Not sure if anyone has tried this before, but here goes...

I have an existing CAT5 cable running between the downstairs and
upstairs of my house, length around 10 metres. Each end terminates on
a wallbox.

I'm now in a position where I would like to connect a downstairs USB
device (my Topfield PVR) to the PC upstairs.

The run length is too long for USB reliably, so I am considering a USB
CAT5 extender. I could run in another CAT5 cable for this, but it
would be a bit of a pain. HOWEVER, 10/100 BaseT network connections
only use 2 of the 4 available twisted pairs, hence I have 2 spare
pairs in my existing cable. It would be a trivial matter inside the
wallboxes to split these pairs off to a 2nd RJ45 module and send the
CAT 5 side of the extender modules down that. The question is, would
it work i.e. does USB over CAT5 cable only use 2 pairs in the same way
that real 10/100BaseT signals do?

These modules are quite common, but has anyone ever tried them with a
non fully wired CAT5 cable?

"Bill"  wrote in message 
news:encth1hea798cf7p2i6oni1feaei2hrb0j@4ax.com...

> Not sure if anyone has tried this before, but here goes...
>
> I have an existing CAT5 cable running between the downstairs and
> upstairs of my house, length around 10 metres. Each end terminates on
> a wallbox.
>
> I'm now in a position where I would like to connect a downstairs USB
> device (my Topfield PVR) to the PC upstairs.
>
> The run length is too long for USB reliably, so I am considering a USB
> CAT5 extender. I could run in another CAT5 cable for this, but it
> would be a bit of a pain. HOWEVER, 10/100 BaseT network connections
> only use 2 of the 4 available twisted pairs, hence I have 2 spare
> pairs in my existing cable. It would be a trivial matter inside the
> wallboxes to split these pairs off to a 2nd RJ45 module and send the
> CAT 5 side of the extender modules down that. The question is, would
> it work i.e. does USB over CAT5 cable only use 2 pairs in the same way
> that real 10/100BaseT signals do?
>
> These modules are quite common, but has anyone ever tried them with a
> non fully wired CAT5 cable?


Christ knows how many wires the USB converter uses, but in order to split 
the cat 5 cable into two, do a quick google for cat 5 economisers.  I know 
for a fact that www.videk.co.uk do them for about 4 notes a pop, and youd 
need two of them...

Okay, first things, is it a USB 1.1 or a USB 2 device that you want to
extend? If it's a USB 2 device then make sure that you don't mind it
dropping down to being USB 1.1 performance as USB 2 only has very
severe drop off range.

Second, make darn sure that you split the other end of the cable before
it plugs into your router/switch/hub/modem/etc other wise you may blow
the poor thing up.

Third, be prepared for the performance of the network cable to drop
down to about 25mbps due to the ammount of interference on the line
(packet collisions, dropped packets, retransmissions etc).

Other than that it's fairly basic wiring. The USB bus is a 4/5 wire bus
with the fifth wire commonly used as earth, this nearly always the
outer shell of the USB connector. Just make sure that the pins all
correspond and your away. No technical challenges what so ever.

Hope this helps a little.

Seri

Bill  wrote:

> Not sure if anyone has tried this before, but here goes...
> 
> I have an existing CAT5 cable running between the downstairs and
> upstairs of my house, length around 10 metres. Each end terminates on
> a wallbox.
> 
> I'm now in a position where I would like to connect a downstairs USB
> device (my Topfield PVR) to the PC upstairs.
> 
> The run length is too long for USB reliably, so I am considering a USB
> CAT5 extender. I could run in another CAT5 cable for this, but it
> would be a bit of a pain. HOWEVER, 10/100 BaseT network connections
> only use 2 of the 4 available twisted pairs, hence I have 2 spare


The cable doesn't make a difference, you don't get any greater distance
by going to CAT5.
Obtain a hub.
Plug it into the middle of the run, on two 5m cables.
Job done.

In article <431f801c$0$17473$ed2e19e4@ptn-nntp-reader04.plus.net>, 
root@mauve.demon.co.uk says...

