Allied Telesis AT-200 Series CentreCOM - Handbuch (Seite 13)

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The SQE/Heartbeat is factory set to the “0” (disabled) position. Unless your
application calls for the heartbeat signal to be enabled, leave this switch in the “0”
position. (See “Heartbeat configuration” on page 1.)
Figure 4: AT-200 with N-Series Thicknet Backbone Connector (AT-208)
Data cabling considerations. When configuring 10BASE5 coax segments,
IEEE 802.3 specifications provide the following rules to follow:
❑ MAU attachments limited to 100 per segment
❑ MAU attachments spaced at multiples of 2.5 meters (8.2 ft.) measured
accurately from the cable end (50
Ω
terminator included)
❑ Segment length cannot exceed 500 meters (1,640 ft.)
❑ Worst case “end-to-end” propagation delay for the segment is 2165 ns

Propagation delay of 10BASE5 Ethernet coax is calculated at 4.33 ns/
meter
❑ Both ends of the segment must be terminated with a 50
Ω
termination with a
power rating of 0.5 watts or greater
❑ Earth grounding of the segment shield must take place at only one point on
the cable
Attach the N-series tap to cable
1. Attach 10BASE5 coaxial cable, using male N-series connectors, to either
end of the transceiver’s N-series connector.
There is no internal termination on the AT-200 series transceiver. Be
sure both sides of the N-series connector on the tap body are connected
to a cable.
2. Be sure the cable is terminated at both ends. Figure 3 on page 5 shows a
terminator installed at one end of a thicknet segment.
Note
613-10423-00Book Page 6 Monday, March 4, 1996 2:29 PM