Short-Haul Modem (2-Wire)
Contents
1.2. After completing the installation procedure slide the printed circuit card back into the case if necessary while pulling the data and power cables through the holes in the back 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 The final step is to set the DTR switches at both ends to the HI position 2 4 Step Four Connect Your PC or Terminal Equipment Connect the SHM to your computer or terminal with standard RS 232 cable and DB25 connectors Refer to your PC or terminal equipment manual if you need more information on the exact RS 232 signals required by the equipment If your equipment does not require hardware flow control use only the Transmit Data TD Receive Data RD and ground lines The table on the next page describes the pin connection at the SHM nn SHORT HAUL MODEM 2 WIRE FLOW CONTROL The SHM uses the Data Terminal Ready DTR control signal to turn the transmitter off and on Normally the attached RS 232 equipment will control the state of DTR If the attached RS 232 equipment is disconnected or turned off the DTR switch on the SHM s front panel controls the state of DTR Signal Name Direction Protective Ground Transmit Data TD From attached RS 232C equipment Receive Data RD To attached RS 232C equipment Request to Send RTS From attached RS 232C equipment tied to CTS and pulled high Clear to Send CTS To a
3. loopback mode any data sent to the SHM will be echoed to the sender Ifa CRT terminal is connected to the SHM typing characters on the keyboard should result in the same characters appearing on the CRT screen If your terminal is configured for local echo two of each character should appear on the CRT screen If no characters appear check your RS 232 connections See the diagram below for a description of the loopback mode The TD DTR and RD DCD LED indicators on the SHM s front panel indicate the status of the SHM 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 Remember that these LEDs are monitoring the actual received and transmitted signals not the TD and RD lines of the RS 232 interface CHAPTER 3 Operation SHM 1 in SHM 2 in Normal Mode Normal Mode SHM 1 in SHM 2 in Loopback Mode Normal Mode When the loopback test is completed press the loopback switch again to return the SHM to the normal mode The switch button indicator will become black Data transmission between the two modems will now be possible If you still encounter difficulty refer to Chapter 5 SHORT HAUL MODEM 2 WIRE 4 Specifications Distance Bit Rate Table Bit Rate bps 19 2K 9600 4800 lt 2400 Distance miles 1 1 115 1 9 29 NOTE These specifications are valid for un
4. verified and both LED indicators should be GREEN Begin with both Loop Length switches set to 0 Turn the DTR switch to LO on the near end SHM The TD DTR indicator should go off Go to the far end SHM and observe the status of the RD DCD indicator making sure that the DTR switch at that end is in the HI position If the distance between the modems is extremely short less than 100 feet the RD DCD indicator should be off If so no adjustments are necessary Normally it will be on and an adjustment will be necessary Begin by turning the left rotary switch red actuator one position ata time using a small Phillips or straight blade screwdriver Keep advancing one position at a time until the RD DCD indicator goes off This is now the correct position for the red switch See Table 2 1 for the correct setting for the orange switch Repeat this procedure for the near end SHM by placing the DTR switch in the LO Position on the far end SHM the one you just calibrated Go back to the near end SHM and place the DTR switch in the HI position and follow the above procedure to get the RD DCD indicator to turn off The settings obtained for both ends should be the same 10 CHAPTER 2 Installation Table 2 1 Loop Length Settings for 24 or 26 AWG Non Shielded Cable Red Switch Orange Switch OWwrewoaonouagpr won a O 0 1 2 3 4 5 6 Y 8 9 A B C D E U NOTE Do not use the F position on the RED Loop Length switch
5. Mt LL LL LL OCTOBER 1989 ME755 ME755 C ME755 E lt BLACK BOX Short Haul Modem 2 Wire CUSTOMER Order toll free in the U S Call 877 877 BBOX outside U S call 724 746 5500 SUPPORT FREE technical support 24 hours a day 7 days a week Call 724 746 5500 or fax 724 746 0746 INFORMATION Mailing address Black Box Corporation 1000 Park Drive Lawrence PA 15055 1018 Web site www blackbox com E mail info blackbox com 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 excee
