Page 1
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 724-746-0746
Mail order: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018
Web site: www.blackbox.com • E-mail: info@blackbox.com
256-Kbps V.35 Line Driver
(LDM-MR128)
Page 2
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
Page 3
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
Page 4
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
Page 5
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
Page 6
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
Page 7
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)
Page 8
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 userselectable 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
Page 9
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.
Page 10
9
CHAPTER 2. Introduction
2.2.1 E
NCODERMODULATOR
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
ODULATIONTIMING
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
IGNALLEVELS
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.
Page 11
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-PATTERNGENERATOR ANDRECEIVER
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.
Page 12
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)
Page 13
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
Page 14
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
Page 15
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 SWn and Jn numbers 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
Page 16
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.
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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.
Page 18
17
CHAPTER 3. Installation
Figure 3-1. Layout of the LDM-MR128’s printed circuit board.
Page 19
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.
Page 20
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 ASINGLEUNIT IN A
19-I
NCHRACK
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
NSTALLINGTWOUNITS IN A
19-I
NCHRACK
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.
Page 21
20
128-KBPS V.35 LINE DRIVER (LDM-MR128)
Figure 3-2. Installing a single unit in a 19-inch rack.
2. Using four included screws and flatwashers for each bracket, attach
the two short brackets to the vacant sides of the LDM-MR128s.
3. Slide the two LDM-MR128s’ side rails into each other, fastening the
two units together.
4. Secure the included plastic caps to the ends of the rails, to protect
the rail ends and prevent the units from moving.
5. You can now use four screws (not supplied with the kit), two on each
side, to fasten the assembled units to the side rails of the 19-inch rack.
Page 22
21
CHAPTER 3. Installation
Figure 3-3. Installing two units in a 19-inch rack.
Page 23
22
128-KBPS V.35 LINE DRIVER (LDM-MR128)
3.4 Connecting Data Cables
After you set the LDM-MR128
’s internal controls, the LDM-MR128 is ready
to be cabled for operation.
Its electrical connectors are located on its rear panel, as shown in
Figure 3-4 below. These consist of a female V.35 interface connector labeled
“DTE,” a 5-screw terminal block, and an IEC 320 AC inlet that contains an
integral fuse compartment.)
The V.35 interface connector, a 34-pin M-block female, carries input/
output data, clock signals, and control signals
between the LDM-MR128
and the DTE or DCE
(refer to Table 3-2 on the next page).
The terminal block has five screws for connecting transmit and receive
lines—the transmit pair where XMT is indicated (for data output from the
unit), the receive pair where RCV is indicated (for data input to the unit),
and a drain wire from the cable shield, if you are using shielded cable, where
GND is indicated. The XMT and RCV pairs are not sensitive to polarity.
Connect power and data cables to the LDM-MR128 as described in the
following subsections.
Figure 3-4. The LDM-MR128’s rear panel.
Page 24
23
CHAPTER 3. Installation
Table 3-2. Pinout of the LDM-MR128’s V.35 Connector
SIGNAL ITU-TSS LEAD V.35
NAME (ABBREV.) CIRCUIT TYPE PIN
Frame (Protective) Ground (FGND) 101 A
Signal Ground (SGND) 102 B
Send Data (SD) 103 A P
BS
Receive Data (RD) 104 A R
BT
Request to Send (RTS) 105 C
Clear to Send (CTS) 106 D
Data Set Ready (DSR) 107 E
Data Terminal Ready (DTR) 108 H
Received Line Signal Detector (RLSD), 109 F
a.k.a. Carrier Detect (CD)
Serial Clock Transmit External (SCTE), 113 A U
a.k.a. External Clock (EXTC) B W
Serial Clock Transmit (SCT), 114 A Y
a.k.a. Transmit Clock (TC) B AA
Serial Clock Receive (SCR), 115 A V
a.k.a. Receive Clock (RC) B X
Remote Digital Loopback (RL) 140 HH
Local Analog Loopback (LL) 141 JJ
Test Mode (TM) 142 KK
Page 25
24
128-KBPS V.35 LINE DRIVER (LDM-MR128)
3.4.1 P
OWERCONNECTION
The power connection provides AC voltage to the LDM-MR128.
To make this connection on the 115-VAC (ME444A-R3) models, first attach
the IEC 320 female outlet of the included power cord to the IEC 320 male
inlet on the LDM-MR128’s rear panel.
