Black Box ME760A-R2 User manual

CUSTOMER
SUPPORT
INFORMATION
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: Bla k Box Corporation 1000 Park Drive Lawrence PA 15055-1018
Web site: www.bla kbox. om • E-mail: info@bla kbox. om
SEPTEMBER 2002
ME760A-R2
ME760AE-R2
ME760C
19.2 kbps RS-232 Line Driver
(LDM-MR19.2)

1
FCC AND IC STATEMENTS
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.

2
LDM-MR19.2
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 parato 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.

3
NOM STATEMENT
10. El equipo eléctrico deber ser situado fuera del alcance de fuentes de calor
como radiadores, registros de calor, estufas u otros aparatos (incluyendo
amplificadores) que producen calor.
11. El aparato eléctrico deberá ser connectado a una fuente de poder sólo del
tipo descrito en el instructivo de operación, o como se indique en el aparato.
12. Precaución debe ser tomada de tal manera que la tierra fisica y la polarización
del equipo no sea eliminada.
13. Los cables de la fuente de poder deben ser guiados de tal manera que no
sean pisados ni pellizcados por objetos colocados sobre o contra ellos,
poniendo particular atención a los contactos y receptáculos donde salen
del aparato.
14. El equipo eléctrico debe ser limpiado únicamente de acuerdo a las
recomendaciones del fabricante.
15. En caso de existir, una antena externa deberá ser localizada lejos de las lineas
de energia.
16. El cable de corriente deberá ser desconectado del cuando el equipo no sea
usado por un largo periodo de tiempo.
17. Cuidado debe ser tomado de tal manera que objectos liquidos no sean
derramados sobre la cubierta u orificios de ventilación.
18. Servicio por personal calificado deberá ser provisto cuando:
A: El cable de poder o el contacto ha sido dañado; u
B: Objectos han caído o líquido ha sido derramado dentro del aparato; o
C: El aparato ha sido expuesto a la lluvia; o
D: El aparato parece no operar normalmente o muestra un cambio
en su desempeño; o
E: El aparato ha sido tirado o su cubierta ha sido dañada.

4
LDM-MR19.2
TRADEMARK USED IN THIS MANUAL
AS/400 is a registered trademark of International Business Machines Corporation.
Any other trademarks mentioned in this manual are acknowlegded to be the property
of the trademark owners.

5
TABLE OF CONTENTS
Contents
Chapter Page
1. Specifications ............................................................................................. 6
2. Introduction ............................................................................................. 10
2.1 Functional Description ..................................................................... 11
2.2 Applications ....................................................................................... 15
3. Standalone Installation ............................................................................ 18
3.1 Complete Package ............................................................................ 18
3.2 Physical Placement ............................................................................ 18
3.3 Data Cables ........................................................................................ 18
3.4 Setting the Internal Controls ........................................................... 21
3.5 AC Power Cord .................................................................................. 21
4. Card Installation ......................................................................................... 26
4.1 The RackNest 2/14 ........................................................................... 26
4.2 The RackNest 2/14’s Power Supply ................................................. 27
4.3 The RackNest 2/14 Illustrated ......................................................... 28
4.4 Card-Configuration Procedure ........................................................ 31
4.5 Card-Installation Procedure ............................................................. 35
5. Operation ................................................................................................. 36
5.1 Controls and Indicators .................................................................... 36
5.2 Turning the Unit ON ....................................................................... 39
5.3 Operating Procedure ........................................................................ 39
5.4 Remote Power Failure (RPF) ........................................................... 39
5.5 Turning the Unit OFF ...................................................................... 40
5.6 Reconfiguration ................................................................................ 40
6. Troubleshooting ...................................................................................... 41
6.1 Loopback Testing ............................................................................. 41
6.2 Calling Black Box .............................................................................. 44
6.3 Shipping and Packaging ................................................................... 44

