B&B Electronics USR604 - Manual - Manual (Page 20)

Section 5 - Hardware Installation
Page 20 of 45 Document Number: USR60x-0812m
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Connecting to the Serial Ports
The USR602 provides two serial ports; the USR604 has four. DB-9M
connectors are used for RS-232, RS-422 and RS-485 two-wire and
four-wire connections.
Figure 10: DB-9M Serial Port Connectors
The following illustration shows the pin numbering of the DB-9M
connector.
Figure 11: DB-9F Pin Numbering
The following table shows the wiring pin-outs for RS-232, RS-422 and
RS-485 two-wire and four-wire connections.
Pins RS-232 (DTE) RS-422/RS-485 (4-wire) RS-485 (2-wire)
1 Data Carrier Detect (DCD) RDA(-) ---
2 Receive Data (RD) RDB(+) ---
3 Transmit Data (TD) TDB(+) DATA B(+)
4 Data Terminal Ready (DTR) TDA(-) DATA A(-)
5 Signal Ground (GND) GND GND
6 Data Set Ready (DSR) --- ---
7 Request To Send (RTS) --- ---
8 Clear To Send (CTS) --- ---
9 Not Used --- ---