ME260A ME260AE ME261C ME262C ME263C AUGUST 2000 ME265C ME266C ME267C ME268C Modular Modem Eliminator RATE A INT. CONV. TD-1 RD-1 TD-2 E MOD EM MOD IN. TIC M ELAS ER ELI BUFF 8M 0 - 2.044 M 1 - 1.544 M 2 - 1.02 768 K 3 - 512 K 4 - 384 K 5 - 256 K 6 - 128 K 7- K 8 - 48 K 9 - 56 K A - 64 K 2 11 B- RD-2 PWR CUSTOMER SUPPORT INFORMATION Order toll-free in the U.S. 24 hours, 7 A.M.
FCC AND IC STATEMENTS 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.
MODULAR MODEM ELIMINATOR 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.
NOM STATEMENT 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.
MODULAR MODEM ELIMINATOR TRADEMARKS The trademarks mentioned in this manual are the sole property of their owners.
TABLE OF CONTENTS CONTENTS Chapter Page 1. Specifications.............................................................................................................7 1.1 Interface-Converter Mode .................................................................................7 1.2 Modem-Eliminator Mode ..................................................................................7 1.3 Elastic-Buffer Mode ............................................................................................7 1.
MODULAR MODEM ELIMINATOR CONTENTS (continued) Chapter Page 3. Installation (continued) 3.4 Installing of Interface Modules .......................................................................35 3.5 Connecting the Cables .....................................................................................36 3.5.1 Connector Locations ..............................................................................36 3.5.2 Data Connections .....................................................................
CHAPTER 1: Specifications 1. Specifications 1.1 Interface Converter Mode Internal Data Rates—Up to 2048 kbps Transmission Format—Synchronous Transmission Mode—Full- or half-duplex 1.
MODULAR MODEM ELIMINATOR 1.6 Physical Data Size—ME260A, ME260AE: 1.7"H x 10.5"W x 9.6"D (4.4 x 2.7 x 2.4 cm); Interface Modules: 2.7"H x 0.06"W x 3.9"D (7.0 x 0.1 x 9.9 cm) Weight—ME260A, ME260AE: 4.1 lb. (1.9 kg); ME261C, ME263C: 2.4 oz. (70 g); ME262C: 4.0 oz. (115 g); ME265C: 2.6 oz. (75 g); ME266C: 3.2 oz. (90 g); ME267C, ME268C: 2.8 oz. (80 g) 1.
CHAPTER 2: Introduction 2. Introduction 2.1 Functional Description The Modular Modem Eliminator is a universal interface converter that can be used to interface between two synchronous data communication equipment units that have incompatible interfacing characteristics. For this purpose, the Modular Modem Eliminator can perform the function of an Interface Converter, Modem Eliminator, or Elastic Buffer.
MODULAR MODEM ELIMINATOR General-Purpose Interface Modules The general-purpose interface modules are: • RS-232 Module (part number ME261C), EIA RS-232 (ITU V.24) • V.35 Module (part number ME262C), ITU V.35 • X.21 Module (part number ME263C), ITU X.21/V.11 • V.36 Module (part number ME265C), EIA RS-449/RS-422 (ITU V.36/V.11) These modules provide the corresponding electrical and physical interface.
CHAPTER 2: Introduction 2.2.3 OPERATING MODES The Modular Modem Eliminator has three operating modes, which are described below. Interface-Converter Mode The interface-converter mode lets you connect a Data Terminal Equipment (DTE) device to a Data Communications Equipment (DCE) device that has a different interface. A physical and electrical conversion between the DTE and DCE interfaces is performed. The data rate is determined by the equipment connected to the Modular Modem Eliminator.
MODULAR MODEM ELIMINATOR 2.2.4 TIMING OPTIONS FOR THE INTERFACE MODULES The timing options offered by the Modular Modem Eliminator depend on two factors: • Types of interface modules installed in the Modular Modem Eliminator (general purpose, or ITU G.703), and the settings on these modules. • Modular Modem Eliminator operating mode. This section covers the timing options offered by the various interface modules. For information on the timing options available in each operating mode, refer to Sections 2.2.
CHAPTER 2: Introduction • DTE—the interface module accepts clock signals for the receive and transmit paths. Note that for the X.21 interface, the module has only a receive clock input. Figure 2-2 shows the flow of timing signals for the DTE mode. Transmit Clock TC Transmit Data TD Interface Module (DTE Mode) Receive Clock RC Receive Data RD Figure 2-2. Flow of timing signals for DTE mode.