6
LDM-MR19.2
1. Specifications
Compliance — FCC Part 15 Subpart J Class A, DOC Class/MDC classe A
Cable Required — Between ME760 units: Unloaded twisted pair, 19 to
26 gauge; 4 wires for full duplex, at least 2 wires for
half-duplex; DC continuity not required;
Between standalone ME760 unit and DTE: TIA RS-232
cable with DB25 male connector on ME760 end
Interface — Serial EIA RS-232-D/CCITT V.24, DCE
Protocol — Synchronous or asynchronous
Clock Source — Either internal, external from local DTE, or recovered
from remote LDM-MR19.2
Data Format — 5, 6, 7, or 8 data bits; 1, 1.5, or 2 stop bits; even, odd, or
no parity (but see Table 3-3 on page 26)
Operation — 2– or 4-wire half-duplex or 4-wire full-duplex; point-to-
point or multipoint
Data Rate — Sync: 1.2, 2.4, 3.6, 4.8, 7.2, 9.6, 14.4, or 19.2 Kbps;
Async: Up to 19.2 Kbps
RTS/CTS Delay — 0, 8, or 64 ms (user-selectable)
Modulation — Differential diphase Eurocom Standard D1
Transmit Level — 0, –3, –6, or –9 dBm (user-selectable)
Transmit
Impedance — 600, 300, or 150 ohms or “LOW” (user-selectable)
Receive
Impedance — 150, 300, or 600 ohms or “HIGH” (user-selectable)
Return Loss — Greater than 15 dB

7
CHAPTER 1: Specifications
Carrier — Controlled by RTS or constantly ON (user-selectable)
Maximum
Transmission
Distance — See Table 1-1 on page 11
User Controls — (3 or 4) Front-mounted pushbuttons:
DIG (local digital loopback);
ANA (local analog loopback);
REM (remote digital loopback);
ME760C only: RPF (reset after remote power failure);
(15 or 16) Internal:
(1) Dial for data rate;
(1) Four-position DIP switch for async character length
and stop-bit shortening;
(13 or 14) Jumpers:
Transmit timing;
2- or 4-wire operation;
CTS delay;
Carrier control;
Transmit level;
Transmit-line impedance;
Receive-line impedance;
Enable/disable analog-loopback command on Pin 18;
Enable/disable remote-loopback command on Pin 21;
Enable/disable front-panel pushbuttons;
Connect/disconnect signal ground and chassis ground;
AGC control;
Activate/deactivate V.54 delay;
ME760A(E)-R2 only: Enable/disable RPF tone
Diagnostics — Comply with V.54 standard:
Local analog loopback, mechanically or electrically
user-controllable;
Local digital loopback, mechanically user-controllable;
Remote digital loopback, mechanically or electrically
user-controllable

8
LDM-MR19.2
Indicators — (6 or 7) Front-mounted LEDs: PWR (power), RTS, TD,
RD, DCD, TEST, and (ME760C only) RPF (remote
power failure)
Connectors — (2) Rear-mounted: (1) DB25 for cable to DTE,
(1) 4-wire terminal block for modem-to-modem line
Power — Directly from outlet through detachable 5-ft. (1.5-m) line
cord and rear-mounted IEC 320 male inlet:
ME760A: 115 VAC, 47 to 63 Hz, 3 watts; input cord
terminated with N. American standard NEMA 5-15P
plug;
ME760AE: 230 VAC, 47 to 63 Hz, 3 watts; input cord
unterminated when shipped, terminated by user
Protection — AC/DC overvoltage-protection circuits connected
through transformers to transmit and receive lines
Mean Time
Between Failures — 163,000 hours
Temperature
Tolerance — 32 to 158˚ F (0 to 70˚ C)
Humidity
Tolerance — 0 to 90% noncondensing
Enclosure — High-impact plastic
Size — 1.6"H x 9.6"W x 7.6"D (4 x 24.4 x 19.3 cm)
Weight — 3.1 lb. (1.4 kg)

9
CHAPTER 1: Specifications
Table 1-1. Maximum Transmission Distance.
SPEED 19 AWG 24 AWG 26 AWG
(bps)
19,200 6 mi. (9.8 km) 4 mi. (6.5 km) 2.7 mi. (4.4 km)
14,400 7.5 mi. (12.1 km) 5 mi. (8.1 km) 3.4 mi. (5.4 km)
9,600 9.8 mi. (15.8 km) 6.5 mi. (10.5 km) 4.4 mi. (7 km)
7,200 10.5 mi. (17.3 km) 7 mi. (11.5 km) 4.7 mi. (7.7 km)
4,800 13.5 mi. (21.8 km) 9 mi. (14.5 km) 6 mi. (9.7 km)
3,600 15 mi. (24 km) 10 mi. (16 km) 6.7 mi. (10.7 km)
2,400 16.5 mi. (27 km) 11 mi. (18 km) 7.4 mi. (12 km)
1,800 19.5 mi. (30.8 km) 13 mi. (20.5 km) 8.7 mi. (13.7 km)
1,200 22.5 mi. (36 km) 15 mi. (24 km) 10.1 mi. (16 km)

