Black Box Modem MD3317 User Manual

AUGUST 1997  
ME840A-M  
ME840A-S  
MD3317  
MD3318  
Short-Haul Modem-FSK  
RS-485 Modules  
SHM-FSK  
PWR  
LPBK  
TxD  
R
RxD  
CD  
R
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 724-746-0746  
Mail order: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018  
 
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.  
4
 
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.  
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SHORT HAUL MODEM (SHM-FSK)  
TRADEMARKS  
All applied-for and registered trademarks are the property of their respective owners.  
6
 
SHORT HAUL MODEM (SHM-FSK)  
CONTENTS  
1. Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8  
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9  
2.1 Master Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9  
2.2 Remote Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9  
2.3 Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10  
2.4 Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10  
3. Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13  
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15  
5. Jumper Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16  
5.1 DCE and DTE Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16  
5.2 Transmitter Output Level. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16  
5.3 Receiver Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17  
5.4 Carrier Detect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17  
5.5 Chassis Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17  
5.6 Half Duplex Operation/Carrier Control . . . . . . . . . . . . . . . . . . . . . 17  
6. LED Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18  
7. General Operating Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19  
7.1 Tuned Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19  
7.2 Proper Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19  
7.3 Loopback Test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19  
8. RS-485 Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20  
7
 
SHORT HAUL MODEM (SHM-FSK)  
1. Specifications  
Data Format — RS-232C (RS-422/485 optional)  
Operation — Full-duplex or half-duplex controlled carrier,  
serial asynchronous data  
Mode — Point-to-point or multipoint  
Data Transmission Speed — Up to 9600 baud  
Modulation — Frequency shift key; carrier signal inductively  
and capacitively isolated  
Distance — Up to 48,000 feet (9.1 miles or 14.6 km) on single twisted pair  
Operating Temperature — 32 to 140 °F (0 to 60 °C)  
Enclosure — All-metal enclosure, 16 gauge steel; polyurethane paint  
Interface — DTE/DCE jumper selectable; Female DB25 connector for  
RS-232C; green two-position pluggable terminal block for carrier; black two-  
position pluggable terminal block for power  
LED Indicators — Carrier Detect, Receive Data, Transmit Data, Power  
Power Requirements — 120 VAC 50/60 Hz at 9.6 watts or 24 VDC at 10 watts  
Size — 1.75” H x 7.5” W x 10.5” D (4.45 x 19.1 x 26.7 cm)  
Weight — 4.5 lb. (2 kg)  
8
 
SHORT HAUL MODEM (SHM-FSK)  
2. Introduction  
The Short Haul Modem (SHM-FSK) is a private-line modem that allows  
half- and full-duplex RS-232 data communications at 9600 bps over a single  
dedicated wire pair and across sliding contacts. The SHM-FSK operates using  
pure Frequency Shift Key (FSK) at high carrier frequencies (100KHz,  
106.5KHz to 150KHz, 156.5KHz). These high frequencies make the  
SHM-FSK particularly immune to crosstalk and outside noise interference,  
providing highly reliable, continuous data transmission over distances  
of several miles in harsh industrial environments.  
The SHM-FSK converts digital signals to modulated high-frequency sine-  
wave carrier signals that can be transmitted much longer distances, with  
greater noise immunity, than square-wave digital signals. The digital Space  
and Mark (or 0 and 1) are converted in the transmitter to carrier signals  
having two slightly different frequencies that are identified by the receiver  
and reconverted to the digital signals. The SHM-FSKs are configured as either  
Master or Remote units and can be used for either point-to-point or multi-  
drop data communications.  
The SHM-FSKs send data asynchronously. They are transparent to protocol,  
and to data rate from DC to 9600 baud.  
The SHM-FSK can be configured as a master unit or as a slave unit.  
See page 13 for more information.  
2.1 SHM-FSK Master Units (part number ME840A-M)  
The SHM-FSK Master unit transmits at 106.5/100 KHz (Space/Mark) and  
receives at 156.5/150 KHz. A green pluggable two-position terminal block  
at the back of the unit is used for connection to the data line. There is no  
polarity to the data-line connection.  
2.2 SHM-FSK Remote Units (part number ME840A-S)  
The SHM-FSK Remote unit transmits at 156.5/150 KHz and receives at  
106.5/100 KHz. It has the same data-line connector as the Master unit.  
Both the Master and Remote SHM-FSKs are powered by nominal 24 volts  
DC, which is supplied to a black two-position plugabble terminal block (+ on  
the left, if you’re facing the pins) on the rear panel. The units are delivered  
from the factory with 120VAC to 24DC wall transformers which have a black  
plug attached. An external 24VDC supply can also be used to power up the  
MDLs. The current draw is 250mA.  
9
 
