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LibUSB / Win 7/64: Only 3 Cams regognized

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Offline Peter Machtschuß

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LibUSB / Win 7/64: Only 3 Cams regognized
« on: 28 / January / 2015, 10:45:43 »
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I tried to connect up to 6 A480 via an USB-Hub to my PC.
When  only 3 cams are  connected, everyting works fine (CHDKPTP). No matter, which of the 7 ports of the hub I use.
After connecting the 4th cam, the system plays up:
Sometimes ony 2 or 3 cams are recognized, sometime the Windows Device Manager updates every second and shows alternating 1 or 4 cams.

Who can help??
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Offline reyalp

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Re: LibUSB / Win 7/64: Only 3 Cams regognized
« Reply #1 on: 28 / January / 2015, 15:54:37 »
Quote from: Peter Machtschuß on 28 / January / 2015, 10:45:43
I tried to connect up to 6 A480 via an USB-Hub to my PC.
When  only 3 cams are  connected, everyting works fine (CHDKPTP). No matter, which of the 7 ports of the hub I use.
After connecting the 4th cam, the system plays up:
Sometimes ony 2 or 3 cams are recognized, sometime the Windows Device Manager updates every second and shows alternating 1 or 4 cams.

Who can help??
Did you use the INF driver?

Are you using the chdkptp GUI? If so, try using the CLI. The GUI tries to poll the available cameras periodically.

Have you tried other hubs or having some some of the cameras plugged directly into the PC's USB ports?

Are you using battery power, or external power supplies for the camera?

Does A480 return a serial number in the "list" command? This seems to affect how the INF driver works.

Some issues with large numbers of cameras were discussed in:
http://chdk.setepontos.com/index.php?topic=11667.0

People have successfully used significantly more than 4 cameras with libusb on windows.
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Offline Peter Machtschuß

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Re: LibUSB / Win 7/64: Only 3 Cams recognized
« Reply #2 on: 28 / January / 2015, 16:51:35 »
I use the INF driver, cams are shown in device manager as "libusb-win32 devices".
Cams are running on battery power.
Serial numbers are shown.

Obviously the hub is the problem. When connecting the cams directly to the mainboard USB ports, everything works fine.

I use a 7 port hub like this:


Every single port works fine, even without external power supply.

Is there a special kind of USB hubs required / not suitable?
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Offline reyalp

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Re: LibUSB / Win 7/64: Only 3 Cams recognized
« Reply #3 on: 28 / January / 2015, 17:21:01 »
Quote from: Peter Machtschuß on 28 / January / 2015, 16:51:35
Is there a special kind of USB hubs required / not suitable?
In theory, there shouldn't be, but in practice there's a lot of marginal USB hardware out there. I recall reading before about hubs with large numbers of ports that don't actually work with all the ports populated.

The cameras draw very little power over USB (2mA reported in bMaxPower), so a powered hub probably isn't strictly required even with a relatively large number of cameras.

edit:
If you are buying hubs, I'd still recommend going with powered.
« Last Edit: 28 / January / 2015, 17:22:51 by reyalp »
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Offline Peter Machtschuß

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Re: LibUSB / Win 7/64: Only 3 Cams regognized
« Reply #4 on: 10 / February / 2015, 13:42:59 »
There is obvoiusly a wide quality range in USB hubs.

Just bought a new one (almost ten times the price of the old one  :-[) and it works perfectly with 7 cams:


Belkin Hi-Speed USB 2.0 Hub
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