10
LDM-MR19.2
2. Introduction
The 19.2 kbps RS-232 Line Driver (LDM-MR19.2 for short) is a short-range
modem which operates at full- or half-duplex with synchronous or asynchronous
transmission over unconditioned telephone lines. With an extended range of up
to 34 miles (55 km), the LDM-MR19.2 operates at any of eight selectable data rates,
up to 19,200 bps.
By using conditioned differential diphase modulation (Eurocom Std. D1), the
LDM-MR19.2 provides immunity from background noise, eliminates normal line
distortion, and enables efficient transmission and reception of serial data over
twisted-pair cable.
The LDM-MR19.2 is coupled to the telephone line through isolation
transformers. The transformers and electronic circuitry protect against AC or DC
overvoltages. The protection circuitry allows operation even when DC is connected
to the line, because of the following features:
• Transmit Level and Transmit and Receive Impedances are independently
selectable.
• Transmit timing is provided internally, derived externally from the
data terminal, or regenerated from the Receive signal.
• Receive timing is regenerated from the Receive signal.
Line communication is always synchronous. When you set the LDM-MR19.2 to
asynchronous mode, it performs an async-to-sync conversion in compliance with
the CCITT V.22 bis standard.
The LDM-MR19.2 also features V.54 diagnostic capabilities for performing local
analog loopback and local and remote digital loopback. In the digital loopback
mode, the operator at either end of the line may test both of the modems and
the line. The operator can control the loopback with either the front-panel
pushbuttons or Pins 18 and 21 of the V.24/RS-232 interface.

11
CHAPTER 2: Introduction
2.1 Functional Description
This section contains functional descriptions of the LDM-MR19.2’s circuit blocks
(primarily the circuits required for correctly configuring the unit).
2.1.1 E NCODER
The encoder modulates the input data from the DTE using the “conditional
diphase modulation” technique. You can configure the encoder to operate in
one of five modes:
• 4-wire full-duplex
• 4-wire half-duplex
• 2-wire half-duplex
• 4-wire multipoint
• 2-wire multipoint
2.1.2 M ODULATION T IMING
The modulation-timing circuit supplies the Transmit clock to the encoder. Four
clock sources are available:
•INT.CK (internal clock—from the modem’s internal crystal oscillator)
•EXT.CK (external clock—from DTE, Pin 24)
•RCV.CK (receive clock—recovered from Receive signal)
•ASYNC (asynchronous timing for working with the async-to-sync converter
in an async application)
Setting the XMT TIMING jumpers determines the timing option.

12
LDM-MR19.2
2.1.3 A SYNC
- TO -S YNC C ONVERTER
The LDM-MR19.2 provides internal conversion from async to sync in compliance
with CCITT V.22 bis. According to this standard, frequency deviation between the
modem and the DTE is compensated for by shortening or lengthening the stop bit
of the async character. When the modem’s frequency is higher than the DTE’s, the
local converter extends the stop bit. When the modem’s frequency is lower than
the DTE’s, the local converter may delete one stop bit every four or eight
characters. The remote converter adds a shorter stop bit before sending the
data to the remote DTE.
For frequency deviations of up to 1.1%, the stop bits should be shortened every
eight characters (12.5%). For frequency deviations of 1.2% to 2.3%, the stop bits
should be shortened every four characters (25%).
Use switch position 2 (S2) of the “ASYNC LENGTH” DIP switch to select 25% or
12.5% frequency deviation. For proper operation of the async-to-sync converter, set
the async character length by adjusting switch positions 3 and 4 (S3 and S4) of the
“ASYNC LENGTH” DIP switch. See Table 3-3 on page 26 for detailed settings.
2.1.4 XMT L EVEL
Four options are available for the XMT level (signal level): 0, –3, –6, or –9 dBm.
XMT level is controlled by the XMT LEVEL jumper.

