Connecting to the serial ports – B&B Electronics USR604 - Manual User Manual
Page 20
Section 5 - Hardware Installation
Page 20 of 45
Document Number: USR60x-0812m
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(-)
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2
Receive Data (RD)
RDB(+)
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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)
---
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7
Request To Send (RTS)
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8
Clear To Send (CTS)
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9
Not Used
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