SHORT HAUL MODEM (SHM-FSK)  
2.3 Operating Mode  
The SHM-FSKs can be operated in either point-to-point or multipoint polling  
mode.  
For multi-drop data communications, the SHM-FSK can be operated with  
one Master and typically up to eight Remote units. The transmitter in each  
Remote unit is controlled by the intelligent device it is connected to. The  
Master unit’s transmitter remains on all the time. The green two-position  
pluggable terminal block at the receptacle marked “LINE” on the back of the  
SHM-FSK unit is used with any two-wire cable (does not need to be twisted).  
Since the FSK signal is AC, there is no polarity required on any of the data-  
line connections.  
2.4 Diagrams  
Figure 2-1 shows the location of the LEDs on the front of the SHM-FSK.  
CD  
RxD  
TxD  
LPBK  
PWR  
Figure 2-1. Location of LEDs on the SHM-FSK.  
10  
 
SHORT HAUL MODEM (SHM-FSK)  
Figure 2-2 is a pinout of the RS-232 port.  
SIGNAL  
PIN  
PIN  
SIGNAL  
DESTINATION  
NUMBER  
NUMBER  
DESTINATION  
1
2
3
4
5
6
7
8
9
PROTECTIVE GROUND  
TRANSMITTED DATA  
RECEIVED DATA  
REQUEST TO SEND  
CLEAR TO SEND  
SECONDARY TRANSMITTED DATA 14  
DCE TRANSMITTER SIGNAL ELEMENT TIMING 15  
SECONDARY RECEIVED DATA 16  
17  
18  
19  
20  
21  
22  
23  
24  
25  
RECEIVER SIGNAL ELEMENT TIMING  
LOCAL LOOPBACK  
SECONDARY REQUEST TO SEND  
DATA TERMINAL READY  
DATA SET READY  
SIGNAL GROUND / COMMON RETURN  
RECEIVED LINE SIGNAL DETECTOR  
+ VOLTAGE  
SIGNAL QUALITY DETECTOR  
RING INDICATOR  
DATA SIGNAL RATE SELECTOR  
DTE TRANSMITTER SIGNAL ELEMENT TIMING  
TEST MODE  
10 - VOLTAGE  
11  
12 SECONDARY RECEIVED LINE SIGNAL INDICATOR  
13 SECONDARY CLEAR TO SEND  
Figure 2-2. Pinout of the RS-232 Port.  
11  
 
SHORT HAUL MODEM (SHM-FSK)  
Figure 2-3 is an illustration of a typical full-duplex or half-duplex,  
point-to-point application.  
Copper Pairs up to  
48,000 feet  
(9.1 miles or 14.6 km)  
RS-232  
Cable  
RS-232  
Cable  
SHM-FSK  
SHM-FSK  
Remote  
Telemetry Unit  
Programmable  
Logic Controller  
(PLC)  
Figure 2-3. Typical Application Connections.  
12  
 
SHORT HAUL MODEM (SHM-FSK)  
3. Installation  
The SHM-FSK units are shipped ready for either full-duplex or half-duplex  
multi-drop operation. The jumpers have been factory-set in full-duplex mode.  
The Master and Remote units are both factory-configured as DCEs (Data  
Communications Equipment) with the jumpers on headers P1 and P2 in the  
B-C position. Data into the DB25 is on pin 2 and data out is on pin 3. (Also  
see Chapter 5, Jumper Settings.)  
Before installing the SHM-FSK units, make sure that the digital devices to  
be connected to the SHM-FSK units are capable of communicating with each  
other if connected with a conventional three-wire RS-232 data cable. Once  
this has been established, the devices can be connected to the SHM-FSK units  
and RS-232 data communications will take place transparently.  
NOTE  
Make sure that the wire pair to be used for data communications between  
SHM-FSK units is connected only to those units; has no branches; has  
no attached inductance, capacitance, or resistance; and has no loading  
coils, filters or any other load; and that all connections are clean and  
solid. Since the data line is transformer-isolated from the rest of the  
circuit, neither leg of the data-carrying twisted pair should be grounded.  
The installation procedure is as follows:  
1. Remove the unit’s cover by taking out the four screws on top of the  
modem.  
2. Set the Remote units for either full- or half-duplex operation by  
positioning the jumper on header P4, located behind the DB25  
connector. For full-duplex operation, the jumper should be in the B-C  
position; for half-duplex, multi-drop operation using RTS line carrier  
control, the jumper should be in the A-B position.  
13  
 
