How do I access any USB device in LabVIEW?

[Ben321]

I have Labview 8.5.1 Professional Development version. I noticed that it has specific block diagram blocks I can place to control various NI brand equipment. It also has some blocks to directly control the serial port (like the old 9-pin and 25-pin ports), but I see NOTHING to let me control devices connected to USB ports, ESPECIALLY nonthing that would let me controll non-NI brand equipment. I have a Logitech webcam called Quickcam Deluxe and would like to be able to control it (such as exposure and gain) as well as receive the image stream and caputre frames to save as pictures, all done in LabVIEW. Does someone have some suggestions for how I can gain access to the USB port in a way that will allow LabVIEW to directly communicate with the device connected to the USB port?

[Dennis_Knutson]

You must have missed the USB functions a couple of levels down on the VISA palette. If you are WILLING to put in the work, you can control ANY USB device.

If however, you just want to control this specific type of USB device and not just 'any' USB device, there is the NI-IMAQ for USB Cameras. This does require some toolkits that are not free. Search the forums for 'Logitech camera' and you will find numerous posts.

[rolfk]

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Dennis Knutson wrote:

You must have missed the USB functions a couple of levels down on the VISA palette. If you are WILLING to put in the work, you can control ANY USB device.

If however, you just want to control this specific type of USB device and not just 'any' USB device, there is the NI-IMAQ for USB Cameras. This does require some toolkits that are not free. Search the forums for 'Logitech camera' and you will find numerous posts.

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Logitech does not publish the USB protocol used for their cameras and does typically not even answer negatively to such requests. For me that means accessing a Logitech camera on USB Raw level is simply impossible.

However USB cameras typically make also use of more advanced features of the USB protocol such as isochronous transfers or specific interrupts that were not supported by VISA USB Rawlast time I checked. Last but not least I can't imagine someone knowing what is involved and being in his good mind to really consider to write a VISA USB Raw driver for a webcam even if the protocol would be clearly documented. This would be going to be a very painful project.

IMAQ for USB cameras from NI or IVision from Hytek Automation would be the way to go. If you insist on going lower level you could consider to access the WIA COM interface in Windows directly (requires an external C DLL), which is what the two mentioned solutions also do. But trying to access a webcam directly is something even most Linux kernel hackers shy away from

Rolf Kalbermatter

Message Edited by rolfk on 12-10-2008 08:37 AM

[Ben321]

I believe the USB functions you described are in Labview 8.6, because in my Labview 8.5.1 I don't see ANY usb Visa functions, LET ALONE camera specific ones under IMAQ.

Could you post a screenshot of your screen showing these items, so I can see where I should expect them to be if I have them? And also please post the version of your copy of Labview.

And since my logitech camera has its own drivers on a disk that came with it. I'm not sure how it could work with Labview without making some driver conflict. Or are you saying the USB camera control can control it without using the regular Logitech driver.

Even if I could get it to work with what you suggest somehow, I want it to work beyond its original design capabilities (such as making it do long exposures). It's longest exposure setting is 1/5 of a second with the Logitech drivers. But if I had RAW control I could theoretically send it a signal coresponding to ANY arbitrary length exposure. So theoretically I could set it do a 1 minute exposure (great for photographing the Orion Nebula through my telescope) if I could directly control it with Labview. I'm thinking about doing astrophotography with it. That's cheaper than buying a $10000 dedicated astrophotography camera from the company SBIG.

Message Edited by Ben321 on 12-10-2008 05:25 PM

[Dennis_Knutson]

The VISA USB functions have been included with the last several versions of LabVIEW. They were introduced around LabVIEW 6.1 (either 6.0, 6.1, or 7.0). In LabVIEW 8.x, they are on the Instrument I/O>VISA>VISA Advanced>Bus/Interface Specific>VISA USB palette. You could simply use the 'Search' function on the functions palette or use the LabVIEW on-line help and search for USB.

Also, as I mentioned, the toolkit I pointed you to requires add-on software from NI, not just the limited IMAQ functions you get with just the LabVIEW license.From what I understand, it works very closely with the Logitech drivers.

Also, pay attention to what Rolf said. Without the information from Logitech, you trying to use USB RAW would be a waste of time and if the camera does use isochronous transfers, even if you had the information from Logitech, NI-VISA does not support this.

Lastly, there is a dedicated Machine Vision board where there have been numerous posts regarding Logitech cameras. The few that I looked at were using the toolkit with full versions of NI-Vision/IMAQ but in any case, that would prbably be a more appropriate board for your questions.

[rolfk]

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Dennis Knutson wrote:

Also, as I mentioned, the toolkit I pointed you to requires add-on software from NI, not just the limited IMAQ functions you get with just the LabVIEW license.From what I understand, it works very closely with the Logitech drivers.

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Actually no. The IMAQ for USB Camera add-on (which is free but unsupported and by the way is only useful if you have the IMAQ Vision Add-on, which is not free) has no knowledge about the specific drivers it is using. It simply accesses the Windows Image Acquisition (WIA) COM interface and lets that manage the DirectShow (DirectX or one of the other names MS has given this technology since its inception) drivers each camera comes with.

Rolf Kalbermatter

Message Edited by rolfk on 12-11-2008 09:55 AM