Black Box MX870A, MX870AE User Manual

JULY 1998

MX870A

MX870AE

Miniature 2-Channel Statistical

Multiplexor

POWER

OVF

TEST

RESET

SYNC DATA

S1

A1

A2

S1

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: [e-mail]

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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

FEDERAL COMMUNICATIONS COMMISSION

AND

CANADIAN DEPARTMENT OF COMMUNICATIONS

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 the Canadian Department of
Communications.

Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limites
applicables aux appareils numériques de la classe A prescrites dans le Règlement sur le
brouillage radioélectrique publié par le ministère des Communications du Canada.

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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

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.

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.

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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

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 2-CHANNEL STATISTICAL MULTIPLEXOR

TRADEMARKS

The trademarks mentioned in this manual are the sole property of their owners.

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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Contents

Chapter Page

1. Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.1 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.2 Sub-Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.3 Composite Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2. Quick-Start Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.2 What You Need . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.3 Configuration Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

3.1 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

3.2 Typical Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4. Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.1 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.2 Site and Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.2.1 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.2.2 Ambient Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.3 Description of Internal Jumpers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.4 Cable Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.4.2 Sub-Channel Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.4.3 Main (Composite) Channel Connection . . . . . . . . . . . . . . . . . . . . . . . . 17

4.5 Power-On Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.6 Configuration Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.7 Starting the Configuration Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4.7.1 Using the Configuration Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4.7.2 Preparation for Configuration Session . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4.7.3 Starting the Configuration Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

4.8 Configuration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.9 Main Menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.10 System Configuration Menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

4.11 X-ON Control Character Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4.12 X-OFF Control Character Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

4.13 Modify Password Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

4.14 Sub-Channel 1/2 Configuration Screens . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

4.15 Baud Rate Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

4.16 Data Bits Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Contents (continued)

Chapter Page

4.17 Parity Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

4.18 Stop Bits Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

4.19 Multiplexor to DTE Software Flow Control Screen . . . . . . . . . . . . . . . . . . . 32

4.20 End-to-End Software Flow Control Screen . . . . . . . . . . . . . . . . . . . . . . . . . . 33

4.21 End-to-End DTR Flow Control Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

4.22 RTS Control Pass Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

4.23 Diagnostics Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

4.24 Local Loops Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

4.25 Remote Loops Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

4.26 Modem Loops Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.27 Loop Control Screens. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.28 Remote Multiplexor Configuration Menu . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.29 Transfer Configuration from Remote to Local Screen . . . . . . . . . . . . . . . . 38

4.30 Remote Multiplexor Configuration Screen . . . . . . . . . . . . . . . . . . . . . . . . . 39

4.31 Examine Remote Multiplexor Configuration Screen . . . . . . . . . . . . . . . . . 40

4.32 Save in Local Multiplexor Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

4.33 Transfer Configuration from Local to Remote Screen . . . . . . . . . . . . . . . . 40

4.34 Prepare Remote Multiplexor Configuration Menu . . . . . . . . . . . . . . . . . . . 41

4.35 Remote Multiplexor System Configuration Menu . . . . . . . . . . . . . . . . . . . . 41

4.36 Remote Sub-Channel 1, 2, Configuration Screens . . . . . . . . . . . . . . . . . . . . 42

4.37 Activate Remote Multiplexor Configuration . . . . . . . . . . . . . . . . . . . . . . . . 42

5. Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

5.1 Controls, Indicators, and Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

5.2 Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

5.2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

5.2.2 Power-On. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

5.2.3 Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

5.2.4 Power-Off. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

5.3 What to Do in Case of Malfunction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

5.3.1 Preliminary Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

5.3.2 Check Multiplexor Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

5.3.3 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Contents (continued)

Chapter Page

6. Diagnostics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

6.1 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

6.2 Description of Test Loops. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

6.2.1 Local Loops. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

6.2.2 Remote Loops. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

6.2.3 Modem Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Appendix A: Functional Interface Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . 52

A.1 Main (Composite) Channel Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

A.2 Sub-Channel Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Appendix B: Configuration Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

1. Specifications

1.1 General

Test Modes—Main Channel and Sub-Channels: Local and remote loopback; Main

Channel Modem: Local analog and remote digital loopback Control; Command
Port: Any sub-channel port

Indicators (LEDs)—(1) SYNC for main channel, (2) DATA LEDs (one for each

sub-channel), (1) POWER, (1) OVF, (1) TEST, (1) RESET

Power—MX870A: 115 VAC; MX870AE: 230 VAC; 47 to 63 Hz; 5 VDC, 700 mA,

regulated

Temperature—32 to 122°F (0 to 50°C)

Humidity—Up to 95%, noncondensing

Size—0.9"H x 2.1"W x 4.3"D (2.2 x 5.3 x 11 cm)

Weight—3.3 oz. (90 g)

1.2 Sub-Channel

Configuration—DCE

Number of Sub-Channels—2

Data Rate—300 to 19200 bps, user-selectable

Interface—Control Signals: RTS, CTS, DTR, DCD; Local Control Signal: RTS

to DCD

Transmitted End-to-End Character Code—5, 6, 7, or 8 data bits

Stop Bits—1, 1.5, or 2

Parity—Odd, even, none

Connectors—(2) RJ-45 female

Flow Control—Hardware: DTR/CTS for end-to-end (DTE-DTE) flow control,

CTS flow control from sub-channel to DTE; Software: X-ON, X-OFF. X-ON,
X-OFF characters are selectable from DCI (11H) to DC4 (14H) and 91H to
94H

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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

1.3 Composite Channel

Configuration—DTE

Transmission Format—Synchronous, external timing

Data Rate—Up to 19.2 kbps

Connector—(1) DB25 female

Control Signals—RTS, CTS, DCD, DTE, analog loopback (pin 18), remote

digital loopback or signal quality (pin 21)

Protocol—Proprietary variant of HDLC framing protocol as defined in CCITT

X.25 level 2

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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

2. Quick-Start Guide

2.1 Scope

This guide provides concise instructions for configuring your Miniature 2-Channel
Statistical Multiplexor. Use it if you’re already familiar with the Multiplexor, or if
you’re an experienced user and have a good basic understanding of data­communication principles and know the applications and characteristics of
statistical multiplexors.

Use this guide together with Figure 4-6, Configuration Tree.

Whenever you want more details, refer to Tables 4-1 and 4-2 and to Sections 4.9

and 4.10.

Once you start the configuration program, the Multiplexor will guide you

through any desired configuration.

2.2 What You Need

You configure the Multiplexor from a data terminal connected to one of
the Multiplexor sub-channels. The terminal communication parameters must
match the parameters of the selected sub-channel. If you do not know what
these parameters are, or you just received a new Multiplexor, use the following
default parameters:

Baud Rate: 9600 bps
Format of Data: Character length 8 data bits

No parity
1 stop bit

The Multiplexor is shipped to you with these defaults. If you’re re-installing an

already-configured Multiplexor, you can reset it to factory defaults. Read Sections

4.3 and 4.4, them turn the Multiplexor off, set its internal INIT/NOR jumper to
INIT, and turn the Multiplexor on again. Return the INIT/NOR jumper to NOR
before starting the configuration.

Whenever the Multiplexor is already installed in a link, establish
communication with the remote Multiplexor before starting. In this way,
you will be able to configure the two units from the terminal connected
to the local Multiplexor.

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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

2.3 Configuration Instructions

Pay attention to use of capital letters whenever required.

1 . If necessary, power up the Multiplexor and connect your terminal to

one of the sub-channels. Check terminal communication parameters.

2. Allow an idle period of at least one second, type @ @ @, wait at least one
second, and type S.

3. The Multiplexor enters the command mode. Enter the password.

NOTE

The default password is RD. If you do not know the password, initialize
the Multiplexor via the INIT/NOR jumper.

4. The STM displays the Main Menu. Use Figure 4-6 to plan your configuration
actions. Record the configuration on the form given at the end of the
appendix. Keep the filled-up form for reference.

IMPORTANT

Each configuration change takes effect immediately. Each time you
change one of the communication parameters of the sub-channel you
use now, you must immediately change the corresponding
communication parameter of your terminal to the same value. If you
don’t, you lose communication with the Multiplexor. If you make an error
that you cannot correct, initialize again the Multiplexor with the
INlT/NOR jumper and start again.

