Use text-based measurement files (.lvm) to save data that the Write To Measurement File Express VI generates. The text-based measurement file is a tab-delimited text file you can open with a spreadsheet application or a text-editing application. In addition to the data an Express VI generates, the .lvm file includes header information about the data, such as the date and time the data was generated. LabVIEW saves data with up to six digits of precision in a .lvm file. Use binary measurement files (.tdm or .tdms) to exchange data with higher precision.
The .lvm file uses commas as a delimiter between numbers. To convert data in a .lvm file from a string to a number, specify the decimal separator as a period, using the localization code format specifier.
Refer to the NI Developer Zone for more information about .lvm files.