USB hubs

[Big Steel]

I got this USB hub as a xmas present from my company. It has 7 USB ports
for different devices using USB like SD/MMC, M2, Micro SD and two other
weird looking ones. I don't know what they are used for, but I have 3
USB ports that work the same as the USB ports on the computer.

I can plug a USB stick into one of the 3 plugs on the hub, W7 detects
plug the hub into the computer and it sees it as a drive, it sees the
USB memory stick and I can access the files on the stick through the hub.

However, I plug in my USB hard drive into one of the ports like the USB
stick is using, the USB hard drive is not detected but the USB hard
drive has power.

Is the USB hard drive suppose to be seen and used through this USB hub
like the USB stick can be used?

 

[Evan Platt]

I got this USB hub as a xmas present from my company. It has 7 USB ports
for different devices using USB like SD/MMC, M2, Micro SD and two other
weird looking ones. I don't know what they are used for, but I have 3
USB ports that work the same as the USB ports on the computer.

That's not a USB hub. That's a Multi Card Reader.

I can plug a USB stick into one of the 3 plugs on the hub, W7 detects
plug the hub into the computer and it sees it as a drive, it sees the
USB memory stick and I can access the files on the stick through the hub.

However, I plug in my USB hard drive into one of the ports like the USB
stick is using, the USB hard drive is not detected but the USB hard
drive has power.

Is the USB hard drive suppose to be seen and used through this USB hub
like the USB stick can be used?

A make and model of this device would help.

 

[Big Steel]

That's not a USB hub. That's a Multi Card Reader.


A make and model of this device would help.

The company that made the USB mouse and this multi card reader is
called Xoopar out of China I found them on Google. The only products I
saw were the mouse stuff and no multi card reader. The instructions were
not in English with the my consulting company's logo stamped on the stuff.

I don't know where the 1 little page instruction sheet went that may
have had model numbers on it because there are none on the mouse or this
multi card reader. I got a nice ink pen too with the company logo on it.

 

[Rich/rerat]

Big Steel,
Is this the hub that you are talking about?
http://www.gizmowatch.com/entry/funky-xoopar-podium-memory-card-reader/

1. The hub may not provide enough power to run the USB device properly. Even
though the device's indicator light blinks and the disc spins. USB sticks do
not require much power to run them.
2. Some USB devices, such as hdd's a CD/DVD-ROM drives cannot be run through
a USB hub, and must be run through the USB connectors of the PC, often times
the rear ones.

--
Rich/rerat
(RRR News) (message rule)
((Previous Text Snipped to Save Bandwidth When Appropriate))


--
Rich/rerat
(RRR News) (message rule)
((Previous Text Snipped to Save Bandwidth When Appropriate))


I got this USB hub as a xmas present from my company. It has 7 USB ports
for different devices using USB like SD/MMC, M2, Micro SD and two other
weird looking ones. I don't know what they are used for, but I have 3
USB ports that work the same as the USB ports on the computer.

I can plug a USB stick into one of the 3 plugs on the hub, W7 detects
plug the hub into the computer and it sees it as a drive, it sees the
USB memory stick and I can access the files on the stick through the hub.

However, I plug in my USB hard drive into one of the ports like the USB
stick is using, the USB hard drive is not detected but the USB hard
drive has power.

Is the USB hard drive suppose to be seen and used through this USB hub
like the USB stick can be used?

 

[Desk Rabbit]

Big Steel,
Is this the hub that you are talking about?
http://www.gizmowatch.com/entry/funky-xoopar-podium-memory-card-reader/

1. The hub may not provide enough power to run the USB device properly. Even
though the device's indicator light blinks and the disc spins. USB sticks do
not require much power to run them.
2. Some USB devices, such as hdd's a CD/DVD-ROM drives cannot be run through
a USB hub, and must be run through the USB connectors of the PC, often times
the rear ones.

Mostly correct apart from the bit about rear sockets.

 

[James Silverton]

Big Steel,
Is this the hub that you are talking about?
http://www.gizmowatch.com/entry/funky-xoopar-podium-memory-card-reader/

1. The hub may not provide enough power to run the USB device properly. Even
though the device's indicator light blinks and the disc spins. USB sticks do
not require much power to run them.
2. Some USB devices, such as hdd's a CD/DVD-ROM drives cannot be run through
a USB hub, and must be run through the USB connectors of the PC, often times
the rear ones.

For interest, why does this restriction occur?

--


James Silverton, Potomac

I'm *not* (e-mail address removed)

 

[Bob Hatch]

The company that made the USB mouse and this multi card reader is called
Xoopar out of China I found them on Google. The only products I saw were
the mouse stuff and no multi card reader. The instructions were not in
English with the my consulting company's logo stamped on the stuff.

