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Multiple USB Camera Image Acquisition using Vision Acquisition



I'm having trouble acquiring continuous images from 2 USB cameras using the Vision Assistant package in LabVIEW. Right now, I set up two different Vision Acquisiton VIs in a single block diagram--each initialized to a different camera--but when it comes to running the VI, one camera always returns an error message that says that particular camera has "Timed out". I've also explored using the NI-IMAQdx route and received the same sort of error message. However, when I use the VI on one single USB camera, and another camera I have linked to network, the VI works perfectly. For my application I need to use two USB cameras to capture a single image from two different points of view (x and z points of view on a coordinate plane). It seems that the VI is having problem differentiating between the cameras, at least that's my guess.


Is there an easier way to run two USB cameras simultaneously? Any suggestions are greatly encouraged



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Hello Evan,


What is the version of Vision Acquisition Software (specifically IMAQdx) that you are using?

You can acquire from multiple USB cameras simultaneously using IMAQdx, with some caveats. 
IMAQdx driver goes through the camera driver and some USB camera drivers are not capable of acquiring from two cameras simultaneously.  Since the , if the camera driver is unable to acquire from multiple cameras simultaneously, then IMAQdx will not be able to acquire from these cameras simultaneously.  

As there are many varieties of USB Cameras on the market and the Creative VF0220 and VF0330 have been confirmed to work.

Another limitation is the computers USB bus itself.  Ensure that your computer can handle the amount of data that will be passed over the bus with multiple acquisitions running at once.  Additionally, if you have several USB devices plugged into your computer, these can take up bandwidth and cause a timeout error. 

Andy Chang
National Instruments
LabVIEW Control Design and Simulation
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The USB bus concern is the one I'm exploring now. I have LabVIEW 2009 and Vision Acquisition 8.6, I'm hoping that the increased bandwidth will alleviate my concerns, but if it doesn't there might be an inadequacy in my VI and I'll post the code.



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Is there any updates to the list of usb cameras that work for multiple image aquisition?  I am looking for very compact usb cameras and ideally would be reading 4 different cameras at one time.  Just want to get ones that are compatible with LabVIEW Vision.




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IMAQdx can support any USB camera that supports Microsoft's DirectShow standard.  When using multiple cameras, it comes down to how well their drivers deal with that.  Our drivers interact with the camera through DirectShow, so it will be up to how the camera manufacturers' drivers handle multiple cameras.  Because of this, there isn't any exhaustive list of cameras as far as I know.  You would have to contact the manufacturers of the cameras to find out what kind of performance you can expect.

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