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Multitech MMH900 User Manual

Mmh900 series statistical multiplexer
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Summary of Contents for Multitech MMH900

  • Page 1 MMH900 Series Statistical Multiplexer User Guide...
  • Page 2 Furthermore, Multi-Tech Systems, Inc. reserves the right to revise this publication and to make changes from time to time in the content hereof without obligation of Multi-Tech Systems, Inc. to notify any person or organization of such revisions or changes.

  • Page 3: Table Of Contents

    Contents Chapter 1 - Introduction & Description ... 8 Introduction ... 9 About This Manual ... 9 Background ... 11 1.3.1 Description of Statistical Multiplexing ... 12 1.3.1.1 Statistical Multiplexing ... 12 Product Description ... 14 System Features ... 17 1.5.1 Response Time Control ...
  • Page 4 Chapter 3 - Front & Rear Panel Descriptions... 34 Introduction ... 35 Front Panel ... 35 LED Indicators ... 36 Back Panel ... 40 3.4.1 ON/OFF Switch ... 40 3.4.2 Power Connector ... 40 3.4.3 COMMAND MODEM DIAL-UP Connector ... 40 3.4.4 COMMAND PORT Connector ...
  • Page 5 5.2.7 Internal Composite Link DSU Commands ... 86 5.2.8 Test Commands ... 87 5.2.9 Command Modem commands ... 89 Chapter 6- Operating Procedures ... 90 Introduction ... 91 MultiMux Operating Procedures ... 91 Command Modem Operating Procedures ... 95 Chapter 7 - Troubleshooting ... 97 Introduction ...
  • Page 6 Appendix C ... 121 Cabling Diagrams ... 121 Appendix D ... 125 Command Modem Commands ... 125 Appendix E Command Modem S-Register Function ... 138 Appendix F ... 143 Flow Control Background ... 143 Appendix G ... 146 MMH2834 S-Registers ... 146 Appendix H ...

  • Page 7: Chapter 1 - Introduction & Description

    Chapter 1 - Introduction & Description...

  • Page 8: Introduction

    This chapter defines the configurations of the MMH900 series and provides some typical examples of how the MultiMux is configured. The MMH900 series is available in two models; the four and eight channel units with an internal command modem, various composite link modems supporting synchronous or asynchronous communications.
  • Page 9 Chapter 8 provides instructions on getting service for the MultiMux at the factory, a statement of the limited warranty, information about our user bulletin board service, and space for recording information about your multiplexer prior to calling Multi-Tech's Technical Support.

  • Page 10: Background

    Chapter 1 - Introduction & Description Background Any data communications environment that has more than one asynchronous line going between common locations can probably benefit by installing a pair of statistical multiplexers (stat muxes). A stat mux performs the function of combining several asynchronous data communication channels into one composite signal that can be transmitted between two locations more inexpensively than the cost of the individual lines.

  • Page 11: Description Of Statistical Multiplexing

    Chapter 1 - Introduction & Description on one end of the link and then broken up into individual components on the other end. Someone wishing to "tap" into a muxed signal must not only have the link protocol which is typically a proprietary version of High Level Data Link Control (HDLC), but must also know the individual channel assignment schemes and data formats.
  • Page 12 Chapter 1 - Introduction & Description 1.3.1.2 Communications The basic functions of multiplexing are to make communications more efficient, to provide a means of improving accuracy of asynchronous communications by using synchronous techniques, and to improve data security by encrypting several data streams into one coded link. The channel devices can be any asynchronous RS232 compatible units, from “dumb terminals”...

  • Page 13: Product Description

    Workstation PC Figure 1-3. MultiMux MMH900 Series Block Diagram To setup a MultiMux MMH900 series, the async devices have to be connected to the channels, the composite link connected to the public data network (PDN) and the MultiMux has to be configured for the Chapter 1 - Introduction &...
  • Page 14 A number of internal and external composite link devices can be used to connect the MultiMux to the PDN. The MMH900 series has an internal 28,800 bps composite link modem or an internal 56,000 bps DSU. The modem is connected to the PDN through the INTERNAL COMPOSITE LINK LEASED MODEM connector on the back panel of the MultiMux.
  • Page 15 The type of MultiMux at the other end of the composite link is determined by the setting of a four position DIP switch within the MultiMux. The MultiMux MMH900 series is now ready to transfer data from its async devices through an internal composite link...

