Switch S3-6: RS-232 Initiation of Remote Loopback Test
The setting for switch S3-6 determines whether or not the Model
1080A Series’ remote digital loopback test can be initiated by raising
pin 21 on the RS-232 interface.
S3-6
Setting
On
RS-232 initiation enabled
Off
RS-232 initiation disabled
Switches S3-7 and S3-8: Anti-stream Control
Switches S3-7 and S3-8 are set in combination to determine the
time out period for the Model 1080A Series’ anti-stream control timer.
S3-7
S3-8
Setting
Off
Off
Disabled
Off
On
12.5 seconds
On
Off
50.0 seconds
On
On
12.5 seconds
11
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 (below) 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.
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 1080A or 1080A-64s for each circuit—one at each end of the
single pair wire. In single-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.
12
Figure 3. Rear view of Model 1080A Series
RS-232 Interface (Female)
Made In the USA
Line
Power
Powered Short Range
Modem
RX+ RX- GND TX- TX+