13
CHAPTER 2: Introduction
2.1.5 R ECEIVER
The receiver contains several circuits (shown in Figure 2-1 below):
• The RECEIVE FILTER removes all the out-of-band frequencies.
• The AUTOMATIC EQUALIZER is made up of several equalizers activated
according to data rate.
• The digital AGC (automatic gain control) automatically compensates for
the attenuation of the line. You can choose between the two modes of AGC
operations by setting the AGC jumper:
ON: The AGC operates continuously.
CNTR: The AGC is active only when DCD is ON. When DCD is OFF,
the AGC will remain in the state to which it was most recently set.
In full-duplex point-to-point applications, there is no difference between the
two AGC modes of operation.
Figure 2-1. Block diagram for the LDM-MR19.2.

14
LDM-MR19.2
However, there is a difference in multipoint applications, where the master
modem communicates with modems at different distances. When the master
modem is set to AGC-ON, the master can communicate across long distances (up
to its maximum range) to the slave modems. However, this setting increases the
RTS-to-CTS delay. For example, under AGC-ON, the CTS delay of all slaves must
be set to 64 ms when the data rate is less than 9.6 Kbps.
When the master modem is set to AGC-CNTR, it can’t transmit or receive across
as much distance. However, the polling goes faster. For example, under AGC-
CNTR, the CTS delay of all units can be set to 8 ms when the data rate is greater
than or equal to 4.8 Kbps.
Table 2-1, below, contains general guidelines for choosing AGC and CTS-delay
settings. Each application is unique, however; you might find that your LDM-
MR19.2 system works better when the units are set slightly differently.
Table 2-1. Recommended Multipoint AGC and CTS-Delay Settings
Distan e Data Rate Master Master Slave Slave
Between AGC CTS Delay AGC CTS Delay
Modems*
Short range ≤2.4 Kbps CNTR 64 ms CNTR 64 ms
Short range >2.4 Kbps, CNTR 8 or 64 ms ON 64 ms
<4.8 Kbps
Short range ≥4.8 Kbps CNTR 8 or 64 ms ON 8 or 64 ms
Long range <9.6 Kbps ON 8 or 64 ms ON 64 ms
Long range ≥9.6 Kbps ON 8 or 64 ms ON 8 or 64 ms
* “Short range” = up to 2.8 mi. (4.5 km) for data rates of 9.6 or 19.2 Kbps or up to 3.7 mi. (6 km)
for data rates of 3.6 to 7.2 Kbps. “Long range” represents distan es greater than these.

15
CHAPTER 2: Introduction
2.1.6 V.54 D IAGNOSTICS
You can activate V.54 loops with either the front-panel pushbuttons or Pins 18
and 21 of the V.24/ RS-232 interface. The pushbuttons, Pin 18, and Pin 21 can
be enabled or disabled separately by the SWITCH, PIN 18, and PIN 21 jumpers,
respectively.
When you use the LDM-MR19.2 as a tail end to a DDS network, set the V.54
DELAY jumpers of the modems located close to the DDS network to ON to
prevent multiple loopbacks. The DELAY switch prevents the last modem from
receiving the complete V.54 data sequence and being induced into a loop. V.54
is required only for operation in synchronous mode.
NOTE
The V.54 DELAY jumper must be set to OFF when you operate
in asynchronous mode.
2.2 Applications
Figures 2-2 through 2-5 on the next two pages illustrate the LDM-MR19.2 in various
configurations.
(text continues on page 18)

16
LDM-MR19.2
Figure 2-2. Point-to-point application.
Figure 2-3. Multipoint application.
A S 400
LDM-MR19.2 LDM-MR19.2
LDM-MR19.2
LDM-MR19.2
LDM-MR19.2
SLAVE 1
XMT IMP.-150Ω
RCV IMP.-HIGH
SLAVE 2
XMT IMP.-150Ω
RCV IMP.-HIGH
SLAVE 3
XMT IMP.-150Ω
RCV IMP.-HIGH
SLAVE N
XMT IMP.-150Ω
RCV IMP.-150Ω
A S 400
LDM-MR19.2 LDM-MR19.2
PC
4-wire twisted pair,
up to 34 mi. (55 km)
AS 400®
MASTER
XMT IMP.-LOW
RCV IMP.-150Ω
AS 400
PC running
emulation
software