I don't know where the 1 little page instruction sheet went that may
have had model numbers on it because there are none on the mouse or this
multi card reader. I got a nice ink pen too with the company logo on it.

Probably this one, or one like it.

http://www.gadgetshunter.com/index....index.php?route=product/product&product_id=52

My guess on why your USB hard drive won't work is that there is not
enough power to the hub to run the drive and get the data. If you had a
powered USB hub, there most likely would not be a problem with the USB
drive.

--
Rumors are carried by haters, spread by fools,
and accepted by idiots.
"Anon"
http://www.bobhatch.com
http://www.tdsrvresort.com

 

[Paul]

For interest, why does this restriction occur?

Passive hubs, have a 100mA per port limit. And that's because
the 500mA coming from the host, has to be split four or more ways.

Too much voltage drop in the cabling, means you can't stay within
the USB spec voltage margin. Adding a power adapter, down near
the "load end" of your USB tree, fixes that.

Active hubs (with their own power supply), can provide up
to 500mA per port (at least, up to the limitations of the
power supply itself). It's been some time, since an active
hub came with an adequate power supply. For example, a four
port hub you buy today, might come with a 5V 1 amp supply,
suited to run two ports at full power (500mA each). Maybe
one 2.5" hard drive can be used on such a thing, without
concern about it being able to spin up.

OK, this one comes pretty close. This is a seven port, with
a 5V 3A supply. Which means you can run six ports at 500mA each,
before the supply is a limitation. That's a bit better than
a four port with a 1 amp adapter.

http://www.amazon.com/Plugable-Port...G3I6/ref=sr_1_2?ie=UTF8&qid=1324563713&sr=8-2

Paul

 

[James Silverton]

Passive hubs, have a 100mA per port limit. And that's because
the 500mA coming from the host, has to be split four or more ways.

Too much voltage drop in the cabling, means you can't stay within
the USB spec voltage margin. Adding a power adapter, down near
the "load end" of your USB tree, fixes that.

Active hubs (with their own power supply), can provide up
to 500mA per port (at least, up to the limitations of the
power supply itself). It's been some time, since an active
hub came with an adequate power supply. For example, a four
port hub you buy today, might come with a 5V 1 amp supply,
suited to run two ports at full power (500mA each). Maybe
one 2.5" hard drive can be used on such a thing, without
concern about it being able to spin up.

OK, this one comes pretty close. This is a seven port, with
a 5V 3A supply. Which means you can run six ports at 500mA each,
before the supply is a limitation. That's a bit better than
a four port with a 1 amp adapter.

http://www.amazon.com/Plugable-Port...G3I6/ref=sr_1_2?ie=UTF8&qid=1324563713&sr=8-2


Paul

Thanks! Sounds most reasonable. I used to have trouble even with powered
hubs on my previous machine. The present one has six USB ports, two on
the front.

--


James Silverton, Potomac

I'm *not* (e-mail address removed)

 

[Big Steel]

Big Steel,
Is this the hub that you are talking about?
http://www.gizmowatch.com/entry/funky-xoopar-podium-memory-card-reader/

1. The hub may not provide enough power to run the USB device properly. Even
though the device's indicator light blinks and the disc spins. USB sticks do
not require much power to run them.
2. Some USB devices, such as hdd's a CD/DVD-ROM drives cannot be run through
a USB hub, and must be run through the USB connectors of the PC, often times
the rear ones.

Yes that's the USB device. Thanks for the info. Is there any device that
can drive the my USB HD.

 

[Paul]

Yes that's the USB device. Thanks for the info. Is there any device that
can drive the my USB HD.

Some USB 2.5" hard drives, have a jack for connecting a power supply.

If your "Xoopar Podium" hub doesn't have a DC input (a barrel connector),
then the USB ports on it will be rated for 100mA. In which case, the
USB hard drive will need an additional source of power.

The 100mA per port may not be enforced in a precise way, but the
thing is, there will be sufficient voltage drop in the cable, if
you draw high currents, to put the bus voltage out of spec. And some
drives check the voltage present, and they won't operate if it is too low.

*******

If you connect this hub to your Xoopar, then connect the 2.5" drive
to this hub, at least that solves the power issue.

http://www.amazon.com/Plugable-Port...G3I6/ref=sr_1_2?ie=UTF8&qid=1324563713&sr=8-2

And if one USB port doesn't seem to have the necessary current output,
you can use a "Y cable" to get around any current limiter which is
in the way. You can't use this on the Xoopar, as there really
isn't enough power to go around, even when combining currents. But
if you had any USB device with an active source of power, this would
work. Sometimes, people need to use one of these with two of
their laptop USB ports, to make an external 2.5" drive work.

http://www.amazon.com/StarTech-com-...1?s=electronics&ie=UTF8&qid=1324570194&sr=1-1

How that cable works, is the black connector in the center, uses all four
pins. The red connector on the right, only has +5V and GND pins, for
picking up power. By combining the +5V and GND from those two connectors,
you can get 1 ampere of current for the left hand connector. Which is
enough to spin up a 2.5" HDD. Once the drive is running at normal speed,
the current demand drops back to around 400mA or less.

