Black Box Network Hardware ME800A User Manual

AUGUST 2000  
ME800A  
ME800A-R2  
ME805-C  
ME805-C-R2  
ME810  
Short-Haul Modem B  
(SHM-B Async)  
NORMAL  
LOOPBACK  
RD  
TD  
MODEM  
ASYNC SHORT HAUL  
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 724-746-0746  
Mailing address: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018  
 
SHM-B 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.  
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SHM-B ASYNC  
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.  
3
 
SHM-B ASYNC  
TRADEMARKS USED IN THIS MANUAL  
Any trademarks mentioned in this manual are  
acknowledged to be the property of the trademark  
owners.  
4
 
SHM-B ASYNC  
1. Specifications  
Transmission —  
Data Rate (bps)  
Distance (miles/km)  
19,200  
9600  
4800  
2400  
1/1.6  
2/3.2  
3/4.8  
4/6.4  
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 µf/mile. 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  
Equipment Interface — EIA-232/CCITT V.24 interface  
with a hardware handshake (selected through use of an  
internal strap). Carrier Detect (CD) true (high)  
indicates operating short-haul modem at the remote  
5
 
SHM-B ASYNC  
end of the loop. Interface is switch-selectable for  
DTE/DCE configuration (pins 2 and 3 are reversed)  
Connectors — (1) DB25 female, (1) 5-screw terminal  
block  
Diagnostics — Loopbacks provided by a front-panel  
switch: Analog loopback on a 4-wire loop and digital  
loopback on equipment interface (EIA-232)  
Status Indication — Two bi-color LEDs indicate the  
status of the transmitter and receiver. A green light  
indicates a “low” logic level (-3 to -25V) on the EIA-232  
interface; a red light indicates a “high” logic level (+3 to  
+25V).  
Operating Temperature — 32 to 112°F (0 to 50°C)  
Humidity — 95%maximum, noncondensing  
Enclosure — Standalone: High-impact plastic;  
Rackmount: Aluminum alloy  
Power — Power is supplied by a wall-mounted power  
transformer. No more than 16 Vrms is present in unit.  
6
 
SHM-B ASYNC  
Primary: 115 VAC 10%, 60 Hz, 5 watts (12 watts max.);  
Primary: 230 VAC 10%, 50/60 Hz; Secondary: 17 VAC,  
700 mA  
Size — Standalone: 1.4"H x 4.25"W x 4.5"D (3.8 x 10.9 x  
11.7 cm); Rackmount: 5.25"H x 17"W x 9"D (13 x 43 x  
23 cm)  
Weight — Standalone: 1.3 lb. (0.6 kg), including  
transformer; Rackmount: 3.7 lb. (1.7 kg), including  
transformer  
7
 
SHM-B ASYNC  
2. Introduction  
The Short-Haul Modem Model B Async (SHM-B Async)  
is an asynchronous full-duplex 4-wire line  
driver/receiver which allows two EIA-232 devices to  
communicate at distances of up to 4 miles and at data  
speeds of up to 19,200 bps. In addition to the  
transmitter and receiver circuits, the SHM-B Async  
includes EIA-232 control line interfaces, status monitor  
LEDs, and a loopback switch. The SHM-B is available in  
both a standalone version (ME800A) and a rackmount  
version (ME805-C). Models ME800A-R2 and ME805-C-  
R2 include cables.  
The SHM-B is designed to operate over a 4-wire metallic  
circuit. Optimum performance is obtained with twisted-  
pair cable (see specifications). Most types of twisted-pair  
cable may be used, often with little or no performance  
degradation.  
The SHM-B 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.  
8
 
SHM-B ASYNC  
3. Installation  
Installation involves three basic steps: four-wire  
connections; EIA-232 connection; switch settings.  
3.1 Four-Wire Connections  
Figure 1 shows the location of the terminal block on the  
circuit board. Refer to Figure 2 to make the proper  
connections between two SHM-B units.  
NOTE: Transmit + (TX+) on one modem is wired  
to Receive + (RX+) on the other modem; Transmit -  
(TX-) is wired to Receive - (RX-). A ground  
connection is optional.  
1. If the unit is assembled, separate the top and  
bottom panels at the front of the unit.  
2. Push the rear connector to force out the front  
panel and printed circuit board.  
3. Route the four-wire cable through the open hole in  
the rear panel of the enclosure.  
1
4. Strip each of the four wires about 8".  
9
 
