USB 2 Maximum Cable Length

  • Thread starter Thread starter Bennett Price
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Bennett Price

My backup device is a USB 2.0 250 MB Iomega Hard Drive.I'd like to put
it in my garage, requiring about 20 to 25 feet of wire. The official
USB specs say 5 meters max; if further use a hub/repeater.

I'm wondering how realistic the 5 meter spec is. I recall that parallel
printer cables were supposed to be limited to 10 feet or so; 75 foot
cables worked just fine. Same thing with the specs for RS-232 cables.

Does anyone have any real world experience with long USB 2.0 cables?
I'm thinking of building mine using unshielded CAT5 cable, one twisted
pair for power, another for data. Wise? foolish?
 
Bennett said:
My backup device is a USB 2.0 250 MB Iomega Hard Drive.I'd like to put
it in my garage, requiring about 20 to 25 feet of wire. The official
USB specs say 5 meters max; if further use a hub/repeater.

I'm wondering how realistic the 5 meter spec is. I recall that parallel
printer cables were supposed to be limited to 10 feet or so; 75 foot
cables worked just fine. Same thing with the specs for RS-232 cables.

Does anyone have any real world experience with long USB 2.0 cables?
I'm thinking of building mine using unshielded CAT5 cable, one twisted
pair for power, another for data. Wise? foolish?
Click to expand...

I'm sorry I don't have any experienc in that regard. It seems like a
simple enough enterprise, though, to just try it and run some
performance test reading and writing to the volume. If it's not living
up to spec, the addition of a single *powered* hub should fix you right
up. You might have some difficulty in finding a 25-30 ft cable
though--I can't remember seeing one much more that 15 ft.

A pricier altenative, but still nifty to check out is IOGear's Cat-5 USB
extender:

http://www.iogear.com/main.php?loc=product&Item=GUCE51&name=USB Ethernet Extender

If you had to go 150 ft it would definitely be worth a look, but as it
is a couple of 15 ft and a hub should be enough. I hope you have an
electrical outlet at your midpoint.
 
Grinder said:
I'm sorry I don't have any experienc in that regard. It seems like a
simple enough enterprise, though, to just try it and run some
performance test reading and writing to the volume. If it's not living
up to spec, the addition of a single *powered* hub should fix you right
up. You might have some difficulty in finding a 25-30 ft cable
though--I can't remember seeing one much more that 15 ft.

A pricier altenative, but still nifty to check out is IOGear's Cat-5 USB
extender:

http://www.iogear.com/main.php?loc=product&Item=GUCE51&name=USB Ethernet Extender
Click to expand...

Thanks for the URL; surprising that it's only USB 1.1
 
You plan on using "UNshielded CAT 5 cable" as a 25 foot USB 2 cable? Well,
I think you'll greatly enjoy the data corruption from the noise interference
your cable will be subject to. Why bother with Standards anyway...
 
My backup device is a USB 2.0 250 MB Iomega Hard Drive.I'd like to put
it in my garage, requiring about 20 to 25 feet of wire. The official
USB specs say 5 meters max; if further use a hub/repeater.

I'm wondering how realistic the 5 meter spec is. I recall that parallel
printer cables were supposed to be limited to 10 feet or so; 75 foot
cables worked just fine. Same thing with the specs for RS-232 cables.

Does anyone have any real world experience with long USB 2.0 cables?
I'm thinking of building mine using unshielded CAT5 cable, one twisted
pair for power, another for data. Wise? foolish?
Click to expand...

I thought I recalled a 1.8M limit for USB. But I remember not finding
the usb spec at the time! I know of 2 options for extending USB.

-USB Booster/Extender/Repeater cables.
-Cat5 USB Extender
- USB Hubs with external power

Regarding the USB Booster cables. I think they are 5M long and plug
into each other. I don't know how many you can plug into each other,
it may go up to 30M/100ft

I have a cat5 USB Extender.. I think they come in 2 kinds,. When I
bought mine in 2003 , it was 2 large boxes about 6 inches wide. Cost
over £100. Looking on ebay, it seems now there's a new kind 2 small
units and cheaper. Maybe USB2 £50 and USB1 £25. Some of them may be
quite cheap from Hong Kong.

