Black Box FALLBACK RS-232 Prospecto

Compliance: FCC Part 15, Class A;

DOC Class/MDC classe A; CE

Compatibility: Compatible with

dialup modems using ITU-TSS
V.34, V.32 bis, V.32, and most
other major modem standards

Data Format: Transparent to data

format

Data Rate: Up to maximum rate

supported by cabling

Distance (Maximum): 50 ft. (15.2 m)

to any attached RS-232 device
using standard cables

Flow Control: Transparent to flow

control, but monitors/ switches
on DSR, CTS, or RLSD (DCD); also
passes or forces DTR

2 through 6, 8, 15, 17, 20 through
22, and 24 (TD, RD, RTS, CTS,
DSR, RLSD [CD], TSETC [TC],
RSETC [RC], DTR, RI, and TSETT
[EXTC] respectively); 1 and 7
(PGND and SGND respectively)
are tied common

User Controls: (1) front-mounted

toggle switch for selecting
automatic/ primary/alternate;
(4) internal configuration jumpers

MTBF: 180,000 hours

Interfaces: EIA RS-232C, modular

telco

Connectors: (3) rear-mounted

DB25 F: Common (master),
primary, and alternate ports

Indicators: (2) front-mounted LEDs

showing active channel
(ALT/PRI)

Temperature Tolerance: Operating: 

32 to 122˚F (0 to 50˚C);

Storage: -4 to +158˚F

(-20 to +70˚C)

Humidity Tolerance: Up to 95%

noncondensing

Enclosure: High-impact ABS plastic

Power: SW901A: 115 VAC, 60 Hz, 

through detachable power 
cord (included) and internal 
power supply;

SW901AE 230 VAC, 50 Hz, 

through detachable power 
cord (not included) and 
internal power supply;

Consumption (both models): 

8 watts

Size: 2.5"H x 8"W X 12"D 

(6.4 x 20.3 x 30.5 cm)

Weight: 2.7 lb. (1.2 kg)

• The RS-232 Fallback Switch

• Detachable power cord

• Users’ manual

Package Includes

Specifications

RS-232 Fallback Switch

115-VAC....................................................................SW901A
230-VAC..................................................................SW901AE

You may also need…
RS-232 Cable, 25 Conductors (12

1

⁄

2

Pairs)—Pins 1–25

(Specify gender and length)................................ECM25C

Dedicated 

Modem (A)

Dialup

Modem (B)

Dialup
Circuit

Dedicated

Line

Server

Typical Application

procedure includes:

• Running cable from your

primary modem (or other
device) to the rear-panel
PRIMARY connector.

• Running cable from your

alternate modem (or other
device) to the rear-panel
ALTERNATE connector. 

• Running cable from the

master or common device
(server, PC, host, printer,
etc.) to the rear-panel
MASTER connector.

• Attaching the switch’s

power cord.

The RS-232 Fallback Switch

begins operating when it
receives power. The type of
switching, whether it’s automatic
or manual, is determined by the
position of the front-panel toggle
switch. LEDs light up to show
whether it’s switched
(automatically or manually) to the
primary device, or if it’s switched
to the alternate device.

NOTE: For all DCE connections to the the PRIMARY and ALTERNATE
connectors, use straight-through pinned RS-232 cable. For DTE
connections to the same ports, you’ll need specially cross-pinned cable
(for details, call Black Box Tech Support). For DTE connections to the
MASTER connector, use straight-through-pinned RS-232 cable. To
attach a DCE device to the MASTER port, use specially cross-pinned
cable (for details, call Black Box Tech Support).