Black Box LDM-MR128 User manual

CUSTOMER
SUPPORT
INFORMATION
JULY 2000
ME444A-R3
ME444AE-R3
ME444A-530-R3
ME444AE-530-R3
Order toll-free in the U.S. 24 hours, 7 A.M. Monday to midnight Friday: 877-877-BBOX
FREE technical support, 24 hours a day, 7 days a week: Call 724-746-5500 or fax [phone]
Mail order: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018
Web site: www.blackbox.com • E-mail: [email protected]
256-Kbps V.35 Line Driver
(LDM-MR128)

FEDERAL COMMUNICATIONS COMMISSION
AND
INDUSTRY CANADA
RADIO FREQUENCY INTERFERENCE STATEMENTS
This equipment generates, uses, and can radiate radio frequency
energy and if not installed and used properly, that is, in strict
accordance with the manufacturer’s instructions, may cause
interference to radio communication. It has been tested and found
to comply with the limits for a Class A computing device in
accordance with the specifications in Subpart 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 Industry Canada.
Le présent appareil numérique n’émet pas de bruits radioélectriques
dépassant les limites applicables aux appareils numériques de
classe A prescrites dans le Règlement sur le brouillage radioélectrique publié
par Industrie Canada.
TRADEMARKS USED IN THIS MANUAL
AS/400 and IBM are registered trademarks of International
Business Machines Corporation.
Any other trademarks mentioned in this manual are acknowledged to be
the property of the trademark owners.
FCC AND IC STATEMENTS, TRADEMARKS
1

128-KBPS V.35 LINE DRIVER (LDM-MR128)
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.
2

NOM STATEMENT
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.
3

128-KBPS V.35 LINE DRIVER (LDM-MR128)
4
Contents
Chapter Page
1. Specifications ............................................................................................. 5
2. Introduction ............................................................................................... 7
2.1 Physical Description ............................................................................ 7
2.2 Functional Description ....................................................................... 8
2.2.1 Encoder Modulator ................................................................. 10
2.2.2 Modulation Timing ................................................................ 10
2.2.3 Signal Levels ........................................................................... 10
2.2.4 Receiver .................................................................................. 11
2.2.5 V.54 Diagnostics ..................................................................... 11
2.2.6 Test-Pattern Generator and Receiver ................................... 11
2.3 Applications ........................................................................................ 12
3. Installation ................................................................................................ 14
3.1 Site Preparation ................................................................................ 14
3.2 Mechanical Assembly ........................................................................ 14
3.3 Installation in 19-Inch Racks ............................................................ 19
3.3.1 Installing a Single Unit in a 19-Inch Rack ............................ 19
3.3.2 Installing Two Units in a 19-Inch Rack ................................. 19
3.4 Connecting Data Cables ................................................................... 22
3.4.1 Power Connection .................................................................. 24
3.4.2 LINE Connection ................................................................... 25
3.4.3 DTE Connection .................................................................... 26
4. Operation ................................................................................................. 27
4.1 Controls and Indicators .................................................................... 27
4.2 Operating Procedure ........................................................................ 29
5. Troubleshooting ...................................................................................... 30
5.1 Loop Tests ......................................................................................... 30
5.2 Bit-Error-Rate Tester (BERT) .......................................................... 30
5.3 The Modem Self-Test ........................................................................ 32
5.4 Local Analog Loopback .................................................................... 33
5.5 Remote Digital Loopback ................................................................. 34
5.6 Local Digital Loopback .................................................................... 35
5.7 Calling Black Box .............................................................................. 37
5.8 Shipping and Packaging ................................................................... 37
Appendix: Maximum Distances ..................................................................... 38

