Db25 Null-Modem Cables (Rs-422 Or Rs-485 Full-Duplex); Db25 Straight-Through Cables (Rs-232 Or Rs-485 Half-Duplex); Db25M: Fan-Out Cable Loopback Plugs; Db25F: Standard Interface Box - Comtrol RocketPort INFINITY User Manual

Connecting Serial Devices
DB25 Null-Modem
Cables (RS-422 or
RS-485 Full-Duplex)
DB25 Straight-
Through Cables (RS-
232 or RS-485 Half-
Duplex)
DB25M: Fan-out
Cable Loopback
Plugs
DB25F: Standard
Interface Box
16 - Connecting Serial Devices
Use the following figure if you need to build an
RS-422 or RS-485 full-duplex null-modem
cable. A null-modem cable is required for
connecting DTE devices.
Interface boxes have optional pins available
for these signals. Refer to
Signals on Page 15 for more information.
Note: RS-422 and RS-485 signals are not
standardized and each serial
manufacturer uses different pinouts. Refer to the serial device
documentation to determine the pinouts for the signals above.
Use the following figure
if you need to build an
RS-232 or RS-485 half-
duplex 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.
RocketPort INFINITY models with DB25 male connectors on the interface are
shipped with a a single loopback plug (RS-232/422).
Wire the following pins together to build additional
RS-232/422 plugs or replace a missing RS-232/422
loopback plug.
• Pins 2 to 3
• Pins 4 to 5 to 22
• Pins 6 to 8 to 20
You can wire the following pins together for an RS-422 only loopback plug.
• Pins 2 to 3
• Pins 4 to 5
RocketPort INFINITY models with DB25 female connectors on the interface box
are shipped with a a single loopback plug (RS-232/422).
Wire the following pins together to build additional
RS-232/422 plugs or replace a missing RS-232/422
loopback plug.
• Pins 2 to 3 or alternately, Pins 25 to 17
• Pins 4 to 5 to 22 or alternately, Pins 19 to 15 to 22
• Pins 6 to 8 to 20
You can wire the following pins together for an RS-422 only loopback plug.
• Pins 2 to 3 or alternately, Pins 17 to 25
• Pins 4 to 5 or alternately, Pins 15 to 19
RocketPort
Signal
TxD+
TxD-
Interface Box
RxD+
RxD-
RocketPort
DB25
Signal Pins
8
DCD
3
RxD*
2
TxD* or TRxD-
20
DTR
7
GND
6
DSR
4
RTS* or TRxD+
5
CTS*
RI 22
* Interface boxes have alternate pins available for this signal.
Refer to Interface Box Signals for more information.
RocketPort INFINITY User Guide: 2000465 Rev. G
DTE Serial
Device
DB25
Pins
Signal
4 RxD+
2 RxD-
5 TxD+
TxD-
3
DCE Serial Device
DB9
DB25
Pins Pins Signal
1
8
DCD
2 3
RxD
3 2
TxD or TRxD-
4 20
DTR
5
7
GND
6 6
DSR
7 4
RTS or TRxD+
8 5
CTS
9 22 RI
RS-232/422 (Back View)
Pin 1 Pin 13
Pin 14
Pin 25
Male
RS-232/422 (Back View)
Pin 13
Pin 25 Pin 14
Female
Pin 1