Paul

 

[John Williamson]

Yes that's the USB device. Thanks for the info. Is there any device that
can drive the my USB HD.

A powered hub, four way with a 2A power supply is best, or direct from
two sockets on the PC. It is possible to get a lead that will draw power
from 2 sockets, and has a single output, which lets the USB HD draw up
to 1000mA. I use one to power my Samsung DVD writer or a USB caddy
mounted HD, neither of which will operate from a single socket.

 

[Big Steel]

On 12/22/2011 11:15 AM, Paul wrote:

<snipped>

Thanks, I'll look into this.

 

[Big Steel]

On 12/22/2011 11:29 AM, John Williamson wrote:

<snipped>

Thanks, I'll look into this.

 

[Gene E. Bloch]

The 100mA per port may not be enforced in a precise way, but the
thing is, there will be sufficient voltage drop in the cable, if
you draw high currents, to put the bus voltage out of spec. And some
drives check the voltage present, and they won't operate if it is too low.

You mentioned "power drop in the cable" twice in this thread.

My suspicion is that the power drop in the cable amounts to millivolts
out of 5 volts. These are not microwires drawing several amps, after
all. Besides, if this were so, a long cable wouldn't work as well as a
short cable, even connected directly to the computer.

There are two reasons why certain devices won't work on a hub.

One is that the hub itself limits power, as described a couple of times
in this thread. External power to the hub will help with this.

The other is that the daisy chaining causes timing and possibly
protocol problems, and some devices won't work with a hub even with
external power.

Well, there is a third cause that I've experienced. Badly designed or
manufactured hub

 

[Big Steel]

On 12/22/2011 9:16 AM, Bob Hatch wrote:

<snipped>

Thanks, I am going to get one that will drive the USB HD, because it's a
pain to get down on my keens to plug the thing into the desktop computer
setting on the floor. I can have this USB device on my desk and plug
things in there.

 

[Paul]

You mentioned "power drop in the cable" twice in this thread.

My suspicion is that the power drop in the cable amounts to millivolts
out of 5 volts. These are not microwires drawing several amps, after
all. Besides, if this were so, a long cable wouldn't work as well as a
short cable, even connected directly to the computer.

There are two reasons why certain devices won't work on a hub.

One is that the hub itself limits power, as described a couple of times
in this thread. External power to the hub will help with this.

The other is that the daisy chaining causes timing and possibly protocol
problems, and some devices won't work with a hub even with external power.

Well, there is a third cause that I've experienced. Badly designed or
manufactured hub

A voltage drop budget is defined in the USB spec. So
somebody thinks it matters.

http://img62.imageshack.us/img62/7181/usbbudget.gif

And that drawing, would be under the defined current values
used in the USB spec, of 100mA and 500mA. The 2.5" hard
drive draws 1 amp when it starts up, which is why there are
cases of USB drives being unable to spin. (Using Ohms law,
the drop would be doubled, as V = R * I and I is twice the
assumed value. So the voltage at the end of the cable, during
spinup, is now lower than the values in the figure.)

In the case of the 3.5" hard drives, they have a "power bug" to
check the voltage on the controller board. The drive stays in reset,
until the voltage gets to around 11V (on the 12V rail). So at least
on the 3.5" drive the spec is reasonably tight. I've had a "spinup loop"
condition inside my current computer case, by daisy chaining too many loads
on a Molex four wire cable, and you know how heavy those wires are.

I don't know what the trip point is for a 2.5" drive. I've run into
enough reports of failure to operate, to suspect power problems
on USB 2.5" drives. Especially when later someone reports they eventually
got it to work (i.e. not a dead drive).

*******

This is an example of a typical 2.5" drive.

http://storage.toshiba.com/main.asp...CNotebook/MKxx61GSYN/MKxx61GSYNSpecifications

The voltage spec for that drive is defined as 5V +/- 5% or 4.75V lowest value.
Of course, that doesn't tell us, what the power bug is set to. It has
to be set to a lower value than the 4.75V. What the power bug does
for the controller, is declares a "power_good" state, so that
operation can begin.

And in the USB spec, you can see the potential for voltages lower than
that, to be present. Some tolerance is assumed on the ATX supply, but
it typically isn't as bad as depicted. 4.75V on an ATX supply 5V rail,
would be a worst case (for a properly working supply).

