Example Code

Running a C DLL in LabVIEW

Products and Environment

This section reflects the products and operating system used to create the example.

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  • LabVIEW

Code and Documents




This VI uses DLL files developed in C to sort a numerical array



This example demonstrates that LabVIEW users can use code developed in an external development environment, including C++.  The LabVIEW program below generates and sorts a numerical array by calling a C-built DLL via LabVIEW's Call Library Function Node. This example also contains the C source code that the DLL was built from. It contains a .c file and a .prj file that can be built in LabWindows/CVI, as well as a .cpp file and all of the project files necessary to build this in Microsoft Visual C++. If you see a broken arrow when you open the LabVIEW VI, double-click on the Call Library Function Node and relink to the exact path of the DLL.

Any C compiler can you be used to view and execute the C code. If you do not have a C compiler, you can download the LabWindows/CVI Evaluation Software to run the C code and to try the premium C environment for measurement and automation applications. At a minimum, the LabWindows/CVI Run Time Engine is required to run the CVI executable.



LabVIEW 2012 or compatible

Any C compiler


Steps to Implement or Execute Code

  1. Run the VI
  2. Select "Generate", then "Sort" to observe the resulted array
  3. Press “Quit” to stop the VI


Additional Information or References

VI Block Diagram

c dll BD.png

 **This document has been updated to meet the current required format for the NI Code Exchange. **


Justin Parker
National Instruments
Product Support Engineer

Example code from the Example Code Exchange in the NI Community is licensed with the MIT license.

Active Participant
Active Participant

Excellent, Justin.  I have a question regarding the performance of the Call Library Node - do you know if you incur any kind of penalty on performance for calling this node?  That is, would a VI that runs at the same rate as the C code run at the same rate when called using the Call Library Node or might it run slower?  Should we expect the C code called with this node to run at the same rate as it would if called using standard IO?  (This question is related to a post I put up recently)

Also, not to steal NI's thunder , but I believe that Netbeans has a free IDE in which one might view and develop C++ and it seems that Microsoft has recently made their Visual C++ Express Edition available as well.