Optelecom 9522A Installation And Operation Manual page 32

RS422 and RS485 Connections
When operation with RS422 or RS485 is required, make the connections as listed in Table 10. In RS422 or RS485
model there are no RTS or CTS control lines. Rather the RTS and CTS signals are internally enabled. The RTS and
CTS indicator will always be illuminated when the unit is operated with RS422/RS485 data. Refer to the Priority
Select section in System Architecture, for additional considerations when operating in RS485 2-wire mode.
Table 10 — RS422/RS485 Pinouts, Primary and Secondary Data Ports
Identification
RS422/RS485 4-wire TD (+) input
RS422/RS485 4-wire TD (–) input
RS422/RS485 4-wire RD (+) output
RS422/RS485 4-wire RD (–) output
RS485 2-wire Data (+) input/output
RS485 2-wire Data (–) input/output
Ground
 External Master/Local Control Connection. The Local/Master mode may be externally controlled by attaching
an external contact closure between Pin 18 and Pin 7 of the Secondary Data Port. Alternately, an active LOW
TTL logic level may be input to Pin 18. With this feature, different units in a network may serve as the master
at different times. NOTE:
or LOCAL position.
pulled to ground, the unit will switch to MASTER mode. Care must be taken to insure that any user logic or
controls used to drive this input allow only one master unit in a redundant ring at a time.
F 10
IGURE
To use this feature the internal Master/Local dipswitch, S12, must be in the UP (OFF)
When this input is left open, the unit will remain in LOCAL mode. When shorted, or Pin 18 is
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Pin Numbers
11
10
13
12
11
10
7