# Webcam not working though USB hub

## rcast

Hi,

I am having a problem with my usb webcam (creative ct6840) which works perfectly when i run it directly from the usb ports on my laptop, but whenever i plug it into a hub i get an error message: 

```

Can't open device /dev/video0

```

the same modules are loaded and all i am doing is plugging it in into the hub. The video0 does appear in /dev/v4l/video0 as soon as i plug it into the hub.

Any body have an idea how to solve this, as i only have 2 ports on my laptop and would prefer not to use one on my webcam.

Thanks

Rene

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## NeddySeagoon

rcast,

How much power does your webcam take ?

My one wants 500mA, which is the maximum a USB port can supply.

If you try to run a device like this from an unpowered hub (no mains lead) then the 500mA from the laptop has to power the hub and all connected USB devices. It often doesn't work.

Have a look at your webcam info with 

```
usbview
```

 .

If its 500mA (or close) its a port from the laptop on its own or a powered hub (which should be able to supply 500mA to *each* port).

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## rcast

I checked the information from usbview, it stated that the maximum power needed was 500ma. But the hubs that i am using are all power and should be capable of suppluing the required power. 

In both cases the light for the webcam is on.

I tried a comparing the devices files in /proc/bus/usb/, doing a diff but the only difference to me was :

```

< T:  Bus=01 Lev=02 Prnt=25 Port=01 Cnt=01 Dev#= 26 Spd=12  MxCh= 0

---

> T:  Bus=03 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#=  4 Spd=12  MxCh= 0

```

and if i am right this is just refering to where it is connected.

I also tried removing and installing the modules after unpluging from laptop and plugging back into the hub without success.

Rene

----------

