JUNE 2002ME800A-PLUS

ME800AE-PLUS

Short-Haul Modem B (SHM-B)Plus Async

CUSTOMER SUPPORT INFORMATIONOrder 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 724-746-0746Mailing address: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018Web site: www.blackbox.com • E-mail: info@blackbox.com

TDRD

NORMAL

LOOPBACK

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FCC/IC RFI STATEMENTS, TRADEMARKS

FEDERAL COMMUNICATIONS COMMISSION ANDINDUSTRY CANADA

RADIO-FREQUENCY INTERFERENCE STATEMENTS

This equipment generates, uses, and can radiate radio-frequency energy, and ifnot installed and used properly, that is, in strict accordance with themanufacturer’s instructions, may cause interference to radio communication.It has been tested and found to comply with the limits for a Class A computingdevice in accordance with the specifications in Subpart B of Part 15 of FCC rules,which are designed to provide reasonable protection against such interferencewhen the equipment is operated in a commercial environment. Operation ofthis equipment in a residential area is likely to cause interference, in which casethe user at his own expense will be required to take whatever measures may benecessary to correct the interference.

Changes or modifications not expressly approved by the party responsible forcompliance could void the user’s authority to operate the equipment.

This digital apparatus does not exceed the Class A limits for radio noise emission fromdigital apparatus set out in the Radio Interference Regulation of Industry Canada.

Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limitesapplicables aux appareils numériques de classe A prescrites dans le Règlement sur lebrouillage radioélectrique publié par Industrie Canada.

TRADEMARKS USED IN THIS MANUALBLACK 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 thetrademark 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 antesde que el aparato eléctrico sea operado.

2. Las instrucciones de seguridad y operación deberán ser guardadas parareferencia futura.

3. Todas las advertencias en el aparato eléctrico y en sus instrucciones deoperación 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 pedestalesque sean recomendados por el fabricante.

7. El aparato eléctrico debe ser montado a la pared o al techo sólo como searecomendado por el fabricante.

8. Servicio—El usuario no debe intentar dar servicio al equipo eléctrico másallá a lo descrito en las instrucciones de operación. Todo otro serviciodeberá ser referido a personal de servicio calificado.

9. El aparato eléctrico debe ser situado de tal manera que su posición nointerfiera su uso. La colocación del aparato eléctrico sobre una cama,sofá, alfombra o superficie similar puede bloquea la ventilación, no sedebe colocar en libreros o gabinetes que impidan el flujo de aire por losorificios de ventilación.

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NOM STATEMENT

10. El equipo eléctrico deber ser situado fuera del alcance de fuentes de calorcomo radiadores, registros de calor, estufas u otros aparatos (incluyendoamplificadores) que producen calor.

11. El aparato eléctrico deberá ser connectado a una fuente de poder sólo deltipo descrito en el instructivo de operación, o como se indique en elaparato.

12. Precaución debe ser tomada de tal manera que la tierra fisica y lapolarización del equipo no sea eliminada.

13. Los cables de la fuente de poder deben ser guiados de tal manera que nosean pisados ni pellizcados por objetos colocados sobre o contra ellos,poniendo particular atención a los contactos y receptáculos donde salendel aparato.

14. El equipo eléctrico debe ser limpiado únicamente de acuerdo a lasrecomendaciones del fabricante.

15. En caso de existir, una antena externa deberá ser localizada lejos de laslineas de energia.

16. El cable de corriente deberá ser desconectado del cuando el equipo nosea usado por un largo periodo de tiempo.

17. Cuidado debe ser tomado de tal manera que objectos liquidos no seanderramados 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 delaparato; o

C: El aparato ha sido expuesto a la lluvia; o

D: El aparato parece no operar normalmente o muestra un cambio ensu 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 .................................. 93.1 Making the Four-Wire Connection .................... 93.2 Making the RS-232 Connections ...................... 123.3 Setting the DTE/DCE Switch (S1) ................... 133.4 Setting the Flow-Control Switch (S3) ............... 15