  • Page 16: System Features

    Chapter 1 - Introduction & Description System Features 1.5.1 Response Time Control Response time control is the technique used by a mux to make sure that no user experiences undue delays in performance due to a specific channel using too much link time. This can occur if one of the channels is performing a high volume batch function, such as a print dump or program transfer.

  • Page 17: Flow Control

    Downline Parameter Loading Operational parameters for both local and remote MultiMux units can be set from one location. The MMH900 series can downline load parameters to each other, but they cannot send parameters to the MM16xx/MM32xx and MMH16/MMH32 units. When power is first applied...

  • Page 18: Operational Statistics And Auto-Reporting

    1.5.6 Operational Statistics and Auto- Reporting Operational statistics provides the activity report for the MultiMux network, and Auto-Reporting provides a means to report on these statistics through the supervisory console on a set periodic time cycle. Statistics such as receive-block errors pinpoint modem or line problems, and flow control time totals indicate channel devices being set at excessive speeds.

  • Page 19: Composite Link

    Chapter 1 - Introduction & Description 1.5.10 Composite Link The composite link of the MultiMux is capable of synchronous, asynchronous and digital communications. The MultiMux can be connected to several different types of communications links through various modems and DSUs connected internally and externally. Internally the MultiMux can be configured with synchronous lease line modem at a link speed up to 28.8K bps or a Data Service Unit (DSU) at link speeds up to 56K bps.

  • Page 20: Fcc Regulations For Telephone Line Interconnection

    6. If trouble is experienced with this equipment (the model of which is indicated below) please contact Multi-Tech Systems, Inc. at the address shown below for details of how to have repairs made. If the...
  • Page 21 Connection to Party Line Service is subject to state tariffs. (Contact the state public utility commission, public service commission or corporation commission for information.) If required, this equipment is hearing aid compatible. Manufacturer: Multi-Tech Systems, Inc. Model Number: #MMH904/MMH908 FCC Registration No.: AU7USA-73205-FA-E...

  • Page 22: Doc Terminal Equipment

    Chapter 1 - Introduction & Description DOC Terminal Equipment Notice: The Canadian Department of Communications label identifies certificated equipment. This certification means that the equipment meets certain telecommunications network protective, operational and safety requirements. The department does not guarantee the equipment will operate to the user’s satisfaction.

  • Page 23: Specifications

    Specifications 1.8.1 Channels Number of Channels Maximum Speed Channel Speeds Data Format Parity Local Echo Flow Control Pacing Interface 1.8.2 System Control Local Access Device Command Functions Chapter 1 - Introduction & Description Up to four (#MMH904), or up to eight (#MMH908) 38,400 bps All Channels All standard speeds from 150 bps to 38.4K...

  • Page 24: Composite Link

    Diagnostics Memory test, Analog Loop, Digital Loop, Remote Analog Loop, Switch test, LED test, Non-Volatile RAM test, Watchdog Timer 1.8.3 Composite LInk Data Format Synchronous or Asynchronous Link Speeds Up to 128,000 bps Link Protocol Proprietary modified HDLC Error Correction 16-bit CRC block check with ARQ Interface RS232C/CCITT V.35/V.24, or use MultiMux...

  • Page 25: Isdn Terminal Adapter

    1.8.6 ISDN Terminal Adapter Description Integral ISDN terminal adapter card Operating Mode ISDN Basic Rate; 1B+D or 2B+D Synchronous Data Rates 2.4–128K bps Clocking Normal network clock (slaved to network receive clock); private network master (internal); external clock of DTE data Commands Menu system D-Channel Switch...

  • Page 26: Chapter 2 - Configuration

    Chapter 2 - Configuration...

  • Page 27: Introduction

    Introduction The MultiMux MMH900 Series is available in two models; the four and eight channel units with an internal command modem, a composite link modem or DSU, dial-up capability from a remote location into the command modem and a command port for local AT command configuration information.