5
CHAPTER 1: Specifications
Compliance — FCC Class A, IC Class/classe A
Standards — Loopback tests: ITU-TSS V.54;
BERT: ITU-TSS V.52
Interfaces — Line side: Proprietary;
Device side: ITU-TSS V.35
Protocol — Synchronous
Clock Source — Internal, external (from attached device), or
recovered (from remote LDM-MR128)
Flow Control — None
Operation — 4-wire, full- or half-duplex, point-to-point or
multipoint
Data Rate — 256, 192, 144, 128, 112, 96, 72, 64, 56, 48, 32, or
19.2 Kbps (user-selectable)
Maximum
Distance — See the tables in the Appendix
User Controls — (4) Front-mounted pushbuttons for loopback testing
and BERT;
(1) Internal data-rate screwdial;
(14) Internal jumpers and (1) internal 3-position DIP
switch for timing, testing, signal levels/impedances,
and other features
Diagnostics — V.54-compliant loopback tests; V.52-compliant BERT
1. Specifications

6
128-KBPS V.35 LINE DRIVER (LDM-MR128)
Indicators — (7) Front-mounted LEDs: PWR (power), RTS, TD,
RD, DCD, TEST, ERR (error)
Connectors — (2) Rear-mounted: (1) 34-pin M-block female,
(1) 5-position terminal block
Leads/Signals
Supported — See Table 3-2 on page 25
Power — ME444A-R3: Directly from outlet through
detachable 5-ft. (1.5-m) power cord (included):
Optimal Input: 115 VAC, 60 Hz;
Input Ranges: 103.5 to 126.5 VAC, 47 to 63 Hz;
Consumption: 5 watts;
ME444AE-R3: Directly from outlet through
detachable 5-ft. (1.5-m) power cord:
Optimal
Input: 230 VAC, 50 Hz;
Input Ranges: 207 to 253 VAC, 47 to 63 Hz;
Consumption: 5 watts
MTBF — 75,500 hours
Maximum
Altitude — 8000 ft. (2438.4 m)
Temperature
Tolerance — 32 to 122˚ F (0 to 50˚ C)
Humidity
Tolerance — Up to 90% noncondensing
Enclosure — High-impact plastic
Size — 1.8"H x 7.6"W x 9.6"D (4.6 x 19.3 x 24.3 cm), but the
unit’s pushbuttons protrude up to 0.3" (66 mm)
from the front panel and the connectors protrude
up to 0.8" (1.9 cm) from the rear panel
Weight — Net: 3.1 lb. (1.4 kg); Shipping: 6 lb. (2.7 kg)

7
CHAPTER 2. Introduction
The 128-Kbps V.35 Line Driver (LDM-MR128) is a short-range modem for
synchronous transmission—full- or half-duplex—over unconditioned lines.
With a range of up to 11.8 miles (19 km), the LDM-MR128 operates at user-
selectable data rates from 19.2 to 256 Kbps.
The LDM-MR128 uses conditional differential diphase modulation
(EUROCOM Std. D1) to provide immunity from background noise, eliminate
normal line distortion, and enable efficient transmission and reception of
serial data over a twisted-pair cable. The modem is coupled to the line
through isolation transformers which, in conjunction with protective circuitry,
safeguard against AC or DC overvoltages. With this protective circuitry, the
LDM-MR128 can operate even when DC is connected to the line.
Transmit timing is provided internally, derived externally from the PC or
terminal, or regenerated from the Receive signal. Receive timing is always
regenerated from the Receive signal.
The LDM-MR128 features V.54 diagnostic capabilities for local analog
loopback and local and remote digital loopback testing. In the digital
loopback mode, the operator at either end of the line may test both modems
and the line. The loopback is controlled either by pressing front-panel
pushbuttons or by manipulating signals on the V.35 (DTE) interface.
The LDM-MR128 incorporates a built-in Bit Error Rate Tester (BERT). The
internal BERT enables complete testing of both modems and the line without
external test equipment. Pressing the LDM-MR128’s front-panel PATT button
causes the unit to generate a pseudo-random test pattern (511-bit, according
to ITU-TSS V.52) for testing end-to-end connectivity. The ERR LED flashes
when a bit error occurs.
2.1 Physical Description
The LDM-MR128 is designed as a desktop unit only, but can be mounted in
a 19-inch rack with optional brackets (see Section 3.3). For descriptions of its
controls and indicators, see Section 4.1.
2. Introduction

8
128-KBPS V.35 LINE DRIVER (LDM-MR128)
2.2 Functional Description
This section describes the operation of the LDM-MR128’s circuit blocks,
primarily the circuits required for correctly configuring the modem
(see Figure 2-1 below).
Figure 2-1. LDM-MR128 block diagram.