4. Operation .................................................................. 17

5. Troubleshooting ....................................................... 19

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CHAPTER 1: Specifications

1. SpecificationsData Rate and Maximum Distance:

Data Rate (bps) AWG (mm)24 (0.5) 26 (0.4)

Distance in miles115,200 0.8 0.757,600 1.2 0.838,400 1.3 0.919,200 1.5 1.2

9600 2 1.54800 2.6 22400 4 31200 4.8 4

NOTE: The above specifications are valid for 24- or 26-AWG unshieldedtwisted-pair telephone cable insulated by polyethylene with amutual capacitance of 0.083 pF/mile (0.52 pF/km). Shieldedtwisted-pair cable will reduce the distance to one-third of the tablevalue, due to the additional capacitance contributed by the cable’sshielding. Actual distances may vary depending on your specificoperating equipment and the cable you use.

Protocol: Asynchronous

Operation: 4-wire, full duplex, point-to-point

Line Interface: Balanced current loop; receive lines areprotected through optical isolators rated at 1500 volts

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SHM-B PLUS ASYNC

Equipment Interface: TIA/EIA RS-232/ITU V.24interface with a hardware handshake (selected throughuse of an external switch); Data Carrier Detect (DCD)true (high) indicates operating short-haul modem at theremote end of the loop; interface is switch-selectable forDTE/DCE configuration (pins 2 and 3 reversed, pins 4and 5 reversed with pin 8, pin 6 reversed with pin 20)

Connectors: (1) DB25 female, (1) 4-screw terminalblock, (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 loopbackon equipment interface (RS-232)

Indicators: (2) Front-mounted bi-color LEDs indicatethe status of the RS-232 transmitter and receiver: greenindicates 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 than16 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, includingtransformer

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SHM-B PLUS ASYNC

2. IntroductionThe Short-Haul Modem Model B Plus Async (SHM-BPlus Async) is a standalone asynchronous full-duplex4-wire line driver/receiver which allows two TIA/EIARS-232 devices to communicate at distances of up to4.8 miles (7.7 km) or at data rates up to 115.2 kbps.In addition to the transmitter and receiver circuits, theSHM-B Plus Async includes RS-232 control-lineinterfaces, 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 a4-wire metallic circuit. Optimum performance isobtained with twisted-pair cable (see Chapter 1). Mosttypes of twisted-pair cable may be used, often with littleor no performance degradation.

The SHM-B Plus Async is designed for maximumoperator safety. There are no voltages greater than12 VDC or 16 VAC present on the circuit board of theunit. The Receive lines are protected from potentialground differences through optical isolators rated at1500 volts.

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CHAPTER 3: Installation and Configuration

3. Installation and ConfigurationYou can install and configure the SHM-B Plus Async inthree 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 eachother through either their terminal blocks or their RJ-11connectors. Figure 3-1 on the next page shows thelocation of the terminal block and the RJ-11 jack.

a) TERMINAL BLOCK:

Refer to Figure 3-2 to make the proper connectionsbetween two SHM-B units using the terminal block.

NOTE: Transmit + (TX+) on one modem is wiredto 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 thescrew 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-11cable (refer to Figure 3-3). A crossover cable has theRJ-11 tabs on the same side of the cable.

2. Insert the RJ-11 cable into the RJ-11 jack on themodem.

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 orterminal with a standard RS-232 cable that has a DB25male connector on the SHM-B end. Refer to yourequipment’s installation manual if you needinformation on the exact RS-232 signals required foryour equipment. Often, it is best to use only theTransmit Data (TD), Receive Data (RD), and groundlines if your equipment does not require the use of thecontrol signals Request To Send (RTS), Clear To Send(CTS), Data Set Ready (DSR), etc. The SHM-Bgenerates levels for the control signals if you need to usethem. Table 3-1 shows the SHM-B’s pinout.

Table 3-1. The SHM-B’s universal RS-232 pinout.

Pin Number Signal Name1 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 theDTE/DCE switch S1 on the circuit board. See Section 3.3 for details.