  • Page 28: Configuration 1

    Chapter 2 - Configuration Configuration 1 Configuration 1 is two Multi-Tech MultiMux MMH904Ca/144 which are four channel multiplexers with internal 28.8K bps composite link modems linking sites one and two over a 4-wire analog lease line. The local site has the MMH904Ca/288 connected to a host minicomputer. The remote site has three terminals and a shared printer connected to the asynchronous channels of the remote mux.
  • Page 29 Local Channel Parameter FLOW CHN SPD WORD PARITY CONTROL 19200 NONE XON/XOFF 19200 NONE XON/XOFF 19200 NONE XON/XOFF 19200 NONE XON/XOFF Configuration 1 Local Site Channel Parameters Local Channel Parameter FLOW CHN SPD WORD PARITY CONTROL 19200 NONE XON/XOFF 19200 NONE XON/XOFF 19200...

  • Page 30: Configuration 2

    Configuration 2 Configuration 2 is two MultiMux MMH904Ca four channel multiplexers with two external Multi-Tech MultiModemII MT2834BLs linking the two sites over an async dial-up line. The MultiModemII's are connected to the dial-up line and the RS232C interface from the modems is connected to the EXTERNAL COMPOSITE LINK connector on the back panel of the MMH904Ca's.

  • Page 31: Configuration 3

    Configuration 3 Configuration 3 is two MultiMux MMH908Ca/56 eight channel multiplexers connecting a minicomputer at the local site to eight remote terminals over a digital composite link. The MMH908Ca/56s have internal 56K bps Digital Service Units (DSUs) tieing the MultiMuxes to the Digital Data Service (DDS) network provided by your teleco facility.
  • Page 32 Configuration 3 Composite Link Configuration Local Channel Parameter FLOW CHN SPD WORD PARITY CONTROL 19200 NONE XON/XOFF 19200 NONE XON/XOFF 19200 NONE XON/XOFF 19200 NONE XON/XOFF 19200 NONE XON/XOFF 19200 NONE XON/XOFF 19200 NONE XON/XOFF 19200 NONE XON/XOFF Configuration 3 Local Site Channel Parameters Local Channel Parameter FLOW CHN SPD...

  • Page 33: Chapter 3 - Front & Rear Panel Descriptions

    Chapter 3 - Front & Rear Panel Descriptions...

  • Page 34: Introduction

    This chapter describes all of the front panel LEDs, switches, jumpers and the shunt on the base and the back panel connectors. The front panel contains all the LEDs for all the MultiMux MMH900 Series models. Some of the LEDs on your particular model will not be active, for...

  • Page 35: Led Indicators

    RCV/XMT The Transmit (XMT) and Receive (RCV) indicators are used when the MultiMux MMH900 series is configured for an external composite link device and the network is on-line by flashing with data activity between the two multiplexers.
  • Page 36 Channel Indicator Description Channel 1-8 The Channel Receive (RCV) and Transmit RCV/ XMT(XMT)indicators show the activity level on each channel.MultiMux MMH904 uses Channel One through Channel Four indicators. The MultiMux MMH908 can connect up to eight async devices which use Channel One through Channel Eight indicators.
  • Page 37 Chapter 3 - Front & Rear Panel Descritpions Internal Composite Link (DSU) Indicator Description The Carrier Detect (CD) indicator lights when the composite link DSU detects a carrier signal from the remote MultiMux. The Transmit (XMT) indicator flashes as data is being transmitted to the remote multiplexer on the composite link.
  • Page 38 Chapter 3 - Front & Rear Panel Descritpions The Receive (RCV) indicator flashes as data is being received by an internal composite link 9600 or 14,400 bps modem from a remote multiplexer. The Clear To Send (CTS) indicator lights when an internal composite link 9600 or 14,400 modem is ready to transmit data.

  • Page 39: Back Panel

    COMMAND PORT Connector The command port connector is used to connect the supervisory console to the MultiMux MMH900 series. The supervisory console can be either an ASCII terminal or a pc with a serial port running communications software. The command port connector has a DCE physical interface with a DB25 female connector.

  • Page 40: Composite Link Internal Modem Leased Connector

    COMPOSITE LINK INTERNAL MODEM LEASED Connector This connector is used when the MultiMux MMH900 series is connected to a lease line with an internal Multi-Tech 9600, 14.4K, or 28.8K bps modem installed. The composite link internal modem leased connector provides an RJ11 connection.

