Black Box SHM-B Plus Async Series User manual

JUNE 2002
ME800A-PLUS
ME800AE-PLUS
Short-Haul Modem B (SHM-B)
Plus Async
CUSTOMER SUPPORT INFORMATION
Order toll-free in the U.S.: Call 877-877-BBOX (outside U.S. call 724-746-5500)
FREE technical support 24 hours a day, 7 days a week: Call 724-746-5500 or fax [phone]
Mailing address: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018
Web site: www.blackbox.com • E-mail: [email protected]
TD
RD
NORMAL
LOOPBACK

1
FCC/IC RFI STATEMENTS, TRADEMARKS
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 B 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
BLACK BOX and the logo are registered trademarks of Black Box
Corporation.
Any other trademarks mentioned in this manual are acknowledged to be the property of the
trademark owners.

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SHM-B PLUS ASYNC
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.

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.

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SHM-B PLUS ASYNC
Contents
Chapter Page
1. Specifications .............................................................. 5
2. Introduction ............................................................... 8
3. Installation and Configuration .................................. 9
3.1 Making the Four-Wire Connection .................... 9
3.2 Making the RS-232 Connections ...................... 12
3.3 Setting the DTE/DCE Switch (S1) ................... 13
3.4 Setting the Flow-Control Switch (S3) ............... 15
4. Operation .................................................................. 17
5. Troubleshooting ....................................................... 19

5
CHAPTER 1: Specifications
1. Specifications
Data Rate and Maximum Distance:
Data Rate (bps) AWG (mm)
24 (0.5) 26 (0.4)
Distance in miles
115,200 0.8 0.7
57,600 1.2 0.8
38,400 1.3 0.9
19,200 1.5 1.2
9600 2 1.5
4800 2.6 2
2400 4 3
1200 4.8 4
NOTE: The above specifications are valid for 24- or 26-AWG unshielded
twisted-pair telephone cable insulated by polyethylene with a
mutual capacitance of 0.083 pF/mile (0.52 pF/km). Shielded
twisted-pair cable will reduce the distance to one-third of the table
value, due to the additional capacitance contributed by the cable’s
shielding. Actual distances may vary depending on your specific
operating equipment and the cable you use.
Protocol: Asynchronous
Operation: 4-wire, full duplex, point-to-point
Line Interface: Balanced current loop; receive lines are
protected through optical isolators rated at 1500 volts

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SHM-B PLUS ASYNC
Equipment Interface: TIA/EIA RS-232/ITU V.24
interface with a hardware handshake (selected through
use of an external switch); Data Carrier Detect (DCD)
true (high) indicates operating short-haul modem at the
remote end of the loop; interface is switch-selectable for
DTE/DCE configuration (pins 2 and 3 reversed, pins 4
and 5 reversed with pin 8, pin 6 reversed with pin 20)
Connectors: (1) DB25 female, (1) 4-screw terminal
block, (1) RJ-11 female (6 positions, 6 contacts),
(1) 4-pin mini-DIN female
Diagnostics: Loopbacks provided by a front-panel switch:
Analog loopback on a 4-wire loop and digital loopback
on equipment interface (RS-232)
Indicators: (2) Front-mounted bi-color LEDs indicate
the status of the RS-232 transmitter and receiver: green
indicates a “low” logic level (-3 to -15V), red indicates a
“high” logic level (+3 to +15V)
Temperature Tolerance: 32 to 112°F (0 to 50°C)
Humidity Tolerance: Up to 90% noncondensing
Enclosure: High-impact plastic

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CHAPTER 1: Specifications
Power: From external power supply (no more than
16 Vrms is present in unit):
Input (ME800A-PLUS): 115 VAC ±10%, 60 Hz, 5 watts
(12 watts maximum);
Input (ME800AE-PLUS): 230 VAC ±10%, 50/60 Hz;
Output (both models): 17 VAC, 700 mA
Size: 1.3"H x 4"W x 4.2"D (3.3 x 10.2 x 10.7 cm)
Weight: 1.4 lb. (0.6 kg), standalone, including
transformer

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SHM-B PLUS ASYNC
2. Introduction
The Short-Haul Modem Model B Plus Async (SHM-B
Plus Async) is a standalone asynchronous full-duplex
4-wire line driver/receiver which allows two TIA/EIA
RS-232 devices to communicate at distances of up to
4.8 miles (7.7 km) or at data rates up to 115.2 kbps.
In addition to the transmitter and receiver circuits, the
SHM-B Plus Async includes RS-232 control-line
interfaces, status-monitor LEDs, and a loopback switch.
The 115-VAC version is product code ME800A-PLUS;
the 230-VAC version is product code ME800AE-PLUS.
The SHM-B Plus Async is designed to operate over a
4-wire metallic circuit. Optimum performance is
obtained with twisted-pair cable (see Chapter 1). Most
types of twisted-pair cable may be used, often with little
or no performance degradation.
The SHM-B Plus Async is designed for maximum
operator safety. There are no voltages greater than
12 VDC or 16 VAC present on the circuit board of the
unit. The Receive lines are protected from potential
ground differences through optical isolators rated at
1500 volts.