5. When the link to the remote Multiplexor operates, use Remote System
Configuration to transfer local configuration to remote Multiplexor,
and/or to configure the remote Multiplexor as required.

6. If you initialized the Multiplexor, modify the password as required.
Record the password.

7. Exit the command mode by typing 6 on the Main Menu.

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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

3. Introduction

3.1 Functional Description

The Miniature 2-Channel Statistical Multiplexor is an advanced, full function and
compact statistical multiplexor.

The Multiplexor multiplexes two asynchronous data sub-channels, at data rates
of 300 to 19,200 bps onto a single composite synchronous channel of up to 19.2
kbps. Composite channel rate is automatically determined by an external clock
signal, whereas sub-channel characteristics and other system features are selected
by the user, using a menu-driven configuration function.

The Multiplexor uses a dynamic data buffer management technique, to allocate
available buffer capacity according to sub-channel activity. Error-free end-to-end
data transmission is ensured by powerful and efficient error detection and
automatic retransmission, completely transparent to the user.

The Multiplexor provides independent hardware and software flow control for
each sub-channel (both end-to-end flow control (DTE to DTE), and terminal flow
control (DCE to DTE). For compatibility with most applications, hardware flow
control (DTR) and several software flow-control characters are available.

The Multiplexor provides for full system configuration (including configuration
downloading from the local Multiplexor to the remote Multiplexor, and vice-versa)
from any sub-channel port. Password protection is used, to prevent unauthorized
configuration changes.

Configuration can be carried out using any standard CRT terminal, using a
simple, menu-driven facility. Configuration parameters are stored in non-volatile
memory and are immediately available upon power-up.

To facilitate initial system configuration, the Multiplexor stores, in addition
to the user-selected configuration, a set of default configuration parameters
(factory setting), that can be selected by means of a jumper (see Section 4.3).

The Multiplexor has comprehensive diagnostics functions, including automatic
self-test upon power-on, local and remote sub-channel loopback, and local and
remote composite channel loopback. Front-panel indicators show the condition
of each sub-channel and the composite-link synchronization status. In addition,
the Multiplexor can control the V.54 pins (pins 18 and 21) of the RS-232 interface
serving the composite link. This provides control over the analog and remote
digital loopback functions of the modem connected to the Multiplexor.

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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

3.2 Typical Application

Figure 3-1 shows a typical Multiplexor application. In this application, the
Multiplexor sub-channels receive data provided by the host computer via channels
operating at various rates, and statistically multiplexes the sub-channel data to form
a composite data stream having a rate much smaller than the arithmetical sum of
the individual sub-channel rates. The required composite link rate depends on
Multiplexor buffer capacity versus sub-channel traffic statistics and allowable delay.
The composite data is sent via modems to the remote Multiplexor, where it is
demultiplexed and distributed to the local users, at their nominal rate (that may
differ from the nominal host transmission rate).

Figure 3-1. Typical Application.

Reliable operation of any statistical multiplexor requires the equipment
connected to its sub-channels to use some form of flow control. However, an
important feature of the Multiplexor is that the flow-control methods used at
each of the two sub-channel ends can be different (hardware control at one end,
software control at the other end), the conversion being transparently performed
by the Multiplexor.

Async

19.2

kbps

19.2

kbps

Mux

Mux

Sync

Modem

Sync

Modem

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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

4. Installation

4.1 General

The Multiplexor is delivered completely assembled. It’s designed for desktop use.

4.2 Site and Power Requirements

4.2.1 P

OWER

The Multiplexor is powered by an external power supply of 5 VDC/700 mA. A
115-VAC power supply is included with the MX870A model and a 230-VAC power
supply is included with the MX870AE model.

The power supply is connected to the Multiplexor by a cable ending in a
miniature phone jack (tip positive, sleeve–ground).

4.2.2 A

MBIENTREQUIREMENTS

Both Multiplexor models will operate properly in any ambient conditions suitable
for operation of electronic computer equipment and peripherals. Multiplexors,
however, can operate without performance degradation over a wide range
of temperatures, 32 to 22°F (0 to 50°C), at relative humidities (up to 95%,
non-condensing).

4.3 Description of Internal Jumpers

The Multiplexor has three internal jumpers, used according to the following
description:

(1) INIT - NOR jumper (JP1).

This jumper is used to select the default set of configuration parameters stored
in the Multiplexor. The jumper has two positions:

NOR - Normal operation.

The Multiplexor uses parameters selected by the user during the last configuration
session, and stored in the Multiplexor’s non-volatile RAM.

15

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

INIT - Initialization.

The Multiplexor uses the default configuration (determined by the factory and
common to all Multiplexor units). To select the default configuration, set the
jumper to INIT, then apply power to Multiplexor. The default configuration is
loaded upon power-up (factory setting is NOR).

When delivered, the non-volatile memory of the Multiplexor is already loaded
with the default configuration, therefore the Multiplexor is configured in
accordance with the factory settings.

You may have to select again the default configuration (INIT) in the following
cases:

• After an error was made during the configuration session, which either
prevents communication between the control terminal and the Multiplexor, or
proves difficult to trace and correct.

• The description of the configuration loaded into the Multiplexor has been lost,
and it is therefore not possible to enter the configuration mode in the NOR
mode. To avoid this inconvenience, always keep a record of the last
configuration parameters (a typical record form is shown in Appendix B).

After the default configuration is loaded by setting the jumper to INIT and
powering up the Multiplexor, it becomes the current Multiplexor configuration
and the jumper should be returned to the NOR position to allow configuration.

(2) PIN 21 ON-OFF jumper (JP3).

Pin 21 of the standard RS-232 interface can serve either as a signal-quality
indication (SQ) line, or as a remote-loopback command line. The actual function
of pin 21 depends on the specific model of modem in use, and a jumper allows
adapting the Multiplexor to the modem connected to the composite (main) link
connector.

The jumper has two positions:

PIN 21 ON

Set the jumper to this position when the modem uses pin 21 as a remote loopback
command line. This connects the internal Multiplexor pin 21 driver to this pin,
and allows the user to control this modem function using the diagnostics screen.

16

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

PIN 21 OFF

Set the jumper to this position when the modem uses pin 21 as a signal- and
quality-indication output. You should also use this position whenever in doubt
about the actual function of the pin in the specific modem model you use. In this
position, you no longer have control of the modem remote loopback function
from the diagnostics screen.

Factory setting is OFF.

(3) TXCLK jumper (JP2)

This jumper enables checking of TXCLK (main channel).

The jumper has two positions:

• Connect - TXCLK sample connected

• Disconnect - TXCLK sample disabled

Factory setting is Connect.

WARNING

Disconnect the power supply from the mains before opening the
Multiplexor. You might be shocked!

Figure 4-1. Location of the Jumpers.

JP1

RJ-45

Disconnect—Connect

INIT NOR

OFF ON

RJ-45

DB25

JP2

JP3

17

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

4.4 Cable Connections

4.4.1 G

ENERAL

The Multiplexor has one standard DB25 connector, serving the main channel, and
two RJ-45 connectors for the sub-channels.

4.4.2 SUB-

CHANNELCONNECTIONS

Multiplexor sub-channel interfaces are configured as data communication
equipment (DCE) interfaces, thereby allowing direct connection, via RS-232 port
cables, to data terminal equipment (DTE). When modems are used to extend
range (tail-end circuits), crossover cables are required. Sub-channel interfaces are
asynchronous; therefore, clock signals are not supported or required.

4.4.3 M

AIN(COMPOSITE

) C

HANNELCONNECTION

The Multiplexor composite channel interface is configured as a DTE interface,
intended for connection to a synchronous modem, that is capable of providing the
clock signal that determines the Multiplexor’s composite-channel data rate.
Appendix A also lists the pin allocation for the main composite=channel
connector.

4.5 Power-On Procedure

To turn the Multiplexor on, connect the power cable to the Multiplexor power
supply, then plug the power supply unit into the mains. Plug the power supply into
the Multiplexor. The POWER indicator should light.

