HP AD278A and AD279A PCI Multiplexer Support Guide, Edition 2 - September 2006

Peripheral Connections
RS-232 Asynchronous: DB-25
Appendix B
46
This cable is a three-wire null modem cable. Transmitted data on one end of the cable is connected to
Received data at the other end, and vice versa. The male DB-25 end can be plugged directly into most serial
terminals and printers without any adapters. The female DB-25 end plugs directly into any RoHS DB-25
serial port.
DB-25 4-Wire Hardware Handshaking (DTR) Cable
The four-wire cable is sufficient for an older terminal, printer, or other DTE (Data Terminal Equipment)
devices configured for DTR (hardware) flow control. However, some terminals and printers may use a signal
other than DTR (Data Terminal Ready) for flow control. In addition, some terminals and printers may have
other cable requirements. Consult your terminal or printer manual for this information. For more universal
compatibility, use a fully-wired DB-25 terminal/printer cable.
Table B-3 lists the pin-out connection between the DB-25 adapter and the DB-25 terminal/printer with DTR
handshaking.
IMPORTANT Some terminal or printer manufacturers may use different methods of flow control. Consult
your documentation for specific wiring requirements.
GND Shell Connected
(via shield)
to
Shell GND
Table B-3 Terminal/Printer C abl e with DTR Handshaking
DB-25 Female (Card End)
DB-25 Male (Peripheral)
Signal Pin Pin Signal
TxD 2 Connected to 3 RxD
RxD 3 Connected to 2 TxD
CTS 5 Connected to 20 DTR
SG 7 Connected to 7 SG
GND Shell Connected
(via shield)
to
Shell GND
Jumpered 4+5 RTS+CTS
Table B-2 Simple Terminal/Printer Cable (Continued)
DB-25 Female (Card End)
DB-25 Male (Peripheral)