  • Page 41: Switches/Jumper/Shunt

    Switches/Jumper/Shunt Switch settings can be changed by taking off the front panel. To change RKWL/144 jumper, V.24/V.35 shunt, V.29/V.33 shunt, or the 2834 shunt, the front panel and top cover need to be removed. The switches, jumper and shunts are shown on the base in Figure 3-3. OTHER RKWL14.

  • Page 42: 4-Position Dip Switch

    Chapter 3 - Front & Rear Panel Descritpions With an MMH904 Unit C = Closed O = Open (Up) Channel # 9-12 Switch Position 6: Switch Position 7: Switch Position 8: With an MMH908 Unit Channel # 9-16 Switch Position 6: Switch Position 7: Switch Position 8: 3.5.2...

  • Page 43: 144Rkwl/Otherjumper

    V.24/V.35 Shunt An external composite link device with either an RS232C/V.24 or a V.35 interface can be connected to a MultiMux MMH900 series. When an external composite link device with an RS232C/V.24 interface is connected to the MultiMux, the V.24 shunt should be installed. When the external composite link device has a V.35 interface, the V.35 shunt...

  • Page 44: Chapter 4- Installation

    Chapter 4- Installation...

  • Page 45: Introduction

    Inspect the MultiMux cabinet for visible shipping damage. If damage is observed, do not power-on the unit; refer to Chapter 8 of this Guide and contact Multi-Tech's Tech Support for advice. If no damage is observed, place the MultiMux cabinet in its final location.

  • Page 46: Installation

    MultiMux is being connected to an external modem with a V.35 interface: Connect a V.35 interface adapter cable Multi-Tech (#90056210) to the COMPOSITE LINK EXTERNAL RS232C/V.35 connector on the back panel and to the V.35 connector on the external modem.
  • Page 47 External modem with V.35 interface is being connected: Remove the top cover and move the V.24/V.35 shunt from the V.24 position to the V.35 position. Replace the top cover. OTHER RKWL14.4 Figure 4-2. Shunts Connect the AC power cord shipped with your MultiMux to the AC power connector on the back panel and to the AC outlet.
  • Page 48 Supervisory Console If you are connecting a supervisory console to the MultiMux, connect a terminal or PC to the COMMAND PORT connector via an appropriate RS232C cable. The PC needs to be running communications software. Note: Any cables connected to the computer should be shielded to reduce interference.
  • Page 49 Channel Route and connect your channel devices to the MultiMux back panel CHANNEL 1 - CHANNEL 4 on a MultiMux MMH904 or CHANNEL 1 - CHANNEL 8 on aMultiMux MMH908 connectors using RS232 cables. Do this at both of your sites, so that channel 1 at one site communicates with channel 1 at the other site, and so on.
  • Page 50 Chapter 4 - Installation As you change operational parameters, they will not actually be incorporated into your running system until you execute a Store New Parameters (&W) command.

  • Page 51: Chapter 5 - Commands

    Chapter 5 - Commands...

  • Page 52: Introduction

    Introduction This chapter presents a command summary followed by a detailed description of each command used in the MultiMux. The structure of the commands is that they all begin with the prefix AT. Each command line may contain any number of commands in a string (no spaces) up to a limit of 40 characters.
  • Page 53 Table 5-1. Command Summary (cont.) TYPE COMMAND DESCRIPTION Channel Channel Off Command Parameter Bxxx Baud Rate Select Universal Channel Parameters Command C1-C8 Channel Select for Parameter Change Destination Channel Destination Node Number Echo Off Echo On Flow Control Off CTS (RS232C) Flow Control Xon/Xoff Flow Control Enq/Ack On EnqAck Off...
  • Page 54 Table 5-1. Command Summary (cont.) TYPE COMMAND DESCRIPTION Channel R0-3 Response Time Priority Parameter SB1 Stop Bit 1 SB1.5 Stop Bit 1.5 Stop Bit 2 Local Source Node Number Word Length 5 Word Length 6 Word Length 7 Word Length 8 &F Load Factory Defaults &SL...
  • Page 55 Table 5-1. Command Summary (cont.) TYPE COMMAND DESCRIPTION Internal 9600/14.4K Composite Link Modem Modem Configuration Select Echo Protect Tone Link Amp Set Link Delay Set Cable Equalization Receive Level Transmit Level T/2 Adaptive Equalizer Write Configurations to modem Internal MMH2834 Modem Configuration $M(ASYNC/SYNC) $M(DIAL/LEASED) $MWIRE(2/4)
  • Page 56 Table 5-1. Command Summary (cont.) TYPE COMMAND DESCRIPTION Command Modem Command Modem Select Remote Command Modem Access Chapter 5 - Commands...

