USB Direct Cable Connection
Introduction
Serial and Parallel Direct Cable Connections are considered
to be a bit "old fashioned" these days.
USB Direct Cable Connection (DCC),
on the other hand, belongs in the "new fashioned" category
:) USB DCC is a few years old, but because most people would use their
network card to transfer data, the DCC hasn't been very well known for
the USB port, but does exist.... and the catch is that you
can't make it, but you must buy it ! But don't be tempted
to leave the page just as yet, there is a lot of information on USB
which is always good to know. Keep reading .... :)
Let's have a closer look and see what it's all about !
About USB
USB stands for Universal Serial Bus. Most peripherals
for computers these days come in a USB version. The USB port was designed
to be very flexible and for this reason you are able to connect printers,
external hard drives, cdroms, joysticks, scanners, digital cameras,
modems, hubs and a lot of other cool stuff to it.
The Universal Serial Bus gives you a single, standardized,
easy-to-use way to connect up to 127 devices to a computer. The 127
number is a theoretical number :) In practice it's a lot less ! The
devices you connect can even power through the USB port of your computer
if they draw less than 500mA, which is half an Ampere (I). A good example
is my little Canon scanner, it only has one cable which is used to power
the scanner up and to transfer the data to the computer !
Currently there are 2 versions of the USB port, the initial
version which is USB v1.1 and the newer version USB v2 which has hit
the market since the end of 2001. Most people have computers and devices
which use the first version, but all new computers will now come with
USB v2. This new version of the USB port is backwards compatible with
the older version and also a lot faster.
The table below compares the two USB ports so you can
see the speed difference:
Keep in mind that when you're using a USB DCC cable, you
won't get such great speeds, but somewhere around the 500KBytes/sec.
This also depends on the type of CPU, O/S, the quality of the cable
and electronic components and protocols running on your system.
Another thing which you should keep in mind is the Windows
operating system that supports the USB port:
The USB Cable
The USB standard uses A and B connectors to avoid confusion.
"A" connectors head "upstream" toward the computer,
while "B" connectors head "downstream" and connect
to individual devices. This might seem confusing to some, but it was
designed to avoid confusion between consumers because it would be more
complicated for most people to try and figure out which end goes where.
And this is what the USB cable and connectors actually
look like:
 
As mentioned earlier, the USB port can power certain devices
and also transfer data at the same time. For this to happen, the USB
port must have at least 4 cables of which 2 are for the power, and 2
for the data.
The diagram is to help you understand what the cable contains:
The USB DCC (Finally :) )
As I mentioned in the introduction of this page, the USB
DCC cable cannot be made, because it requires special electronic circuits
built around the cable. Parallel Technologies
manufacture USB DCC cables and they call it the "NET-LinQ":
 ..........................
The USB DCC cable can also be used to connect a computer
to your network. The way it works is pretty simple. Assuming you have
Computers A, B , C and D. Computer A, B and C are connected via an Ethernet
LAN and Computer D hasn't got a network card to connect to the network.
Using the NET-LinQ or other similar cables you can connect Computer
D with any of the other 3 computers as long as they have a USB port,
then by configuring the network protocols on Computer D, it will be
able to see and connect to the rest of the network !
This completes the discusion about USB Direct Cable Connection. |
