Optelecom 9525AY/SM-FC Installation And Operation Manual page 22

Table 4 – RS232 Pinouts on DB25S Connector
Pin # Identification
2 Transmit Data (TD)
3 Receive Data (RD)
4 Request to Send (RTS)
5 Clear to Send (CTS)
6 Data Set Ready (DSR)
7 Signal/Chassis Ground
8 Carrier Detect (CD)
2.7.2 RS422 and RS485 Connections
When operation with RS422 or RS485, refer to table 5 for the pinouts. 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
section 2.3.4, Priority Select, for an additional consideration when operating in RS485 2 wire mode.
Table 5 – RS422/RS485 Pinouts on DB25S Connector
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
2.7.3 Expansion Port
When using the expansion port to branch the network, wire the EXP port to the DB25 port on a second
Model 9525AY. See the figure below for cable wiring diagram. NOTE: The extended 9525AY must be in
RS232 mode.
Input/Output to modem and auxiliary information.
Input to model 9525AY
Output from model 9525AY
Input to model 9525AY
Output from model 9525AY
Normally high, goes low if there is a fault (FAULT
LED on)
Fixed Pull-up resistor to +5 VDC output from
Model 9525AY
Pin Numbers
11
10
13
12
11
10
7
22