Check that after a few seconds (during which the Multiplexor performs a self­test), the TEST indicator goes out. If the link to the far Multiplexor is not yet
operational, the TEST indicator will flash.

4.6 Configuration Information

The Multiplexor can operate in three modes:

1. Normal operation mode (described in detail in Chapter 5)

2. Parameter configuration mode

Allows user to set-up parameters of local and remote Multiplexor units. This
mode provides two types of functions:

18

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

• Parameter-selection functions.

• System management functions, used to save (store) selected parameters,
transfer configurations between the local and remote units, activate new
configurations, and select passwords.

3. Diagnostics mode

Multiplexor diagnostic functions include local and remote loops on each
sub-channel and on the composite channel, and modem loops (analog and
optionally remote digital loopback). Refer to Chapter 6 for additional details.

The parameter-configuration mode and the diagnostics mode are activated
by the user from the command terminal, using the Multiplexor configuration
program. For those already familiar with the Multiplexor, there is a Quick-Start
Guide in Chapter 2. This section provides an outline of the configuration
parameters available to the user. Section 4.7 provides step-by-step instructions
on starting configuration and diagnostics sessions. Section 4.8 provides in-depth
information on each menu, and the purpose of each parameter or diagnostics
screen.

The Multiplexor has two types of configuration parameters:

1. System parameters that affect both Multiplexor units connected in a link,
andalso affect all their sub-channels. System parameters are listed in
Table 4-1.

2. Sub-channel parameters, that affect only the operation of a single
sub-channel. Sub-channel parameters are listed in Table 4-2.

19

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Table 4-1. System Parameters and Factory Settings.

No. Parameter Function Available Factory

Selections Setting

1 PASSWORD Controls access Any two characters RD (capital

to configuration except those used letters)

as X-ON and X-OFF

control characters

2 X-ON CONTROL When using software 11H (DC1) 11H

CHARACTER flow control, causes 12H (DC2)

the receiving terminal 13H (DC3)

to start data transfer 14H (DC4)

91H

92H

93H

94H

3 X-OFF When using software Same range as for 13H

CONTROL flow control, causes X-ON; however,

CHARACTER the receiving terminal selected character

to stop transfer of must be different

data from the X-ON

character

20

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Table 4-2. Sub-Channel Parameters and Factory Settings.

No. Parameter Function Available Factory

Selections Setting

1 BAUD RATE Sub-channel data 300, 600, 1200, 1800, 9600

rate 2400, 4800, 7200,

9600, 14400, and
19200 bps

2 DATA BITS Number of data bits in 5, 6, 7, 8 8

sub-channel data frame

3 PARITY Type of parity used in Odd None

sub-channel data frame Even

None

4 STOP BITS Number of stop bits 1, 1.5, 2 1

in sub-channel data
frame

5 MUX TO DTE Controls software flow On On

SOFTWARE control function at the Off
FLOW local end of the sub­CONTROL channel. When on,

see also Table 4-1,
No. 2, 3.

6 END-TO-END Activates end-to-end On On

SOFTWARE software flow control Off
FLOW When on, see also
CONTROL Table 4-1, No. 2, 3.

7 END-TO-END Activates end-to-end On On

DTR FLOW hardware flow control Off
CONTROL (via DTE line)

8 RTS CONTROL Enables the transfer On Off

PASS of the RTS state to

the remote DCD line

21

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

4.7 Starting the Configuration Session

The rest of this chapter explains in detail how to configure the Multiplexor.
If you are already acquainted with the Multiplexor, a Quick-Start Guide is
given in Chapter 2.

4.7.1 U

SING THECONFIGURATIONPROGRAM

The Multiplexor configuration program can be run on any standard CRT terminal,
connected to any sub-channel port. It is a simple menu-driven program that guides
you through the various configuration steps:

1. At each step, you are presented with a screen that shows all available
selections, and when applicable, also shows the current selections.

2. A standard selection procedure is used throughout: the available options are
marked with numbers, and you indicate your selection by typing the option
number.

3. To leave the current screen, you always type “Q”. This returns you to the
previous screen. When you are on the main menu of the Multiplexor, you
must type 6 to exit.

The program checks your entries and does not accept invalid entries. For
example, if the program expects a numerical entry in a certain range, and you
press a key outside this range, the program ignores your entry and waits for a valid
response. After a valid response is provided, it is immediately executed by the local
Multiplexor. As you will see later, when you prepare the configuration for the
remote Multiplexor, three different stages are used: preparation of configuration,
transfer to remote Multiplexor, and activation of transferred configuration. When
changing parameters related to the communications format of the sub-channel
used to configure the Multiplexor, you must immediately change terminal
communication format as well.

However, if you make a mistake and lose communication with the Multiplexor,
you can always quit the configuration program and start again from the default
configuration (see Section 4.3 for instructions). You can always stop the
configuration session at any point, by pressing the ESC key of the terminal;
however, any changes made before pressing the ESC key remain in effect.

4.7.2 P

REPARATION FORCONFIGURATIONSESSION

1. Power on the Multiplexor.

Wherever possible, establish communication with the remote Multiplexor.

22

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

However, configuration can usually be done without connection to the
remote Multiplexor. There is one exception to this rule: you must establish
communication with the remote Multiplexor if you set the RTS-to-DCD
control passing to ON (screen 14), and your command terminal requires
DCD active in order to communicate.

2. Select one of the terminals connected to Multiplexor sub-channels as a
command (configuration) terminal, or connect a CRT terminal to one
of Multiplexor ports.

3. When a new terminal is connected to the Multiplexor sub-channel selected
as the command port, program the communications parameters of this
terminal according to those of the selected Multiplexor port (factory setting
is 9600 bps, 8 data bits, I stop bit, no parity bit).

4.7.3 S

TARTING THE

C

ONFIGURATIONPROGRAM

The configuration program requires the user to enter a password before
proceeding any further. If you enter an incorrect password, the Multiplexor
immediately returns to start again the configuration session.

NOTES

1. The following examples assume that the command mode is activated
via sub-channel 1.

2. Multiplexor commands requiring alphanumeric inputs are case­sensitive. Observe use of lower-case and upper-case letters in the
following examples.

1. To start the configuration session, allow an idle period of at least one second,
type @ @ @, then wait at least one second and type S (typing any other
character after the @ @ @ string returns the Multiplexor to the normal mode,
and you will see the message: Multiplexor IN NORMAL MODE).

2. After correctly typing the starting command, the Multiplexor stops data
transfer through the sub-channel used as a command sub-channel, its TEST
indicator lights, and the opening screen appears as follows:

COMMAND MODE IS ACTIVATED VIA CH1

Multiplexor COMMAND MODE

REV 0.0

ENTER MULTIPLEXOR PASSWORD

23

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

3. Enter the password, carefully observing the correct use of upper and
lowercase characters. The password is not echoed to the screen. Factory
setting is RD.

4. If the password is rejected, you will see the following screen appear :

COMMAND MODE IS ACTIVATED VIA CH1

WRONG PASSWORD

MULTIPLEXOR IS IN NORMAL MODE

You must repeat step (1) again.

5. If the password is accepted, the Multiplexor sends the main menu:

MAIN MENU

0) SYSTEM CONFIGURATION

1) SUB-CHANNEL 1 CONFIGURATION

2) SUB-CHANNEL 2 CONFIGURATION

3) DIAGNOSTICS

4) EXIT TO NORMAL OPERATION

SELECT YOUR CHOICE (0 - 4)

You can now start the actual configuration session (Section 4.8).

From this point on, whenever you want to end the configuration session, press

Q as many times as necessary to obtain the following message, or press ESC.

EXIT COMMAND MODE
MULTIPLEXOR IN NORMAL MODE

24

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

4.8 Configuration Procedure

The rest of this chapter presents the menus and the data-entry screens contained
in the configuration program.

These paragraphs describe menu and screen purpose, explain how to fill the

desired data, and present any supplementary information that may be required.

Table 4-3 lists the available menus and screens, their index numbers and the

page on which you will find each screen.

Table 4-3. Multiplexor Configuration Program.

