Control Microsystems SCADAPack 32 - Figure 16: RS 485 Field Wiring - Four Wire Mode; Figure 17: RS 485 Field Wiring - Two Wire Mode

Figure 16: RS 485 Field Wiring – Four Wire Mode
9.6.4.2 Two wire mode
Two-wire operation uses one pair of wires for transmitting and receiving data. The +TX terminal
must be connected to the +RX terminal. The –TX terminal must be connected to the –RX terminal.
This pair of wires becomes the transmitting and receiving pair. See the figure below for an
illustrative example.
+T
X
–
T
X
–
R
X
+R
X
+TX/R
X
–
TX/R
X
+T
X
–
T
X
–
R
X
+R
X
+T
X
–
T
X
–
R
X
+R
X
5232
5232
5232
Other RS-
485 Device
Last station in network
may require terminations.
First station in network
may require terminations.
RS-485 network
4000 feet (1200 m)
maximum length
Figure 17: RS 485 Field Wiring – Two Wire Mode
SCADAPack 32 Controller Hardware Manual
May 24, 2006
34