MODULAR MODEM ELIMINATOR 2.2.5 ITU G.703 64-KBPS CO-DIRECTIONAL INTERFACE MODULE (ME266C) The 64-kbps co-directional interface specified by ITU G.703 includes only one transmit pair and one receive pair. To avoid the need for additional pairs, the line signal waveform specified by G.703 for the 64-kbps co-directional interface includes timing and framing information. By using appropriate signal-processing circuits, it is possible to recover the original data and clock signals from the received signal.
CHAPTER 2: Specifications • LBT—the transmit clock is locked to the recovered receive clock (this mode is called “loopback timing”). Figure 2-4 shows the flow of timing signals with loopback timing. Data Transmit Line Signal Transmit Circuits Clock Interface Module (LBT Mode) Receive Line Signal Receive Circuits Data Recovered Clock Figure 2-4. Flow of timing signals for LBT mode.
MODULAR MODEM ELIMINATOR 2.2.6 ITU 1.544- AND 2.048-MBPS INTERFACE MODULES (ME268C AND ME267C) The ITU G.703 1.544-Mbps and 2.048-Mbps interface modules have four-wire interfaces (one pair for the transmit line and one pair for the receive line). The line signal (which uses B8ZS coding for the G.703 1.544-Mbps interface and HDB3 for the 2.048-Mbps interface)contains sufficient timing information to allow the recovery of the clock signal from the received data.
CHAPTER 2: Introduction 2.2.7 GENERAL CHARACTERISTICS The Modular Modem Eliminator is a compact unit, intended for installation on a desktop or shelf. An adapter kit for mounting in 19” racks is available (part number RM518). The Modular Modem Eliminator is powered from 115-VAC (ME260A) or 230-VAC (ME260AE). Its power consumption is very low.
MODULAR MODEM ELIMINATOR 2.3 Applications This section provides a description of the functions performed by the Modular Modem Eliminator. For illustration purposes, this section includes typical diagrams of interface signals flow. The signal names used on these diagrams are in accordance with the conventions that apply to the RS-232 interface; for information on the signals corresponding to other interface standards, refer to the interface-conversion table in Appendix A. 2.3.
CHAPTER 2: Introduction • Connection of a DTE to a 64 kbps co-directional G.703 1.544 Mbps or G.703 1.048 Mbps network or DTE. In a typical application, a Modular Modem Eliminator could be used to allow LAN interconnection via bridges using an E1 digital network, for example, even when the bridges do not have E1 interfaces. Figure 2-7 shows an application where bridges with a V.35 interface communicate over the E1 digital network (transparent to 2.048 Mbps network with no need for framing). V.
MODULAR MODEM ELIMINATOR 2.3.2 INTERFACING BY GENERAL-PURPOSE MODULES Figure 2-8 shows a typical interface signals flow diagram for an interface converter application that uses two general-purpose interface modules. In this application, the mode jumper of the interface module connected to the DTE must be set to the DCE position, and the mode jumper of the other module must be set to the DTE position. Interface-control signals are then transparently transferred from side to side, as shown in Figure 2-8.
CHAPTER 2: Introduction 2.3.3 INTERFACING WITH 64-KBPS CO-DIRECTIONAL INTERFACE MODULE (ME266C) Figure 2-9 shows a typical interface-signal flow diagram for an interface-converter application that uses a 64-kbps co-directional interface module in conjunction with a general-purpose interface module. This application allows the transfer of data to and from the DTE through a 64 kbps line. In this application, the mode jumper of the UCI interface module connected to the DTE must be set to the DCE position.
MODULAR MODEM ELIMINATOR 2.3.4 INTERFACING WITH T1 OR E1 INTERFACE MODULE Figure 2-10 shows a typical interface-signal flow diagram for an interface converter application that uses a T1 or E1 interface module in conjunction with a generalpurpose interface module. This application allows the transfer of data to and from the DTE—for example, a bridge or a data multiplexor, through a T1 or E1 line.
CHAPTER 2: Introduction 2.3.5 MODEM-ELIMINATOR APPLICATIONS In modem-eliminator applications, the Modular Modem Eliminator is used as a replacement for two synchronous modems to connect two DTEs. The DTEs can have different interfaces. This mode is used when both sides have general purpose interfaces (G.703 interface modules include internal clock source).
MODULAR MODEM ELIMINATOR Timing Modes When set for operation in the modem eliminator configuration, the Modular Modem Eliminator offers two timing modes. The selection of the desired mode is made by an internal jumper: • Internal (INT) timing: the clock signals for the two DTEs are provided by the internal clock oscillator of Modular Modem Eliminator. The data rate is set by means of the front-panel rate selector. In this case, the two DTEs must operate with external clock.
