B. Network Components and Cabling
51
Fiber-Optic Usage
Fiber optic cable provides immunity to noise, cross-talk, and power surging, and allows
for greater cable run lengths. The use of this cable is generally limited to cases in which
the distance between two segments is too great for connection to be achieved with
media previously described. Fiber optic cable can be used to connect a node to a
segment or repeater in a star configuration in a manner similar to that of twisted-pair
wiring. Because of its higher cost, however, fiber optic cable is not generally chosen for
this purpose unless the application's requirements include noise immunity or
connections over large distances.
THIN ETHERNET CABLING
The on-board coaxial transceiver interface (8392) links the driver/receiver to the
external coax cable with a female BNC type connector designated J4. Refer to the
figure "
Frontplane Connectors
". The required cable, type RG58 A/U, contains a
stranded and tinned copper conductor with 50 ohms of nominal impedance (Belden
cable part number 9907 or equivalent).
Note:
Coaxial cable type RG58 U is similar in appearance to RG58 A/U but does not
comply with the IEEE Thin Ethernet standard.
Each Thin Ethernet cable is actually a point-to-point cable that connects each of the
network components together. The cables are fitted with a male BNC connector on both
ends.
Contact Ziatech's
Technical Support
for information regarding where to purchase
interconnecting components and products described in this appendix.
ZT 8995-D2 jumper
W10
must be installed to operate in a Thin Ethernet configuration.
Thin Ethernet "T" Connectors and Terminators
A "T" connector at the ZT 8995-D2 BNC interface provides connection to other Ethernet
components or cards on both sides of the T connector. Refer to the following figure,
"
Thin Ethernet Cable Segment
". Each connection between two nodes consists of a
point-to-point cable. Therefore, a network segment looks like one length of cable with
the network components tapped off the cable.
A 50 ohm (±2%) terminator at each end of the network cabling segment keeps the
correct amount of signal reflection on the line during the data communication. The
terminators install on the open side of the network component T connectors at the ends
of each segment. Proper termination is essential to maintaining a balanced network.
The importance of proper termination is underscored in the definition of a network
segment: a segment length is defined as the distance from one terminated end of the
cable to the other terminated end.
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