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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 PlusAsync’s RS-232 interface. This eliminates the need toswap these signals in your RS-232 cables. If you connectthe SHM-B to your equipment using a “straight-through”or “2:2” cable, then S1 must be set to the opposite ofyour device’s configuration. For example, if your deviceis configured as DTE, select DCE on S1. If you use a nullmodem, “2:3”, or “3:2” cable to connect the SHM-B toyour equipment, then the setting for S1 will be identicalto your equipment’s setting. Refer to your equipment’smanual for information concerning whether it’s a DTEor DCE. Table 3-2 on the next page gives the RS-232pinning of the SHM-B with the DTE/DCE switch in theDCE position.

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SHM-B PLUS ASYNC

Table 3-2. The SHM-B’s RS-232 DCE pinout.

PIN NUMBER SIGNAL NAME DIRECTION1 Shield (SHD) —————2 Transmitted Data (TD)* To DCE3 Received Data (RD)* From DCE4 Request to Send (RTS)* To DCE5 Clear to Send (CTS)* From DCE6 Data Set Ready (DSR)* From DCE7 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 theDTE/DCE switch, S1 on the circuit board.

NOTEConfigure each SHM-B independently. Your local andremote modems won’t necessarily be configured the sameway.

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CHAPTER 3: Installation and Configuration

3.4 Setting the Flow-Control Switch (S3)

You can set the SHM-B Plus Async to use software orhardware or software flow control in order to make itcompatible with a broad range of equipment.

STANDARD RS-232C HANDSHAKING (RTS/DTR CONTROL

SWITCH S3 IN EN POSITION)

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, theremote modem knows to expect data. In this state, “allsystems are go.” The only way this state changes is if yourequipment overrides this condition. For example, if yourequipment drops DTR to a NEGATIVE signal, yourequipment’s DTR being low will override the SHM-B’sDTR, 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 togetherinternally, dropping any one of these four signals to anegative state will also drop DCD on the remote side to anegative state. DCD will also go LOW if the remoteSHM-B is powered down, or if the twisted-pair wire isbroken.

X-ON/X-OFF MODE

(RTS/DTR CONTROL SWITCH [S3] IN DIS POSITION)

If X-ON/X-OFF characters are used for handshakingcontrol, rather than hardware logic levels, move theRTS/DTR control switch to the DIS position.

Typically, units that use software X-ON/X-OFF flowcontrol do not want RTS to affect DCD on the remoteSHM-B. Moving the switch to the DIS position disablesthe RTS/DCD relationship. The only thing that willforce DCD low with the switch in the DIS position is theabsence of power on the remote SHM-B or a brokentwisted-pair wire.

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CHAPTER 4: Operation

4. OperationAfter completing the wiring and configurationprocedure and connecting the SHM-B Plus Async toyour equipment, plug its wall transformer into theSHM-B and a working AC outlet. Check the SHM-Boperation at both ends of the link by pressing theLOOPBACK switch, S2, first on one modem and thenon the other. Pressing this switch on a SHM-B will putthat 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 indicatorwill appear white. If a CRT terminal is connected to theSHM-B, typing characters on the keyboard should resultin the same characters appearing on the CRT screen. Ifno characters appear, check your RS-232 connectionsand the setting of S1.

The TD and RD LEDs on the front panel of your SHM-BPlus Async indicate the status of the SHM-B’s transmitterand receiver, respectively. Green indicates a LOWRS-232 level and red indicates a HIGH RS-232 level. TheLEDs will modulate as data is transmitted and receivedby the SHM-B. Remember that these LEDs aremonitoring the actual received and transmitted signals,not the TD and RD lines of the RS-232 interface.

When the loopback test is completed, press theLOOPBACK switch again to return the SHM-B tonormal mode. The switch button indicator should nowbe black. After you repeat the test at the other SHM-Band both modems are out of loopback mode, normaldata transmission between the two modems will again bepossible.

If the two SHM-Bs have problems communicating, useChapter 5 to help diagnose the problem.

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CHAPTER 5: Troubleshooting

5. TroubleshootingThe following information will help you troubleshootyour SHM-B Plus Async installation if problems develop.If your particular situation isn’t listed here, callTechnical Support for assistance. Have ready adescription of the problem with your installation, themakes and models of the attached equipment, yourequipment’s DTE/DCE configuration and flow-controltype (hardware or software), your RS-232 cable pinouts,and what (if anything) you have already done to test orcorrect the situation.

