Convert LVM to CSV

A LabVIEW instrument or test system may produce .lvm logs, while a spreadsheet, database, or analysis script may require .csv. Converting the data makes the measurement columns easier to edit, filter, plot, and import, but the original file should be retained because CSV does not preserve all LVM metadata.

What the LVM format is

LVM means LabVIEW Measurement file. National Instruments LabVIEW creates these plain-text files with the Write to Measurement File Express VI and related data-acquisition tools. They are used for instrument measurements, automated test systems, data-acquisition hardware, and virtual instruments.

An LVM file normally contains a metadata header followed by measurement data. The header can record the LabVIEW version, date and time, channel names, units, sampling information, and field separator. The data is often tab-delimited, but an export can use another separator. The marker ***End_of_Header*** usually separates the header from the data.

What the CSV format is

CSV is a plain-text table format in which rows are separated by line breaks and fields are normally separated by commas. Excel, LibreOffice Calc, databases, Python, R, statistical packages, and many web applications can import it.

CSV is useful when another program needs only the measurement table. It has no standardized section for LVM’s acquisition settings, channel descriptions, units, or timing metadata, so it is an interchange format rather than a complete replacement for the source file.

Using LibreOffice Calc

1. Back up the original .lvm file.
2. Open LibreOffice Calc and choose File → Open.
3. Select the LVM file. In the text-import dialog, choose Separated by and enable Tab if the header specifies tabs. Disable other separators unless the file uses them.
4. Check the preview for the correct number of columns. Confirm that numeric values, timestamps, and scientific notation are not being imported as text or changed into dates.
5. Choose File → Save As, select Text CSV (.csv), set the field delimiter to a comma, and save.
6. Reopen the CSV and compare its first and last records, row count, column count, and representative values with the LVM file.

LibreOffice is a suitable desktop choice for a single, ordinary LVM data table. Excel can use the same text-import approach, but locale settings may reinterpret decimal commas, dates, leading zeros, or large integers; configure those columns explicitly.

Using LabVIEW

Use LabVIEW when the file contains multiple data segments, repeated headers, waveform timing, or channel-specific settings that a spreadsheet may flatten incorrectly.

1. Add a Read From Measurement File Express VI and select the LVM input.
2. Convert the returned dynamic data or waveform data to arrays when necessary, preserving channel and timing information deliberately.
3. Pass the arrays to LabVIEW’s Write Delimited Spreadsheet File function and set the delimiter to a comma.
4. Choose whether channel names should become the first row, then write the output with a .csv extension.

This method requires LabVIEW but gives control over multiple channels, headers, and waveform timing instead of treating every line as an independent text row.

Using Python for repeatable conversion

For a simple single-segment file whose data is tab-delimited, this script removes the LVM header and writes the remaining rows as comma-separated values:

import csv
from pathlib import Path

source = Path("measurement.lvm")
target = Path("measurement.csv")
lines = source.read_text(encoding="utf-8-sig").splitlines()
end = next(i for i, line in enumerate(lines) if line.strip() == "***End_of_Header***")
rows = csv.reader(lines[end + 1:], delimiter="\t")
with target.open("w", newline="", encoding="utf-8") as f:
    csv.writer(f).writerows(rows)

Save it as convert_lvm.py and run python convert_lvm.py. Change the input delimiter if the LVM header specifies commas, semicolons, or another separator. This example does not parse multiple segments, repeated headers, blank records, or unusual encodings; use LabVIEW or a format-aware parser for those files.

Online conversion and privacy

There is no broadly reliable online service dedicated to LabVIEW LVM files. Generic converters that explicitly accept TXT or TSV may process a simple LVM only after the header is removed, but renaming .lvm to .txt does not perform a conversion. Do not upload confidential, regulated, or proprietary measurement data; local LibreOffice, LabVIEW, or Python processing avoids that exposure.

Quality and compatibility limits

• Keep the original LVM because CSV normally discards units, channel descriptions, acquisition settings, timestamps encoded in the header, and other metadata. Record those details separately if the CSV is archived.
• Spreadsheet applications can change timestamps, decimal precision, scientific notation, leading zeros, and very large integers. Import sensitive columns as text or numeric values with explicit settings.
• A comma-decimal locale may require a semicolon field delimiter when opening the result in a spreadsheet. CSV delimiter conventions depend partly on regional settings.
• Inspect quoted fields, embedded delimiters, blank lines, and repeated headers. A proper CSV writer should quote fields when required; replacing tabs with commas through a text editor can corrupt values containing commas.
• Compare representative numeric values after export. CSV stores formatted text, so displayed precision and date formatting may differ from the values presented by LabVIEW.