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Example Code

Handle File Already Open Error using Queues 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 example handles the "Error 5 - File already open” generated when opening an already opened file



Sometimes you may have are multiple programs accessing the same data file.  If LabVIEW tries opening a file that is another program already has control of (such as data backup software), you will get error 5 when trying to open the file in LabVIEW. This can cause problems if you are logging data and need all of it to be written to the file. This problem can be avoided if you use queues to write the data, and handle this specific error.



LabVIEW Full Development System 2012 or compatible

Steps to Implement or Execute Code

  1. Choose the appropriate file in the file path control.
  2. Run the VI
  3. Simulate the error using the Fake Error button, When error 5 is encountered, the data will be added to the queue so no data is lost.


Additional Information or References

VI Block Diagram



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


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


"Close file reference" should be inside "No error" case structure, else error code 5 generates error code 1 after passing thru "Close file reference" (because input file reference is invalid).