SHORT HAUL MODEM (SHM-FSK)  
3. Confirm that the jumpers on positions P1 and P2 are in the B-C position.  
4. Replace the cover.  
5. Connect the RS-232 communications port of the digital data device  
(PC, PLC, etc.) to the SHM-FSK unit with an appropriate cable.  
6. Connect the transmission line to the unit at the green pluggable terminal  
block. There is no polarity requirement.  
7. Connect the unit’s power cord at the black two-position pluggable  
terminal block marked “PWR” (facing receptacle, + is on the left and - on  
the right) and plug the modular transformer into a convenient 120-VAC  
outlet. Plugging the power in will power up the units; there is no “On-Off”  
switch.  
14  
 
SHORT HAUL MODEM (SHM-FSK)  
4. Operation  
Point-to-point, full- or half-duplex operation is usually conducted with the  
both the Master and Remote SHM-FSK carriers on all the time. This is  
achieved by placing the P4 jumper in the B-C position and either not  
connecting the RTS line (DB25 pin 4) to the SHM-FSKs or making sure that  
the RTS line supplied by the devices connected to the SHM-FSK is either  
floating or logic high.  
In half duplex, multi-drop operating mode, with the P4 jumper in the  
A-B position, the RTS line of the intelligent device that a Remote SHM-FSK  
is connected to (PC, PLC, or RTU) is used to control the the SHM-FSK’s  
transmitted carrier. When logic is low, the carrier is turned off; when logic is  
high, the carrier is turned on. If the RS-232 cable is disconnected, the RTS  
connection on the SHM-FSK is biased low and the carrier remains off. (If the  
P4 jumper is in the B-C position, the RTS connection is biased high and the  
carrier will stay on.)  
When properly configured, the SHM-FSK is capable of half- or full-duplex  
data transmission at rates up to 9600 baud. The SHM-FSKs require no settings  
for data rate and will operate transparently as data is fed to them. They will  
begin communicating data as soon as connections are made and they are  
powered up.  
15  
 
SHORT HAUL MODEM (SHM-FSK)  
5. Jumper Settings  
There are several configuration options that can be selected by jumpers as  
described below. The jumper pins are internal and are identified by lettering  
on the circuit board. They are accessed by removing the four retaining screws  
on the top cover of the enclosure and removing the cover. Be sure that the  
unit is disconnected from power before removing the cover.  
5.1 DCE and DTE Settings  
Both the SHM-FSK Master and Remote units are configured at the factory  
as DCE (Data Communication Equipment) for connection to DTE (Data  
Terminal Equipment). A PC, PLC, or multiplexor is usually configured as  
DTE. If either the Master or Remote must be changed from DCE to DTE,  
move the jumpers on blocks “P1” and “P2,” which are located directly behind  
the DB25 RS-232 connector on the rear panel.  
5.2 Transmitter Output Level  
The SHM-FSK allows the selection of either normal or high-power (HP)  
transmitter output. The high-power output has six times greater peak-to-peak  
transmitted signal and provides correspondingly greater signal-to-noise ratio.  
High-power transmitter operation is generally best in applications involving  
sliding contacts or in very noisy EMI environments. However, caution is  
advised in some cases since high power carrier signals will result in more  
crosstalk to adjacent conductors.  
The jumper to select normal or high power is located at position TP2. High  
power is selected when the jumper is positioned center to left (marked “H”);  
normal output is selected with center to right (marked “N”). When using the  
HP setting, the receiver gain should be set to low for data-line lengths under  
5000 feet. (see Section 5.3). The factory setting is normal (center to right,  
“N”).  
16  
 
SHORT HAUL MODEM (SHM-FSK)  
5.3 Receiver Gain  
The SHM-FSK incorporates a receiver amplifier on the circuit board. This  
amplifier has low, normal, and high gain settings configured by a “T” shaped  
pin block near the center of the circuit board with pins marked “G1/H,”  
“G2,” “G3/L,” and “N” (the leg of the “T”). G1/H-G2 is the high-gain setting;  
G2-N, the normal medium gain; and G3/L-G2, the low gain. The units are  
delivered from the factory set at normal gain because the transmitter has  
been factory-set at normal output. If the data line is under 5000 feet long, the  
low-gain setting should be used whenever the high- power transmitter option  
is selected.  
5.4 Carrier Detect:  
Carrier Detect to the RS-232 connector is enabled or disabled by Jumper  
Matrix P3. The SHM-FSK units are shipped with the Carrier Detect enabled  
(jumper on).  
5.5 Chassis Ground  
Chassis ground can be connected to signal ground via Jumper P5. This  
is generally not recommended. A separate chassis ground wire may be  
connected to the SHM-FSK’s metal enclosure by means of any of the  
cover mounting screws as desired to avoid a possible shock hazard.  
5.6 Half-Duplex Operation/Carrier Control  
The SHM-FSK can be operated in multi-drop/half-duplex mode by  
controlling the transmitter’s carrier on/off using external signals. The most  
common external carrier-control signal is through the RS-232 port RTS line  
(pin 4). This line are selected by Jumper P4, A-B. When an external RTS logic  
high is asserted, the SHM-FSK carrier is turned on; logic low or ground turns  
the carrier off. The SHM-FSK RTS line is biased low, so that if the RS-232  
cable is disconnected or the external controlling device is turned off, the  
carrier will go off. A-B selects RTS and B-C selects DSR. Usually only the  
Remote units have their carriers controlled by the devices they are connected  
to. The Master unit’s carrier is left on all the time. (There is no interference,  
since the Master and Remote carrier frequencies are different.)  
The factory setting for both SHM-FSK Masters and Remotes is P4, A-B,  
for full- or half-duplex point-to-point operation.  
An alternative carrier-control method is to connect a cable to the SW1  
header, which allows external contact closure or solid-state switch control  
of the transmitter. Please call technical support for special instructions.  
17  
 
