Comparing Two VIs in LabVIEW

Updated Jul 17, 2019

Reported In


  • LabVIEW Professional

Issue Details

  • I have two different versions of the same VI. How can I efficiently compare them and find differences and similarities?
  • I cannot locate the Compare VIs tool in LabVIEW.
  • Do I have different options to compare two VIs?


You have different options to compare two LabVIEW VIs:
  1. VI Comparison feature:
    1. Check your LabVIEW version and ensure that you have LabVIEW Professional Development System. If you do not have LabVIEW Professional Development System you are required to upgrade your license to gain access to this tool.
    2. Use the VI Comparison feature by opening LabVIEW and selecting Tools»Compare»Compare VIs... This will bring up the Compare VIs dialog box:

    3. In the dialog box, select the VIs you want to compare.  Note that the VIs must be open so they are loaded into LabVIEW's memory. 
    4. Choose which items from the VI you would like to compare by placing a check next to that item (e.g., Front Panel, Block Diagram, etc.)
    5. When you have selected the VIs to compare and the attributes to compare, click the Compare button. This will bring up the two VIs side-by-side with the Differences dialog box below.
    6. Explore the difference between the VIs.
      • Click on a difference in the left pane to see its details. The details will describe what type of difference each item is referring to (e.g., Deleted/Added item, Value difference).
      • Place a check next to the Circle Differences option. This will place a red circle around the item in each VI that a particular difference is referring to.
      • Click on the Show Detail button, and it will highlight the particular detail you have selected for a particular difference (and also place a check next to the detail).
  2. Use the windows command line to start the LVCompare.exe:
  • lvcompare.exe <absolute path to VI 1> <absolute path to VI 2> [-lvpath <path to LabVIEW>][-noattr][-nofp][-nofppos][-nobd][-nobdcosm][-nobdpos]
  • -noattr means do not compare VI attributes
  • -nofp means do not compare the front panels
  • -nofppos means do not compare the size or position of front panel objects
  • -nobd means do not compare the block diagrams
  • -nobdcosm means do not compare the appearance of block diagram objects
  • -nobdpos means do not compare the size or position of block diagram objects.​​
  1. You can configure a third-party source control provider to use LVCompare.exe  as the default comparison tool.

Additional Information

This feature is only available in LabVIEW Professional Development System. If you don't have LabVIEW Professional Development System, you can try programmatically comparing VIs.