CHAPTER 2: Introduction Figure 2-13 shows the flow of the clock signals in this mode, as well as the flow of interface control signals. DTE DCE Mode DCE Mode DTE TTC RC TC RD TD DCD RTS TC RC TD RD DCD RTS DSR DTR DTR DSR CTS CTS FG PG SG SG Internal Clock J1 J2 External Clock Figure 2-13. Modem-eliminator application (showing the flow of clock and interface-control signals in the EXT timing mode).
MODULAR MODEM ELIMINATOR 2.4 Elastic-Buffer Applications In a typical elastic-buffer application, the Modular Modem Eliminator connects two DCEs that operate at the same nominal data rate, but use different timing sources. This means that data bits are clocked into the Modular Modem Eliminator at a rate slightly different from the rate at which the data is clocked out.
CHAPTER 2: Introductions DTE Mode DCE DTE Mode DCE TC RC TD RD RTS DCD RC TC RD TD DCD RTS DSR DTR DTR DSR CTS CTS PG PG SG SG Internal Clock J1 DCD-1 controls Buffer A DCD-2 controls Buffer B J2 Internal Clock Figure 2-15. Elastic buffer application (data, check, and interface control signals diagram).
MODULAR MODEM ELIMINATOR 3. Installation 3.1 General The Modular Modem Eliminator is designed for installation as a desktop unit, however, a rackmount kit is available (ordered separately, part number RM518). Mechanical and electrical installation procedures for the Modular Modem Eliminator are provided in the following paragraphs. These procedures include the setting of internal jumpers, and the installation of interface modules. 3.1.
CHAPTER 3: Installation 3.2 Configuration Information 3.2.1 GENERAL Before installing the Modem Eliminator, set the internal jumpers as explained below. This paragraph describes how the internal jumpers function, to help you select the correct setting for your particular application, and gives you step-by-step instructions for changing the position of these jumpers. In addition to setting the jumpers, you must set the internal switches on each interface module.
MODULAR MODEM ELIMINATOR 3.3.3 JUMPER LOCATION AND FUNCTIONS Modular Modem Eliminator jumpers are identified in Figure 3-2. CHASSIS GROUND JP7 CONNECT DISCONNECT MODE SELECT ME IC TE ME CARRIER-2 JP5 CTL ON ME CARRIER-2 JP4 CTL ON XMT-TIMING JP3 DELAY-1 JP2 DELAY-2 JP1 JP6 INT EXT 0 ns 6 ns 51 ms 0 ns 6 ns 51 ms Figure 3-2. Jumpers. CHASSIS GROUND SELECTION, JP7 • CONNECT—The signal ground is connected to chassis ground. • DISCONNECT—The signal ground is not connected to the chassis ground.
CHAPTER 3: Installation NOTE The functions of all the following jumpers are used only in the ME (modem eliminator) mode. CARRIER-2, JP5 (ME mode only) • ON—The DCD line in connector J2 is continuously on. • CTRL—The DCD line in connector J2 tracks the RTS line in connector J1. The Modular Modem Eliminator is shipped with the jumper set at ON. CARRIER-1, JP4 (ME mode only) Same as JP5 for the DCD line in connector J1.
MODULAR MODEM ELIMINATOR 3.2.4 SETTING THE JUMPERS CAUTION Disconnect the unit from the power line before removing cover. Avoid adjusting, maintaining, and repairing the opened Modem Eliminator under voltage as much as possible. When inevitable, repairs under voltage should be carried out only by a skilled person who is aware of the hazard involved. Capacitors inside the Modem Eliminator may still be charged even after it has been disconnected from its source of supply.
CHAPTER 3: Installation E TIM ING JP2 XMT RAT bps s 64 k kbp 128 INT LBT XM TT IM ING K CL K INT CL EX LK TC LB JP1 XMT TIMING INT CLK EX CLK 64 kbps co-directional interface module G.703 E1/T1 interface module LBT CLK Figure 3-4. G.703 interface modules.
MODULAR MODEM ELIMINATOR 3.3 Configuring Interface Modules 3.3.1 GENERAL-PURPOSE INTERFACE MODULES Each general-purpose interface module has a DTE/DCE selector, designated SW1. Figure 3-3 in Section 3.2.4 shows the position of the selector on each module, as well as the location of the module-type marking. Set the switch in accordance with the function implemented by the attached equipment. 3.3.2 ITU G.703 INTERFACE MODULES The ITU G.