9
CHAPTER 3: Installation and Configuration
3. Installation and Configuration
You can install and configure the SHM-B Plus Async in
three basic steps: making the four-wire connections,
making the RS-232 connection, and setting the switches.
3.1 Making the Four-Wire Connections
Connect a pair of SHM-B Plus Async modems to each
other through either their terminal blocks or their RJ-11
connectors. Figure 3-1 on the next page shows the
location of the terminal block and the RJ-11 jack.
a) TERMINAL BLOCK:
Refer to Figure 3-2 to make the proper connections
between two SHM-B units using the terminal block.
NOTE: Transmit + (TX+) on one modem is wired
to Receive + (RX+) on the other modem; Transmit -
(TX-) is wired to Receive - (RX-).
1. Strip each of the four wires about 1⁄8".
2. Loosen the screw terminals in the terminal block.
Insert the wires into the terminal strip; tighten the
screw terminals.

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SHM-B PLUS ASYNC
Figure 3-1. Bottom view.
Figure 3-2. Wiring diagram—terminal block.
SHM #1
Pair 1
Pair 2
SHM #2

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CHAPTER 3: Installation and Configuration
b) RJ-11 JACK:
1. Connect pairs of modems using a crossover RJ-11
cable (refer to Figure 3-3). A crossover cable has the
RJ-11 tabs on the same side of the cable.
2. Insert the RJ-11 cable into the RJ-11 jack on the
modem.
Figure 3-3. Pinning of the RJ-11 jacks and crossover cable.

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SHM-B PLUS ASYNC
3.2 Making the RS-232 Connection
Connect the SHM-B Plus Async to your computer or
terminal with a standard RS-232 cable that has a DB25
male connector on the SHM-B end. Refer to your
equipment’s installation manual if you need
information on the exact RS-232 signals required for
your equipment. Often, it is best to use only the
Transmit Data (TD), Receive Data (RD), and ground
lines if your equipment does not require the use of the
control signals Request To Send (RTS), Clear To Send
(CTS), Data Set Ready (DSR), etc. The SHM-B
generates levels for the control signals if you need to use
them. Table 3-1 shows the SHM-B’s pinout.
Table 3-1. The SHM-B’s universal RS-232 pinout.
Pin Number Signal Name
1 Shield (SHD)
2 Transmit Data/Receive Data (TD/RD)*
3 Receive Data/Transmit Data (RD/TD)*
4 Request to Send/Data Carrier Detect (RTS/DCD)*
5 Clear to Send/Request to Send (CTS/RTS)*
6 Data Set Ready/Data Terminal Ready (DSR/DTR)*
7 Signal Ground (SGND)
8 Data Carrier Detect/Ready to Send (DCD/RTS)*
20 Data Terminal Ready/Data Set Ready (DTR/DSR)*
*TD and RD, RTS and CTS/DCD, and DSR and DTR can be reversed using the
DTE/DCE switch S1 on the circuit board. See Section 3.3 for details.

13
CHAPTER 3: Installation and Configuration
3.3 Setting the DTE/DCE Switch (S1)
Refer to Figure 3-1. Switch S1 is used to reverse the TD,
RD, and hardware flow-control lines on the SHM-B Plus
Async’s RS-232 interface. This eliminates the need to
swap these signals in your RS-232 cables. If you connect
the SHM-B to your equipment using a “straight-through”
or “2:2” cable, then S1 must be set to the opposite of
your device’s configuration. For example, if your device
is configured as DTE, select DCE on S1. If you use a null
modem, “2:3”, or “3:2” cable to connect the SHM-B to
your equipment, then the setting for S1 will be identical
to your equipment’s setting. Refer to your equipment’s
manual for information concerning whether it’s a DTE
or DCE. Table 3-2 on the next page gives the RS-232
pinning of the SHM-B with the DTE/DCE switch in the
DCE position.

