Black Box 38892-R2 User manual

Support up to 4, 8, or 16 channels over
fiber optic cable in limited-distance applications.
Support up to 4, 8, or 16 channels over
fiber optic cable in limited-distance applications.
4-, 8-, and 16-Port Fiber Optic Muxes
© 2007. All rights reserved. Black Box Corporation.
FREE 24-hour Tech Support: 724-746-5500
blackbox.com

2 of 3
6/7/2007
#22505
724-746-5500 blackbox.com
FEATURES
• Fiber optic multiplexor and line driver
in one compact unit.
• Ideal for limited-distance applications.
• Easy to install—no option switches to
set.
• Transparent to speed and protocol.
• Operates at distances up to 10,000 feet
(3048 m) over duplex multimode fiber
optic cable.
• Supports software (X-ON/X-OFF)
flow control.
Use the multimode fiber optic cable in your small-to-medium-sized campus
to connect 16 PCs to an async host up to 10,000 ft. (3048 m) away
with the 16-Port Fiber Optic Mux.
OVERVIEW
Why buy a mux and a line driver separately when you can
get both in one convenient package. If you have fiber optic
cable installed in your small-to-medium-sized campus,
consider our 4-, 8-, or 16-Port Async Local Fiber Optic RS-232
Muxes.
These async time-division multiplexors support up to 4,
8, or 16 channels at speeds up to 19.2 kbps (38890-R2 or
38892-R2) or 64 kbps (38888-R2). And the integral line driver
for duplex multimode fiber gives you point-to-point
communications over short distances (up to 10,000 feet
[3048 m]).
Compared to statistical multiplexors and leased-line
modems, the TDM (Time-Division Multiplexor) and line-driver
combination offers a couple of advantages for limited-
distance applications:
• Although SPM (Statistical Packet Multiplexing) is very
efficient, it’s also much more expensive than TDM.
If you have limited distances to carry data, the fixed
bandwidth used by TDMs gets you more for your money.
• Leased-line modems are not used between devices in
the same building or close to each other. To send data
a short distance over private, point-to-point fiber optic
cable systems, you’d typically use a line driver.
Synchronization between Asynchronous Local RS-232
Muxes is maintained continuously with no operator control
required. A Sync Loss indicator on the front of the unit alerts
you if loss of sync occurs.
These muxes automatically adapt port speeds to the rates
of the individual terminals, without requiring a clock source.
All ports operate at maximum throughput levels with virtually
no multiplexing delay. As DTE speeds vary, high-speed
data sampling on each port makes the unit transparent to
error control, EIA signal propagation, or flow control.
16-Port Fiber Optic Mux
(38892-R2)
Async Host
PCs
16-Port Fiber Optic Mux
(38892-R2)
PCs

3 of 3
6/7/2007
#22505
724-746-5500 blackbox.com
TECH SPECS
Maximum Distance — 10,000 ft. (3048 m) over duplex multimode fiber
Multiplexing Technique — Time-division
Operation — Full duplex
Protocol — Async
Speed — 38892-R2, 38890-R2: 19.2 kbps;
38888-R2: 64 kbps
Interface — Channel: RS-232;
Composite: Dual ST®
Connectors — Composite: All: (2) ST;
Channel: 38888-R2: (4) RJ-45;
38890-R2: (8) RJ-45;
38892-R2: (16) RJ-45
Indicators — (3) LEDs: Power, Composite Data, Sync Loss
Power — 115-VAC, 60-Hz external power supply
Size — 38888-R2, 38890-R2: 1.7"H x 7"W x 5.3"D (4.3 x 17.8 x 13.5 cm);
38892-R2: 2.2"H x 7"W x 5.3"D (5.6 x 17.8 x 13.5 cm)
Weight — 38888-R2, 38890-R2: 2 lb. (0.9 kg);
38892-R2: 2.5 lb. (1.1 kg)
Item Code
Async Local Fiber Optic RS-232 Multiplexor
4-Port 38888-R2
8-Port 38890-R2
16-Port 38892-R2
Optional accessories include…
Telephone Bulk Cable EL08A
Fiber Optic Duplex Bulk Cable EXN062A
Modular Adapters
DB25 Male/RJ-45 for DTE 523951
DB9 Female/RJ-45 for DTE 523953
DB25 Female/RJ-45 for DTE 523954
DB25 Male/RJ-45 for DCE 523952
Time-division multiplexing.
TDM operates by dividing the available bandwidth into
fixed-duration segments. Each segment or channel is assigned
to a user and is given its own time slot to access the network.
First, information from Channel A is transmitted, then
information from Channel B, and so on in a regular sequence,
continually cycling back to Channel A. Bandwidth allocation is
static: Each channel receives a fixed amount of bandwidth,
preset by the network administrator.
TDM is a relatively inexpensive multiplexing technique and
is simple to implement, so it has typically been the first
multiplexing technique applied to any new high-speed
bandwidth service at first offerings. TDM introduces very little
signal delay, so it’s well suited to transport data, voice, and
video traffic, provided enough bandwidth is available.
The figure on page 2 shows a mux merging 16 data
channels over dual fiber optic cable. Each data channel can
achieve speeds of up to 19.2 kbps with the 38892-R2 or 38890-
R2, 64 kbps with the 38888-R2.
Technically Speaking
38892-R2
Why choose fiber?
Fiber optic cable offers several clear advantages over
twisted-pair:
• Using fiber completely eliminates the potential for
ground loops and electrical problems like crosstalk
(interference from an adjacent communication
channel).
• With fiber you also get more bandwidth and speed, as
well as longer distances, which means more data goes
farther faster.
Technically Speaking