  • Page 57: Command Description

    Command Description The following command descriptions explain the effect that executing each command has on your MultiMux network. Refer to Chapter 6 for instructions on how to execute the commands. 5.2.1 General Commands Reset The Reset command will set the operating parameters of the MultiMux to its most recently stored values.
  • Page 58 The H command menu is as follows: General Help - Each command line must begin with the prefix AT. - Each command line may contain any number of commands up to characters total. - Most command letters must be followed by a value. - For help on specific commands, enter "ATH"...
  • Page 59 The H1 Menu is as follows: CHANNEL PARAMETER COMMANDS BAUD RATE SELECTION PARITY SELECTION CHANNEL SELECTION RESPONSE TIME PRIORITY DEST. CHANNEL SELECTION STOP BIT SELECTION DEST. NODE SELECTION LOCAL SOURCE NODE NUMBER LOCAL ECHO CHANNEL STATISTICS FLOW CONTROL &SL SELECT LOCAL PARAMETERS &F READ IN FACTORY DEFAULTS &SR...
  • Page 60 The H2 Menu is as follows: MULTIMUX Eight Position DIP-Switch Definitions and Settings Switch 1 Switch 2 Switch 3 Switch 4 Initiate Link Remote Device Channel Access Line Load UP = ON INTERNAL 8 CHAN ENABLED DN = OFF EXTERNAL 4 CHAN DISABLED CURRENT SETTINGS:...
  • Page 61 The H3 Mend is as follows: COMPOSITE LINK FORMAT COMMANDS #EOFR - SELECTS RECEIVE END OF FRAME CHARACTER FOR ASYNC LINK. #EOFT - SELECTS TRANSMIT END OF FRAME CHARACTER FOR ASYNC LINK. $MUXCL - SELECTS INT/EXT CLOCKING OF MUX COMPOSITE LINK.
  • Page 62 STATUS REPORTING STATUS OF FRONT PANEL LEDS For HELP on a specific command, enter “ATH” followed by a command letter. The H5 Menu is as follows: MISCELLANEOUS COMMANDS ID CODE MODEM ACCESS FOR COMMAND MODEM REMOTE ACCESS FOR COMMAND MODEM &T TEST MODES &W...
  • Page 63 The H7 Menu is as follws: INTERNAL DSU COMMANDS #DSUCL SELECTS CLOCKING FOR INTERNAL DSU. #DSUSP SELECTS SPEED FOR INTERNAL DSU. For HELP on a specific command, enter “ATH” followed by a command letter. The H8 Menu is as follows: INTERNAL MMH2834 COMMANDS $M(ASYNC/SYNC) $M(DIAL/LEASED)