SYMPTOM: LEDs do not light when power transformeris plugged into a wall outlet.

1. Is the power connection loose? Make sure that thetransformer is securely connected to the outlet andthe 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 notlight, the SHM-B may be defective.

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SHM-B PLUS ASYNC

SYMPTOM: No data transfer in one or both directions(to, from, or to-and-from the SHM-B Plus Async).

1. Monitor the TD LED on the sending-end modemwhile sending data. The light should flash red/green.If not, check the DCE/DTE switch on that unit. Onceyou get a TD LED flashing on that unit, the RD LEDshould simultaneously flash on the other SHM-B unit.If not, go to step 2.

2. Inspect the wiring between the two modems. Have thewires been properly installed? Transmit + (TX+) onone modem must be wired to Receive + (RX+) on theother modem; also, Transmit - (TX-) must be wired toReceive - (RX-). Refer to Figure 3-2 during yourinspection of the four-wire circuit.

3. Try a local test using the Loopback mode (seeChapter 4). If there is no transfer, check the setting ofswitch S1 and the wiring of your RS-232 cable.

4. The RS-232 control signals are at the wrong levels.Check the RS-232 interface using a breakout box.Pins 4, 5, 6, 8, and 20 should all be HIGH to enablecommunication.

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CHAPTER 5: Troubleshooting

5. If pin 8 (Data Carrier Detect) is low, this indicates:

• a defective transmission line or connection,

• a defective remote SHM-B, or

• a remote SHM-B without power.

SYMPTOM: TD and RD LEDs indicate data activity, butdata communication doesn’t exist.

1. Check the wiring of the RS-232 port. Refer toSection 3.2 for information.

2. Check the setting of switch S1. Refer to Section 3.3 forinformation.

SYMPTOM: Transmitted and/or received data is full oferrors (garbled data).

1. Check for reversal of polarity on the four-wireconnection. Refer to Section 3.1 and Figure 3-2.

2. Check communication settings (baud rate, parity,word size) on your computing equipment forconsistency.

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SHM-B PLUS ASYNC

3. Wire the SHM-B units back-to-back, eliminating thetwisted-pair; see if you still have errors.

• If you do have errors, then test each SHM-Bindividually in the following way: loop back oneSHM-B’s Transmit to its own Receive by using twoshort pieces of wire. Connect that SHM-B to adumb terminal and key in characters; look for agood loopback. A good loopback verifies a SHM-Bin proper working condition.

• If you don’t have errors, you have verified aproblem with the twisted-pair cable.

SYMPTOM: Occasional data errors.

1. You might be trying to send data too far or too fast forthe SHM-B to handle. Refer to Chapter 1 forinformation about valid data-transmission distancesand data rates.

2. You have a poor-quality loop (four-wire circuit). Tryusing a different four-wire circuit, or rewire theexisting circuit.

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CHAPTER 5: Troubleshooting

3. Check the path of your four-wire circuit for potentialsources of interference (fluorescent lighting,electrical motors, etc.). Such sources of electricalnoise can provide an environment in which unwantedsignals are induced onto your four-wire circuit. Also,check to see if an adjacent four-wire cable carrying aseparate data stream is creating crosstalk. It may bethat the data signal is jumping from the adjacentcable onto the four-wire circuit between the twoSHM-B modems (another type of induced signal).

• While you are checking your cable for sources ofnoise and crosstalk, check the cable forirregularities in the shield. Also, reconsider thecable’s ratings for attenuation, capacitance, andimpedance. You may need to install a higher-quality cable for your particular installation.

• Your AC power source may be the culprit. Checkyour AC power at the wall socket and confirm thatit is within the range given in Chapter 1.

SYMPTOM: TD or RD indicator is steadily on red withno data attempting to pass (no DTEs attached).

Check for reversal of polarity on the four-wireconnection.

NOTES

1000 Park Drive • Lawrence, PA 15055-1018 • 724-746-5500 • Fax 724-746-0746

© Copyright 2002. Black Box Corporation. All rights reserved.