6. are handshaking The SHM operates over a two wire metallic circuit Optimum performance is obtained with 22 to 26 AWG twisted pair telephone cable See Chapter 4 for more information However nearly any twisted pair cable can be used with little or no performance degradation In addition to the transmitter and receiver circuits the modem includes RS 232 control line interfaces status monitor LEDs and a loopback switch The SHM is available in a standalone version and a rackmount version Both versions are identical however the standalone version is packaged in a plastic case from which it can be removed and installed in a chassis if desired Rack Mount Power Connectors RS 232 Connector Power Transformer Connections Terminal Block Loop Length Loopback oe TD DTR RD DCD ET CHAPTER 2 Installation 2 Installation Before installing your modem be certain that it is not plugged into the power source and that the RS 232 equipment is turned off Installation is accomplished in four steps 1 Connect the two wire cable 2 Test the connections 3 Set the Loop Length switches 4 Connect your PC or terminal equipment The following instructions apply to both the standalone model and the rackmount model Refer to Section 2 5 for installation of the card chassis into a standard 19 inch panel 2 1 Step One Connect the Two Wire Cable The standalone model SHM is shipped with the faceplate and a modular connect
7. ck Tighten the screw terminals After you have made the connections wrap the nylon cable tie provided around the wires and pull tightly until the cable tie has secured the wires to the printed circuit board Remove the excess nylon tie with a pair of wire cutters or scissors Two Wire Twisted Pair SHORT HAUL MODEM 2 WIRE 2 2 Step Two Test the Cabling Apply power to both of the modems The front panel switches should be in the following positions Loopback Switch Normal position center of button is black DTR Switch HI position Loop Length Switches Rotary switches set to 0 zero Observe the two LEDs on the front panel of both of the modems They should be GREEN If the RD DCD indicator is RED on both modems the wire polarity is reversed Correct the wiring and re test If either or both indicators are off check to make sure that power is applied and that your cable connections are making good contact When both LEDs on each SHM are GREEN you are ready to set the Loop Length switches 2 3 Step Three Set the Loop Length Switches In order for the SHM to function properly it is necessary to adjust these rotary switches for each installation The setting procedure should be necessary only once when you install the units To establish the proper settings both of the SHMs should have power applied but should not be connected to any RS 232 equipment By following the above test procedure the cable connections have been
8. d the Class A limits for radio noise emission from digital apparatus set out in the Radio Interference Regulation of Industry Canada Le pr sent appareil num rique n met pas de bruits radio lectriques d passant les limites applicables aux appareils num riques de la classe A prescrites dans le R glement sur le brouillage radio lectrique publi par Industrie Canada SHORT HAUL MODEM 2 WIRE 10 ll NORMAS OFICIALES MEXICANAS NOM ELECTRICAL SAFETY STATEMENT INSTRUCCIONES DE SEGURIDAD Todas las instrucciones de seguridad y operaci n deber n ser le das antes de que el aparato el ctrico sea operado Las instrucciones de seguridad y operaci n deber n ser guardadas para referencia futura Todas las advertencias en el aparato el ctrico y en sus instrucciones de operaci n deben ser respetadas Todas las instrucciones de operaci n y uso deben ser seguidas El aparato el ctrico no deber ser usado cerca del agua por ejemplo cerca de la tina de ba o lavabo s tano mojado o cerca de una alberca etc El aparato el ctrico debe ser usado nicamente con carritos o pedestales que sean recomendados por el fabricante El aparato el ctrico debe ser montado a la pared o al techo s lo como sea recomendado por el fabricante Servicio El usuario no debe intentar dar servicio al equipo el ctrico m s all a lo descrito en las instrucciones de operaci n Todo otro servicio deber
9. e transformer lines from the board then inserting the card into the chassis 1 CHAPTER 4 Specifications Physical Specifications Parameter SHM 16 Card Chassis Size 1 5 H x 4 3 W x 4 5 D 5 25 H x 17 W x 9 D 3 8 x 10 9 x 11 4 cm 13 3 x 43 2 x 22 9 cm Weight 1 3 lb 0 6 kg with 3 7 lb 17 kg with transformer transformer Housing Material High impact plastic Aluminum alloy with acrylic faceplate Operating 32 to 112 F 0 to 44 C Same Temperature Operating Max 95 relative humidity Same Humidity noncondensing 5 Troubleshooting LEDs do not light when power transformer is plugged into the wall outlet 1 Loose power connections try moving or wiggling the wall transformer 2 Broken power leads remove the SHM printed circuit board and check the three leads from the transformer for continuity 3 Rackmount Version be sure the printed circuit board is properly inserted and fully seated against the motherboard RD DCD indicator does not light no receive carrier 1 Far end SHM is not plugged in correct as necessary 2 Loop Length switches are not set correctly recalibrate using the described procedure 3 DTR isn t HI at far end SHM make sure that the attached RS 232 equipment is wired properly If DTR Pin 20 is not being used make sure that the DTR switch on the front panel is in the HI position 4 Improper wiring recheck the circuit No data transfer in one or both directions 1 Improper w