> Bill  wrote:
> > Not sure if anyone has tried this before, but here goes...
> > 
> > I have an existing CAT5 cable running between the downstairs and
> > upstairs of my house, length around 10 metres. Each end terminates on
> > a wallbox.
> > 
> > I'm now in a position where I would like to connect a downstairs USB
> > device (my Topfield PVR) to the PC upstairs.
> > 
> > The run length is too long for USB reliably, so I am considering a USB
> > CAT5 extender. I could run in another CAT5 cable for this, but it
> > would be a bit of a pain. HOWEVER, 10/100 BaseT network connections
> > only use 2 of the 4 available twisted pairs, hence I have 2 spare
> 
> The cable doesn't make a difference, you don't get any greater distance
> by going to CAT5.


But he said he was going to use a USB-to-Cat5 extender, which is not the 
same as just using Cat5 cable with a USB plug on each end.


> Obtain a hub.
> Plug it into the middle of the run, on two 5m cables.
> Job done.
> 

Better to use an active USB extension cable, which is effectively a 
single port self-powered hub designed for precisely this purpose.

On Thu, 8 Sep 2005 01:43:16 +0100, Rob Morley 
wrote:


>In article <431f801c$0$17473$ed2e19e4@ptn-nntp-reader04.plus.net>, 
>root@mauve.demon.co.uk says...

>> 
>> The cable doesn't make a difference, you don't get any greater distance
>> by going to CAT5.
>
>But he said he was going to use a USB-to-Cat5 extender, which is not the 
>same as just using Cat5 cable with a USB plug on each end.
>


Precisely, that was my intention. USB-CAT5 extenders are good for
several tens of metres of usable distance.



>> Obtain a hub.
>> Plug it into the middle of the run, on two 5m cables.
>> Job done.
>> 
>Better to use an active USB extension cable, which is effectively a 
>single port self-powered hub designed for precisely this purpose.


A hub in the middle of the run would end up sitting on the outside
wall of the house! Am now looking into active extension cables. 

Cheers.

Seri wrote:

> Okay, first things, is it a USB 1.1 or a USB 2 device that you want to
> extend? If it's a USB 2 device then make sure that you don't mind it
> dropping down to being USB 1.1 performance as USB 2 only has very
> severe drop off range.
> 
> Second, make darn sure that you split the other end of the cable before
> it plugs into your router/switch/hub/modem/etc other wise you may blow
> the poor thing up.
> 
> Third, be prepared for the performance of the network cable to drop
> down to about 25mbps due to the ammount of interference on the line
> (packet collisions, dropped packets, retransmissions etc).
> 
> Other than that it's fairly basic wiring. The USB bus is a 4/5 wire bus
> with the fifth wire commonly used as earth, this nearly always the
> outer shell of the USB connector. Just make sure that the pins all
> correspond and your away. No technical challenges what so ever.
> 
> Hope this helps a little.
> 
> Seri
> 


Unfortunately this isn't how the USB over CAT5 devices work - you would 
run into the 5m limit straight away.  The 5m limit is NOT attenuation, 
it's timing  - signal reflections, and while you can push it to ~6m in 1 
section this isn't reliable.  The USB-over-CAT5 senders normally show up 
as a hub (just 1 for the 2 units and cable) becuase the USB timing spec 
allows for some delay in the hub.

btw USB cabling consists of Data+, Data-, +5V, 0V and screen. D+ and D- 
are often thinner than the power connectors.

-- 
Spamtrap in use
To email replace 127.0.0.1 with blueyonder dot co dot uk

Bill wrote:


> 
> Precisely, that was my intention. USB-CAT5 extenders are good for
> several tens of metres of usable distance.

I have used 2 models.  1 is from CPC, about 30 and seems reliable.  The 
other was around 200 but was one of the first to come on the market a 
few years ago.  I had 2 failures out of 4 (1 DOA, and 1 after about a 
year).  I know for a fact having asked your original question direct to 
the manufacturer (small UK firm and I got through to the design 
department) that it uses all 8 cables.  IIRC a pair was used for +5V, a 
pair was used for 0V and the other 2 pairs for the data in a proprietary 
way.  I can't promise this holds for the newer cheaper ones, but it's 
likely (if you consider wire gauges, currents and voltage drops).

I think it'll have to be a new length of cta5 (or use the old one and 
run your LAN over wireless)

Chris

-- 
Spamtrap in use
To email replace 127.0.0.1 with blueyonder dot co dot uk