To make this connection on the 230-VAC (ME444AE-R3) models, first
attach the IEC 320 female outlet of an appropriate power cord to the
IEC 320 male inlet on the LDM-MR128’s rear panel. (This power cord
must have a plug on the other end that will fit the site’s mains outlets.)
WARNING!
BEFORE PLUGGING THIS UNIT INTO AN OUTLET OR OTHER LIVE
POWER SOURCE, make sure its protective earth contact is connected to
the protective conductor of the (mains) power cord. The mains plug must
be inserted only in a socket outlet provided with a protective earth
contact. The protective action must not be negated by use of an
extension cord (power cable) without a protective (grounding) conductor.
If the LDM-MR128’s fuse blows (opens), make sure that you replace it
only with a fuse rated for the required amount of current. You must avoid
using repaired fuses or short-circuiting the fuse holders. The fuse, and
one replacement fuse, are located in the top part of the mains connector
on the LDM-MR128’s rear panel. The nominal current value of the fuse is
0.125 A for 230-VAC operation or 0.25 A for 115-VAC operation.
Whenever it is likely that the protection offered by the fuse has been
impaired, the unit must be made inoperative and secured against any
unintended operation.
After you have attached the power cord and have made sure that the cord is
properly grounded, you can plug the power cord into a working mains outlet.
CAUTION!
The unit has no power switch. It starts operating as soon as power
of the proper type is applied to its POWER connector.
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CHAPTER 3. Installation
3.4.2 LINE C
ONNECTION
The LINE connection provides an interface for the TX and RX signals
between pairs of LDM-MR128s. To make this connection, attach the line
wires to the terminal block on the LDM-MR128 this way:
• XMT + (remote LDM-MR128) to RCV + (local unit);
• XMT – (remote unit) to RCV – (local unit);
• RCV + (remote unit) to XMT + (local unit);
• RCV – (remote unit) to XMT – (local unit);
• Optional: Shield or drain wire (line cable) to ground (local
LDM-MR128—the rightmost terminal).
Attach the wires using the procedure shown in Figure 3-5 below:
Figure 3-5. Wire-insertion details.
1) Insert screwdriver into square hole.
2) Raise inserted screwdriver, putting
pressure on ramp inside square hole.
Wire clamp in round hole will open.
3) Insert stripped end of wire and remove screwdriver.
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128-KBPS V.35 LINE DRIVER (LDM-MR128)
3.4.3 DTE C
ONNECTION
The interface (DTE) connector provides an interface for input/output data,
as well as clock and control signals, between the LDM-MR128 and a V.35 DTE
or DCE. This connector is a standard 34-pin M-block (“M/34”) female. The
pinout of this connector is shown in Table 3-2 on page 25.
To connect the LDM-MR128 to a V.35 DTE or DCE, use an appropriate
cable that is pinned correctly (straight-through for DTE, properly crossed for
DCE). Run this cable from the other device to the LDM-MR128 and attach it
to the LDM-MR128’s interface connector.
Your LDM-MR128 should now be ready for continuous operation.
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CHAPTER 4: Operation
This chapter contains a list of the LDM-MR128’s controls and indicators
and their functions, as well as a brief description of how to operate the unit.
Installation procedures must be completed and checked before you attempt
to operate the LDM-MR128.
4.1 Controls and Indicators
The front panel of the LDM-MR128 is shown in Figure 4-1 below. It contains
all of the unit’s external controls and indicators: four pushbutton switches
and seven LEDs. The functions of the controls are described in Table 4-1 on
the next page, and the meanings of the indicators are described in Table 4-2,
also on the next page. In each of these tables, the letters and numbers under
the heading “Item” correspond to the letters and numbers in Figure 4-1.
4. Operation
CB
PWR RTS TD RD DCD TEST ERR
DIG ANA REM PATT
1234567 A D
Figure 4-1. The front panel of the LDM-MR128.
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128-KBPS V.35 LINE DRIVER (LDM-MR128)
Table 4-1. The Controls
The Item labels in this table correspond to those in Figure 4-1.
ITEM CONTROL FUNCTION
A DIG Pressing the local digital loopback button causes the local LDM-MR128 to
loop received data and clock to its transmitter. Data Set Ready goes low.
B ANA Pressing the local analog loopback (V.54 Loop 3) button causes the local
LDM-MR128 to loop its transmitter output back to its receiver. This
loopback may also be activated from the DTE when the “ALB DTE” jumper
is set to EN.