Index Menu/Data Entry Screen Page

MULTIPLEXOR MAIN MENU

SYSTEM CONFIGURATION Menu

X-ON CONTROL CHARACTER Screen

X-OFF CONTROL CHARACTER Screen

MODIFY PASSWORD Screen

SUB-CHANNEL 1/2 CONFIGURATION Screens

BAUD RATE Screen

DATA BITS Screen

PARITY Screcn

STOP BITS Screen

STM TO DTE SOFTWARE FLOW CONTROL Screen

END TO END SOFTWARE FLOW CONTROL Screen

END TO END DTR FLOW CONTROL Screen

RTS CONTROL PASS Screen

DIAGNOSTICS Menu

LOCAL LOOPS Screen

REMOTE LOOPS Screen

MODEM LOOPS Screen

LOOP CONTROL Screens

REMOTE Multiplexor CONFIGURATION Menu

TRANSFER CONFIGURATION FROM REMOTE

TO LOCAL Screen

REMOTE Multiplexor CONFIGURATION Screen

EXAMINE Remote Multiplexor Configuration Screen

25

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Table 4-3 (continued). Multiplexor Configuration Program.

Index Menu/Data Entry Screen Page

SAVE IN LOCAL MULTIPLEXOR Screen

TRANSFER CONFIGURATION FROM LOCAL

TO REMOTE Screen

PREPARE REMOTE MULTIPLEXOR

CONFIGURATION Menu

REMOTE Multiplexor SYSTEM

CONFIGURATION Menu

REMOTE SUB-CHANNEL 1,2 SYSTEM

CONFIGURATION Screens

ACTIVATE REMOTE Multiplexor

CONFIGURATION Screen

4.9 Main Menu

Purpose: Select the configuration task to be carried out.

Description: (see Table 4-4).

Table 4-4. Description of the Main Menu.

Code Item Description

0 SYSTEM CONFIGURATION Used for selection of system-

wide parameters (see Section

4.6)

Select X-ON and X-OFF flow

control characters

Change password

Prepare remote Mux

configuration

26

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Table 4-4 (continued). Description of the Main Menu.

Code Item Description

1 SUB-CHANNEL 1 These two items are used to

CONFIGURATION select local sub-channel

parameters of the command

sub-channel as the last item

2 SUB-CHANNEL 2 Always change the parameters

CONFIGURATION of the command sub-channel

as the last item

3 DIAGNOSTICS Used to control the various

test loops that can be

controlled by the Mux (see

Section 6.2)

4 EXIT TO NORMAL OPERATION Ends the current configuration

session

Procedure:

To select a configuration task, type the corresponding code number; the

Multiplexor will switch to the corresponding screen.

To end the configuration session, type 6. The TEST indicator will turn off, and

you will receive the message:

EXIT COMMAND MODE
MULTIPLEXOR IS lN NORMAL MODE

4.10 System Configuration Menu

Select the parameters that affect the whole system: change X-ON and X-OFF
characters, change password, and prepare remote Multiplexor configuration.

27

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Table 4-5. System Configuration Parameters.

Code Item Description

1

X-ON CONTROL CHARACTER Used to display X-ON

character selection screen

2 X-OFF CONTROL CHARACTER Used to display X-OFF

character selection screen

3 MODIFY PASSWORD Used to display password-

changing screen

4 REMOTE MUX CONFIGURATION Used to display the main

menu used for remote

Multiplexor configuration

Q EXIT Used to return to the main

menu.

To select a configuration task, type the corresponding code number: the

Multiplexor will switch to the corresponding screen.

Type Q to return to the main menu.

4.11 X-ON Control Character Screen

View the character currently used to start data transfer when using software flow
control, and select if desired, another character.

Code numbers 1) through 8) present the various characters that can be used as
X-ON control characters: 11 (DC 1),12H (DC2),13H (DC3),14H(DC4), 91H, 92H,
93H or 94H.

The CURRENT STATE line shows the X-ON character now in use.

To change the current selection, type the code number corresponding to the
desired character: always check that this character is different from the current
X-OFF control character. The CURRENT STATE line reflects the change.

To exit with or without change, type Q. You will return to the SYSTEM
CONFIGURATION menu.

28

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

4.12 X-OFF Control Character Screen

View the character currently used to stop data transfer when using software flow
control, and select another character.

Code numbers 1) through 8) present the various characters that can be used as
X-OFF control characters: 11 (DC 1), 12H (DC2), 13H (DC3), 14H (DC4), 91 H,
92H, 93H, or 94H.

The CURRENT STATE line shows the X-OFF character now in use.

To change the current selection, type the code number corresponding to the
X-ON control character.

To exit with or without change, type Q. You will return to the SYSTEM
CONFIGURATION menu.

4.13 Modify Passwords Screen

Select a new password. The new password is activated after its verification.

The screen prompts you to enter the new password (any two characters, except
the characters serving as X-ON and X-OFF flow control characters), or exit to the
SYSTEM CONFIGURATION menu.

a. Type the desired password. You will receive the following message:

ENTER NEW PASSWORD AGAIN FOR VERIFICATION

b. Type the same characters again.

1. If no difference is found, the new password is accepted and you will receive
the following message:

NEW PASSWORD HAS BEEN ACTIVATED

ENTER ANOTHER PASSWORD (two characters) OR PRESS Q TO EXIT J

If the password need not be changed again, press Q to return to the SYSTEM

CONFIGURATION menu. Otherwise, repeat password entry procedure.

2. If the two passwords differ, no change is made, and the following screen is
presented:

29

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

INCORRECT VERIFICATION, PASSWORD HAS NOT BEEN CHANGED

ENTER NEW PASSWORD (two characters) OR PRESS Q TO EXIT

You can now repeat the procedure, or quit.

4.14 Sub-Channel 1/2 Configuration Screens

Select and view the current values of the parameters of the sub-channel whose
number appears in the screen header, and enter the corresponding sub-channel
parameter configuration screens when changes are needed. The various
parameters that can be selected are explained in Section 4.6).

Code numbers 1 through 8 list the various sub-channel parameters that can be

changed:

1. Sub-channel baud rate

2. Number of data bits in sub-channel data frame

3. Type of parity used in sub-channel data frame

4. Number of stop bits in sub-channel data frame

5. Software flow control function at the local end of the sub-channel

6. End-to-end software flow control

7. End-to-end hardware flow control (by means of DTR line).

8. RTS-to-DCD control passing

Code Q is used to return to the SYSTEM CONFIGURATION screen.

The CURRENT CONFIGURATION line lists the current parameter values.

Type the code number corresponding to the desired configuration action.

4.15 Baud Rate Screen

View the current sub-channel baud rate and select, if desired, a new rate.

30

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Code numbers 1 through 9 list the available sub-channel rates; 19200, 14400,
9600, 7200, 4800, 2400, 1200, 600, and 300 bps. Code Q is used to return to the
SUB-CHANNEL CONFIGURATION screen.

The CURRENT STATE line shows the current sub-channel rate.

To change sub-channel rate, type the appropriate code number. The new
selection appears in the CURRENT STATE line.

If you changed the rate of the command sub-channel (the sub-channel to which
you are now connected), reprogram your terminal for the new rate, so that you will
be able to continue.

NOTE

If you made an error and lost communication with the Multiplexor being
programmed, select the default configuration described in Section 4.3
and start again.

After completing the required actions, type Q to return to the SUB-CHANNEL
CONFIGURATION screen.

4.16 Data Bits Screen

View the current number of data bits used on this sub-channel and select, if
desired, a new value.

Code numbers 1 through 4 list the available selections of data bits number: 5, 6,
7, or 8. Code Q is used to return to the SUB-CHANNEL CONFIGURATION
screen.

The CURRENT STATE line shows the current code number of data bits.

To change the number of data bits, type the appropriate code number. The
new selection appears in the CURRENT STATE line.

If you changed the number of data bits on the command sub-channel (the sub­channel to which you are now connected), reprogram your terminal for the new
value, so that you will be able to continue.

After completing the required actions, type Q to return to the SUB-CHANNEL
CONFIGURATION screen.

31

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

4.17 Parity Screen

View current parity used by the sub-channel and select, if desired, a new type.