SHM-B ASYNC  
5. Insert the wires into the terminal strip; tighten the  
screw terminals.  
6. After you have made all four connections, wrap the  
nylon cable tie (packaged with the SHM-B) around  
the wires. Pull the tie tight around the wires to  
secure them to the printed circuit board. Trim the  
excess nylon tie with wire cutters or scissors.  
J1 RS-232  
CONNECTOR  
EN  
JUMPER  
DIS  
RTS/DTR  
CONTROL  
DCE  
DTE/DCE  
DTE  
S2 (LOOPBACK)  
Figure 1. SHM-B board; 5-screw terminal block.  
10  
 
SHM-B ASYNC  
TX+  
TX-  
RX+  
RX-  
TX+  
TX-  
RX+  
RX-  
SHM #1  
SHM #2  
Figure 2. Wiring diagram for two SHM-B units.  
3.2 EIA-232 Connection  
Connect the SHM-B to your computer or terminal with a  
standard EIA-232 cable and DB25 connectors. Refer to  
your equipment’s installation manual if you need  
information on the exact EIA-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. The table shows the pin connections at the  
SHM-B.  
11  
 
SHM-B ASYNC  
Table 1. EIA-232 Pin Connections on SHM-B  
Pin Number  
Signal Name  
1
2
3
4
5
Protective Ground  
Transmit Data/Receive Data (TD/RD)*  
Receive Data/Transmit Data (RD/TD)*  
Request to Send (RTS)  
Clear to Send (CTS)  
6
7
Data Set Ready (DSR)  
Signal Ground  
8
Carrier Detect (CD)  
20  
Data Terminal Ready (DTR)  
*TD and RD can be reversed using the DTE/DCE switch, S1 on the circuit board. See  
Section 3.3 for details.  
3.3 Switch Settings  
Refer to Figure 1 in this chapter. Switch S1 is used to  
reverse the TD and RD lines on the EIA-232 interface.  
This eliminates the need to swap these two lines in your  
EIA-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 “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  
12  
 
SHM-B ASYNC  
information concerning its DTE/DCE setting. Table 2  
gives the EIA-232 pinning of the SHM-B with the  
DTE/DCE switch in the DCE position.  
Table 2. Pinning with DTE/DCE switch in the DCE position.  
PIN NUMBER  
SIGNAL NAME  
DIRECTION  
1
2
3
4
5
6
7
8
Protective Ground  
Transmitted Data TD*  
Received Data RD*  
Request to Send (RTS)  
Clear to Send (CTS)  
Data Set Ready (DSR)  
Signal Ground  
Received Line Signal Detector  
Data Terminal Ready (DTR)  
—————  
To DCE  
From DCE  
To DCE  
From DCE  
From DCE  
—————  
From DCE  
To DCE  
20  
*Pins 2 and 3 (TD and RD) can be reversed using the DTE/DCE switch, S1 on the circuit  
board. See Section 3.3 for details.  
NOTE  
Configure each SHM-B independently. Your local and  
remote modems won’t necessarily be configured the same.  
13  
 
SHM-B ASYNC  
3.4 Flow Control  
The SHM-B uses a clever, yet simple way to allow this  
unit to work with a broad line of equipment.  
STANDARD EIA-232C HANDSHAKING (RTS/DTR CONTROL  
JUMPER IN EN POSITION)  
The individual SHM-B modems force their own DTR,  
RTS, CTS, and DSR control lines HIGH (>+3V) when:  
• The twisted-pair wires are installed correctly.  
• Power is applied to both 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.  
14  
 
SHM-B 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 MODE  
(RTS/DTR CONTROL JUMPER IN DIS POSITION)  
If X-ON/X-OFF characters are used for handshaking  
control, rather than hardware logic levels, move the  
RTS/DTR control jumper 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 jumper to the DIS position disables  
the RTS/DCD relationship. The only thing that will  
force DCD low with the jumper in the DIS position is the  
absence of power on the remote SHM-B or a broken  
twisted-pair wire.  
15  
 