10. iring recheck the circuit 2 Try local test using loopback mode If there s no transfer check the RS 232 cable If local loopback works try far end loopback if there s no transer check the twisted pair and Loop Length switch settings 3 RS 232 control signals 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 enable communication If Pin 8 DCC is low this indicates a defective transmission line or connection or a far end SHM without power TD DTR and RD DCD LEDs indicate data activity but no data communication 1 Check wiring of the RS 232 port s M CHAPTER 5 Troubleshooting Garbled data all data erroneous 1 Check for reversal of polarity on the two wire connection 2 Incorrect setting of Loop Length switches recalibrate Occasional data errors 1 Distance bit rate capability exceeded See Chapter 4 2 Poor quality loop 2 wire circuit try using another 2 wire circuit or rewire the circuit 3 Extremely noisy environment or extreme crosstalk in cable between modems reroute cable away from noise sources such as lighting fixtures motors etc 4 Marginal AC power source check your AC power at the wall socket and confirm that it is within the range given in Chaper 4 NOTES lt BLACK BOX O Copyright 1989 Black Box Corporation All rights reserved 1000 Park Drive Lawrence PA 15055 1018 724 746 5500 Fax 724 746 0746
11. llips head mounting screws that were shipped with the chassis Fasten the chassis to your rack using these screws Do not attempt to use screws that are not countersunk as this will result in damage to the front panel when it is installed Wire each SHM board according to the procedures in this manual It is usually easier to feed all of the necessary wires and cables through the chassis then work with the circuit boards in front of the chassis to make the connections After each board is wired it can then be inserted into an open slot in the SHM chassis Be certain that the board has mated with the power pins on the SHM chassis before applying force to fully seat the board otherwise damage to the board and power pins could result When all boards have been wired and plugged into the chassis plug the wall transformer into its power source Proceed with the installation according to instructions given in this chapter When all channels are operating attach the plunger latches with their respective holes in the chassis Press on the top and bottom of the panel to properly seat it then firmly press in all six of the plunger latches to retain the panel 3 Operation Connect the SHM to your equipment then plug the wall transformer into its power source As a first step to checking the communication link place the far end SHM into loopback by pressing its loopback switch When in loopback mode the switch button indicator will appear white In
12. no sean derramados sobre la cubierta u orificios de ventilaci n 18 Servicio por personal calificado deber ser provisto cuando A El cable de poder o el contacto ha sido da ado u B Objectos han ca do o l quido 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 desempe o o E El aparato ha sido tirado o su cubierta ha sido da ada SHORT HAUL MODEM 2 WIRE TRADEMARKS USED IN THIS MANUAL Any trademarks mentioned in this manual are acknowledged to be the property of the trademark owners CONTENTS Contents Chapter Page o a ne ee 6 NUS Pa TEE LE cesta Eo on o E E arenas ouceeeeeeeeceeeaeese 7 2 1 atep One Connect ihe Lwo Wire Cable session 1 2 LE UNIO ON ATA Connec HOI Se ne O TAO 8 2102 Termal Block Connec HoN menesteres 9 o a a AAA ee E E 10 2 3 Step Three Set the Loop Length Switches sisas 10 2 4 Step Four Connect Your PC or Terminal Equipment 11 20 Back MOUNDE dd 13 e A e o eo Le noie ion 14 o o C1 IC A ONS AAA A an 16 Dr FOUN eS OO I O rajo nee bte ae pa 18 SHORT HAUL MODEM 2 WIRE 1 Overview The Short Haul Modem 2 Wire is an asynchronous full duplex line driver and receiver which requires only two wires to transmit data A pair of SHMs enables two RS 232 devices to communicate at distances of up to two miles 3 2 km and at bit rates of up to 19 200 bps while fully supporting hardw
