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(see Appendix A). See note below for required pairs.
INVERTED PAIRS: If any of the pairs are present but have incorrect
polarity (i.e. the "1,2" pair is really "2,1") the pair's LED will light
red. A cable with an inverted pair will also cause the Main Unit's
Data and Link LEDs to light red when performing tests using the
10/100/1000 LAN TEST jack. Inverted pairs can slow down or stop
a link.
PAIR NOT PRESENT: The LEDs will not light, if the pair does not
exist or if the pair is shorted across itself.
STRAIGHT THRU OR CROSSOVER: If the LEDs light in a
top-down order, the cable is wired in a straight thru configuration
(e.g. "1,2" to "3,6" to "4,5" to "7,8" indicates a straight thru cable
connection. If the LEDs light in a bottom-up order, the cable is wired
crossover configuration (e.g. "7,8" to "4,5" to "3,6" to "1,2") indicates
a crossover cable). LEDs not lighting in order indicates pairs may
be swapped.
SHORTED PAIRS: If a pair is shorted across itself, it will show up
as a non existent pair (LED will be OFF). If the short is across pairs
it will either light one pair red and the other green (simultaneously)
or an individual LED will alternate red and green. Summary: Any
red color indicates a wiring problem.
Notes: If pairs "1,2" and "3,6" are not both present, there is no
possibility of communication. If pairs "4,5" or "7,8" are not present,
data rates maybe impaired (some 100 MB/s systems and all 1000
MB/s require 4 pairs). The Remote Probe will not interfere with an
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Appendix A. Wiring Primer.
Twisted Pair Cable: Base-T LANs are based on a star topology
(every PC on the network is linked to a central location). The central
location is termed a hub or switch. The cabling is always twisted
pair wire terminated with 8 position modular connectors (RJ45).
PC and Hub/Switch defined: A "PC" transmits on a pair of wires
that use pins 1 and 2 ("1,2"). A "hub" and switch transmits on pins 3
and 6 ("3,6"). The TVR1000 bases its testing on this standard.
Cable types: A "straight thru" cable connects a PC to a hub and
does not change the wiring of the cable (e.g. pins 1 and 2 are con-
nected to pins 1 and 2, etc). A "crossover cable" swaps the transmit
and receive pairs of the connection (pins 1 and 2 are connected to
pins 3 and 6). The TVR1000 includes two straight thru patch cables.
Connecting Devices: Base-T devices (PCs/hubs/switches) are
connected together by connecting the "Transmit pair" from one
device to the "Receive pair" of the other. A "PC" transmits on pins
1 and 2 ("1,2"). A hub and a switch transmit on pins 3 and 6 ("3,6").
Because of these pinouts, a PC connects to a hub or switch with a
straight-thru cable. It follows that two hubs or switches connected
together require a crossover cable (the same is true for two PCs
connected together). Autocrossover: Some devices adapt them-
selves to either straight thru or crossover configuration, depending
on what is required. During Single Port Testing, the TVR1000 will
light LEDs in both the "PC" and "Hub" columns if a device has
autocrossover capability.
Number of pairs: All 10 Base-T and most 100 Base-T devices
(called 100 Base-TX) use 2 pairs to function but 100 Base-T X4
devices and all 1000 Base-T devices require 4 pairs.
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