SHM-B ASYNC  
4. Operation  
After completing the wiring and configuration  
procedure, slide the printed circuit card back into the  
case while pulling the data and power cables through  
the holes in the back panel. The front panel will snap  
into the front of the case when the printed circuit board  
has been completely pushed to the back of the case.  
Connect the SHM-B to your equipment, then plug the  
wall transformer into its power source. Check the SHM-  
B operation at both ends of the loop by pressing the  
LOOPBACK switch, S2.  
TX+  
TX-  
RX+  
RX-  
TD  
(RS-232)  
RD  
RD  
(RS-232)  
TD  
RX+  
RX-  
TX+  
TX-  
SHM #1 in NORMAL mode.  
SHM #2 in NORMAL mode.  
TX+  
TX-  
RX+  
TD  
RD  
(RS-232)  
TD  
RX-  
(RS-232)  
RD  
RX+  
RX-  
TX+  
TX-  
SHM #1 in LOOPBACK mode.  
SHM #2 in NORMAL mode.  
Figure 3. Activating the LOOPBACK switch.  
16  
 
SHM-B ASYNC  
When in loopback mode, the switch button indicator  
will appear to the sender. 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 EIA-232  
connections and the setting of S1. See Figure 3 for an  
illustration of the loopback mode.  
The TD and RD LEDs on the front panel of your SHM-B  
indicate the status of the SHM-B transmitter and  
receiver, respectively. Green indicates a LOW EIA-232  
level and red indicates a HIGH EIA-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 EIA-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. Data transmission between the two modems  
will now be possible.  
If you experience problems communicating between the  
two SHM-Bs, use Table 1 to help diagnose the problem.  
17  
 
SHM-B ASYNC  
5. Rackmount Installation  
The SHM-B Async Card is a rack mount unit (ME805-C)  
that installs in a standard 19-inch panel rack. (You can  
use the SHM-B Rack [ME810], which can hold up to 16  
cards.) The SHM-B Async Card will occupy 5.25 inches  
of vertical rack space, and is 9 inches deep.  
To install the SHM-B Rack, first remove the acrylic front  
panel by pulling out the six plunger latches on the front  
of the panel, then pulling on opposite-side plungers to  
loosen and remove the panel.  
Locate the four 10/32 Phillips-head screws that were  
shipped with the SHM-B Rack. Use these screws to fasten  
the SHM-B Rack to your rack.  
CAUTION  
Do not attempt to use screws which are not countersunk, as  
this will result in damage to the plastic front panel when it is  
installed.  
Wire each SHM-B board according to Figures 1 and 2 in  
this manual. It is easiest to first feed all of the wires and  
cables through the rack. Then you can make the  
necessary circuit board connections with the circuit  
boards positioned in front of the rack; this allows for the  
18  
 
SHM-B ASYNC  
easiest access to the terminals, switches, etc.  
After a SHM-B Card is wired, it can then be inserted into  
an open slot in the SHM-B rack. Be certain that the circuit  
board has mated with the power pins on the SHM-B rack before  
applying force to fully seat the board; otherwise you may  
damage the board and power pins.  
When all boards have been wired and plugged into the  
rack, plug the wall transformer into its power source.  
You should be able to communicate as described in  
Chapter 4. When all channels are operating, attach the  
SHM-B Rack front panel by first aligning the plunger  
latches with their respective holes in the rack. Press on  
the top and bottom of the panel to properly seat it, then  
firmly press in all six of the plunger latches to retrain the  
panel.  
19  
 
SHM-B ASYNC  
6. Troubleshooting Guide  
The following information will help you troubleshoot  
your 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, your DTE equipment make and  
models, your equipment’s DTE/DCE configuration and  
flow control type (hardware or software), your EIA-232  
cable pinouts, and what (if anything) you have already  
done to correct the situation.  
SYMPTOM: LEDs do not light when power transformer  
is plugged into a wall outlet.  
1. Is the power connection loose? Try moving or  
nudging the wall transformer.  
2. Are there broken power leads? Disconnect the power  
supply. Remove the printed circuit board from the  
chassis. Inspect the three leads from the transformer  
for continuity.  
3. The SHM-B is defective.  
4. SHM-B Async Card: Make certain that the SHM-B’s  
20  
 
