file. If you disable buffering when using the Advanced TDMS VIs and functions, the data size you read or write must be a multiple of the sector size of the hard disk. |
The VIs and functions on this palette can return TDM streaming error codes.
| Palette Object | Description |
|---|---|
| TDMS Advanced Close | Closes the .tdms file that you opened with the TDMS Advanced Open function and releases extra disk space that the TDMS Reserve File Size function reserves. |
| TDMS Advanced Open | 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. |
| TDMS Convert Format | Converts the file format version of a .tdms file from 1.0 to 2.0 or vice versa. This VI overwrites the .tdms file with the new file format version you specify in the target version input. This VI also changes the byte order of the .tdms file to native, host order. |
| TDMS Create Scaling Information | Creates scaling information for unscaled data in a .tdms file. This VI writes the scaling information to the .tdms file. You must manually select the polymorphic instance to use.
To call this VI with TDMS Advanced functions, only call the TDMS Set Channel Information function after any calls to this VI. |
| TDMS Delete Data | Deletes data from a channel or multiple channels in a group. |
| TDMS Reserve File Size | Pre-allocates disk space for writing and prevents fragmentation on a file-system level. If you are running this function on Windows with User Account Control enabled, you must run LabVIEW or the application with administrator privileges to avoid a run-time error. |
| TDMS Set Channel Information | Defines the channel information of the raw data that you want to write to the specified .tdms file. The channel information includes the data layout, name of the group, names of the channels, data type, and number of samples. |
| TDMS Set Next Read Position | Configures the offset at which the TDMS Advanced Asynchronous Read function starts reading data from a .tdms file. |
| TDMS Set Next Write Position | Configures the offset at which the TDMS Advanced Asynchronous Write or TDMS Advanced Synchronous Write function starts overwriting the existing data in a .tdms file. |
| Subpalette | Description |
|---|---|
| TDMS Advanced Asynchronous I/O Functions | Use the TDMS Advanced Asynchronous I/O functions to asynchronously read data from or write data to .tdms files. |
| TDMS Advanced Data Reference I/O Functions | Use the TDMS Advanced Data Reference I/O functions to interact with data that is owned by a component external to LabVIEW, such as the direct memory access (DMA) buffer of a device driver that controls a data-streaming device. You can use these functions to asynchronously write data from the DMA buffer of a device driver to .tdms files without needing to copy the data into a LabVIEW array first. You also can use these functions to asynchronously read data from .tdms files and place the data directly into the DMA buffer. |
| TDMS Advanced Synchronous I/O Functions | Use the TDMS Advanced Synchronous I/O functions to synchronously read data from or write data to .tdms files. |
| TDMS In Memory Functions | Use the TDMS In Memory functions to open, close, read from, and write to .tdms files in memory. |