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4.0 INSTALLATION
Once you have properly set the configuration switches, you are
ready to connect the Model 2085 to your system. This section tells you
how to properly connect the Model 2085 to the RS-485 and RS-232
interfaces, and how to operate the Model 2085.
4.1 CONNECTION TO THE RS-485 INTERFACE
To function properly, the Model 2085 must have one or two twisted
pairs of metallic wire. These pairs must be "dry" (unconditioned)
metallic wire, between 19 and 26 AWG (the higher number gauges may
limit distance somewhat).
For your convenience, the Model 2085 is available with several
different physical interfaces on the RS-485 side: DB-25 (following the
RS-520 standard), RJ-11 jack, RJ-45 jack, and terminal blocks with
strain relief.
4.1.1 4-WIRE CONNECTION USING THE DB-25
The DB-25 connector on the Model 2085's RS-485 side conforms to
the RS-530 interface standard. When connecting to an RS-485 device
that also conforms to the RS-530 standard, your cable should be
"crossed over" in the manner shown below:
MODEL 2085
SIGNAL
DB-25 PIN
XMT+
2 ...........................3
XMT-
14 ...........................16
RCV+
3 ...........................2
RCV-
16 ...........................14
NOTE: It is not necessary that the RS-485 device adhere to the RS-530
standard. However, you must make sure that the signals, polarities, and pairing
of your connection conform to the above diagram.
9
RS-485 (530) DEVICE
DB-25 PIN
SIGNAL
RCV+
RCV-
XMT+
XMT-
4.1.2 4-WIRE CONNECTION USING RJ-11 OR RJ-45
The RJ-11 and RJ-45 connectors on the Model 2085's RS-485 side
are pre-wired for a standard TELCO wiring environment. The signal/pin
relationships are shown below:
RJ-11
SIGNAL
1...................GND*
2...................RCV-
3...................XMT+
4...................XMT-
5...................RCV+
6...................GND
*Connection to ground is optional
1
2
3
4
5
6
In most modular RS-485 applications it is necessary to use a "cross
over" cable. The diagram below shows how a cross over cable should
be constructed for an environment where both the Model 2085 and the
RS-485 device use a 6-wire RJ-11 connector. Similar logic should be
followed when using RJ-45 connectors or a combination of the two.
MODEL 2085
SIGNAL
PIN#
GND
†
1 -------------------N/C
RCV-
2 -------------------4
XMT+
3 -------------------5
XMT-
4 -------------------2
RCV+
5 -------------------3
GND
6 -------------------N/C
†
10
RJ-45
SIGNAL
1 .................N/C
2 .................GND*
3 .................RCV-
4 .................XMT+
5 .................XMT-
6 .................RCV+
7 .................GND
8 .................N/C
1
2
3
4
5
6
7
8
RS-485 DEVICE
PIN#
RS-422 SIGNAL
XMT-
RCV+
RCV-
XMT+
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