Code numbers 1 through 3 list the available parity types: odd, even or none.

Code Q is used to return to the SUB-CHANNEL CONFIGURATION screen.

The CURRENT STATE line shows the current type of parity.

To change the type of parity, type the appropriate code number. The new
selection appears in the CURRENT STATE line.

If you changed the type of parity on the command sub-channel (the sub­channel to which you are now connected), reprogram your terminal for the new
value, so that you will be able to continue.

After completing the required actions, type Q to return to the SUB-CHANNEL
CONFIGURATION screen.

4.18 Stop Bits Screen

View the current number of stop bits used by the sub-channel and select, if desired,
a new value.

Code numbers 1 through 3 list the available selections of stop bits number: 1,

1.5, or 2.

Code Q is used to return to the SUB-CHANNEL CONFIGURATION screen.

The CURRENT STATE line shows the current code number of stop bits.

To change the number of stop bits, type the appropriate code number. The new
selection appears in the CURRENT STATE line.

If you changed the number of stop bits on the command sub-channel (the sub­channel to which you are now connected), reprogram your terminal for the new
value, so that you will be able to continue.

After completing the required actions, type Q to return to the SUB-CHANNEL
CONFIGURATION screen.

32

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

4.19 Multiplexor to DTE Software Flow Control Screen

View the current status of end-to-end software flow control used on this sub­channel and select, if desired, a new status.

The Multiplexor must be able to command the DTE connected to it to
interrupt the flow of data when Multiplexor buffers fill, and restart the flow when
the Multiplexor can accept new data for transmission. This function is mandatory
whenever statistical multiplexors are used, and is additional to the end-to-end flow
control function (see Sections 4.20 and 4.21).

Some DTEs have the capability to stop data flow when receiving a special
character, X-OFF, and renew data flow when receiving another character, X-ON.
This capability is termed “software data flow control,” and the Multiplexor can be
programmed to use this capability by selecting the ON option on this screen.

If the DTE cannot recognize the X-ON and X-OFF characters, the OFF option
must be selected. In this case, the control of data flow between the Multiplexor and
the DTE connected to it is performed by means of the CTS control line contained
in the RS-232 interface.

NOTE

The CTS line of the Multiplexor is always active, regardless of the
selection made on this screen.

Screen selections are as follows:

Code numbers 1 and 2 list the available selections of software flow control
status: on or off.

Code Q is used to return to the SUB-CHANNEL CONFIGURATION screen.

The CURRENT STATE line shows the current status of software flow control
used on this sub-channel.

To change the status of software flow control, type the appropriate code
number.

The new selection appears in the CURRENT STATE line.

Type Q to return to the SUB-CHANNEL CONFIGURATION screen.

33

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

4.20 End-to-End Software Flow Control Screen

View the current status of end-to-end software flow control used on this sub­channel and select, if desired, a new status.

In addition to the STM-to-DTE control function (Section 4.19), the Multiplexor
provides a DTE-to-DTE (or “end-to-end”) flow-control function. This function
allows a receiving DTE to command the remote transmitting DTE to interrupt data
flow, because temporarily it can not accept new data, flow required action on the
local sub-channel. This avoids problems that could be caused by the link
transmission delay.

This is done by selecting the ON option on this screen. The Multiplexor is then
configured to recognize the two special flow control characters (selected by means
of the screens presented in Sections 4.11 and 4.12): X-OFF, that conveys local DTE
“stop flow” command, and X-ON, that conveys local DTE “restart flow” command.

The detected X-ON/X-OFF commands are sent to the remote Multiplexor,
which converts them to flow-control commands for the remote DTE connected
to it.

When an X-OFF command is received from the local DTE, the local Multiplexor
interrupts immediately the transfer of received data to the local DTE. The
additional data sent by the remote DTE during the time it takes to transfer the
X-OFF command accumulates in Multiplexor buffers. Similarly, when an X-ON
command is received from the local DTE, the local Mux immediately starts the
transfer of received data (accumulated as explained before).

The flow control commands supplied to the remote DTE depend on the Mux­to-DTE flow control mode selected at the remote DTE: the same X-ON/X-OFF
characters, or use of CTS line (see Section 4.19).

When the local DTE does not have software flow control capability, the
Multiplexor “end-to-end software flow control” must be configured as OFF, to
prevent the Multiplexor from responding to the X-ON and X-OFF characters.
In this case, see also Section 4.21. Screen selections are as follows:

Code numbers 1 and 2 list the available selections of end-to-end software
flow-control status: on or off.

Code Q is used to retum to the SUB-CHANNEL CONFIGURATION screen.

The CURRENT STATE line shows the current state of end-to-end software
flow control used on this sub-channel.

34

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

To change the status of end-to-end software flow control used on this sub­channel, type the appropriate code number. The new selection appears in the
CURRENT STATE line.

Type Q to return to the SUB-CHANNEL CONFIGURATION screen.

4.21 End-to-End DTR Flow Control Screen

View the current status of end-to-end hardware flow control (via the DTR line)
used on this sub-channel and select, if desired, a new status.

There are applications in which end-to-end (DTE-to-DTE) software flow control
cannot be used, but the end-to-end flow control function described in Section 4.20
is nevertheless essential.

In these applications, the Multiplexor can be configured to use “end-to-end”
DTR flow control by setting ON in this screen.

In this mode, the Multiplexor monitors the DTR line contained in the local
sub-channel RS-232 interface, and transmits the status of this line to the remote
Multiplexor. The remote Multiplexor then supplies to the DTE connected to it the
flow control commands according to the Mux-to-DTE flow control modes selected
at the remote Multiplexor.

Selecting OFF on this screen disables the transmission of flow control
commands to the remote Multiplexor when the DTR line changes state.

Screen selections are as follows:

Code numbers 1 and 2 list the available selections of end-to-end hardware flow
control status: on or off.

Code Q is used to return to the SUB-CHANNEL CONFIGURATION screen.

The CURRENT STATE line shows the current status of end-to-end hardware
flow control.

To change the status of end-to-end hardware flow control used on this sub­channel, type the appropriate code number. The new selection appears in the
CURRENT STATE line.

Type Q to return to the SUB-CHANNEL CONFIGURATION screen.

35

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

4.22 RTS Control Pass Screen

View the current status of the RTS-to-DCD control function used on this sub­channel, and select, if desired, a new status.

The Multiplexor stand-alone and card models can transfer end-to-end (in both
directions) one RS-232 interface control signal per channel; when this function
is enabled, the condition of the RTS line is copied to the remote DCD line.

NOTES:

1. You must always select the same mode for both Multiplexors
connected in a link.

2. When you select OFF, the DCD line is always active (DCD on).

3. When you select ON, the remote DCD line follows the local RTS line.
In case synchronization is lost, the DCD lines switches to the not-active
state (DCD OFF). If your command terminal requires DCD to be active in
order to communicate, you must establish communication with the
remote Multiplexor before starting a configuration session.

Screen selections are as follows:

Code numbers 1 and 2 list the available selections of the RTS-to-DCD transfer
status: on or off.

Code Q is used to return to the SUB-CHANNEL CONFIGURATION screen.

The CURRENT STATE line shows the current status of the RTS-to-DCD
transfer.

To change the status of the RTS-to-DCD transfer for this sub-channel, type the
appropriate code number. The new selection appears in the CURRENT STATE
line.

Type Q to return to the SUB-CHANNEL CONFIGURATION screen.

4.23 Diagnostics Menu

Select the control screens for the various test loops that can be activated from the
local Multiplexor, for diagnostic purposes. See Chapter 6 for a description of the
test loops.

Code numbers 1 through 3 are used to select the desired test loop type: local
loops, remote loops and modem loops.

36

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Code Q is used to retum to the MAIN MENU screen.

When you first enter the DIAGNOSTICS menu, the CURRENT STATE line
shows: ALL TESTS IN THE OFF STATE.

Type the code number corresponding to the desired test loop type.

Type Q to retum to the MAIN MENU screen.

4.24 Local Loops Screen

View the current status of the local sub-channel and composite channel loops
and go, if desired, to the control screen for any of these loops.

