Black Box ME935A User manual

CUSTOMER
SUPPORT
INFORMATION
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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]
NOVEMBER 2000
ME935A
Async Short-Haul Modem MP
Power TD RD
Control
IN
Control
OUT Loopback
Test

1
TRADEMARKS
Trademarks
AT&T is a registered trademark of American Telephone and Telegraph Company.
Any other trademarks mentioned in this manual are acknowledged to be the
property of the trademark owners.

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ASYNC SHORT-HAUL MODEM MP
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 J 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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NOM STATEMENT
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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ASYNC SHORT-HAUL MODEM MP
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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CONTENTS
Contents
Chapter Page
1. Specifications............................................................................................................6
2. Introduction ............................................................................................................7
2.1 Overview ..........................................................................................................7
2.2 Features ..........................................................................................................7
3. Configuration ..........................................................................................................8
3.1 Quick Set-Up Instructions..............................................................................8
3.1.1 Point-To-Point Configuration ..............................................................8
3.1.2 Multipoint Configuration ....................................................................8
3.2 DCE/DTE Switch Settings ............................................................................9
3.3 Special Configuration ....................................................................................9
4. Installation..............................................................................................................11
4.1 Twisted-Pair Wiring Overview......................................................................11
4.1.1 Twisted-Pair Connection Using Terminal Blocks ............................12
4.1.2 Twisted-Pair Connection Using RJ-11 ................................................12
4.2 Wiring For Multipoint Circuits....................................................................13
4.2.1 Daisychain Topology ..........................................................................13
4.2.2 Star Topology ......................................................................................14
4.3 RS-232 Connection ......................................................................................14
5. Operation ..............................................................................................................15
5.1 LED Indicators..............................................................................................15
5.2 Loopback Test Modes ..................................................................................15
5.2.1 Local Analog Loop ..............................................................................15
5.2.2 Remote Analog Loop ..........................................................................16
6. Troubleshooting ....................................................................................................17
Appendix A. Cable Recommendations ....................................................................19
Appendix B. Interface Pin Assignments....................................................................20
Appendix C. Block Diagram ......................................................................................21

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ASYNC SHORT-HAUL MODEM MP
1. Specifications
Transmission Format— Asynchronous
Transmission Line— 19 to 26 AWG twisted pair
Range— See table in Appendix A
Serial Interface— EIA RS-232 (CCITT V.24), DB25 female
Twisted-Pair Interface— Terminal blocks, RJ-11 jack
Data Rates— Up to 115,200 bps
Applications— Point-to-point, multipoint
Indicators— Tri-state for transmit data, receive data, control in,
control out; dual-state for power, loopback test
Diagnostics— Local Analog Loopback (LAL), Remote Analog
Loopback (RAL)
Optical Isolation— 2500V RMS minimum
Surge Suppression— Over-voltage protection for opto-isolators via Silicon
Avalanche Diodes
Temperature Range— 32 to 140°F (0 to 60°C)
Humidity Tolerance— 5 to 95%, noncondensing
Maximum Altitude Range— Up to 15,000 feet (4572 m)
Power Supply— Wallmount, outputs 10 VAC, 700 ma
Size— 1.5"H x 4.1"W x 5"D (3.8 x 10.4 x 12.7 cm)
Weight— 13.2 oz. (374.2 g) without transformer

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CHAPTER 2: Introduction
2. Introduction
2.1 Overview
The Async Short-Haul Modem MP is equipped with a virtual wish list of “bells and
whistles.” Point-to-point or multipoint applications are supported. Two separate
control signals may be passed (one each way), each with switch-selectable pin
assignments. Data lines are protected from ground loops and electrically volatile
environments by optical isolation and Silicon Avalanche Diodes. System integrity
can be evaluated using two built-in test modes: local analog loopback and remote
analog loopback. Tri-state LEDs monitor transmit data, receive data, and control
signals. Finally, 4-wire connections may be made using either RJ-11 jack or terminal
blocks—both are included.
In addition, the Async Short-Haul Modem MP is perfect for low-power RS-232
environments. The Modem is AC powered, and therefore is the recommended
solution for RS-232 environments whose interface voltages are below RS-232
specifications. The Modem supports data rates to 115.2 kbps and extends RS-232
transmission distances up to 14 miles (22.5 km) over two twisted pairs.
The Modem is housed in a sturdy metal case and comes with either 115 or 220V
external transformers.
2.2 Features
• Data rates to 115.2 kbps.
• Built-in optical isolation and high-speed surge protection.
• Distances up to 14 miles (19 AWG TWP @ 1200 bps).
• Tri-state LED indicators.
• Point-to-point or multipoint applications.
• Local and remote loopback test modes.
• DCE/DTE switch-selectable.
• Hardware and software flow control support.
• Externally powered.