C REM Pressing the remote digital loopback (V.54 Loop 2) switch causes the
remote LDM-MR128 to loop received data and clock to its transmitter.
Data Set Ready goes low. This loopback may be also activated from the
DTE when the “RLB DTE” strap is set to EN.
D PATT Pressing the PATT button causes the LDM-MR128 to send and receive a
511 test pattern. If errors are encountered, the ERR LED becomes steadily
lit or blinks. Receive Data and Clear to Send go low. Note: The unit’s
“CARRIER” jumper should be set to ON; if it is set to CNTRL, the RTS
signal must be high.
Table 4-2. The Indicators
The item numbers in this table correspond to Figure 4-1.
ITEM INDICATOR FUNCTION
1 PWR Green LED is on when power is on.
2 RTS Yellow LED is on when terminal activates Request to Send.
3 TD Yellow LED is on when steady SPACE is being transmitted. It flickers
when data is transmitted.
4 RD Yellow LED is on when steady SPACE is being received. It flickers
when data is received.
5 DCD Yellow LED is on when a valid Receive signal is present.
6 TEST Red LED is on when the LMD-MR128 is in any of the loopback modes.
7 ERR LED goes ON when PATT switch is activated and then dims. If there are
errors in the test pattern, the LED blinks or remains ON.
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CHAPTER 4: Operation
4.2 Operating Procedure
The LDM-MR128 operates entirely unattended, although we recommend
that you monitor its LEDs occasionally. To turn the unit off, you must unplug
its power cord from the outlet—it has no power switch.
If you want to reconfigure the LDM-MR128 for a different type of
operation, make very sure to unplug the unit first. After the unit is powered
down, change the settings of its internal controls as necessary, following
the instructions in Section 3.2.
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128-KBPS V.35 LINE DRIVER (LDM-MR128)
This chapter explains system-test and fault-isolation procedures.
The LDM-MR128 provides local loopback and remote digital loopback
in compliance with the V.54 standard. Unless you disable them, the unit’s
loopback tests can be activated manually from the unit’s front panel, and
the local analog and remote digital loopbacks can be activated electronically
through the DTE connection.
5.1 Loop Tests
The loop-test buttons (DIG, ANA, and REM) and LEDs built into the LDMMR128 allow you to rapidly check the unit, the attached cables, and the
attached DTEs. Use the test procedures described in this chapter to verify
normal system operation and to isolate faulty equipment if a failure occurs.
(Before testing the operation of the system equipment and line circuits,
make sure that all devices are turned on and are properly configured.)
5.2 The Bit-Error-Rate Tester (BERT)
You can activate the LDM-MR128’s internal Bit Error Rate Tester in any
diagnostics test in which the transmitted test pattern is looped back to the
BERT for comparison. An example is shown in Figure 5-1 on the next page.
The LDM-MR128 is also capable of operating opposite any 511 BERT tester.
When you use one LDM-MR128 opposite another, either with one or both
PATT buttons pressed (see Figure 5-2 on the next page) or with an external
BERT transmitting the same V.52 (511-bit) pattern, you can test the complete
link. To activate the BERT, press the PATT button. The ERR LED will light
momentarily, just to confirm that the LED is working, and then the test will
proceed. If errors are detected, the ERR LED will be continuously lit (if the
errors are continuous) or will blink (for intermittent errors).
NOTE
For the LDM-MR128’s BERT to operate correctly, the CARRIER jumper
must be set to ON or the RTS signal must be high.
While PATT is depressed, the V.35 interface is functionally disconnected.
5. Troubleshooting
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CHAPTER 5: Troubleshooting
PATT
PRESSED
PATTERN
GENERATOR
PATTERN
TESTER
ERROR
RCV
XMT
ASM-20
Figure 5-1. BERT using loops.
PATTERN
GENERATOR
PATTERN
TESTER
ERROR
PATT
DEPRESSED
PATTERN
GENERATOR
ERROR
PATT
DEPRESSED
(DISCONNECTS
EXTERNAL DTE)
PATTERN
TESTER
RCV
DTE
XMT
Figure 5-2. Two LDM-MR128s doing end-to-end BERT.
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128-KBPS V.35 LINE DRIVER (LDM-MR128)
5.3 The Modem Self-Test
To verify that the LDM-MR128 itself is operating correctly, initiate the modem
self-test by pressing the PATT and ANA buttons (refer to Figure 5-3 below):
1. Press ANA to start local analog loopback. Both the TEST and DCD LEDs
should light. If the DCD LED doesn’t light, make sure that the RTS signal
is not OFF (low) while the CARRIER jumper is OFF.