SHORT HAUL MODEM (SHM-FSK)  
6. LED Indications  
There are four LEDs on the front panel of the SHM-FSK. From left to right  
they are:  
Marking  
CD  
Function  
Carrier Detect  
RX  
Data flowing out of the SHM’s RS-232 port  
Data flowing into the SHM’s RS-232 port  
Power connected  
TX  
PWR  
The first diagnostic LED is Carrier Detect. In full-duplex mode, the CD  
LED must be ON on both units; in half-duplex, carrier-control mode, with RS-  
232 cables connected, the CD LED will be ON on all Remote SHMs and OFF  
on the Master SHM. (The Master CD LED will blink during operation as each  
Remote SHM turns on its carrier to answer back to the Master). If the correct  
CD LEDs are not ON, there is likely a carrier cable problem.  
Assuming that the CD indication is correct, a loopback test is recommended  
as described in Section 7.3.  
18  
 
SHORT HAUL MODEM (SHM-FSK)  
7. General Operating Notes  
7.1 Tuned Circuits  
The SHM-FSK uses tuned circuits to achieve its high performance. These  
circuits have been carefully adjusted at the factory to operate over several  
miles of transmission line. In order not to degrade performance, it is  
important not to disturb these adjustments. In particular, coils T1, T2, T3,  
T4, and T5 and potentiometers R18, R20, R31 and R57 should not be  
adjusted. If these adjustments have been inadvertently changed, call for  
technical support.  
7.2 Proper Operation  
Proper operation of SHM-FSK requires that the transmission line be non-  
loaded (free from inductors and capacitors on the line). The presence of  
inductors, capacitors or excessive resistance (from bad connections, for  
example), or shorts between the wires can seriously degrade performance  
or completely block data transmission.  
7.3 Loopback Test  
A loopback test is suggested to confirm the proper operation of SHM-FSKs  
in point-to-point operation, as follows:  
A PC running a communication program in full duplex can be connected  
to one of the SHM-FSKs in a point-to-point configuration. A jumper wire (a  
bent paper clip works very well) is placed between pin sockets 2 and 3 of the  
DB25 on the other SHM-FSK. Data sent to the first SHM-FSK will be looped  
back from the second and appear on the PC screen. If the characters are  
correct, the SHM-FSKs are functioning.  
19  
 
SHORT HAUL MODEM (SHM-FSK)  
8. RS-485 Interface  
Optional RS-485 modules are available for connection to multiple remote  
devices. The following modules are available:  
• RS-485 Module 2-Wire, part number MD3317  
• RS-485 Module, 4-Wire, part number MD3318  
All operating functions and instructions are the same as for the RS-232 full  
duplex version, except that the digital interface through the DB25 connector  
uses pin 12 as the -DO/RI connection and pin 13 as the +DO/RI connection.  
The RS-232 connections (pins 2, 3 and 7) are not functional.  
CAUTION  
Do not connect anything except an RS-485 signal to positions 12 and 13  
on the DB25 or damage to the circuit could occur.  
The AE-485 (Auto Enable) circuit contains a special feature that eliminates  
the need for a separate enable signal or line to command the 485 transmit  
and receive functions. Data will pass through the SHM-FSK’s  
RS-485 port transparently in either direction. The SHM-FSKs are operated in  
full-duplex point-to-point mode (no carrier control) when using the AE-485  
interface. Up to 32 remote RS-485 devices can be multi-dropped off the SHM-  
FSK AE-485 port at distances of up to 4000 feet and at data rates of 9600 baud.  
A 100-ohm termination resistor should be connected at the ends of the 485  
line.  
20  
 
© Copyright 1997. Black Box Corporation. All rights reserved.  
1000 Park Drive • Lawrence, PA 15055-1018 • 724-746-5500 • Fax 724-746-0746  
 

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