SHM-B ASYNC  
printed circuit board is properly inserted and fully  
seated against the motherboard of the rack.  
SYMPTOM: No data transfer in one or both directions  
(to, from, or to-and-from the SHM-B).  
1. Monitor the TD LED on the sending-end modem  
while sending data. The light should flash red/green.  
If not, check the DCE/DTE switch on that unit. Once  
you get a TD LED flashing on that unit,  
simultaneously the RD LED should flash on the other  
SHM-B unit. If not, go to step 2.  
2. Inspect the wiring between the two modems. Have the  
wires been properly installed? Transmit + (TX+) on  
one modem must be wired to Receive + (RX+) on the  
other modem; also, Transmit - (TX-) must be wired to  
Receive - (RX-). Refer to Figure 2 during your  
inspection of the four-wire circuit.  
3. Try a local test using the Loopback mode (see  
Chapter 4). If there is no transfer, check the setting of  
S1 and the wiring of your EIA-232 cable.  
4. The EIA-232 control signals are at the wrong levels.  
Check the EIA-232 interface using a breakout box.  
21  
 
SHM-B ASYNC  
Pins 4, 5, 6, 8, and 20 should all be HIGH to enable  
communication.  
5. If pin 8 (Carrier Detect) is low, this indicates:  
• a defective transmission line or connection  
• a defective remote SHM-B  
• remote SHM-B without power  
SYMPTOM: TD and RD LEDs indicate data activity, but  
data communication doesn’t exist.  
1. Check the wiring of the EIA-232 port. Refer to Section  
3.2 for information.  
2. Check the setting of S1. Refer to Section 3.3 for  
information.  
SYMPTOM: Transmitted and/or received data is full of  
errors (garbled data).  
1. Check for reversal of polarity on the four-wire  
connection. Refer to Section 3.1 and Figure 2.  
2. Check word structure and speed settings on your  
22  
 
SHM-B ASYNC  
computing equipment for consistency.  
3. Wire the SHM-B units back-to-back, eliminating the  
twisted-pair; see if you still have errors.  
• If you do have errors, then test each SHM  
individually in the following way: loopback one  
SHM’s Transmit-to-Receive by using two short  
pieces of wire. Connect that SHM to a dumb  
terminal and key in characters; look for a good  
loopback. A good loopback verifies a SHM-B in  
proper working condition.  
• If you don’t have errors, you have verified a  
problem with the twisted-pair cable.  
SYMPTOM: Occasional data errors.  
1. The transmission distance/bps data rate capability  
rate may have been exceeded. Refer to Chapter 1 for  
information about valid data transmission distances  
and bps rates.  
2. There is a poor quality loop (four-wire circuit). Try  
using a different four-wire circuit, or rewire the  
existing circuit.  
23  
 
SHM-B ASYNC  
3. Check the path of your four-wire circuit for potential  
sources of interference (fluorescent lighting,  
electrical motors, etc.). Such sources of electrical  
“noise” can provide an environment in which  
unwanted signals are induced onto your four-wire  
circuit. Also, check to see if an adjacent four-wire  
cable carrying a separate data stream is creating  
“crosstalk.” It may be that the data signal is jumping  
from the adjacent cable onto the four-wire circuit  
between the two SHM-B modems (another type of  
induced signal).  
• While you are checking your cable for sources of  
noise and crosstalk, check the cable for  
irregularities in the shield. Also, reconsider the  
cable’s ratings for attenuation, capacitance, and  
impedance. You may need to install a higher-  
quality cable for your particular installation.  
• Your AC power source may be the culprit. Check  
your AC power at the wall socket and confirm that  
it is within the range given in Chapter 1.  
24  
 
SHM-B ASYNC  
SYMPTOM: TD or RD indicator is steadily on red with  
no data attempting to pass (no DTEs attached).  
Check for reversal of polarity on the four-wire  
connection.  
25  
 
© Copyright 2000. Black Box Corporation. All rights reserved.  
1000 Park Drive  
Lawrence, PA 15055-1018  
724-746-5500  
Fax 724-746-0746  
 

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