Front Panel Stops Responding After Several Days, but Application Continues Running

[PLSVK]

Hello everyone,

I am experiencing a strange issue with a LabVIEW application that is built as an executable (EXE).

The application is designed to run continuously on a dedicated PC. It consists of a main VI and many subVIs. The subVIs are opened when the user presses buttons on the main front panel. I use the following sequence:

• Call By Reference
• Open VI Reference
• Run the VI
• Close Reference

The application has been working reliably for a long time, but after approximately 3 days of continuous operation, the front panel stops responding to any button clicks.

What is interesting is that the application itself does not appear to be frozen:

• All parallel loops continue to execute.
• I display the execution time of each loop, and these values continue updating.
• Blinking LEDs on the main panel continue blinking.
• Communication with external devices (for example, an Modbus-TCP/fieldbus bus coupler) continues to work correctly.

The only problem is that I can no longer interact with the front panel. None of the buttons respond anymore.

Some additional information:

• The application does not use an Event Structure.
• Communication between loops is implemented using Notifiers.
• The target PC only has the LabVIEW Runtime Engine 2024 Q3 installed.
• I have not observed any error messages or application crashes.

I am trying to understand what could cause the user interface to stop responding while the rest of the application continues running.

My questions are:

1. Has anyone experienced similar behavior?
2. Could this be related to the UI thread, dynamic VI calls, or reference handling?
3. Is there anything specific I should monitor (memory usage, UI thread

[pincpanter]

An obvious check is whether references (to files, queues, notifiers, vi's, etc...) that are repeatedly and frequently opened are also closed. Memory leaks may also be checked, but they typically drive to a program crash.

In one of my applications (LV2017 and LV2021), I had problems reproducing a wav file using Play Sound File. This function could hang the thread in which it was executed. The symptoms however were different: the application behaved normally until I tried to click on its window: then the window content faded away, Windows reported the application as "not responding", the application memory in Task Manager dropped almost to zero.

[PLSVK]

Thanks for your reply and for the suggestions.

The only references that I don't explicitly close are file references, for example those used by Read Delimited Spreadsheet, or internally by EasyXML. As far as I know, those are handled automatically once the operation is complete.

I haven't used Sound.vi or Play Sound File anywhere in my application, so I don't think the issue is related to that.

[Yamaeda]

Do you have millisecond timers? 3 days is very close to a I32 maxing out.

[pincpanter]

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@Yamaeda  ha scritto:

Do you have millisecond timers? 3 days is very close to a I32 maxing out.

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Really? Actually it's more than 24 days, 49 days for a U32.

[PLSVK]

I am only using these two timers in my application.

[Yamaeda]

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@pincpanter wrote:

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@Yamaeda  ha scritto:

Do you have millisecond timers? 3 days is very close to a I32 maxing out.

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Really? Actually it's more than 24 days, 49 days for a U32.

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My bad!