Code numbers 0 through 2 list the available local loops: composite loop
and loops for each sub-channel.

Code Q is used to return to the DIAGNOSTICS screen.

The CURRENT STATE line shows the current status of the available local loops:
on or off.

To change the condition of any test loop, type the appropriate code number
to go to the loop control screen.

After completing the required actions, type Q to return to the DIAGNOSTICS
screen.

4.25 Remote Loops Screen

View the current status of the remote sub-channel and composite channel loops
and go, if desired, to the control screen for any of these loops.

Its functions are similar to those of the LOCAL LOOPS screen.

37

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

NOTE

Remote digital loopback is performed by toggling pin 21 to the modem
connected to the local Multiplexor. This forces the modem to transmit a
command to the remote modem. Before attempting to perform loopback,
make sure that:

1. The local and remote modems do have V.54 remote loopback
capability.

2. Pin 21 of the local modem is configured to accept loop command.

3. Jumper PIN 21 (Section 4.3) of the Multiplexor is set to ON.

4.26 Modem Loops Screen

View the current status of the loops on the modem serving the main (composite)
channel and go, if desired, to the control screen for any of these loops. Its
functions are similar to those of the LOCAL LOOPS screen.

4.27 Loop Control Screens

Change the current status of the test loop selected on one of the loop selection
screens.

Code numbers 1 and 2 list the two possible conditions of the selected loop: on
or off.

Code Q is used to return to the loop selection screen, from which this screen
was accessed.

The CURRENT STATE line shows the current loop status.

To change the condition of any test loop, type the appropriate code number.

After completing the required actions, type Q to return to the loop selection
screen, from which this screen was accessed.

4.28 Remote Multiplexor Configuration Menu

Select screens that provide system management functions, including configuration
tasks, related to the remote Multiplexor.

38

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Table 4-6. Remote Configuration Menu Items.

Code Item Description

1 TRANSFER Used to initiate transfer of current remote Multiplexor

CONFIGURATION configuration to the local Multiplexor. After remote

FROM REMOTE TO configuration is received by the local Mux, it can be

LOCAL examined using the terminal connected to the local

Mux. As an additional convenience, remote Mux

configuration can be stored in the local Mux, thereby

serving as a backup that can be downloaded again

into the remote Mux in case that unit is replaced.

2 TRANSFER Similar to item 1 except that it is used to initiate

CONFIGURATION transfer of the remote Mux configuration, prepared

FROM LOCAL TO on the local Mux, to the remote Mux.

REMOTE

3 PREPARE REMOTE Used to initiate preparation of remote Mux

MULITPLEXOR configuration, using the terminal connected to the

CONFIGURATION local Mux.

4 ACTIVATE REMOTE Used to restart the remote Mux; if a new

MULTIPLEXOR configuration was transferred from the local Mux to

CONFIGURATION the remote Mux, this command will activate the new

configuration.

Q EXIT Return to SYSTEM CONFIGURATION menu.

4.29 Transfer Configuration from Remote to Local Screen

Provides an indication that the Multiplexor is executing the required actions after
selecting item 1 on the REMOTE MULTIPLEXOR CONFIGURATION menu
above.

This screen is displayed after selecting item 1 on the REMOTE MUTLIPLEXOR
CONFIGURATION menu, while the remote configuration information is
transmitted to the local Multiplexor.

39

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

In most cases, the screen is displayed for a very short interval; however, under
certain traffic conditions, the user may become aware of the transmission delay, so
this screen is used to notify that the required action is being cried out:

TRANSFER CONFIGURATION FROM REMOTE TO LOCAL

WAIT FOR SAVING ACKNOWLEDGE

If you want to exit, press Q.

No action is required on this screen, and after the remote configuration
information is received, the REMOTE MULTIPLEXOR CONFIGURATION menu
is automatically displayed.

However, the screen does provide you with the option to abort the operation, by
pressing Q: this will return you to the REMOTE MULTIPLEXOR
CONFIGURATION menu.

4.30 Remote Multiplexor Configuration Screen

Define the action to be performed on the information regarding remote
Multiplexor configuration, just received after selecting item 1 on the REMOTE
MULTIPLEXOR CONFIGURATION menu.

Table 4-7. Remote Configuration Menu Items.

Code Item Description

1 EXAMINE Used to display the received configuration: choose

this action after saving the received configuration

(item 2 below).

2 SAVE IN LOCAL Used to save (store permanently) the received

MULTIPLEXOR configuration in the local Multiplexor.

Q EXIT Return to REMOTE MULTIPLEXOR

CONFIGURATION screen.

Type the code number corresponding to the desired function.

Type Q to return to the REMOTE MULTIPLEXOR CONFIGURATION menu.

40

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

4.31 Examine Remote Multiplexor Configuration Screen

Displays the information regarding remote Multiplexor configuration, received by
selecting item 1 on the REMOTE MULTIPLEXOR CONFIGURATION menu.

The screen displays the parameters selected for the remote Multiplexor sub­channels.

No action is required on this screen. When you finish looking at this
information, press Q to go back to the REMOTE MULTIPLEXOR
CONFIGURATION menu.

4.32 Save in Local Multiplexor Screen

Confirms that a copy of the configuration of the remote Multiplexor has been
stored in the local Multiplexor, as you instructed by selecting item 1 on the
REMOTE MULTIPLEXOR CONFIGURATION menu.

NOTE

The remote configuration does not override the local configuration: it is
only stored for receiving and backup purpose.

REMOTE CONFIGURATION HAS BEEN SAVED ON LOCAL MULTIPLEXOR

Press Q to exit

Typing Q on this menu will return you to the REMOTE MULTIPLEXOR
CONFIGURATION menu.

4.33 Transfer Configuration from Local to Remote Screen

Provide an indication that the Multiplexor executes the required actions after
selecting item 2 on the REMOTE MULTIPLEXOR CONFIGURATION menu
(Section 4.28).

This screen is displayed after selecting item 2 on the REMOTE MULTIPLEXOR
CONFIGURATION menu, while the configuration of the local Multiplexor is
transmitted to the remote Multiplexor, for viewing it there, or for back-up
purposes.

41

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

In most cases, the screen is displayed for a very short interval; however, under
certain traffic conditions, the user may become aware of the transmission delay, so
this screen is used to notify that the required action is being carried out:

TRANSFER CONFIGURATION FROM LOCAL TO REMOTE WAIT
FOR SAVING ACKNOWLEDGE

If you want to exit, press Q.

No action is required on this screen, and after the remote configuration
information is received, the acknowledgment screen shown below is automatically
displayed:

LOCAL CONFIGURATION HAS BEEN SAVED ON REMOTE MULTIPLEXOR

Press Q to exit

However, the screen does provide you with the option to leave without seeing
the acknowledgment message, by pressing Q: this will return you to the REMOTE
MULTIPLEXOR CONFIGURATION menu, while configuration transfer is being
performed.

4.34 Prepare Remote Multiplexor Configuration Menu

Main menu used to select the configuration task to be carried out on the remote
Multiplexor.

Menu functions are similar to the corresponding functions of the main menu.

Typing Q on this screen will return you to the REMOTE MULTIPLEXOR
CONFIGURATION menu.

4.35 Remote Multiplexor System Configuration Menu

Select the X-ON and X-OFF characters and change the password used by the
remote Multiplexor.

Menu functions are similar to the corresponding functions of the SYSTEM
CONFIGURATION menu (2 above), except that the selections made from this
screen affect only the remote Multiplexor.

Typing Q on this screen will return you to the REMOTE MULTIPLEXOR
CONFIGURATION screen.

42

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

4.36 Remote Sub-Channel 1, 2, Configuration

View and select the current parameter values of remote Multiplexor sub-channels.

Configuration screens are identical to the sub-channel 1 configuration screen
described in Section 4.14. The only difference is in the identification of the sub­channel displayed on the screen.

Typing Q on this screen will return you to the PREPARE REMOTE
MULTIPLEXOR CONFIGURATION screen.

4.37 Activate Remote Multiplexor Configuration

Provide an indication that the remote Multiplexor has activated its new
configuration after selecting item 4 on the REMOTE MULTIPLEXOR
CONFIGURATION menu (Section 4.28).