2.
Press PATT to begin test-pattern
transmission. Verify that the TEST
and DCD LEDs are still lit and that the ERR LED lights briefly.
3. If the ERR stays lit or continues to flicker after the initial flash, the
LDM-MR128 is faulty; call Black Box to arrange for repair or replacement.
Otherwise, the unit passes the test; restore all of the buttons to their
normal positions.
PATTERN
GENERATOR
PATTERN
TESTER
ERROR
PATT
DEPRESSED
ANA
DEPRESSED
XMTR
RCVR
Figure 5-3. Modem self-test.
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CHAPTER 5: Troubleshooting
5.4 Local Analog Loopback
Activate the local analog loopback test by pressing the ANA button or by
raising the level of the Local Loopback signal received by the LDM-MR128’s
V.35 connector (Pin JJ). This test checks the performance of the local
LDM-MR128’s modem, the local DTE, and the connections between them.
Perform this test separately at the local and remote sites (refer to Figure 5-4
on the next page):
1. Press ANA or raise Local Loopback to start local analog
loopback. The
TEST LED should
light. The LDM-MR128’s G.703 transmit output should
be connected to its own receiver.
2. Verify that the DTE is operating properly and can be used for a test.
3. Perform the test using one of these methods:
• Send data from the DTE and check the echoed data stream.
• Hook up an external Bit Error Rate Test (BERT) unit in place
of the DTE.
• Use the LDM-MR128’s internal BERT. Press the PATT button.The ERR
LED should light briefly just to confirm that the LED is working, and
then the test will proceed. If errors are detected, the ERR LED will
be continuously lit (if the errors are continuous) or will blink (for
intermittent errors).
4. Repeat Steps 1 through 3 at the remote site.
5. If the BERT tests show no errors, but the data echoed back to either DTE
is bad, check the DTE and the cable connecting it to the LDM-MR128—
one of them is faulty.
6. After the test is complete or the fault has been corrected, restore the ANA
button to its normal position. Proceed with the digital loopback tests.
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128-KBPS V.35 LINE DRIVER (LDM-MR128)
ANA
DEPRESSED
DTE
XMTR
RCVR
LINE
DATA
CLK
CLK
DATA
Figure 5-4. Local analog loopback.
5.5 Remote Digital Loopback
Activate the remote digital loopback test by pressing the REM button
or by raising the level of the Remote Loopback signal received by the
LDM-MR128’s V.35 connector (Pin HH). This test involves creating an
outbound loopback at the remote LDM-MR128 (see Figure 5-5 on the next
page). The test checks the performance of the local and remote units and
the line between them:
1. Press REM or raise Remote Loopback; the local LDM-MR128
will signal
the remote unit to start
remote digital loopback. The TEST LED should
light on both units. The remote LDM-MR128’s receive input should be
connected to its own transmitter.
2. Perform a Bit Error Rate Test (BERT). Either:
• Hook up an external Bit Error Rate Test (BERT) unit in place
of the local DTE; or
• Use the local LDM-MR128’s internal BERT. Press the PATT button. The
ERR LED should light briefly just to confirm that the LED is working,
and then the test will proceed. If errors are detected, the ERR LED
will be continuously lit (if the errors are continuous) or will blink
(for intermittent errors).
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CHAPTER 5: Troubleshooting
3. If the BERT test indicates a fault, but both LDM-MR128s pass their
modem self-tests (see Section 4.3.1), there is a problem somewhere
in the communication line between the units.
4. After the test is complete or the fault has been corrected, restore the
REM button to its normal position. Proceed with local digital loopback.
REM
DEPRESSED
DATA
CLK
RCVR
CLK
DATA
XMTR
LOCAL
DTE
XMTR
RCVR
REMOTE
DTE
Figure 5-5. Remote digital loopback.
5.6 Local Digital Loopback
Activate the local digital loopback test by pressing the DIG button on the
LDM-MR128’s front panel. This test involves creating an outbound loopback
at the local LDM-MR128 (see Figure 5-6 on the next page). It works the same
way as if the remote operator had initiated a remote digital loopback at the
remote site. With this test, the remote operator can check the performance
of the remote and local LDM-MR128s and the line between them:
1. Press DIG; the local LDM-MR128 will signal the remote unit and will
start local digital loopback. The TEST LED should light on both units.
The local LDM-MR128’s receive input should be connected to its
own transmitter.
