Believe it or not this is a pretty popular
question. With all the different types of interfaces (Serial, Parallel, 10BaseT, 100BaseT, USB,
IEEE1394 FireWire, IEEE1284 Parallel
and Antenna for Wireless networks) it gets pretty crazy so
lets see if we can make it a little easier on you.
Serial:  To determine the
maximum length, some will say that the total capacitance cannot exceed 2500 pF.
Every cable has a "capacitance per foot" rating (Click here
to see the capacitance per foot on our common wires). In order to determine the
total capacitance, just take the capacitance per foot and multiply it by the
length in feet. Or to determine the maximum length on a cable, take 2500 and
divide it by the capacitance per foot. For example, if you have a wire that's
15 pF/Ft, and made a 150 foot cable with it. The total capacitance is 15 pF/Ft
times 150 feet or 2250 pF, still within the limit. On the other hand, you want
to determine the maximum length of this 15 pF/Ft wire, take 2500 and divide it
by 15 to get 167 feet as the maximum length.Examples  15 pF/Ft x
150 feet = 2250 pF  2500 pF (max.) ÷ 15 pF/Ft = 167 feet
(max.)  To see our list of serial products, click one
of the following categories:  10BaseT or 100BaseT:  The total length of wire
segments between a PC and a hub or between two PC's cannot exceed 100 Meters
(328 feet or about the length of a football field). To see a list of our
networking products, click one of the following categories: 10BaseT and 100BaseT, NIC, Repeaters, Hubs, Switches, Print servers,
Transceivers, or Converters.  IEEE1284 Parallel:  With the older style
"Centronics" parallel, the length limit is typically 9 to 12 feet although some
30 foot connections have worked. The IEEE1284 can go up to 50 feet in length.
To see a list of our parallel products, click one of the following categories:
Parallel, IEEE1284.Converters, Extenders, IEEE1284
Auto switch boxes, Parallel Auto switch
boxes.  USB:  In
practice, the USB specification limits the length of a cable between full speed
devices to 5 meters (a little under 16 feet 5 inches). For a low speed device
the limit is 3 meters (9 feet 10 inches). most manufacturers do not recommend
and will not support cables longer than 10 feet, although there are active
extensions available that will allow 16 feet runs and will daisy chain to give
you A total of 80 feet ADP3180216,
or extenders that will allow you to have a USB Run 150' over Cat 5 cable, ADP3184. To see
our manual switches for USB Click
Here  IEEE1394
FireWire:  FireWire cables use 28 AWG wire and are limited to 4.5
meters maximum cable length. To see a list of our FireWire products, click one
of the following categories: FireWire Converters, PCMCIA card
and Hubs 
Cable Capacitance Guide Antenna
cables:  Specifically antennas for wireless networks, the length
limit depends on the size of coax;*If the transmitter has a
stronger signal, the length can go further on
LMR600. 
