4.3 FOUR-WIRE, MULTIPOINT INSTALLATION
Multipoint operation involves the connection of several terminals to
one host port. In such an application, one local Model 1080A/1080A-64
is used as a master unit, and it is connected to several remote Model
1080A/1080A-64s that are acting as slaves. Up to 25 Model 1080A
Series slaves may be connected to one host Model 1080A Series
master SRM, provided that the computing hardware and software
support that many terminal drops.
In a multipoint environment the master Model 1080A or 1080A-64
transmits continually. Initiation of two-way communication is carrier-
controlled by each “slave” Model 1080A Series unit. To facilitate
multipoint communication, the master Model 1080A-64 should have its
carrier control DIP switch set to “constantly ON” (S1-8=OFF). Each
slave Model 1080A Series unit should have its carrier control DIP
switch set to “controlled by RTS” (S1-8=ON). Figure 4 illustrates a
typical Model 1080A Series multipoint application.
4.3.1 Multipoint Twisted Pair Connection
The Model 1080A Series supports multipoint applications using a
star topology. Maximum distance between the units will vary based
upon the number of drops, data rate, wire gauge, etc. Call Patton
Technical Support for specific distance estimates. Figures 11 and 12
show how to wire the one-pair and two-pair cables properly for a Model
star topology. Note that the ground connection is not needed.
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Figure 4. Typical multipoint set-up
4.4 RS-232 CONNECTION
Connect the synchronous or asynchronous output of your RS-232
device to the DB-25 interface on the rear panel of the Model 1080A
Series. Note: The Model 1080A Series is wired to connect to a DTE.
If your RS-232 output device is DCE, call Patton Technical Support at:
(301) 975-1007; http://www.patton.com; or, [email protected]
for specific installation instructions.
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HOST
FIRST SLAVE
SECOND SLAVE
XMT
RCV
RCV
XMT
RCV
RCV
RCV
XMT
XMT
RCV
XMT
XMT
HOST
FIRST SLAVE
SECOND SLAVE
XMT
XMT
XMT
XMT
XMT
XMT