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ASYNC SHORT-HAUL MODEM MP
3. Configuration
The Async Short-Haul Modem MP features externally accessible configuration
switches (two DCE/DTE switches and a DIP-switch set), located on the underside
of the unit; there is no need to open the case to configure the Modem.
3.1 Quick Set-Up Instructions
In the majority of applications, you won’t need an in-depth knowledge of the
Modem’s capabilities to get up and running. The following quick-setup DIP-switch
configurations cover most Modem operating environments. (Note that DIP-switch
8 is not used.)
3.1.1 P OINT -T O -P OINT C ONFIGURATION
If you are installing these Modems in a point-to-point application with a computer,
printer, or terminal, configure the DIP switches on both Modems as follows:
Switch Number 1 2 3 4 5 6 7
Positions OFF OFF OFF ON ON ON OFF
3.1.2 M ULTIPOINT C ONFIGURATION
The Modem supports multipoint operation in either daisychain or star
configurations.
In a multipoint topology, you must configure the master Async Short-Haul Modem
MP’s DIP switches differently than those of the slave Modems. These are the
proper DIP-switch settings for a daisychain topology:
Switch Number 1 2 3 4 5 6 7
Master Positions ON ON ON OFF OFF OFF OFF
Slave Positions ON ON ON OFF OFF OFF ON

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CHAPTER 3: Configuration
3.2 DCE/DTE Switch Settings
Correct setting of the DCE/DTE switches eliminates the need for RS-232 crossover
cables. If the RS-232 device you are connecting to the Modem is a PC, terminal, or
host (or is wired like one), set both of the DCE/DTE switches to DCE. If the RS-
232 device you are connecting to the Async Short-Haul Modem MP is a modem or
multiplexor, or is wired like one, set both of the DCE/DTE switches to DTE.
3.3 Special Configuration
If your Modem requires special configuration, use Table 3-1 as a guide. This table
shows all of the possible Modem switch settings. Following the table are brief
descriptions of the Control Input, Control Output, +Voltage Output and Carrier
Controlled by (Cin) parameters shown in the table.
Table 3-1. All possible switch settings for the Modem
Control Control +Voltage Carrier Switch Settings
Mode Input Output Output Controlled
(DCE/DTE) (CIn)(C
Out)(V Out) by (CIn)1234567
DCE 4 8 6 Disabled ON ON ON OFF OFF OFF OFF
DCE 4 8 6 Enabled ON ON ON OFF OFF OFF ON
DCE 4,11,20* 8 6 Disabled OFF ON ON ON OFF OFF OFF
DCE 4,11,20* 8 6 Enabled OFF ON ON ON OFF OFF ON
DCE 4 6 8 Disabled ON OFF OFF OFF ON ON OFF
DCE 4 6 8 Enabled ON OFF OFF OFF ON ON ON
DCE 4,11,20* 6 8 Disabled OFF OFF OFF ON ON ON OFF
DCE 4,11,20* 6 8 Enabled OFF OFF OFF ON ON ON ON
DTE 8 4 11,20** Disabled ON ON ON OFF OFF OFF OFF
DTE 8 4 11,20** Enabled ON ON ON OFF OFF OFF ON
DTE 5,6,8* 4 11,20** Disabled OFF ON ON ON OFF OFF OFF
DTE 5,6,8* 4 11,20** Enabled OFF ON ON ON OFF OFF ON
DTE 8 11,20** 4 Disabled ON OFF OFF OFF ON ON OFF
DTE 8 11,20** 4 Enabled ON OFF OFF OFF ON ON ON
DTE 5,6,8* 11,20** 4 Disabled OFF OFF OFF ON ON ON OFF
DTE 5,6,8* 11,20** 4 Enabled OFF OFF OFF ON ON ON ON
*Multiple input pins are "or-tied"—if any input goes low, carrier is dropped.
**Multiple output pins generate the same signal simultaneously.