Db9 Null-Modem Cables (Rs-232); Db9 Null-Modem Cables (Rs-422); Db9 Straight-Through Cables (Rs-232/485) - Comtrol DeviceMaster MOD Series Hardware Installation And Configuration Manual

DB9 Null-Modem
Cables (RS-232)
DB9 Null-Modem
Cables (RS-422)
DB9 Straight-
Through Cables (RS-
232/485)
DeviceMaster MOD | UP Hardware Installation and Configuration Guide: 2000630 Rev. B
Use the following figure if you need to build an RS-232 null-modem cable. A null-
modem cable is required for connecting DTE devices.
Signal
TxD
RxD
RTS
CTS
DSR
DCD
DTR
GND
Note: You may want to purchase or build a straight-through cable and purchase a
null-modem adapter.
Use the following figure if you need to build an RS-422 null-modem cable.
Note: RS-422 pinouts are not standardized. Each peripheral manufacturer uses
different pinouts. Refer to the peripheral documentation to determine the
pinouts for the signals above.
Use the following figure if you need to build an RS-232 or RS-485 straight-through
cable. Straight-through cables are used to connect modems and other DCE
devices. For example, a straight-through cable can be used to connect COM2 to a
modem.
Signal
DCD
RxD
TxD or TRxD-
DTR
GND
DSR
RTS or TRxD+
CTS
RI
DB9
DB9
Pins
Pins
3
2
2
3
7
8
8
7
6
4
1
1
4
6
5
5
DB9
Signal
Pins
TxD+ 7
TxD- 3
RxD+ 8
RxD- 2
GND 5
DB9 DB9 RJ45
Pins Pins Pins
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
N/A
9 9
Connecting Serial Devices
DB25
RJ45
Pins
Pins Signal
RxD
3 5
TxD
2
4
CTS
5
8
RTS
4
1
DTR
20
2
DCD
8
6
DSR
6
7
GND
7
3
Signal
RxD+
RxD-
TxD+
TxD-
GND
DB25
Pins Signal
6
8
DCD
5 3
RxD
4 2
TxD or TRxD-
2
20
DTR
3
7
GND
7
6
DSR
1 4
RTS or TRxD+
8
5
CTS
22 RI
Connecting Serial Devices - 47