how many devices off of 1 usb line/hub?

**blackcar** · 01-22-2006, 11:23 PM

Hi all
I was planning on running a single USB 2.0 line
from my trunk to the front and into a usb hub/splitter
Just wondering if there were drawbacks to running too many devices off of one USB 2.0 line?
are there limitation on how many devices can be attached?

off the top of my head I need USB for the:
touch screen monitor
keyboard (will prolly be rarely used)
mouse (will prolly be rarely used)
DVD/CD (in dash)
forward facing video camera
and prolly want to have one extra free port for plugging in stuff like a minidrive or something to transfer files to/from the carputer

thanks

PS the monitor and camera will have their own power sources (not sure if that will matter)

**quodus** · 01-22-2006, 11:41 PM

Dont no how many but you can get 5 port usb hubs that run of a single usb port. Problem is that the more ports you run the less speed your devices will run at!!! as soon as you share a usb 2.o port it becomes slower than usb 2.o Win xp will give you an warning message that says ("hi speed usb device plugged into a non high speed usb port, ") it will run slower at about usb 1.o which is not much fun!! and is quite

**Zebelkhan** · 01-22-2006, 11:43 PM

My understanding is that you can have up to 256 devices off of a single USB port (using multiple hubs) but obviously the hubs must be powered hubs.

**WScottCross** · 01-25-2006, 05:32 AM

You can put up to 5 hubs in series (but many in parallel) and a total of 127 devices on a single USB bus.

**Zebelkhan** · 01-25-2006, 12:17 PM

Thanks. I stand corrected.

**RawsonDR** · 01-25-2006, 02:07 PM

Basically you're looking at a worst case scenario of ripping a dvd to an external hard drive, while the camera is recording content to that same hard drive. I think the hard drive, in that particular case, would bottleneck the USB transfer instead of the other way around.
You should be fine. And if you're curious, you can start testing in your home if you have enough components all ready purchased.

The one thing you will want to worry about, is that some USB hubs will limit all ports to USB1.0 if a single USB1.0 device is plugged in. I don't know how to tell which hubs will or won't. There are a lot of interesting threads dealing with USB problems that are worth a read.

**blackcar** · 01-31-2006, 02:39 AM

Originally Posted by RawsonDR

Basically you're looking at a worst case scenario of ripping a dvd to an external hard drive, while the camera is recording content to that same hard drive. I think the hard drive, in that particular case, would bottleneck the USB transfer instead of the other way around.
You should be fine. And if you're curious, you can start testing in your home if you have enough components all ready purchased.

The one thing you will want to worry about, is that some USB hubs will limit all ports to USB1.0 if a single USB1.0 device is plugged in. I don't know how to tell which hubs will or won't. There are a lot of interesting threads dealing with USB problems that are worth a read.

thanks

**blackcar** · 02-03-2006, 06:57 PM

actually I've come up with a solution on line speed
I'm running two USB 2.0 lines now

overkill... maybe

but now I don't have to worry about it
and the cables are cheap anyways
so I can dedicate one line just for the dvd play up front in the dash

btw: the caputer is a laptop on a docking station, which has 4 USB ports, so I figured I might as well make use of the extra ports I had