My one is a bit funny, i wouldn't trust it with a hard drive. But it's
fine for my purposes. I plug a mics in there sometimes, and my
printer. I often have to unplug the eternal power and plug it back
in. It does give a light to indicate when a cable is plugged in and
the device is recognised on some level. So if I dont' get a light I
unplug the power. and plug the power back in again. I'm doing this at
a 30M distance too..

5M is about 15ft. If you only want 25ft, then i'd seriously consider
2 USB repeater cables.


that's what I know on the subject, i'll just add on a related note

Personally, i've never run a hard drive off USB and left it there any
length of time e.g. overnight. I've done it for 2 hours and done a
backup.. It should be ok. I guess you'd know if it is. Lots of people
use USB Ext HDDs. (or internal ones with an adaptor. Or internal ones
in an enclosure) You'd have to be comfortable with USB before using
booster cables. I guess USB is ok! I just hate it when I plug a
device in and get "device not recognised" it's a "helpless" situation!
THe only issue like that i've had with HDDs are once when the HDD
wasn't partitioned - it was recognised perhaps as a disk drive but no
drive letter. And another time when the USB-IDE adaptor was a cheap
light transparent purple thing and didn't fit (the opaque purples ones
are made better).
 
DaveW said:
You plan on using "UNshielded CAT 5 cable" as a 25 foot USB 2 cable? Well,
I think you'll greatly enjoy the data corruption from the noise interference
your cable will be subject to. Why bother with Standards anyway...
Click to expand...
That's why I'm asking. As for Standards, reread what I said about
parallel printer and RS-232 serial cables.
 
That's why I'm asking. As for Standards, reread what I said about
parallel printer and RS-232 serial cables.
Click to expand...

Your printer and RS standards operate in the 0.1 Mbps range.
Do you realy expect the same leniency at 400 Mbps ?
Or are you willing to wait 6 years for your backup to be complete
?
 
That's why I'm asking. As for Standards, reread what I said about
parallel printer and RS-232 serial cables.
Click to expand...


You weren't guaranteed a printer cablel would work at 75
feet either. Was it even in EPP mode? Did you want to
force a slow USB mode? I suggest you just use a USB
Repeater Cable, this is what they are made to do.
 
Bennett said:
My backup device is a USB 2.0 250 MB Iomega Hard Drive.I'd like to put
it in my garage, requiring about 20 to 25 feet of wire. The official
USB specs say 5 meters max; if further use a hub/repeater.

I'm wondering how realistic the 5 meter spec is. I recall that parallel
printer cables were supposed to be limited to 10 feet or so; 75 foot
cables worked just fine. Same thing with the specs for RS-232 cables.

Does anyone have any real world experience with long USB 2.0 cables?
I'm thinking of building mine using unshielded CAT5 cable, one twisted
pair for power, another for data. Wise? foolish?
Click to expand...

Probably the least troublesome way to do this would be to purchase one
of the devices which allows a USB storage device to be utilized as
Network Attached Storage (NAS). Once the device is network-aware the
distance limitations become less troublesome -- 75-100 meters for wired
Ethernet and probably 50 meters for wireless. Do a search for "USB NAS"
(without the quotes of course) and see what pops up.

Out of curiosity, why would one want the backup drive in the garage? I
have three 200gB backup drives I built from spare hard drives and keep
one of them in my safe deposit box at the bank and one in my neighbor's
safe and one in use and I rotate them every couple of weeks. But the
garage really baffles me.
 
John said:
Probably the least troublesome way to do this would be to purchase one
of the devices which allows a USB storage device to be utilized as
Network Attached Storage (NAS). Once the device is network-aware the
distance limitations become less troublesome -- 75-100 meters for wired
Ethernet and probably 50 meters for wireless. Do a search for "USB NAS"
(without the quotes of course) and see what pops up.

Out of curiosity, why would one want the backup drive in the garage? I
have three 200gB backup drives I built from spare hard drives and keep
one of them in my safe deposit box at the bank and one in my neighbor's
safe and one in use and I rotate them every couple of weeks. But the
garage really baffles me.
Click to expand...

Thanks for your suggestions.

NAS is overkill for what I want to do. Active hub/repeater cable will
do what I need more cheaply. What I'm wondering about is whether I even
need to spend any money. I've got USB A parts and lots of CAT 5 cable.
Or at some more expense, I could buy a couple of shielded A-A cables and
use them as extension cords.

