are usb 2.0 devices able to work with usb 1.1 hubs?

**chris in nh** · 06-27-2004, 02:14 AM

i believe the usb port on my laptop is usb 1.1. most of the devices out there are usb 2.0. i want to plug a usb hub into the laptop so i can have 4 ports instead of 1.

is usb 2.0 backwards compatible with usb 1.1? i'm almost sure it is, but i want to be 110% sure before i spend money on a hub. i would think that the devices would auto-negotiate a mutually supported speed. (1.5Mbps, 12Mbps or 480Mbps.)

thanks

**d_sellers1** · 06-27-2004, 02:27 AM

Yes. USB2.0 is backwards compatible. When connected to 1.1, however, they run at 1.1 speeds.

Derek

**chris in nh** · 06-27-2004, 02:35 AM

that's what i needed to hear!

thanks

**d_sellers1** · 06-27-2004, 06:50 AM

Kinda along the same lines: Whenever you attached a 1.1 device to a 2.0 hub, it will drop the speed of all the devices to 1.1.

FYI,
Derek

**Nic** · 06-27-2004, 11:01 AM

thats the wierdest first post ever

**deadweasel** · 06-28-2004, 02:59 AM

Guys, there are a couple instances where USB2.0 devices will NOT work on 1.1 ports.

Case in point : I have an Enermax external HDD enclosure. Typically, under Win XP Pro, drivers are not needed, since XP sees it as another internal HDD. However, try as I might, I could not get it to work on 1.1 ports.

I would get the little "help" balloon saying "You have plugged a USB2 device into a 1.1 port. Your new hardware is installed, but may not be useable etc etc"
The drive would not show up no matter what. Until, that is, I went out and got a USB2 card for my PC, and then, wonder of wonders, the drive takes a moment, scanning the files as if it were a newly-inserted CD, then pops up for perusing in My Computer.

Heh.

**stevewm** · 06-28-2004, 05:49 PM

Originally Posted by d_sellers1

Kinda along the same lines: Whenever you attached a 1.1 device to a 2.0 hub, it will drop the speed of all the devices to 1.1.

FYI,
Derek

Not actually......

When you connect a 1.1 device to a 2.0 hub only that device will operate at 1.1 speeds. All other devices will continue to run at 2.0 speeds. I've never seen a 2.0 hub that worked the other way.

**Yuriy** · 06-28-2004, 05:52 PM

I think it works like this:

You can plug USB 1.1 devices into USB 2.0 port and they will work.
But, not the other way around.

**d_sellers1** · 06-28-2004, 06:01 PM

Originally Posted by stevewm

Not actually......

When you connect a 1.1 device to a 2.0 hub only that device will operate at 1.1 speeds. All other devices will continue to run at 2.0 speeds. I've never seen a 2.0 hub that worked the other way.

These are excerpts from the DLink DUB-H7 USB hub manual:

Remember that when connecting USB 1.1 devices to a USB 2.0 hub or host adapter, the USB 1.1 device will operate only at USB 1.1 speed.

Connecting USB 1.1 devices to the DUB-H7 may cause all USB devices connected to the hub to work at USB 1.1 speed. To ensure 480Mbps throughput for your USB 2.0 devices, do not connect USB 1.1 and USB 2.0 devices to the hub at the same time.

Originally Posted by Yuriy

I think it works like this:

You can plug USB 1.1 devices into USB 2.0 port and they will work.
But, not the other way around.

This isn't true. You can plug a 2.0 device into a 1.1 port. It will operate at the slower speed. Windows will also give you an error saying that there is a high speed device plugged into a low speed port. The device works fine but not at full speed. For example, if you have a 48x USB CD burner when you plug it into a 1.1 port it will only burn at 4x (sometimes 6x or 8x).

Derek