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SHM-B PLUS ASYNC
Table 3-2. The SHM-B’s RS-232 DCE pinout.
PIN NUMBER SIGNAL NAME DIRECTION
1 Shield (SHD) —————
2 Transmitted Data (TD)* To DCE
3 Received Data (RD)* From DCE
4 Request to Send (RTS)* To DCE
5 Clear to Send (CTS)* From DCE
6 Data Set Ready (DSR)* From DCE
7 Signal Ground (SGND) —————
8 Data Carrier Detect (DCD)* From DCE
20 Data Terminal Ready (DTR)* To DCE
*Pins 2 and 3 (TD and RD), and hardware flow control can be reversed using the
DTE/DCE switch, S1 on the circuit board.
NOTE
Configure each SHM-B independently. Your local and
remote modems won’t necessarily be configured the same
way.

15
CHAPTER 3: Installation and Configuration
3.4 Setting the Flow-Control Switch (S3)
You can set the SHM-B Plus Async to use software or
hardware or software flow control in order to make it
compatible with a broad range of equipment.
S TANDARD RS-232C H ANDSHAKING (RTS/DTR C ONTROL
S WITCH S3
IN EN P OSITION )
The individual SHM-B modems force their own DTR,
RTS, CTS, and DSR control lines HIGH (greater than
+3V) when:
• The twisted-pair wires are installed correctly.
• Power is applied to the modems.
• No computer devices are attached to the modems.
This forces DCD HIGH on the remote modem; thus, the
remote modem knows to expect data. In this state, “all
systems are go.” The only way this state changes is if your
equipment overrides this condition. For example, if your
equipment drops DTR to a NEGATIVE signal, your
equipment’s DTR being low will override the SHM-B’s
DTR, and DCD on the remote modem will go LOW.

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SHM-B PLUS ASYNC
Because DTR, DSR, RTS, and CTS are tied together
internally, dropping any one of these four signals to a
negative state will also drop DCD on the remote side to a
negative state. DCD will also go LOW if the remote
SHM-B is powered down, or if the twisted-pair wire is
broken.
X-ON/X-OFF M ODE
(RTS/DTR C ONTROL S WITCH [S3] IN DIS P OSITION )
If X-ON/X-OFF characters are used for handshaking
control, rather than hardware logic levels, move the
RTS/DTR control switch to the DIS position.
Typically, units that use software X-ON/X-OFF flow
control do not want RTS to affect DCD on the remote
SHM-B. Moving the switch to the DIS position disables
the RTS/DCD relationship. The only thing that will
force DCD low with the switch in the DIS position is the
absence of power on the remote SHM-B or a broken
twisted-pair wire.

17
CHAPTER 4: Operation
4. Operation
After completing the wiring and configuration
procedure and connecting the SHM-B Plus Async to
your equipment, plug its wall transformer into the
SHM-B and a working AC outlet. Check the SHM-B
operation at both ends of the link by pressing the
LOOPBACK switch, S2, first on one modem and then
on the other. Pressing this switch on a SHM-B will put
that SHM-B in a loopback mode, as shown in Figure 4-1.
Figure 4-1. Activating the LOOPBACK switch.

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SHM-B PLUS ASYNC
When in loopback mode, the switch-button indicator
will appear white. If a CRT terminal is connected to the
SHM-B, typing characters on the keyboard should result
in the same characters appearing on the CRT screen. If
no characters appear, check your RS-232 connections
and the setting of S1.
The TD and RD LEDs on the front panel of your SHM-B
Plus Async indicate the status of the SHM-B’s transmitter
and receiver, respectively. Green indicates a LOW
RS-232 level and red indicates a HIGH RS-232 level. The
LEDs will modulate as data is transmitted and received
by the SHM-B. Remember that these LEDs are
monitoring the actual received and transmitted signals,
not the TD and RD lines of the RS-232 interface.
When the loopback test is completed, press the
LOOPBACK switch again to return the SHM-B to
normal mode. The switch button indicator should now
be black. After you repeat the test at the other SHM-B
and both modems are out of loopback mode, normal
data transmission between the two modems will again be
possible.
If the two SHM-Bs have problems communicating, use
Chapter 5 to help diagnose the problem.

19
CHAPTER 5: Troubleshooting
5. Troubleshooting
The following information will help you troubleshoot
your SHM-B Plus Async installation if problems develop.
If your particular situation isn’t listed here, call
Technical Support for assistance. Have ready a
description of the problem with your installation, the
makes and models of the attached equipment, your
equipment’s DTE/DCE configuration and flow-control
type (hardware or software), your RS-232 cable pinouts,
and what (if anything) you have already done to test or
correct the situation.
SYMPTOM: LEDs do not light when power transformer
is plugged into a wall outlet.
1. Is the power connection loose? Make sure that the
transformer is securely connected to the outlet and
the SHM-B.
2. Does the outlet actually work? Try plugging a known-
good appliance into it.
3. If the outlet works but the SHM-B’s LEDs still do not
light, the SHM-B may be defective.