9
CHAPTER 2. Introduction
2.2.1 E NCODER M ODULATOR
The encoder modulator receives data from the DTE, then modulates the data
using the “conditional diphase modulation” technique. You can configure the
encoder to operate in one of three modes:
• 4-wire full-duplex (point-to-point)
• 4-wire half-duplex (point-to-point)
• 4-wire multipoint
The appropriate mode is determined by the setting of two jumpers: CARRIER
(J2) and RTS-CTS DLY (J4). For multipoint applications, two additional
jumpers must be set: XMT IMP (J13) and RCV IMP (J10). See Chapter 3
for a more detailed explanation of the correct jumper settings.
NOTE
In multipoint applications, do not use the 0-msec option for the RTS-CTS
delay.
2.2.2 M ODULATION T IMING
This circuit supplies the transmit clock to the encoder. Three clock sources
are available on the XMT CLK jumper (J3):
•INT—Internal clock. From the modem’s internal crystal oscillator.
•EXT—External clock. From DTE.
•RCV—Receive clock. Recovered from the receive signal.
There is also an ASY (asynchronous) setting, but this has no function
and should not be selected.
2.2.3 S IGNAL L EVELS
Two options are available for the transmit and receive signal levels: 0 and
–6 dBm. You can control the transmit level with the XMT LVL jumper.
You can control the receive level with the RCV LVL jumper.

10
128-KBPS V.35 LINE DRIVER (LDM-MR128)
2.2.4 R ECEIVER
The receiver comprises several circuits, as shown in the block diagram
(see Figure 2-1 on page 8):
• The RECEIVE FILTER, which removes all the out-band frequencies.
• The EQUALIZER, which comprises several equalizers activated
according to data rate.
• The digital Automatic Gain Control (AGC), which automatically
compensates for the attenuation of the line.
2.2.5 V.54 D IAGNOSTICS
V.54 loops are activated manually with the front-panel pushbuttons, or
through the DTE interface. The pushbuttons and the DTE interface can be
enabled or disabled separately by the ANA, REM, and SWITCH jumpers.
When you use the LDM-MR128 as a tail-end to a digital network, the V.54
DLY jumper in the modems located close to the network should be set to
ON to prevent multiple loopbacks. The delay switch is used to prevent the last
modem from receiving the complete V.54 data sequence and, in turn, being
induced into a loop.
2.2.6 T EST -P ATTERN G ENERATOR AND R ECEIVER
This feature allows for easy and quick testing of the local modem as well
as the communication link. When the PATT button on the front panel is
pressed, the circuit sends and checks a standard 511-bit pseudo-random
pattern. If the modem encounters errors, the ERR LED remains ON or
blinks.
The test can be carried out in local analog loopback, in remote digital
loopback, or in normal point-to-point operation opposite a remote
LDM-MR128 modem. Press the PATT pushbutton on the remote unit
or connect a Bit Error Rate Tester that uses the standard 511-bit pattern.

11
CHAPTER 2. Introduction
Figure 2-2. Point-to-point application.
Figure 2-3. Tail-circuit application.
2.3 Applications
The diagrams on this page and the following pages illustrate the LDM-MR128
operating in various applications.
AS/400®
SYNC HOST SYNC HOST
CSU/DSU
DDS
(56 Kbps) EXTERNAL
CLOCK
4-WIRE
TWISTED
PAIR
RECEIVE
CLOCK
CSU/DSU
TAIL CIRCUIT
LDM-
MR128
LDM-
MR128
LDM-MR128 LDM-MR128
AS/400
19.2 to
256 Kbps
4-Wire
Up to 11.8 mi. (19 km)

12
128-KBPS V.35 LINE DRIVER (LDM-MR128)
Figure 2-4. LAN application—extending the distance
between two networks.
3.7 miles (6 km) at 256 Kbps
using two twisted pairs
of 19-gauge wire
ETHERNET
BACKBONE
V.35 CABLE
PC
PC
PC
PC
PC
PC
V.35 REMOTE
E-SERIES BRIDGE
(LB3001A)
V.35 REMOTE
E-SERIES BRIDGE
(LB3001A)
V.35 CABLE
LDM-MR128 LDM-MR128
ETHERNET
BACKBONE

