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nikkadim
July 1, 2013, 16:40:55
Hi,
I have 6 x DMM 42BUC03-ML cameras connected each to ARM-based microPC, and I have noticed that second 3 cameras in row always shows low intensity with the same conditions (lens, exposure, gain). I also reproduced this under Win7 x64 with 4 cameras and USB hub (without external power) and single USB 3.0 (900mA) port at PC.

Is it possible that, due to voltage drop in USB bus this camera produce low intensity images? The difference in intensity is about 20-30%.

Thank you.

Stefan Geissler
July 2, 2013, 16:31:19
This is a good question, I never saw this before. But this means, if you disconnect one of the first cameras, one of the last ones must be brighter.

I would like you to ckeck, whether all cameras have the same properties regarding gain and exposure set.

nikkadim
July 3, 2013, 20:47:52
This is a good question, I never saw this before. But this means, if you disconnect one of the first cameras, one of the last ones must be brighter.

I would like you to ckeck, whether all cameras have the same properties regarding gain and exposure set.

Could you please check (or may be ask electrical engineers) - if camera has ~3.7-4.0V instead of 5V can this be a problem for intensity (on images)?
Thank you.

Stefan Geissler
July 4, 2013, 11:05:59
Hello,

Please try a powered USB hub and see, what happens. However, if the "dark" cameras do not "brighten up" if connected alone, then this is no power problem. Please make sure, all cameras receive the 5V which must be available as specified in the USB specification.

nikkadim
July 4, 2013, 13:37:00
Hello,

Please try a powered USB hub and see, what happens. However, if the "dark" cameras do not "brighten up" if connected alone, then this is no power problem. Please make sure, all cameras receive the 5V which must be available as specified in the USB specification.

Unfortunately, I can't use USB hub in real experiment (because I have no room inside box), that's why I'm asking you about what happens if this camera will receive low voltage.
Thank you.

Stefan Geissler
July 4, 2013, 14:41:55
Please check the cameras with a hub outside the box then. And please make sure, you provide 5V for the cameras, as specified in the USB specification.