ST 500 "Piranha" Operation Manual: Supplement #3 - Reference Information
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12. SUPPLEMENT #3. REFERENCE INFORMATION.
12.1. "TWISTED PAIR" CABLE
A twisted pair cable is a type of cable that consists of one or several twisted pairs,
i.e.
,
insulated conductor strands twisted together with relatively few windings per length unit and
enclosed in an outer plastic casing.
Twisting helps increase consistency between two cores of a pair (as electromagnetic
interference from external sources will affect them equally) and to reduce electromagnetic
interference, both external and mutual, when differential signals are being transmitted.
In order to reduce interaction of different pairs in a bundled twisted pair cable, cables of the 5
th
category or higher utilize twisted pairs with different numbers of windings per length unit.
Twisted pair cables are widely used in telecommunications and computer networking, and most
typically consist of one, two, or four twisted pairs.
12.2. RJ CONNECTORS
RJ (Registered Jack) is a standardized physical network interface comprising both connectors
('plug' and 'socket') and their connection scheme. It is widely used in telecommunications. The
most common standards of this kind are RJ11, RJ14, RJ25, and RJ45.
Standard
Scheme
Number of
pins
Purpose
RJ9
4P4C
4
connecting telephone handsets to their bases
RJ11
6P2C
2
connecting two-wire telephone sets to the network
RJ12
6P6C
6
connecting 6-wire telephone sets
RJ11
6P4C
4
connecting 4-wire telephone sets
RJ21
50-pin
50
connecting PBX's or other telecom equipment (sometimes
also called "Telco" or "Amphenol")
RJ25
6P6C
6
connecting 6-wire telephone sets
RJ45S
8P4C with key
4
connecting modems
RJ45
8P8C
8
creating local area networks
RJ50
10P10C
10
used by UPS units made by American Power Conversion and
Eaton Corporation
In the notation "xPyC", the letter "P" stands for 'Positions'
in a plug, and "C", for "Contacts" in a socket.
12.3. WIRING SCHEME OF A FOUR TWISTED PAIR CABLE
For 10Base-T and 100Base-T Ethernet standards, four cores (orange and green pairs) are
used, while the remaining four are reserved for the Gigabit Ethernet (1000Base-T) standard.
There are two wiring schemes, 568A and 568B. The latter is more frequent
.