  • Page 64: Channel Parameter Commands

    5.2.2 Channel Parameter Commands Command Description Channel Off Command The channel off command turns the selected channel off. This command turns off a particular channel or all channels depending on the command. This allows the more efficient use of the dynamically allocated buffers and allows the multiplexer to skip the scanning of unused channels.
  • Page 65 communicate with one other channel. On multinode networks, this command must be entered at both channel locations specifying each other as destinations (channels can pass through two nodes to get to its destination). On point-to-point networks, this parameter can be downline loaded. DNxx Destination Node Number This command is not necessary when a MultiMux...
  • Page 66 keep up with the volume of data sent to it. There are two types of flow control available on the MultiMux. The software based Xon/Xoff and hardware based Clear to Send (CTS). F0 turns flow control off, F1 selects CTS flow control, and F2 selects Xon/Xoff flow control.
  • Page 67 channels to receive EIA control signals through the MultiMux. Since in normal interactive operations, the existence of a multiplexer should be transparent to individual users, the Pass EIA Signals command will allow terminals to operate as if they were connected directly to a communications line and not through a multiplexer.
  • Page 68 Identification Commands The Identification commands identify the type of MultiMux. This information is valuable when communicating with Multi-Tech's Technical Support personnel about your unit or its performance. The l0 command identifies the product. The I1 command indicates the unit’s firmware type.
  • Page 69 console as shown in the following example. To display the parameters for an individual channel, say channel three, you would enter ATL3 and hit your Return key.To display the parameters for all of the channels, enter ATL0 and then hit your Return key. Local Channel Parameter FLOW CHN SPD...
  • Page 70 use an R0 setting. If the mux is configured mainly for interactive users, R0 is the best setting. SB1,SB1.5, SB2 Stop Bits The Stop Bit commands set the number of stop bits used in asynchronous characters. The default condition is one stop bit SB1. An SB1 command sets one, an SB1.5 command sets 1.5, and an SB2 command sets two stop bits.
  • Page 71 &F Load Factory Parameters The factory default command resets the MultiMux parameters to their original factory settings. They are as follows: Channel Speed: Word Length: Stop Bits: Parity: Flow Control: Enq/Ack Control: Echo: Pacing: Pass EIA: Pass Xon/Xoff: Response Time Priority: &SL Select Local Parameters The Select Local Parameters command lists the...
  • Page 72 #S1-S8 Channel Status The Channel Status command displays the individual channel percentage activity levels and signal pin status. The status message is displayed in the following format. STATISTICS FOR CHANNEL NUMBER XX RECEIVE FLOW CONTROL TIME : 00 HRS 00MIN 00SEC BUFFER UTILITZATION EIA STATUS: FLOW CONTROL REQUEST SENT?: NO...

  • Page 73: Composite Link Commands

    5.2.3 Composite Link Commands The Composite Link commands perform the function of a system monitor. In addition to displaying the information available on the MultiMux’s LED display, they also provide additional network statistical information. The purpose of the commands are to allow network monitoring via the supervisory port as an alternative to viewing the LED indicators.
  • Page 74 10 msec and #FT1 sets the flush time value to 20 msec. The default is #FT0. List Composite Link Configuration The List Composite Link Configuration command causes the MultiMux to display its internal composite link parameters on the supervisory console. Five different parameter displays can be shown depending on the internal composite link device.
  • Page 75 conditions that affect the link's operation, such as the downline load, modem type, flush timer value and the response time setting. Local MultiMux Composite Settings INIATE DOWN LINE LOAD TYPE Status Report Baud Rate This command sets the baud rate of the status report generated by the #S0 command on the system supervisor console display.
  • Page 76 Composite Link Status Report This command generates a status message for display on the system supervisor console display. The message is in the following format: COMPOSITE STATISTICS ELAPSED TIME BLOCKS TRANSMITTED RETRANSMITS BLOCKS RECEIVED RECEIVE BLOCK ERRORS LINK ALARMS REMOTE DOWNS RECEIVE FLOW CONTROL TIME : AUTOMATIC REPORTING LED Status...

  • Page 77: Composite Link Format Commands

    5.2.4 Composite Link Format Commands #EOFR Receive End Of Frame Character The Receive End Of Frame character lets the MultiMux accept an End of Frame character when the composite link is in Async mode. When the composite link is in async mode, the #EOFRxx command determines the End of Frame character by the hexadecimal value of xx.
  • Page 78 $MUXSP 2400 $MUXSP 7200 $MUXSP 14400 $MUXSP 38400 $MUXSP 64000 $MUXSP 115200 $MUXB MUX BACK-TO-BACK The Mux Back-to-Back ($MUXB) command is only used during testing of the composite link when the back-to-back cable is connected between two MultiMuxes. The default value is ($MUXB0) and is used during normal operation.
  • Page 79 Chapter 5 - Commands The #CLA0 disables access from the command port to the composite link. The default condition is no access to the composite link thru the command port. #DTR Toggle DTR The Toggle DTR command (#DTR) drops DTR for 500 msec on the composite link.

