Black Box MX873A User manual

MAY 1998
MX873A
Miniature Local Mux-12
CUSTOMER SUPPORT INFORMATION
Order toll-free in the U.S.: Call 877-877-BBOX (outside U.S. call 724-746-5500)
FREE technical support 24 hours a day, 7 days a week: Call 724-746-5500 or fax [phone]
Mailing address: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018
Web site: www.blackbox.com • E-mail: [email protected]
INPUT
9V-DC
TEST POWER
SYNC LOSS
REM LOC

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MINIATURE LOCAL MUX-12
FEDERAL COMMUNICATIONS COMMISSION
AND
INDUSTRY CANADA
RADIO FREQUENCY INTERFERENCE STATEMENTS
This equipment generates, uses, and can radiate radio-frequency energy,
and if not installed and used properly, that is, in strict accordance with the
manufacturer’s instructions, may cause interference to radio communication.
It has been tested and found to comply with the limits for a Class A computing
device in accordance with the specifications in Subpart B of Part 15 of FCC rules,
which are designed to provide reasonable protection against such interference
when the equipment is operated in a commercial environment. Operation of
this equipment in a residential area is likely to cause interference, in which case
the user at his own expense will be required to take whatever measures may be
necessary to correct the interference.
Changes or modifications not expressly approved by the party responsible
for compliance could void the user’s authority to operate the equipment.
This digital apparatus does not exceed the Class A limits for radio noise emission from
digital apparatus set out in the Radio Interference Regulation of Industry Canada.
Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limites
applicables aux appareils numériques de classe A prescrites dans le Règlement sur le
brouillage radioélectrique publié par Industrie Canada.

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MINIATURE LOCAL MUX-12
NORMAS OFICIALES MEXICANAS (NOM)
ELECTRICAL SAFETY STATEMENT
INSTRUCCIONES DE SEGURIDAD
1. Todas las instrucciones de seguridad y operación deberán ser leídas antes
de que el aparato eléctrico sea operado.
2. Las instrucciones de seguridad y operación deberán ser guardadas para
referencia futura.
3. Todas las advertencias en el aparato eléctrico y en sus instrucciones de
operación deben ser respetadas.
4. Todas las instrucciones de operación y uso deben ser seguidas.
5. El aparato eléctrico no deberá ser usado cerca del agua—por ejemplo,
cerca de la tina de baño, lavabo, sótano mojado o cerca de una alberca,
etc..
6. El aparato eléctrico debe ser usado únicamente con carritos o pedestales
que sean recomendados por el fabricante.
7. El aparato eléctrico debe ser montado a la pared o al techo sólo como sea
recomendado por el fabricante.
8. Servicio—El usuario no debe intentar dar servicio al equipo eléctrico más
allá a lo descrito en las instrucciones de operación. Todo otro servicio
deberá ser referido a personal de servicio calificado.
9. El aparato eléctrico debe ser situado de tal manera que su posición no
interfiera su uso. La colocación del aparato eléctrico sobre una cama,
sofá, alfombra o superficie similar puede bloquea la ventilación, no se
debe colocar en libreros o gabinetes que impidan el flujo de aire por los
orificios de ventilación.

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MINIATURE LOCAL MUX-12
10. El equipo eléctrico deber ser situado fuera del alcance de fuentes de calor
como radiadores, registros de calor, estufas u otros aparatos (incluyendo
amplificadores) que producen calor.
11. El aparato eléctrico deberá ser connectado a una fuente de poder sólo del
tipo descrito en el instructivo de operación, o como se indique en el
aparato.
12. Precaución debe ser tomada de tal manera que la tierra fisica y la
polarización del equipo no sea eliminada.
13. Los cables de la fuente de poder deben ser guiados de tal manera que no
sean pisados ni pellizcados por objetos colocados sobre o contra ellos,
poniendo particular atención a los contactos y receptáculos donde salen
del aparato.
14. El equipo eléctrico debe ser limpiado únicamente de acuerdo a las
recomendaciones del fabricante.
15. En caso de existir, una antena externa deberá ser localizada lejos de las
lineas de energia.
16. El cable de corriente deberá ser desconectado del cuando el equipo no
sea usado por un largo periodo de tiempo.
17. Cuidado debe ser tomado de tal manera que objectos liquidos no sean
derramados sobre la cubierta u orificios de ventilación.
18. Servicio por personal calificado deberá ser provisto cuando:
A: El cable de poder o el contacto ha sido dañado; u
B: Objectos han caído o líquido ha sido derramado dentro del
aparato; o
C: El aparato ha sido expuesto a la lluvia; o
D: El aparato parece no operar normalmente o muestra un cambio en
su desempeño; o
E: El aparato ha sido tirado o su cubierta ha sido dañada.