2. Perform a Bit Error Rate Test (BERT). Either:
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128-KBPS V.35 LINE DRIVER (LDM-MR128)
• Hook up an external BERT unit in place of the remote DTE; or
• Use the remote LDM-MR128’s internal BERT. Press the PATT button.
The ERR LED should light briefly just to confirm that the LED is
working, and then the test will proceed. If errors are detected, the ERR
LED will be continuously lit (if the errors are continuous) or will blink
(for intermittent errors).
3. If the BERT test indicates a fault, but both LDM-MR128s pass their
modem self-tests (see Section 4.3.1), there is a problem somewhere
in the communication line between the units.
4. After the test is complete or the fault has been corrected, restore
the DIG button to its normal position.
DIG
DEPRESSED
DATA
CLK
RCVR
DATA
CLK
XMTR
LOCAL
DTE
XMTR
RCVR
REMOTE
DTE
Figure 4-5. Local digital loopback.
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CHAPTER 5: Troubleshooting
5.7 Calling Black Box
If you determine that your LDM-MR128 is malfunctioning, do not attempt to
alter or repair the unit. It contains no user-serviceable parts. Contact Black Box
Technical Support at 724-746-5500. The problem might be solvable over
the phone.
Before you do, make a record of the history of the problem. We will be
able to provide more efficient and accurate assistance if you have a complete
description, including:
• the nature and duration of the problem.
• when the problem occurs.
• the components involved in the problem.
• any particular application that, when used,
appears to create the problem or make it worse.
5.8 Shipping and Packaging
If you need to transport or ship your LDM-MR128:
• Package it carefully. We recommend that you use the original container.
• If you are shipping the LDM-MR128 for repair, make sure you include its
power cord. If you are returning the LDM-MR128, make sure you include
its manual as well. Before you ship, contact Black Box to get a Return
Materials Authorization (RMA) number.
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128-KBPS V.35 LINE DRIVER (LDM-MR128)
The maximum distance that a pair of LDM-MR128s can communicate across
will vary depending on the data rate and the thickness (gauge) of the wires.
In multipoint applications, it will also vary depending on the number of slaves
on the line. Approximate maximum distances for different combinations of
these factors are listed in the tables below. Please be aware that these numbers
are only approximations; the distances shown might not be attainable for all
applications. Also, maximum distances will always be less than those listed
when LDM-MR128s are used in noisy environments.
Appendix: Maximum Distances
19-AWG 22-AWG 24-AWG
19.2 Kbps 11.8 mi. (19 km) 7.2 mi. (11.5 km) 5 mi. (8 km)
32 Kbps 11.8 mi. (19 km) 7.2 mi. (11.5 km) 5 mi. (8 km)
48 Kbps 11.2 mi. (18 km) 6.8 mi. (11 km) 4.7 mi. (7.5 km)
56 Kbps 11.2 mi. (18 km) 6.8 mi. (11 km) 4.7 mi. (7.5 km)
64 Kbps 11.2 mi. (18 km) 6.8 mi. (11 km) 4.7 mi. (7.5 km)
72 Kbps 10.9 mi. (17.5 km) 6.5 mi. (10.5 km) 4.5 mi. (7.2 km)
96 Kbps 9.3 mi. (15 km) 5.5 mi. (8.8 km) 3.8 mi. (6.1 km)
112 Kbps 8.1 mi. (13 km) 5 mi. (8 km) 3.4 mi. (5.5 km)
128 Kbps 7.5 mi. (12 km) 4.5 mi. (7.3 km) 3.1 mi. (5 km)
144 Kbps 6.9 mi. (11 km) 4 mi. (6.4 km) 2.8 mi. (4.5 km)
192 Kbps 5.6 mi. (9 km) 3.3 mi. (5.3 km) 2.3 mi. (3.7 km)
256 Kbps 3.7 mi. (6 km) 2.2 mi. (3.6 km) 1.6 mi. (2.5 km)
Point-to-point applications
5 slaves 4.3 mi. (7 km)
10 slaves 3.7 mi. (6 km)
15 slaves 3.1 mi. (5 km)
25 slaves 2.5 mi. (4 km)
40 slaves 1.2 mi. (2 km)
Multipoint applications
(24-AWG cable, 64 Kbps)
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1000 Park Drive • Lawrence, PA 15055-1018 • 724-746-5500 • Fax 724-746-0746
© Copyright 2000. Black Box Corporation. All rights reserved.
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