Black Box LD485A-MP User manual

1000 Park Drive • Lawrence, PA 15055-1018 • 724-746-5500 • Fax [phone]
© Copyright 1999. Black Box Corporation. All rights reserved.

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AUGUST 1999
ME836A-R3
ME836C-R3
BC00702
FA520A-R2
RS-232 Asynchronous
Multipoint Line Driver
(LD485A-MP)
LD485A-MP
RX TX RTS CD PWR
NORMAL
DLB

3
FCC STATEMENT
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 classe A prescrites dans le Règlement
sur le brouillage radioélectrique publié par le ministère des Communications du
Canada.

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INSTRUCCIONES DE SEGURIDAD
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 .

5
INSTRUCCIONES DE SEGURIDAD
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.

6
RS-232 ASYNCHRONOUS MULTIPOINT LINE DRIVER (LD485A-MP)
TRADEMARKS
All applied-for and registered trademarks are the property of their
respective owners.

7
RS-232 ASYNCHRONOUS MULTIPOINT LINE DRIVER (LD485A-MP)
CONTENTS
1. Specifications. . . . . . . . . . .............................8
2. Introduction . . . . . . . . . . .............................10
3. Installation . . . . . . . . . ...............................11
3.1 Jumper and Switch Configuration ...................11
3.2 DCE/DTE Configuration...........................17
3.3 Typical Application . ..............................24
Appendix: Pinning ....................................29

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RS-232 ASYNCHRONOUS MULTIPOINT LINE DRIVER (LD485A-MP)
1. Specifications
Interface —(1) asynchronous RS-232 port (DTE/DCE selectable),
(1) asynchronous RS-584 port
Connectors —(1) DB25S, female RS-232 port, (1) four-wire terminal block
RS-485 port
Pins Supported —RS-232 port: TD, RD, RTS, CTS, CD, DTR, DSR, SG,
and FG, RS-485 port: TXA, TXB, RXA, RXB
Data Rate —0 to 64 Kbps, transparent to data
Indicators —(5) LEDs (TX, RX, RTS, CD, and PWR)
Temperature — Operating : 32 to 122 °F (0 to 50 °C), Storage : -4to158°F
(-20 to 70 °C)
Humidity —0 to 95% relative humidity, non-condensing
Mean Time Between Failures —Approximately 180,000 hours (ground
benign environment)
Operation —Point-to-Point or Multipoint, Half or Full Duplex, Transparent
to data, Selectable RTS to CTS delay, DTE or DCE configurable RS-232
port, Normal or loopback operation
Timeout Delay —1 msec, 100 msec, or 1 sec (for the RS-485 driver enabled
by data feature)
Power —Wall-mount transformer, 115 VAC, 8.5 watts or 230 VAC, 8.5
watts
Size —Standalone unit: 1.8”H x 5.5”W x 8.5”D (4.5 x 13.9 x 21.5 cm),
Rackmount card: 4.7”H x 7.4”L (11.9 x 18.8 cm)
Weight —Standalone unit (unit only): 1 lb. (454 g), Power supply only:
0.5 lb. (227 g)

9
RS-232 ASYNCHRONOUS MULTIPOINT LINE DRIVER (LD485A-MP)
Typical Speed Versus Distance —(4-wire point-to-point 26 AWG twisted
pair)
Speed Distance
1,200 bps 4.0 miles
2,400 bps 3.0 miles
4,800 bps 2.3 miles
9,600 bps 1.7 miles
19,200 bps 1.2 miles
38,400 bps 0.9 miles
64,000 bps 0.75 miles
NOTE
Speed and distances will depend on actual operating conditions.

10
RS-232 ASYNCHRONOUS MULTIPOINT LINE DRIVER (LD485A-MP)
2. Introduction
The LD485A-MP Line Driver is an RS-232 to RS-485 interface converter
that operates in much the same way as a modem. It allows an RS-232
device to transmit data over much longer distances than is normally
possible (up to 4 miles at 1200 bps). The advantage of the LD485A-MP
over other line drivers and modems is that it can also operate in multipoint
applications. Depending on the operating environment, as many as 64
devices can be linked together using twisted-pair cable.
The LD485A-MP can be jumpered for a user-selectable port timeout.
After the last character is sent from one of the ports and a specified period
of time passes (1 msec, 100 msec, or 1 second), the LD485A-MP disables any
transmission from that port. This timeout would be used in a multipoint
application to prevent one port from monopolizing the line. For example,
if one line driver was still enabled and no data was being sent, the other line
drivers would not be able to transmit or receive data until the one driver
was disabled. Thus, the line would be tied up, with no useful data
communication taking place. The port timeout feature keeps the line free
by disabling inactive ports.
Additional features include a manual loopback test to check the system
wiring for both the RS-232 and RS-485 interfaces, and transient protection
on the RS-485 interface to help prevent damage due to voltage transients
on the data line.
Although designed specifically to connect to other LD485A-MP line
drivers, the RS-485 port may be connected to any device with an RS-422 or
RS-485 interface. This would be useful in an industrial application, for
example, where RS-485 and RS-422 devices would be connected to the
same LD485A-MP.
The LD485A-MP is available in standalone and rackmount versions. The
rackmount card (part number ME836C-R3) is designed to be installed in
the multi-function rack (part number RM700).
A cable and adapter are included with each Driver.