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MINIATURE LOCAL MUX-12
TRADEMARKS USED IN THIS MANUAL
Any trademarks mentioned in this manual are acknowledged
to be the property of the trademark owners.

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MINIATURE LOCAL MUX-12
Contents
Chapter Page
1. Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.1 Sub Channels. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.2 Main Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2 Functional Description . . . . . . . . . . . . . . . . . . . . 10
2.3 Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3. Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2 Physical Installation. . . . . . . . . . . . . . . . . . . . . . . 14
3.3 Site Preparation. . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.4 Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.5 Electrical Installation . . . . . . . . . . . . . . . . . . . . . 16

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MINIATURE LOCAL MUX-12
Contents (continued)
Chapter Page
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.2 Indicators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3 Operating Procedure . . . . . . . . . . . . . . . . . . . . . 20
4.3.1 Powering On the Unit . . . . . . . . . . . . . . . 20
4.3.2 Operation . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.3.3 Powering Off the Unit . . . . . . . . . . . . . . . 21
4.4 Operational Field Strapping Changes. . . . . . . . 21
5. Diagnostics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.1 Remote Loopback. . . . . . . . . . . . . . . . . . . . . . . . 22
5.2 Fault Isolation and Troubleshooting. . . . . . . . . 23
Appendix: Bracket Assembly . . . . . . . . . . . . . . . . . . . . 24

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MINIATURE LOCAL MUX-12
1. Specifications
1.1 Sub-Channels
Transmission Format—Asynchronous
Mode of Operation—Full duplex
Data Rate—Up to 19.2 kbps
Interface—EIA RS-232/CCITT V.24
Connectors—(12) RJ-45 female
Number of Sub-channels—12
Distortion—See Table 1-1. User may select six sub-
channel operation for reduced distortion by internal
strapping.
Table 1-1. Performance at various bit rates.
Sub-channel Distortion (%) Distortion (%)
bit rate (Kbps) 6-channel mode 12-channel mode
19.2 12.5 25
9.6 6.3 12.5
4.8 3.2 6.3
2.4 1.6 3.2
1.2 0.8 1.6

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MINIATURE LOCAL MUX-12
1.2 Main Channel
Transmission Line—4-wire unconditioned telephone
lines (two twisted pairs)
Operating Range—1 mile (1.6 km) maximum on
22 AWG cable (actual distance may vary, depending
on the cable you use)
Data Rate—1.2288 Mbps
Output Format—Balanced bipolar transformer isolated
Output Level—6 V ptp (on 100 ohms)
Input Resistance—110 ohms
Connectors—(1) RJ-45 female
1.3 General
Indicators—Power, Local Sync Loss, Remote Sync Loss
Table 1-2. Indicators.
Indicator Function
Power ON when unit is powered.
Local Sync Loss ON when synchronization is lost at the local Mux.
Remote Sync Loss ON when synchronization is lost at the remote Mux.
Test ON when remote Mux is performing a loopback.

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MINIATURE LOCAL MUX-12
Temperature—32 to 122°F (0 to 50°C)
Humidity—Up to 95%, noncondensing
Power Consumption—Input: 110 VAC, Output: 200 mA
@ 9 VDC
Size—1.3"H x 4.5"W x 7.4"D (3.4 x 11.4 x 18.7 cm)
Weight—10.7 oz. (300 g)

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MINIATURE LOCAL MUX-12
2. Introduction
2.1 General
The Miniature Local Mux-12 is a time-division
multiplexor that enables up to 12 terminals to be
multiplexed onto a single cable, in point-to-point
applications. The Mux-12 contains a built-in line driver
that extends the high-speed multiplexed data over
twisted pairs.
2.2 Functional Description
The Mux-12 has 12 sub-channels that are connected by
RJ-45 connectors accessible from the top panel. The unit
can be strapped for 6 or 12 sub-channels according to
the desired application.
Multiplexing is implemented using an over-sampling
technique that enables each one of the 12 channels to
be sampled at a rate of 78.6 kbps. This technique results
in oversampling distortions, with a magnitude
proportional to the bit rate of the sub-channel. Table 2-1
summarizes the performance at various speeds and
modes of operation.

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MINIATURE LOCAL MUX-12
NOTE
Whenever possible (when the number of channels is 6 or
less), we advise operating the Mux in the 6-channel mode,
which results in less distortion.
Table 2-1. Performance at various bit rates.
Sub-channel Distortion (%) Distortion (%)
bit rate (kbps) 6-channel mode 12-channel mode
19.2 12.5 25
9.6 6.3 12.5
4.8 3.2 6.3
2.4 1.6 3.2
1.2 0.8 1.6
2.3 Applications
The primary application of the Mux-12 is for point-to-
point configurations at distances of up to 0.6 miles
(1 km). A typical application is demonstrated in Figure
2-1, where a cluster of terminals is connected to a host
computer through a single link.