This screen is displayed after selecting item 4 on the REMOTE Multiplexor
CONFIGURATION menu, after the remote configuration information is
transmitted from the local Multiplexor to the remote Multiplexor using item 2 on
that menu, and it carries the message:

ACTIVATE REMOTE MULTIPLEXOR CONFIGURATION

Press Q to exit

No action is required on this screen. After it has been displayed, press Q to
return to the REMOTE MULTIPLEXOR CONFIGURATION menu.

43

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

5. Operating Instructions

5.1 Controls, Indicators, and Connectors

Table 5-1 lists the functions of the Multiplexor indicators and connectors. The
numbers under the heading “Item” refer to the identification numbers in
Figure 5-1.

Figure 5-1. Indicators.

Table 5-1. Multiplexor Controls, Indicators, and Connectors.

Item Control, Indicator, or Connector Function

1 POWER Indicator Lights when the Multiplexor is powered

2 DATA Activity Indicators Indicators, one for each sub-channel,

light when the corresponding channel is

active (receives or transmits frames)

3 SYNC Indicator Indicator for main link, indicates

Multiplexor synchronization status

Condition Indication

Off Mux not powered

On Mux powered and

synchronized

S1 S1

A1
A2

SYNC DATA

POWER

OVF

TEST

RESET

44

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Table 5-1. Multiplexor Controls, Indicators, and Connectors.

Item Control, Indicator, or Connector Function

Condition Indication

Flashing Mux powered, but not

(Continuous) synchronized with

remote Mux

Flashing Mux retransmits data

(Intermittent) frame upon request

of remote Mux

(usually because a

noisy line causes

errors in the data

received by the

remote Mux)

4 OVF Indicator Lights when Mux buffers are full. In a

properly designed system, this

condition usually indicates that one of

the DTE units connected to the Mux

does not respond to configured flow-

control commands.

5 RESET Resets the Mux.

6 TEST Lights to indicate that the Mux is in

diagnostics mode (one of the test loops

active) or in the command mode. In

either case, traffic is interrupted.

7 Power Connection Socket for power supply, 5 VDC

regulated supply

8 Channel Connectors Connections to Mux channels

9 Link Connector Connector to main link

45

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

5.2 Operating Instructions

5.2.1 G

ENERAL

After being prepared for operation as explained in Sections 4.3 through 4.7, the
Multiplexor normally operates unattended. Operator intervention is only required
when the Multiplexor is setup for the first time or must be adapted to new
operational requirements. Multiplexor configuration is stored in a non-volatile
memory, and is not affected when power is tumed off.

5.2.2 P

OWER-ON

Connect the power cable to the Multiplexor jack, then plug the power-supply unit
into the mains. The SYNC indicator should light.

If the link to the far Multiplexor is not yet operational, the SYNC indicator will
flash. Wait until the link becomes operational, and check that the SYNC indicator
stops flashing and lights continuously.

Check that after a few seconds (during which Multiplexor performs its self-test),
the OVF indicator is extinguished.

5.2.3 N

ORMALOPERATION

During normal operation, the PWR (when present), SYNC, and MAIN indicators
should light continuously, and the TEST and OVF indicators must remain off.

Sub-channel activity indicators flash according to the traffic load, and are
extinguished when the sub-channel is idle.

NOTE

When the TEST indicator lights, traffic is interrupted, even if all the other
indications are normal.

On noisy links, the SYNC indicator may flash from time to time: this indicates
automatic retransmission of a data frame. Automatic retransmission occurs upon
remote Multiplexor request: the request is sent when errors are detected in the
received data, and its use ensures that only valid data is transferred.

5.2.4 P

OWER-OFF

To power off the Multiplexor, disconnect the power supply from the mains, then
disconnect, if required, the power cable from Multiplexor jack.

46

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

5.3 What to Do in Case of Malfunction

5.3.1 P

RELIMINARYACTIONS

Here is a list of actions that will help you return to normal operation in case a
problem occurs. Additional information on Multiplexor diagnostics appears in
Chapter 6.

1. Check that the Multiplexor is powered (SYNC indicator lights or flashes).

2. Check that cables are properly connected.

3. Check that the equipment connected to the Multiplexor is powered and
operates normally.

5.3.2 C

HECKMULTIPLEXOR

I

NDICATIONS

Table 5-2. Multiplexor Indications.

No. Indication Probable Cause Action

1 TEST lit Mux in Check whether the Mux is being

command mode configured, and wait until configuration

is completed (at any time, only one

sub-channel can be in the command

mode).

Mux in Enter command mode, and select the

diagnostics DIAGNOSTICS item, to see whether

mode one of the test loops is on. If a test loop

is on, but is no longer needed,

disconnect it.

2 SYNC flashes Remote Mux Check whether the remote Mux is

continuously not operational powered ON, and operates normally.

Problems in Check whether communication

communication equipment is powered and properly

link to remote connected, then use the diagnostics

Mux function described in Chapter 6 to

identify fault location.

47

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Table 5-2. Multiplexor Indications.

No. Indication Probable Cause Action

3 OVF lights Mux buffers full One of the DTE units connected to the

Mux does not respond to flow control

commands; check that all the DTEs do

have a flow control option, and the Mux

flow control is properly configured.

4 One or more No traffic on If traffic is expected, but no activity is

sub-channel sub-channel indicated, check DTE equipment and

indicators are its connections.

permanently off Mux problem Turn the Mux off, then on again. If ERR

indicator lights, replace the Mux.

5.3.3 C

ONFIGURATION

Check the configuration of local and remote Multiplexor and make sure it
corresponds to the requirements of the equipment connected to its sub-channels.

48

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

6. Diagnostics

6.1 General

Multiplexor diagnostics functions use test loops and indicators to provide the user
with the tools required for rapid identification of faults that affect system
operation.

The test loops available for diagnostics and test purposes are:

a. Local Loops:

1. Local sub-channel loop.

2. Local composite channel loop

b. Remote Loops:

1. Remote sub-channel loop

2. Remote composite channel loop

c. Modem Loops:

1. Analog loop.

2. Remote digital loop

(option—depends on the characteristics of the modem used for the
composite channel, as explained in Section 4.3).

The various test loops are identified in Figure 6-1.

The recommended procedure for locating a problem in the system, is to press
the RESET push-button (or turn the Multiplexor off and on again), in order to
obtain the self-test results, then perform test loops in the order given above.

All the test loops are initiated from the DIAGNOSTICS screen, accessed from
the main menu (see Section 4.8).

This paragraph describes the use of the test loops; refer to Section 4.8 for
detailed instructions on loop activation.

49

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

6.2 Description of Test Loops

Whenever a test loop is on, the TEST indicator will light and traffic will be
disrupted.

6.2.1 L

OCALLOOPS

(1) Local composite channel loop

When the local composite channel loop is connected, the composite channel
data transmitted by the local Multiplexor is applied to the receive line of the local
Multiplexor, and the communication link is disconnected (this causes the remote
Multiplexor to lose frame synchronization). All the data arriving from the remote
Multiplexor while this loop is connected is lost.

This loop tests the complete local Multiplexor.

As long as the loop is connected, the SYNC indicator of the local Multiplexor
must light continuously. If they do not, this indicates a local Multiplexor problem.

Sub-channel activity indicators light according to traffic; the lighting of the OVF
indicator means that Multiplexor buffers are full because of flow control problems
caused by the equipment connected to one of the local sub-channels.

(2) Local sub-channel loop

When a local sub-channel loop is connected, the local transmit data is returned
as receive data on the same sub-channel. The local data is also multiplexed into the
transmit data stream sent to the remote Multiplexor. All the data arriving from the
remote Multiplexor sub-channel while this loop is connected is lost.

As long as the loop is connected, the sub-channel activity indicator lights
according to traffic. The equipment connected to the sub-channel must receive its
own transmit data without errors. Failure to do so usually indicates problems with
the sub-channel connection cable or with equipment connected to that sub­channel.

