Allied Telesis AT-200 Series CentreCOM - Handbuch (Seite 15)

8
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
. )
Data cabling considerations. When configuring 10BASE2 coax segments,
IEEE 802.3 specifications provide the following rules to follow:
❑ MAU attachments limited to 29 per cable segment
❑ MAU attachments spaced at no less than 0.5 meter (1.64 ft.)
❑ Segment length cannot exceed 185 meters (607 ft.)
❑ Worst case propagation “end-to-end” propagation delay for the segment is
950.9 ns

Propagation delay of 10BASE2 Ethernet cable is 5.14 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 BNC connector to cable
1. Plug a BNC-T connector into the BNC receptacle.
2. Plug in the 10BASE2 coaxial cable. If the AT-200 series transceiver is
between nodes on the cable, attach a thin coax segment to each side of the
T-connector. If the transceiver is at the end of the segment, attach a thin
coax segment to one side of the T and a 50
Ω
terminator to the other side as
shown in Figure 7.
Figure 7: BNC-T with 50
Ω
Terminator
There is no internal termination on the AT-200 series transceiver. Do
not plug a thinnet coaxial cable directly into the BNC connector on the
tap body without a T-connector.
Attaching AUI drop cables (for all models)
Data cabling considerations. AUI or Drop cables are governed by the
following IEEE 802.3 specification rules:
❑ Length cannot exceed 50 meters (164 ft.)
❑ Attachments may be made only to the cable ends at the 15-pin
D-subminiature connector
Thinnet
terminator
Cable
Note
613-10423-00Book Page 8 Monday, March 4, 1996 2:29 PM