BNC cabling specifications
Specifications and recommendations for Thin Ethernet cable
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The EtherExpress(TM) 16 adapters have a cylindrical, bayonet
BNC connector.
BNC cabling is also known as thin Ethernet, RG-58A/U, Cheapernet,
and 10BASE-2.
This document contains cabling and installation recommendations.
For more information on thin Ethernet cabling,contact your local
network supplier or call the IEEE at 1-800-678-IEEE.
Recommended cables
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Here is a list of IEEE approved and non-approved cables.
Approved cable types
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802.3 10Base2 50 ohms, stranded tinned core
RG-58 a/u 50 ohms, stranded tinned core
RG-58 c/u 50 ohms, stranded tinned core
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NON-Approved cable types
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RG-58 50 ohms, solid center core
RG-58 u 50 ohms, solid center core
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Installation recommendations
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Thin Ethernet is a linear bus topology that uses a COAX cable.
A break in the cable will disrupt the entire segment.
Each node is connected to the cable using a T-connector.
- Don't connect the end of the cable directly to the BNC connector
on the EtherExpress card.
- Don't use cable drops or external transceivers unless you are
using the AUI connector instead of the BNC connector.
Both ends of a trunk must be terminated with 50 ohm terminators. One
end should be grounded.
Up to 5 trunk segments may be connected (through repeaters), but only 3
of these segments can have workstations attached. Repeaters count as a
workstation so if you have two repeaters on a segment, then the maximum
number of user workstations is 28.
Example:
terminator no workstations no workstations terminator
| | | |
v v v v
|--+----------+ +--------+ +------+-------+ +--------+ +----+----|
| | | | | | | | | | |
| repeater repeater | repeater repeater |
| | |
workstation workstation workstation
1-29 1-28 1-29
Cable lengths
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Max trunk length 185 meters (607 feet)
Max number of nodes per trunk 30
Max number of trunks 5 (only 3 can have wkst attached)
Max length of entire network 925 meters (3035 feet)
(all trunks added together)
Min cable length between nodes .5 meters (1 1/2 feet)
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