CHAPTER 3: Installation 3.4 Installing Interface Modules As shown in Figure 3-5, the interface modules are held in place by two rails and are fastened by two captive screws to the rear panel. • To remove a module, release the two captive screws and pull the module out. • To install a module, carefully insert the module board into the rails and push in to mate the module connector, until resistance is felt. Tighten the two module screws. Figure 3-5. Installation of interface modules.
MODULAR MODEM ELIMINATOR 3.5 Connecting the Cables 3.5.1 CONNECTOR LOCATION Figure 3-6 identifies the connectors located on the rear panel of the Modular Modem Eliminator. For information on connector wiring, refer to Appendix A. Fuse Compartment Connector J2 Connector J1 AC Power Connector Figure 3-6. Rear Panel. 3.5.2 DATA CONNECTIONS Refer to the installation plan and connect the data cables to the interface module connectors J1 and J2. 3.5.
CHAPTER 3: Installation 3.5.4 GROUNDING Any interruption of the protective (grounding) conductor (inside or outside the instrument) or disconnecting the protective earth terminal can make this instrument dangerous. Intentional interruption is prohibited.
MODULAR MODEM ELIMINATOR 4. Operation 4.1 Front Panel Control and Indicators 1 2 3 4 5 6 7 8 9 Figure 4-1. Front Panel. Table 4-1 lists the functions of the indicators and the rate selector on the front panel. Table 4-1. Controls and indicators. No.
CHAPTER 4: Operation Table 4-1 (continued). Controls and indicators. No. Control or Indicator Function 6, 7, 8 MODE indicators The indicator corresponding to the selected operating mode lights: INT CONV Interface converter ELASTIC BUFFER Elastic buffer MODEM ELIM Modem eliminator 9 RATE selector 16-position rotary data selector, activated via two buttons. Used only in the modem-eliminator mode, when operating on the internal clock. Available rates are marked on the front panel. 4.
MODULAR MODEM ELIMINATOR 5. Troubleshooting 5.1 Things To Try In case a problem occurs, perform the following checks: • Check that the PWR indicator lights. If not: - Check that both ends of the AC power cable are properly connected. - Disconnect the AC cable from both ends and check the Modem Eliminator’s fuse (located in the AC power connector). If the fuse is blown, replace it with a fuse of proper rating. - Replace the Modular Modem Eliminator. • Check that the appropriate MODE indicator lights.
CHAPTER 5: Troubleshooting 5.3 Shipping and Packaging If you need to transport or ship your Modular Modem Eliminator: • Package it carefully. We recommend that you use the original container. • If you are shipping the unit for repair, please include all parts of its external power supply. If you are returning the unit, please include everything you received with it. Before you ship the unit back to Black Box for repair or return, contact us to get a Return Authorization (RA) number.
MODULAR MODEM ELIMINATOR Appendix A: Interface Data A.1 General-Purpose Modules Table A-1 lists the line functions in the interface connectors of the Modular Modem Eliminator’s general-purpose plug-in modules. Table A-1. Plug-in module’s interface connectors (line functions). Description Ground Protective Ground (Shield) Signal Ground (Common return) Data Control 42 Abbr. Direction of Signal to SG EIA ITU RS-232C RS-232D CircuitPin V.35 V.24 V.35 V.36 V.36 (RS-449) ITU X.
APPENDIX A: Interface Data Table A-1 (continued). Plug-in module’s interface connectors (line functions). Description Timing Tests Abbr. Direction of Signal to EIA ITU RS-232C RS-232D CircuitPin V.35 V.24 V.35 V.36 V.36 Pin Type ITU X.21 Pin Wire Circuit Abbr. Circuit No.
MODULAR MODEM ELIMINATOR A.2 ITU G.703 Balanced Interface Modules The G.703 balanced interface modules have a 15-pin D-type female connector, wired as shown in Table A-2. Table A-2. CCITT Rec. G703 pin connection.
APPENDIX B: Calculation of Elastic Buffer Over/Underflow Rate Appendix B: Calculation of Elastic Buffer Over/Underflow Rate B.1 General An important consideration in many applications is bit count integrity (BCI). In synchronous data transmission systems, bits can be “lost” or “gained” when the receive clock rate is not equal to the transmit rate.
MODULAR MODEM ELIMINATOR transmitted. Other conditions of interest are multiplexed 64-kbps channels transferred by digital multiplexors. When the digital multiplexors are synchronized by secondary atomic clocks, the expected worst-case clock rate difference is approximately 3 x 10-10. In this case, the slippage rate achieved by the Modular Modem Eliminator is given by: Slippage Rate = 64 x 103 x 3 x 10-10 x 1/128=1.
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