Figure 5 (below) shows how to wire the two-pair cables properly for
a Model 1004A star topology. Note that the ground connection is not
needed.
4.2.2 DAISY CHAIN TOPOLOGY
Using a daisy chain topology, you may connect several Model
1004As together in a master/slave arrangement. Maximum distance
between the units will vary based upon the number of drops, data rate,
wire gauge, etc. Call Technical Support for specific distance estimates.
Figure 6 (below) shows how to wire the two-pair cables properly for
a Model 1004A daisy chain topology. Note that the ground connection
is not needed.
Optional Connection: Dual Modular Jacks
To facilitate daisy chaining, the Model 1004A is available in a
“DRJ11” (dual RJ-11) or “DRJ45” (dual RJ-45) version. These units
have two specially wired modular jacks for twisted pair connection.
With the dual modular units, you won't need to build cumbersome
“Y” cables for your daisy chain application. Simply use a crossover
cable to go between the host and the first slave (see Section 4.1.2 for
crossover cable wiring instructions), and straight through cables
between the slaves.
4.3 CONNECTION TO THE RS-232 INTERFACE
Once you have properly configured the Model 1004A and
connected the twisted pair wires correctly, simply plug the Model 1004A
directly into the DB-25 port of the RS-232 device. Remember to insert
and tighten the two captive connector screws.
(Note: If you must use a cable to connect the Model 1004A to the
RS-232 device, make sure it is a
straight through cable of the shortest
possible length—we recommend 6 feet or less).
4.4 OPERATING THE MODEL 1004A
Once the Model 1004A is properly installed, it should operate
transparently—as if it were a standard cable connection. Operating
power is derived from the RS-232 data and control signals; there is no
“ON/OFF” switch. All data signals from the RS-232 and RS-485
interfaces are passed straight through. Additionally, one hardware flow
control signal is passed
in each direction.
15
16
HOST
FIRST SLAVE
SECOND SLAVE
XMT+
RCV+
RCV+
XMT-
RCV-
RCV-
RCV+
XMT+
XMT+
RCV-
XMT-
XMT-
Figure 5. Star wiring for Model 1004A host and slaves
HOST
FIRST SLAVE
OTHER SLAVE(S)
XMT+---------------------RCV+ -----------------------RCV+
XMT- ---------------------RCV- -----------------------RCV-
RCV+---------------------XMT+ -----------------------XMT+
RCV- ---------------------XMT- -----------------------XMT-
Figure 6. Daisy chain wiring for Model 1004A host and slaves
