Comtrol RocketPort Plus Universal PCI - Manual (Page 13)

RocketPort Plus Universal PCI User Guide: 2000369 Rev. C Connecting Serial Devices - 13
Connecting Serial Devices
DB25 Null-Modem
Cables (RS-232) The following image displays the
pinouts for an RS-232 null-
modem cable.
Note: You can also attach a null-
modem adapter to one end
of a straight-through cable
to create a null-modem
cable.
RS-422 pinouts are not
standardized. Each serial device
manufacturer uses different
pinouts. Refer to the serial device
User Manual to determine the signals.
Note: You can also attach a null-modem adapter to one end of a straight-through
cable to create a null-modem cable.
DB25 Straight-
Through Cables (RS-
232) Use the following figure if you need to build an RS-232 straight-through cable.
Straight-through cables are used to connect modems and other DTE devices. For
example, a straight-through cable can be used to connect COM2 of one PC to a
modem.
TxD
RxD
RTS
CTS
DSR
GND
DCD
DTR
Signal
RxD
TxD
CTS
RTS
DTR
GND
DCD
DSR
Signal
DB9
2
3
8
7
4
5
1
6
Pins
DB25
3
2
4
7
8
6
Pins
20
5
DB25
2
3
4
5
6
7
8
20
Pins
RI RI 9 22 22
RocketPort DTE Serial Device
DB9
1
2
3
4
5
8
6
7
Pins
DCD
RxD
TxD
DTR
GND
CTS
DSR
RTS
Signal
DB25
8
3
2
20
7
5
6
4
Pins
DCD
RxD
TxD
DTR
GND
CTS
DSR
RTS
Signal
RI 22 9 RI
DB25
8
3
2
20
7
5
6
4
Pins
22
RocketPort DCE Serial Device