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MINIATURE LOCAL MUX-12
Figure 2-1. Typical point-to-point installation.
For installations involving clusters of terminals
distributed in several locations, the Mux-12 units may be
installed in a ring-type configuration as shown in Figure
2-2. At each site, the unconnected channels must be
bypassed by shorting TX pin to RX pin of the relevant
sub-channel’s connector. Be aware that oversampling
distortions are accumulative, so this application limits
the bit rate of the sub-channels.
Host Terminals
Miniature
Local Mux-12

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MINIATURE LOCAL MUX-12
Figure 2-2. Typical ring installation.
Host
Terminals
Terminals
Miniature
Local Mux-12
Miniature
Local Mux-12
Miniature Local
Mux-12

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MINIATURE LOCAL MUX-12
3. Installation
3.1 General
This chapter provides the information you need to
implement the mechanical and electrical installation
of the Mux-12. After installation is complete, refer
to Chapter 4 for operating information and system
checkout to assure normal operation.
3.2 Physical Installation
The Mux-12 comes completely assembled and is
designed to be secured to a bench or wall using screws.
3.3 Site Preparation
The Mux-12 is installed within 5 ft. (1.5 m) of an AC
outlet enabling connection of the power-supply adapter.
3.4 Setup
Installation of the Mux is straightforward. First review
Table 2-1; the factory setting is for 12 sub-channels.
If this suits your requirements, you can skip steps 1
through 3 below.

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MINIATURE LOCAL MUX-12
1. Open the top half of the plastic case by squeezing
the marked places on the sides.
2. Strap the multiplexor for 6 or 12 sub-channels
according to the printed circuit board.
3. To close the unit, simply press the two halves of the
case together.
4. Install the Mux within 5 ft. (1.5 m) of an AC outlet.
The unit can be wall-mounted by four screws
through the mounting brackets located at both
sides of the unit.
5. Connect 9 to 12 VDC from a wall-mounted AC
adapter into the DC jack of the Mux. The
“POWER” LED should be lit. Other LEDs may be
lit as well.
6. Connect the sub-channels to your equipment. Pin
assignment of the RJ-45 sub-channel connector is
given in Table 3-1. For a description of the RJ-45
connector, see Figure 3-2.
7. Connect the main channel of the Mux to the
wiring that connects it to the remote Mux. Pin
assignment of the RJ-45 main channel connector
is given in Table 3-2. Note that the Transmit Pair

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MINIATURE LOCAL MUX-12
of one unit should be connected to the Receive
Pair of the other unit, and vice versa. All LEDs
should be “OFF” (with the exception of
“POWER”) indicating normal operation.
3.5 Electrical Installation
3.5.1 AC P OWER
The Mux is powered by an external power supply of 9 to
12 VDC capable of supplying at least 300 mA. A
miniature wall-mount power supply can be used to
provide the required power. The power supply is
connected to the Mux by a cable ending with a
miniature 2 mm DC plug (tip positive, sleeve ground).
3.5.2 S UB -C HANNELS
Twelve RJ-45 8-pin jacks located on the top panel enable
end users to be connected to the unit. Detailed
information about the signals present at this jack and
pin configuration are given in Table 3-2 and Figure 3-2.

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MINIATURE LOCAL MUX-12
Table 3-1. Sub-channel connector pin assignments.
CCITT V.24 EIA RS-232C Pin No. Signal Name Description
102 AB 7 Signal Ground Common signal.
103 BA 5 Transmit Data Serial data from
DTE into the Mux.
104 BB 3 Receive Data Serial data output
from the Mux
105 CA 2 Request to Send Connected to CTS.
106 CB 8 Clear to Send Connected to RTS.
107 CC 6 Data Set Ready A positive level
from the Mux
except when either
a sync loss occurs
or remote loopback
is performed.
109 CF 4 Receive Line A positive level
Signal Detector from the Mux
(Carrier Detect) except when either
a sync loss occurs
or remote loopback
is performed.
— — 1 +V output A positive
unregulated voltage
to power external
equipment (up to
120 mA total).
Table 3-2. Main channel’s connector pin assignment.
Pin No. Signal Name Description
1 RX-A Receive Pair
2 RX-B
7 TX-A Transmit Pair
8 TX-B

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MINIATURE LOCAL MUX-12
Figure 3-1. RJ-45 socket (female) external view.
1 8

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MINIATURE LOCAL MUX-12
Figure 3-2. RJ-45 plug (male) clip at rear.
1 8