The poor power distribution, is why I've had to explain about
Y cables to so many people. Because it does happen, that
2.5" drives can't spin up on the end of USB cables. If there
is a powered hub present, next to the drive, that improves
the odds of getting better quality power.

Paul

 

[Gene E. Bloch]

A voltage drop budget is defined in the USB spec. So
somebody thinks it matters.

http://img62.imageshack.us/img62/7181/usbbudget.gif

It's not that I think it doesn't matter, but that I don't think the
drop is as big as that.

Yes, that is merely my *opinion*

Also note that the page doesn't say whether they think these are
typical drops or whether they think a drop that big is the most they
allow, though the limited description as "worst case" makes me think
they mean the latter.

And that drawing, would be under the defined current values
used in the USB spec, of 100mA and 500mA. The 2.5" hard
drive draws 1 amp when it starts up, which is why there are
cases of USB drives being unable to spin. (Using Ohms law,
the drop would be doubled, as V = R * I and I is twice the
assumed value. So the voltage at the end of the cable, during
spinup, is now lower than the values in the figure.)

In the case of the 3.5" hard drives, they have a "power bug" to
check the voltage on the controller board. The drive stays in reset,
until the voltage gets to around 11V (on the 12V rail). So at least
on the 3.5" drive the spec is reasonably tight. I've had a "spinup loop"
condition inside my current computer case, by daisy chaining too many loads
on a Molex four wire cable, and you know how heavy those wires are.

Is that a drop in the wire, or the failure of the power supply to meet
the added load?

I don't know what the trip point is for a 2.5" drive. I've run into
enough reports of failure to operate, to suspect power problems
on USB 2.5" drives. Especially when later someone reports they eventually
got it to work (i.e. not a dead drive).

This is an example of a typical 2.5" drive.

The voltage spec for that drive is defined as 5V +/- 5% or 4.75V lowest
value.
Of course, that doesn't tell us, what the power bug is set to. It has
to be set to a lower value than the 4.75V. What the power bug does
for the controller, is declares a "power_good" state, so that
operation can begin.

And in the USB spec, you can see the potential for voltages lower than
that, to be present. Some tolerance is assumed on the ATX supply, but
it typically isn't as bad as depicted. 4.75V on an ATX supply 5V rail,
would be a worst case (for a properly working supply).

The poor power distribution, is why I've had to explain about
Y cables to so many people. Because it does happen, that
2.5" drives can't spin up on the end of USB cables. If there
is a powered hub present, next to the drive, that improves
the odds of getting better quality power.

Paul

I now have a portable drive that used to work on the USB cable alone
that now requires an external power supply, a wall wart with a barrel
plug, not a USB supply. The Y cable doesn't do the job on this drive.

The drive might be an excellent candidate for disassembly just to see
what the innards are like.

But back to the topic:
Since I can't be sure I'm right, although I don't think I'm wrong, I'll
back away from any pronouncements that might mislead the OP

 

[J. P. Gilliver (John)]

Mostly correct apart from the bit about rear sockets.

No, that isn't incorrect - some PC case designs do supply more power
from the rear sockets, either because they are not designed properly to
the spec. - rare nowadays - or because the front ones are connected to
the motherboard via wires that _are_ quite thin, and go through an extra
connector, whereas the back ones come directly off the motherboard.

 

[J. P. Gilliver (John)]

You mentioned "power drop in the cable" twice in this thread.

My suspicion is that the power drop in the cable amounts to millivolts
out of 5 volts. These are not microwires drawing several amps, after
all. Besides, if this were so, a long cable wouldn't work as well as a
short cable, even connected directly to the computer.

There are two reasons why certain devices won't work on a hub.

One is that the hub itself limits power, as described a couple of times
in this thread. External power to the hub will help with this.

The other is that the daisy chaining causes timing and possibly
protocol problems, and some devices won't work with a hub even with
external power.

One reason for the limitation is that - I think as part of the USB spec.
- the current drawn on each port is monitored. To do this, other than
using hall effect devices and support circuitry which would I think
exceed the price constraints, there has to be some deliberate series
resistance.

Well, there is a third cause that I've experienced. Badly designed or
manufactured hub

Indeed! Although even very cheap ones can be good: I have a couple of
(4-port) ones I got from a poundshop, which work fine - one even has a
socket for external supply, though didn't actually come with such a
supply.

One thing to watch out for with hubs is that the outlet sockets aren't
too close together: I don't know what the spec. says about the matter,
but some devices - memory sticks, MP3 players - can, if chunky, stop
other devices (certainly others of the same body shape) being plugged in
next to them. (My poundshop ones are flying saucer shaped, with the
ports round the edge at right angles to each other, so not a problem.)