7 usb cameras doing real time acquisition

[D.J._Klomp]

For a project I need to capture images of 7 identical USB cameras. The USB cameras are cheap  Reflecta Microscope cameras with no specific drivers and no budget or time to upgrade them. The device is recognized as USB video device and uses the usbvideo.sys and the ksthunk.sys driver. My system is a windows 7 64bit system with a kingston SSD card and two extra USB to PCIe hubs (NEC and TI chipset).

At the moment I am able to read pictures from 3 cameras, as soon as I try to run my vi with 4 cameras one camera will give a IMAQ time out error if the vi get image is called. I thought that with the onboard USB system hubs and the two extra USB hubs I would be able to connect all 7. Can anybody help me or at least point me in the right direction, is this a usb bandwidth problem or some driver problem or anything else.

Thanks in advance for any help you can give.

Attached is my VI.

[BlueCheese]

If the cameras are internally using an isochronous transfer mode (the camera decides this), then it means that they are reserving bandwidth on the bus. If any of them are sharing the same USB controller chip then you might be running into a lack of bandwidth on that bus. With 4 cameras and 3 interfaces (the internal one and two PCIe cards) it sounds like you might be sharing a controller somehwere.

The other possibility is that the USBVideo driver from Microsoft has some internal limitations in your configuration that is preventing it from working with that many cameras simultaneously (although I would be skeptical this is the case).

Eric

[D.J._Klomp]

I do share controller but that is not always a problem.

A single camera uses a bandwidth of 48%. Two cameras can be on the same "enhanced usb controller" both using a bandwidth of 48% and 10% system reserve (I know that is above the 100% but it works without problems). With three I have 2 cameras on one controller and 1 on the other and there is no problem. If i add a fourth on the second controller it does not work anymore.

If i split my cameras over the two on board controllers and over the two controllers on the pci cards I still have a problem if I add a fourth camera.

[Hossein128]

Hi,

I think exactly the same as Eric about the bandwidth limit. I couldn't find any option or workaround to solve this issue.

I apologize for that and hope it could not be a big issue for you.

Best regards,

Hossien

[bcharles]

DJ,

Would you be able to share your vi's for the Reflexa camera saved as 2009 vi's?

Thanks.

Brian Charles