17
CHAPTER 2: Introduction
Figure 2-4. Tail circuit for DDS application.
Figure 2-4. Star application.
AS 400
AS 400
Controller
Controller
Controller
LDM-MR19.2:
EXT CLOCK,
V.54 DLY–ON
LDM-MR19.2:
RCV CLOCK,
V.54 DLY–OFF
MASTER
LDM-MR19.2
SLAVE LDM-MR19.2
SLAVE LDM-MR19.2
SLAVE LDM-MR19.2
CSU DSU
CSU DSU
PC running
5250 emulation
software
The XMT and
RCV
impedances
of all the
LDM-MR19.2s
in this
application
would be set
to 150 ohms.
DIGITAL
SERVICE
NETWORK
Cross-pinned cable
such as our EYN255C

18
LDM-MR19.2
3. Standalone Installation
Follow the directions in this chapter to install the standalone version of the
LDM-MR19.2. Once you’ve done this, see Chapter 5 for operating information.
3.1 Complete Package
With your LDM-MR19.2 order, you should have received (1) LDM-MR19.2,
(1) detachable 5-ft. (1.5-m) AC power cord, and (1) copy of this manual. The
LDM-MR19.2 is fully assembled at the factory. You don’t have to assemble any
part of the unit. However, you will have to attach an appropriate plug to the
power cord if your unit is a 230-VAC (ME760AE-R2) model.
3.2 Physical Placement
Place the LDM-MR19.2 on a tabletop or bench within 5 feet (1.5 m) of a grounded
3-wire AC outlet and within 50 feet (15.2 m) of the associated data terminal. The
unit is not designed to be bolted down.
Allow at least 36 inches (90 cm) of clearance in front of the unit so you can
operate and maintain it. Be sure to leave 4 inches (10 cm) of clearance behind
the unit for signal lines and interface cables.
3.3 Data Cables
The LDM-MR19.2’s data-communication connectors (a five-crimp terminal
block and a DB25 connector) are on its rear panel (see Figure 3-1 below).
Figure 3-1. The LBM-MR19.2’s rear panel (ME760A-R2 model shown).
DTE
XMT RCV GND
115 VAC - 0.2A T 250V
J1 TB1

19
CHAPTER 3: Standalone Installation
The terminal block holds five crimp-style contact positions for connecting the
Transmit (XMT) and Receive (RCV) telephone lines. The Transmit and Receive
pairs are not polarity-sensitive. Using a screwdriver to gently lever open the
contacts, connect the Transmit pair to the XMT terminals; for 2-wire operation,
this is all you need. For 4-wire operation, connect the Receive pair to the RCV
terminals, making sure that local XMT is connected to remote RCV and local RCV
is connected to remote XMT. If you are using shielded cable, there is also a fifth
terminal for optional ground connection (at one end only!).
For detailed information on the pinout of the DB25 connector, see Table 3-1
below and on the next page.
Table 3-1. DB25 Pinout and Interface-Signal List
CCITT EIA DTE SIGNAL
V.24 RS-232-C PIN NAME DESCRIPTION
101 AA 1 Prote tive Chassis ground. Can be isolated from
Ground Signal Ground (refer to GND Strap in
Table 3-2).
102 AB 7 Signal Ground Common signal; DC-power-supply ground.
N/A N/A 9 +8 volts Output +8 VDC
10 –8 volts Output –8 VDC
103 BA 2 Transmitted Serial digital data re eived from (sent by) the
Data lo al DTE. See the Note on the next page.
104 BB 3 Re eived Serial digital data sent to (re eived by) the
Data lo al DTE. See the Note on the next page.
105 CA 4 Request to Lo al DTE sends a “high” (positive) level to
Send the LDM-MR19.2 when it wants to send data.
106 CB 5 Clear to Send After re eiving a Request to Send from the
lo al DTE, the LDM-MR19.2 waits for a
user-sele table period, then sends a “high”
(positive) level to the DTE to signal that it is
ready to re eive data.
107 CC 6 Data Set Ready The LDM-MR19.2 always sends a “high”
(positive) level to the lo al DTE ex ept when
the LDM-MR19.2 is in lo al or remote digital
loopba k.