basic USB questions

RedGTiVR6 · 01-25-2005, 08:53 AM

Ok - so in looking for a simple USB hub for my set-up I got to wondering....

why do some USB hubs come with a power plug and some don't but they all seem to have an input for power?

I noticed that 1.1 hubs don't seem to come with the power plug while the 2.0s do.

Also, lets say that i don't need any of the USB devices to run off of the power that the USB cable provides....for instance the screen and the dvd player...they both have their own power supplys. I shouldn't need power for the hub right? I'll basically be using the hub as an extender...

Also, for the screen and DVD player, will it matter if you go 1.1 or 2.0? Wondering what the difference in data transfer speeds will be on such devices and if it will matter with these devices?

There was something else that I can't seem to remember right now so I'm sure I will post that here in a few mintes as well....lol

DJSmiley · 01-25-2005, 09:02 AM

Well, for non-data-consuming devices, USB1 is enough. (touchscreen, gps and so on). For DVD usb1 is too slow: USB1 is 12Mbit max, which is in the real world like 800k/sec or so. DVD (1x) requires about 1.2Mb/sec or so.

Besides, connecting a USB2 device on a USB1 hub causes windows "to panic": It keeps on mentioning: Fast device connected to a slow usb hub, kinda annoying.

RedGTiVR6 · 01-25-2005, 09:56 AM

mkay - wondering just how slow the dvd will be - or will it just not work?

jcdillin · 01-25-2005, 10:26 AM

I have tried it, I couldnt get it to work.

JC-S60 · 01-25-2005, 11:42 AM

The power plug is for powering the devices connected to the hub, not the hub itself (mostly, i've seen some stupid exceptions).
Normally, each usb-port should provide 500mA of power at 5v. If a hub doesn't have a powersupply of its own, that means that all devices connected to that hub can only draw 500mA TOGETHER, an average of 125mA per device...
When it does have a powersupply, it can deliver 500mA for each port on it.

RedGTiVR6 · 01-25-2005, 11:56 AM

yeah - that's why I was mentioning that the devices being connected wouldn't need any power....because they have their own power....

maybe I'll look again for another cheap, non-powered, small 2.0 hub here locally.....just not worth buying it online and saving $5 but paying $5 for shipping then having to wait a few days to get it....lol