I back up my RAID 5 array to a separate disk inside my PC and
to the USB external HD. I want to put the USB disk in my detached
garage. If my house burns down, my garage will probably remain intact.
Ditto, theft of stuff within the house. I also put occasional images
on DVD and store them in a small fire-resistant safe in my house. If I
were sufficiently worried, I'd rotate bu's far off site - I'm not.

I'm in California - earthquake country. When the big one hits, nothing
is safe.
 
Gerard said:
Your printer and RS standards operate in the 0.1 Mbps range.
Do you realy expect the same leniency at 400 Mbps ?
Or are you willing to wait 6 years for your backup to be complete
?
Click to expand...
But I'm not trying to extend USB 2 cables to 4 or 5 times their spec'd
maximum of 5 meters - 16.5 feet. I need only go about 20-25 feet, less
than twice the spec'd max.

And of course I'm asking because I don't know if it will work. Everyone
points to the spec but so far no one has actually reported trying going
over 5 meters.
 
But I'm not trying to extend USB 2 cables to 4 or 5 times their spec'd
maximum of 5 meters - 16.5 feet. I need only go about 20-25 feet, less
than twice the spec'd max.

And of course I'm asking because I don't know if it will work. Everyone
points to the spec but so far no one has actually reported trying going
over 5 meters.
Click to expand...


Well... a 5-10 foot USB extension cable costs about $4, why
don't you just try it and tell US if it's working ok? I
suggest you buy the largest (lowest) gauge of cable
possible, that you can find I mean, which will tend to raise
the price some as those tend to cost closer to $15 than to
$4... IIRC, Belkin is one manufacturer that lists the gauges
of various offerings, I vaguely recall that mentioned on
listings at Newegg.com but I don't recall for certain if it
was on extension, A/B or what USB cable configuration it
was... this is just an idea of one place and manufacturer
that may have some applicable information.

If you get the extension cable and it doesn't work, buy the
repeater cable. Buy them both and benchmark both ways.
Maybe 20' would work but 25' wouldn't without the repeater.
The whole purpose of the spec is to spec a configuration
that "should" work. You want someone to say they had it
work as if that would be an assurance that if you did it, it
would work... which is not necessary true. If the USB
developers could get > 5 meters to consistently work, they
would've just spec'd it for > 5 meters. Instead, we can see
that with marginal cables, sometimes even 5 meters won't
work.
 
I know of 2 options for extending USB.

-USB Booster/Extender/Repeater cables.
-Cat5 USB Extender
- USB Hubs with external power
Click to expand...

you can try something like this, I developed & used for wifi
UsbKey/dongle for Usb1.1; may work also for Usb2.0 ...
(everything explained on those slides): prolongue with double Sat coax
H123 ... long 5,25 or 10,5m ...

http://193.189.160.28/seibert/HP/UsbEnh/UsbLongCable.gif
http://193.189.160.28/seibert/HP/UsbEnh/UsbLongCable2.gif
the second one should do the trick if your HD enclosure
has external power adapter ...
 
I use either 18 or 20 feet on a Logitech webcam. Eight feet of
pigtail from the camera and a 10 or 12 foot extension cable (I can't
remember which). I've been using it this way for about 9 months and
have seen absolutely no problems.

Everybody I asked on the web warned it wouldn't work but my other
alternatives were very messy. But, the cable only cost about 10 bucks
including shipping, so I tried it and, like I say, it works
flawlessly.

-- jim
 
In message <[email protected]> jim evans
I use either 18 or 20 feet on a Logitech webcam. Eight feet of
pigtail from the camera and a 10 or 12 foot extension cable (I can't
remember which). I've been using it this way for about 9 months and
have seen absolutely no problems.

Everybody I asked on the web warned it wouldn't work but my other
alternatives were very messy. But, the cable only cost about 10 bucks
including shipping, so I tried it and, like I say, it works
flawlessly.
Click to expand...

You're over the spec, but that doesn't mean it won't work, but I
wouldn't expect it to work if you put a hard drive on the other end, ran
the cables near other cables carrying AC power, or used cheapo cables.

I pretty regularly exceed cable limits, you can usually get away with it
if the hardware on both ends is of decent quality, although not always.
 
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