50

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

6.2.2 R

EMOTE

L

OOPS

(1) Remote composite channel loop

When the remote composite channel loop is connected, the composite channel
data transmitted by the local Multiplexor is returned from the remote Multiplexor
after regeneration but without any other processing. Any data transmitted from
theremote Multiplexor sub-channels is lost during loop connection. This loop tests
the complete transmission path, including the local Multiplexor and the
communication link.

As long as the loop is connected, the SYNC indicator of the local Multiplexor
must light continuously; failure to do so, after the local Multiplexor performed
satisfactorily on the local composite channel loop, indicates a problem in the
communication link. For example, intermittent flashing of the SYNC indicator
indicates high error rate on the link.

Sub-channel activity indicators light according to traffic; the lighting of the OVF
indicator means that the Multiplexor buffers are full because of flow control
problems caused by the equipment connected to one of the local sub-channels.

(2) Remote sub-channel loop

When a remote sub-channel loop is connected, the local transmit data is
transmitted to the remote Multiplexor, and returned to the local Multiplexor sub­channel instead of the transmit data connected to the remote Multiplexor sub­channel. All the data arriving from the remote Multiplexor sub-channel while this
loop is connected is lost.

As long as the loop is connected, the sub-channel activity indicator lights
according to traffic. The equipment connected to the sub-channel must receive its
own transmit data without errors. Failure to do so, after the local Multiplexor

51

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

performed satisfactorily on the local sub-channel loop, usually indicates a problem
in the remote Multiplexor.

6.2.3 M

ODEM

L

OOPS

(1) Analog modem loop

When the analog modem loop is connected, the composite channel data
transmitted by the local Multiplexor is returned to the receive line of the local
Multiplexor after passing through the local modem, and the communication link
is disconnected. All the data arriving from the remote Multiplexor while this loop
is connected is lost.

This loop tests the complete local Multiplexor, its composite-channel
connection cable, and the local modem.

As long as the loop is connected, the SYNC indicator of the local Multiplexor
must light continuously; failure to do so, after the local Multiplexor performed
satisfactorily on the local composite-channel loop, indicates a problem in the
composite-channel connection cable and/or in the local modem.

(2) Remote digital modem loop

When the remote digital modem loop is connected, the composite channel data
transmitted by the local Multiplexor is returned. from the remote modem, after
passing through the communication link and the local modem, to the receive line
of the local Multiplexor. Any data transmitted from the remote Multiplexor is lost
during loop connection.

This loop tests the complete transmission path, including the local Multiplexor,
its composite-channel connection cable, the communication link, and the local
and remote modems.

As long as the loop is connected, the SYNC indicator of the local Multiplexor
must light continuously. Failure to do so, after satisfactory performance in the
analog modem loop, usually indicates a problem in the communication channel
and/or in the remote modem.

52

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Appendix A: Functional Interface

Specifications

A.1 Main (Composite) Channel Interface

Table A-1. Main (Composite) Channel Connector.

CCITT EIA Pin Signal Name Description
V.24 RS­Circuit 232C
Number Line

101 AA 1 Protective Ground Chassis ground (may be isolated from

signal ground or connected to it—refer

to Section 4.3)

102 AB 7 Signal Ground Common signal and DC power supply

ground

103 BA 2 Transmit Data Serial digital transmit data from the

Mux

104 BB 3 Receive Data Receive data from modem

105 CA 4 Request to Send Continuous positive level from the Mux

109 CF 8 Data Carrier Detect Data carrier detect indication from

modem

114 DB 15 Transmitter Signal Transmit clock from modem

115 DD 17 Receiver Signal Receive clock from modem

Element

141 18 Loop 3 Test Command Control signal from Mux: positive level

commands the modem into analog

loopback

53

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Table A-1. Main (Composite) Channel Connector.

CCITT EIA Pin Signal Name Description
V.24 RS­Circuit 232C
Number Line

108 CD 20 Data Terminal Ready Remains positive for a period of 20

seconds then drops to a negative level

for approximately 1 second and returns

to the positive level for another 20

seconds continuously until

synchronization with the remote Mux is

established

140 21 Loop 3 Test Command Control signal from Mux to modem.

Positive level commands the attached

modem to send a remote loopback

command to the remote modem. If the

attached modem uses pin 21 as a signl

quality indication output, set pin 21 to

OFF, disabling this function (refer to

Section 4.3)

A.2 Sub-Channel Interface

Multiplexor sub-channel interfaces are configured as asynchronous DCE RS-232
interfaces. The sub-channel connectors have RJ-45 sockets. Pin allocations are
listed in Table A-2.

54

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Table A-2. Sub-Channel Connector.

CCITT EIA Pin Signal Name Description
V.24 RS­Circuit 232C
Number Line

101 AA 1 Protective Ground Chassis ground (may be isolated from

signal ground or connected to it; refer to

Section 4.3.

102 AB 7 Signal Ground Common signal and DC power-supply

ground.

103 BA 5 Transmit Data Serial digital transmit data from the Mux.

104 BB 3 Receive Data Receive data provided by Mux receiver.

105 CA 2 Request to Send Received by Mux from DTE, controls

DCD at remote side.

106 CB 8 Clear to Send A positive level from the Mux indicates

that the terminal is allowed to send

data. This pin is used for hardware flow

control. Computers or terminals that do

not support this pin (they send data evn

if CTS is negative) must have software

flow control.

107 CC — Data Set Ready The Mux sends positive level to DTE

when it is powered.

109 CF 4 Data Carrier Detect If local and remote Muxes are

synchronized, then follows CTS from

sub-channel of remote Mux.

108 CD 6 Data Terminal Ready Used for end-to-end flow control.

55

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Sub-channel connection cables depend on application: a port (“straight­through”) cable is generally used to connect the Mux to a DTE, and a modem
(“crossover”) cable is used to connect the Mux to a tail-end modem (see
Figure A-1).

Figure A-1. Typical Sub-Channel Cable Wiring.

1
2
3
5
6
7
4
8

20

CHASSIS GND

TD
RD

CTS

DSR

SIGNAL GND

RTS

DCD

DTR

1
5
3
8

7
2
4
6

SUB-CHANNEL

CONNECTOR

RJ-45

PIN-OUT

DTE

CONNECTOR

STRAIGHT-THRU

(PORT) CABLE

1
3
2
5

20

7
8
4
6

CHASSIS GND

TD
RD

CTS

DSR

SIGNAL GND

RTS
DCD
DTR

(1)
(5)
(3)
(8)

­(7)
(2)
(4)
(6)

SUB-CHANNEL

CONNECTOR

RJ-45

PIN-OUT

MODEM

CONNECTOR

CROSS-OVER

CABLE

1
2
3
5
6
7
4
8

20

CHASSIS GND

TD

RD
CTS
DSR

SIGNAL GND

RTS
DCD
DTR

1
5
3
8

7
2
4
6

SUB-CHANNEL

CONNECTOR

RJ-45

PIN-OUT

DTE

CONNECTOR

STRAIGHT-THRU

(PORT) CABLE

1
3
2
5

20

7
8
4
6

CHASSIS GND

TD

RD
CTS
DSR

SIGNAL GND

RTS
DCD
DTR

(1)
(5)
(3)
(8)

­(7)
(2)
(4)
(6)

SUB-CHANNEL

CONNECTOR

RJ-45

PIN-OUT

MODEM

CONNECTOR

CROSS-OVER

CABLE

NOT CONNECTED

Flow Control X-ON/X-OFF or DTR/DSR.

Flow Control X-ON/X-OFF or RTS/CTS.

56

MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR

Appendix B: Configuration Record

This appendix presents a typical configuration record form, which you can use as a
worksheet during configuration planning, and as a permanent record of the actual
configuration.

Multiplexor Configuration Form

Date:___________________ Prepared by:____________________

Location:_______________ Far Location:____________________

Multiplexor Serial No.

Local_________________ Remote_________________________

System Password_________________________________

X-ON Character__________ X-OFF Character__________________

Character Length______________________

Flow Control (FC)______________________

Data Sub-Channel Data Rate______________

Parity___________________ Stop Bits__________________

1000 Park Drive • Lawrence, PA 15055-1018 • 724-746-5500 • Fax [phone]

© Copyright 1998. Black Box Corporation. All rights reserved.