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Figure 8-9. Auxiliary serial port
and expansion board
When configured for RS-232 applications through the AUX port, neither of
the integrated chips U7 nor U8 (Figure 8-9) is installed in their respective
sockets on the expansion board. J4-5 (OUT) and J4-6 (GND) terminal
connections are used for output-only RS-232 communication. Output-only
20 mA Current Loop transmission is also available simultaneously on J4-4
(20 mA CL-) and J4-6 (20 mA CL+ ). See Table 8-2 below for terminal
connections.
Table 8.2.
Auxiliary serial port connection points on expansion board
AUX
RS-232
J4-1
J4-2
J4-3
J4-4
J4-5
RS-232 OUT
J4-6
RS-232 GND
When used for RS-485 applications, the AUX port can be configured to
operate as a transmitter-only on a multi-drop twisted-pair line. U7 must be
installed in the proper socket on the expansion board to configure the AUX
port as an RS-485 transmitter. Before installing U7, make certain that U8 is
not installed. J4-1 (RS-485-A) and J4-2 (RS-485-B) terminal connections
are used for RS-485 applications.
J2
J1
J3
RS-485
485-A
485-B
U7
U8
Integrated Chip U7
J5
must be installed for
RS485 Communication
onnAuxiliary Serial Port
20 mA
20 mA CL-
20 mA CL+
J4
1 2 3 4 5 6
J6
J7
Optional features
8-11
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