13
CHAPTER 2. Introduction
Figure 2-5. Multipoint application.
IBM®S/3X
MAINFRAME
V.35 INTERFACE
V.35
CABLE
4-WIRE
TWISTED
PAIR
(64 KBPS)
LDM-MR128
LDM-MR128
LDM-MR128
LDM-MR128
V.35
CABLE
V.35
CABLE
V.35
CABLE
V.35 INTERFACE
V.35 INTERFACE
V.35 INTERFACE
IBM 3274
CONTROLLER
IBM 3274
CONTROLLER
IBM 3274
CONTROLLER

14
128-KBPS V.35 LINE DRIVER (LDM-MR128)
This chapter explains how to install your LDM-MR128. After you install it,
see Chapter 4 for how to operate it and Chapter 5 for how to test the system.
3.1 Placement
Install the LDM-MR128 within 5 ft. (1.5 m) of a grounded, easily accessible
AC outlet. The outlet should be capable of providing either 115 VAC (if your
LDM-MR128 is an ME444A-R3 model) or 230 VAC (if your unit is an
ME444AE-R3).
The LDM-MR128 is designed to be placed on a tabletop or bench, and is
shipped completely assembled. Allow at least 36" (90 cm) of frontal clearance
for operation and access for maintenance. You also need at least 4" (10 cm)
of clearance at the rear of the unit for signal lines and interface cables.
3.2 Configuration
Before attaching anything to the LDM-MR128, determine which data rate
you’re going to use, what the system’s clock source should be, and how you
want to set all of the other user-configurable options on the LDM-MR128.
(Refer to Table 3-1 on the next two pages for a list of all of these options;
the SWnand Jnnumbers in the table’s “Element” column correspond to
the locations with the same numbers in Figure 3-1 on page 19.)
(text continues on page 18)
3. Installation

15
CHAPTER 3. Installation
Table 3-1. User-Configurable Options
Element Function Possible Standard
Settings Factory
Setting
SW3 Select the data rate in kilobits per second. Opt. 1
BAUD RATE F-256
Dial 0-192
1-144
2-128
3-112
4-96
5-72
6-64 64 Kbps
7-56
8-48
9-32
D-19.2
J1 Enable or disable requests for V.54 digital DIS
V54 DIS loopback tests from the remote LDM-MR128. EN EN (enabled)
Jumper
J2 Select the Transmit-carrier mode. When you CNTRL
CARRIER set this jumper to “ON,” Transmit carrier is ON ON
Jumper constantly ON. When you set this jumper to
jumper to “CNTRL,” Transmit carrier is ON only
when RTS is high.
Use the CNTRL setting for multipoint
applications.
J3 Select the source of the Transmit timing signal: INT INT (Internal)
XMT CLK internal clock, external clock (from DTE), or EXT
Jumper receive clock (from remote unit). Do not select RCV
the ASY (asynchronous, no clock) setting. ASY
SW2 [This switch only comes into play when ASY
Data-Format (asynchronous) is selected on jumper J3. ASY
DIP Switch should never be selected on this unit, so the
settings of this switch are irrelevant.]
J4 Select the delay in milliseconds that 0
RTS-CTS occurs during RTS-to-CTS transitions. 9 9 ms
DLY Jumper Do not select 0 for multipoint applications. 70
J5 Turn V.54 delay ON or OFF. When you turn ON
V54 DLY it ON, V.54 delay prevents multiple loopback OFF OFF
Jumper of tail-end circuits.
J6 Enable or disable the DIG, ANA, and REM ON ON (enabled)
SW. EN. loopback-control buttons on the unit’s front OFF
Jumper panel.