13. or adapter installed All switches are accessible on the back panel so access to the printed circuit card shouldn t be necessary If the installation does not require using modular connections it may be necessary to access the card To remove the faceplate and expose the card apply pressure at the front of the unit to separate the top and the bottom halves of the case then push on the rear connector to force out the front panel and printed circuit assembly SHORT HAUL MODEM 2 WIRE 2 1 1 MODULAR CONNECTION Installing the SHM requires that the positive terminal on one SHM is connected to the positive terminal of the other SHM and that the negative terminal is wired directly to the negative terminal Modular Adaptor Red supplied with SHM Straight Through Modular Cable NOTE A modular cable with a twisted connection may be used but will require changing the red green polarity on one SHM CHAPTER 2 Installation 2 1 2 TERMINAL BLOCK CONNECTION Installing the SHM requires that the positive terminal of one SHM is wired directly to the positive terminal of the other SHM and that the negative terminal is wired directly to the negative terminal Remove the modular connector from the terminal block and route the new wires through the same hole in the rear of the case Strip approximately 4 to 6 of the insulation from the ends of both wires before inserting the wires into the terminal blo
14. ser referido a personal de servicio calificado El aparato el ctrico debe ser situado de tal manera que su posici n no interfiera su uso La colocaci n del aparato el ctrico sobre una cama sof alfombra o superficie similar puede bloquea la ventilaci n no se debe colocar en libreros o gabinetes que impidan el flujo de aire por los orificios de ventilaci n El equipo el ctrico deber ser situado fuera del alcance de fuentes de calor como radiadores registros de calor estufas u otros aparatos incluyendo amplificadores que producen calor El aparato el ctrico deber ser connectado a una fuente de poder s lo del tipo descrito en el instructivo de operaci n o como se indique en el aparato gt 12 Precauci n debe ser tomada de tal manera que la tierra fisica y la polarizaci n 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 atenci n a los contactos y recept culos donde salen del aparato 14 El equipo el ctrico debe ser limpiado nicamente de acuerdo a las recomendaciones del fabricante 15 En caso de existir una antena externa deber ser localizada lejos de las lineas de energia 16 El cable de corriente deber 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
15. shielded twisted pair telephone cable having 24 or 26 AWG conductors insulated by polyethylene and a mutual capacitance of 0 083 uF mile Shielded twisted pair cable will reduce the distance to one third of the table value This is due to additional capacitance contributed by the shield Line Interface Balanced 2 wire current loop Equipment Interface RS 232 interface DCE configured Loopback Digital loopback on RS 232 interface provided by front panel switch Idle Status DTR Control DTR may be pulled either high true on or low false off using a front panel switch When active RS 232 equipment is attached the status of the DTR signal is controlled by the equipment Status Indication Two bi color LEDs indicate the status of the transmitter and receiver Green indicates a low logic level 3 to 25V on the RS 232 interface Red indicates a high logic level 3 to 25V Off indicates the associated control signal is low The control signal that controls the transmitter is DTR The control signal that shows the status of the receiver is DCD Power 120 VAC 10 60 Hz wall mounted transformer 230 Vrms 10 50 60 Hz for 230 volt version option available Rackmount The SHM is available as a standalone unit in a plastic enclosure or as a rackmount unit SHM boards may be removed from the plastic case and used as a rackmount unit by simply removing the printed circuit card from the case and desoldering the thre
16. ttached RS 232C equipment tied to RTS and pulled high Data Set Ready DSR To attached RS 232C equipment pulled high Signal Ground Data Carrier Detect DCD To attached RS 232C equipment flow control output Data Terminal Ready From attached RS 232C equipment DTR flow control input The SHM on the other end of the loop detects the presence or absence of the transmitted signal and reflects that condition with the Data Carrier Detect DCD control signal If the far transmitter is on DCD at the near end will be high giving an all systems go status to the attached RS 232 equipment Another common flow control method is X ON X OFF flow control In this case hardware flow control lines are generally not needed If your equipment uses X ON X OFF flow control do not connect the DCD and DTR lines to your RS 232 equipment You must also set the DTR switch to the HI position at both SHMs gt CHAPTER 2 Installation 2 5 Rack Mounting The SHM rackmount version mounts in either an 8 card desktop chassis or a 16 card chassis which mounts in a standard 19 inch 48 3 cm panel This 16 card chassis will occupy 5 25 13 3 cm of vertical rack space and is 9 22 9 cm deep To install the 16 card chassis into a 19 inch 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 Phi
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