USB hub questions

Archived from groups: alt.comp.hardware.homebuilt (More info?)

True. All devices on the hub run at the speed of the SLOWEST device.

--
DaveW



"o-chan" <poda@REMOVEmac.com> wrote in message
news:ct9lba$7ae9$1@netnews.upenn.edu...
>I need a USB hub and would really like a small one that doesn't need to be
>plugged in, but I just want to clear up a few things I'm not sure of:
>
> If all the hardware attached to a USB hub is powered (like an external
> drive), does it matter if I use a powered USB hub or not? Does this
> become a requirement if the sum length of cable from the peripheral to the
> computer is over a certain length? For example my printer is on the end
> of a 12' cable, and I'm planning on plugging it into a hub once I get my
> external DVD burner.
>
> I hear rumors that in some cases, a USB 1.1 device on a USB 2.0 hub may
> cause all devices on that hub to transfer at 1.1 speeds. Any truth to
> that?
>
> TIA.

Archived from groups: alt.comp.hardware.homebuilt (More info?)

> I need a USB hub and would really like a small one that doesn't need to
> be plugged in, but I just want to clear up a few things I'm not sure of:
>
> If all the hardware attached to a USB hub is powered (like an external
> drive), does it matter if I use a powered USB hub or not? Does this
> become a requirement if the sum length of cable from the peripheral to
> the computer is over a certain length? For example my printer is on the
> end of a 12' cable, and I'm planning on plugging it into a hub once I
> get my external DVD burner.
>
> I hear rumors that in some cases, a USB 1.1 device on a USB 2.0 hub may
> cause all devices on that hub to transfer at 1.1 speeds. Any truth to that?
>
> TIA.

In your situation an unpowered hub will be fine. You only end up
needing a powered hub if you are using devices that use parasitic
power. The cable length should not matter.

A USB 1.1 device will not cause the rest of devices to drop speeds.
They will run at there normal speed.

-- Chris

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"o-chan" <poda@REMOVEmac.com> wrote in message
news:ct9lba$7ae9$1@netnews.upenn.edu...
>I need a USB hub and would really like a small one that doesn't need to be
>plugged in, but I just want to clear up a few things I'm not sure of:
>
> If all the hardware attached to a USB hub is powered (like an external
> drive), does it matter if I use a powered USB hub or not? Does this
> become a requirement if the sum length of cable from the peripheral to the
> computer is over a certain length? For example my printer is on the end
> of a 12' cable, and I'm planning on plugging it into a hub once I get my
> external DVD burner.
>
> I hear rumors that in some cases, a USB 1.1 device on a USB 2.0 hub may
> cause all devices on that hub to transfer at 1.1 speeds. Any truth to
> that?
>
> TIA.

I would go ahead and get a powered hub if you have very many devices. I have
a USB 2.0 Belkin that is small (approx. 6x4") and it has 5 inputs on the
back and 2 on the top that are handy for thumb drives, USB HDDs and
joysticks or whatever. I plug in my permanent devices in the back and
temporary ones into the very accessible top two. 1.1 devices have no effect
at all on the other inputs. Good luck.

Ed

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"DaveW" <none@zero.org> wrote in message
news:IdOdnUvdb8p7GmTcRVn-1A@comcast.com...
> True. All devices on the hub run at the speed of the SLOWEST device.

Not true!

Mixing Different-Speed Devices on a Single Port
If you are using one USB device or a single USB device per computer port,
there are no issues concerning mixing devices of different speeds. If you
have a USB 2.0 port, you simply plug in any USB device. The system will
recognize the device’s speed and communicate accordingly.

If you plug a high-speed 2.0 device into a 1.1 port, the device should be
recognized, installed, and actually work. However, you will not necessarily
achieve the sample rates that you would obtain from a 2.0 port.

To connect more than one USB device to a single port on your computer, you
must install a USB hub. Hubs are available in both 1.1 and 2.0
configurations. You may plug any combination of 1.1 and 2.0 devices into
either hub, and they should work.

You also may mix low-speed, full-speed, and high-speed devices on a single
hub without typically reducing the performance of the higher speed devices.
To take advantage of high-speed transfers, the device, the hub, and the
computer port all must be 2.0. The USB has been designed to minimize, if not
eliminate, the penalty for mixing older and newer technology.

Ian Boys (Thanks BCastner!)