I have a problem with finding a PnP USB audio device when you search for available audio devices.


I am building an application that can find a PnP USB audio device and play a tone if the device is connected. I am able to search audio devices using "Sound Device Info.vi" of the lvsound2.llb that comes with labview.

The vi can find the USB device in good conditions, but there are problems - I'll try to describe 2 scenarios.

1. the USB device is connected before 'Sound Device Info.vi' is called for the first time.

In this case, the program can find the USB device. If I unplug it, the device disappears from the list of found audio devices. If I reconnect to the same USB port, it reappears in the list. It's all good.

If I reconnect it however a new USB port, the device is not found. This is not good.

2. the USB devices is not connected when 'Sound Device Info.vi' is called for the first time.

"Sound Device Info.vi" is not able to find the device. Disconnect and reconnect does not make a difference.

I'm under labview 2012 on windows 7.

I am running the application as an exe to build.

I call 'Sound Device Info.vi' as a 'call for reference"and the reference is closed between calls to the vi. I was hoping this would unload the dll used in "Sound Device Info.vi" and would solve the problem, but it didn't.

Is there a way to reset the information usb labview during execution?



Hey Stephan.

The sounds screws require a DLL located in:

C:\Program Files (x 86) \National Instruments\LabVIEW 2012\resource\lvsound2.dll

Internally, LabVIEW uses the DirectX API to enumerate devices. The one caveat is that probe us for devices when loading the DLL. We probe not later. So that it works for Bluetooth, USB, fire wire, etc. devices that can be inserted or removed at any time, you control somehow when this DLL charge and discharge. To do this, please see the following document:

Dynamically that I can load and unload a DLL in LabVIEW?


I would also recommend that you provide a Kudo to this idea:

Updated library lvsound2 (Sound Input/output Sound live) to support audio devices change on the fly


Tags: NI Software

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