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4.0 INSTALLATION
The Model 1080A Series operates in four twisted pair topologies: 2-
wire/point-to-point,
2-wire/multipoint,
4-wire/point-to-point,
and
4-
wire/multipoint. In each of these topologies, the twisted pair wire must be
19 - 26 AWG "dry", unconditioned metallic wire (see Appendix C for wire
recommendations). Dial-up analog circuits, such as those used with a
standard Hayes-type modem, are not acceptable. The twisted pair may
be shielded or unshielded. Both types yield favorable results.
The Model 1080A Series offers two methods of twisted pair connection:
RJ-45 jack and terminal blocks. Figure 3 shows the location of these
interfaces on the rear panel of the Model 1080A Series. Connect the wire
to each Model 1080A Series as described in the instructions that follow
the illustration. The "+" and "-" indicators are for reference only. The
Model 1080A Series is not sensitive to polarity.
Made In the USA
RX+ RX- GND TX- TX+
12V, 2A
RS-232 Interface (Female)
Line
Figure 3. Rear view of Model 1080A Series - AC Power
Made In the USA
RX+ RX- GND TX- TX+
Power
+ -
RS-232 Interface (Female)
Line
Figure 4. Rear view of Model 1080A Series - DC Power
4.1 TWO-WIRE INSTALLATION
When communicating over a single twisted pair circuit, the Model 1080A
Series operates half duplex: that is, it transmits in only one direction at a
time. This method of operation is effective for both point-to-point and
multipoint applications.
In single-pair point-to-point applications, you will need a pair of Model
1080As for each circuit—one at each end of the single pair wire. In sin-
gle-pair multipoint applications you will need three or more Model 1080A
Series units. These can be connected using a star topology, although a
daisy chain topology is usually used.
15
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