16
128-KBPS V.35 LINE DRIVER (LDM-MR128)
Table 3-1. User-Configurable Options (continued)
Element Function Possible Standard
Settings Factory
Setting
J7 Enable or disable electronic control of EN EN (enabled)
RLB DTE* remote digital loopback testing through the DIS
Jumper DTE interface.
J8 Enable or disable electronic control of EN EN (enabled)
ALB DTE* local analog loopback testing through the DIS
Jumper DTE interface.
J9 Select the level (in dBm) of Receive -6
RCV LVL input from the line. 0 0 dBm
Jumper
J10 Select the Receive-line impedance. In 150 [Ω] 150 ohms
RCV IMP multipoint applications, it is advisable to HIGH
Jumper set the master modem and the last modem
in the line to 150 Ω, and all others to HIGH.
J11 Enable or disable the Remote Power ON ON
RPF. Failure feature. OFF
Jumper
J12 Select the level (in dBm) of Transmit -6
XMT LVL output to the line. 0 0 dBm
Jumper
J13 Select the Transmit-line impedance in 150 [Ω] 150 ohms
XMT IMP ohms. In multipoint applications, it is a LOW
Jumper good idea to set the master modem to
“LOW.”
J14 Set to CON to connect Signal Ground to DIS
CHASS Chassis Ground. Set to DIS to keep the CON
CON (connected)
Jumper two grounds isolated from each other.
*NOTES: If the DTE does not provide the test pins for analog and remote loopback, the ALB DTE
and RLB DTE jumpers must be always set to DIS.

17
CHAPTER 3. Installation
Figure 3-1. Layout of the LDM-MR128’s printed circuit board.

18
128-KBPS V.35 LINE DRIVER (LDM-MR128)
When you have everything at least tentatively decided, take these steps to set
the unit’s internal controls:
CAUTION!
Disconnect the unit from the power line before removing it from its
housing.
WARNING: HIGH VOLTAGE!
Any adjustment, maintenance, and repair of the open instrument under
voltage should be avoided as much as possible, and, when inevitable,
should be carried out only by a skilled person who is aware of the hazard
involved. Capacitors inside the instrument may still be charged even
after the instrument has been disconnected from the power source.
1. Disconnect the AC power cord from the AC mains outlet.
2. Unscrew the two rear-panel screws until the rear panel becomes loose.
This releases the unit’s “drawer” mechanism; now you can pull the screws
as if they were the knobs on a drawer and expose or remove the unit’s
circuit board.
3. Identify the control(s) (refer to Figure 3-1 on page 19).
4. Move the control(s) to your desired position(s).
5. Replace the circuit board and screw the rear-panel screws back in.

19
CHAPTER 3. Installation
3.3 Installation in 19-Inch Racks
3.3.1 O VERVIEW
The LDM-MR128 can be installed in 19-inch racks. It is 1U (1.75", 4.4 cm)
high and is slightly less than half as wide as the available mounting area.
Two rack-adapter kits are available as special quotes: One kit provides the
hardware necessary to install a single unit, and the other provides the
hardware necessary to install two units side by side. Sections 3.4.2 and 3.4.3
provide step-by-step instructions for installation of single or dual units.
CAUTION!
Disconnect the units from AC power while performing the following
procedures.
3.4.2 I NSTALLING A S INGLE U NIT IN A 19-I NCH R ACK
The rack-adapter kit for single-unit installation includes one short bracket
and one long bracket. The brackets are fastened with screws to the two side
walls of the case, as shown in Figure 3-2 on the next page.
To prepare the LDM-MR128 for rack installation, attach the two brackets to
the sides of the unit. Do this by inserting screws and flat washers into the two
holes at the front of each side of the LDM-MR128 (nuts are already in place
inside the unit).
After attaching the brackets, install the unit in your 19-inch rack by
fastening the brackets to the rack’s side rails with four screws (not included
in the kit), two on each side.
3.4.3 I NSTALLING T WO U NITS IN A 19-I NCH R ACK
The adapter kit includes two long side rails (one for each unit), which slide
into each other to fasten the units together, and two short side brackets,
which hold the two LDM-MR128s side by side in a 19-inch rack. Refer to
Figure 3-3 on page 23 when you perform the following procedure:
1. Fasten one long side rail to each LDM-MR128—one rail on the right side
of one unit, the other rail on the left side of the other unit—using the
four included screws and flat washers. The rails must be attached so that
they “oppose” each other: The narrow flange of the first rail must face
the wide flange of the second rail.