  • Page 80: Internal 9600/14.4K Composite Link Modem Commands

    The $EP0 command shuts off echo protection on the line. This parameter should be changed only under the direction of Multi-Tech's Technical Support personnel. The echoprotect tone commands are as follows: $EP0:...
  • Page 81 $LA0: $LA1: $LA2: $LD0-2 Link Delay This command enables cable equalization that compensates for delay distortion in the public telephone network in a similar manner to the amplitude done by the Link Amplitude command. $LD0: $LD1: $LD2: $CQ0-3 Cable Equalization The Cable Equalization command incorporates a compromise equalizer that minimizes the effect of how much direct wiring there is in the modem’s...
  • Page 82 The Receive Level settings are as follows: $RL0: -43 dbm (default) $RL1: -26 dbm $TL0-7 Transmit The Transmit Level Command selects the level of the modem Level output transmissions. The closer the transmit level is to zero the greater the level (strength) of the output signal.

  • Page 83: Internal Mmh2834 Modem Configuration Commands

    5.2.6 Internal MMH2834 Modem Configuration Commands The internal MMH2834 modem configuration commands configure the composite link for the internal MMH2834 modem. Additional commands for setting up the modem are provided in Appendix J. Command Description Internal MMH2834 Modem Sync/Async Mode (ASYNC/SYNC) The sync or async mode of the MMH2834 modem is enabled by the $M(ASYNC/SYNC) command.The...
  • Page 84 $M, #M Internal MMH2834 Modem Lease LIne Answer/ Originate Mode The Answer/Originate Mode $M (Answer/Originate) command sets the leade line frequency for the MMH2834 modem originating a call and the remote MMH2834 that is receiving the call. The #M(Answer) command places the MMH2834 in answer mode.

  • Page 85: Internal Composite Link Dsu Commands

    5.2.7 Internal Composite Link DSU Commands Command Description $DSUCL DSU Clock The DSU Clock command allows the internal DSU to accept timing from it's internal timing oscillator ($DSUCLI) or from the DDS Network's Receive Bipolar Signal. DDS Clocking command ($DSUCLD) is used whenever the internal DSU is connected to DDS network line.

  • Page 86: Test Commands

    5.2.8 Test Commands Command Description &T1-2 MemoryTest There are two memory tests available on the MultiMux. The first test (&T1) will alter the contents of the basic system memory, which is automatically restored when power is turned on to the system or when a reset command is executed.
  • Page 87 &T6 Test Mode 6 Test Mode 6 is the Remote Analog Loop test which causes any data from the composite link to be echoed through just the analog half of the internal modem back to the link. The function of this command is similar to Test Mode 5 except it checks only the modem’s analog circuitry.

  • Page 88: Command Modem Commands

    5.2.9 Command Modem commands The command modem select and remote access commands are described in this section. Additional command modem AT commands are provided in Appendix D. Command Description Command Modem Select The Command Modem Select command (#MA1) sends all subsequent commands generated on your supervisory console to the command modem.

  • Page 89: Chapter 6- Operating Procedures

    Chapter 6- Operating Procedures...

  • Page 90: Introduction

    Introduction The following procedures assume that your MultiMuxes (local and remote) have been installed properly and the appropriate channel devices have been connected to each channel. MultiMux Operating Procedures The MultiMux operating procedures cover entering parameters for both your local and remote MultiMux units. Table 6-1.
  • Page 91 Table 6-1. MultiMux Operating Procedures (cont.) Source Node #01 Local Channel Parameter FLOW ENQ/ CHN SPD WORD PARITY CONTROL 19200 NONE XON/XOFF 19200 NONE XON/XOFF 19200 NONE XON/XOFF 19200 NONE XON/XOFF To reconfigure the channel parameters to match your actual channel requirements enter commands as described in Chapter 5 or Appendix D of this manual.
  • Page 92 The following will be displayed on your system monitor if your MultiMux is configured with an internal composite link DSU: LINK LINK DEVICE FORMAT SPEED CLOCKING CHARACTER CHARACTER BACK SYNC 56000 If the internal composite link modem is either a V.34/28800, the INTERNAL LINK DEVICE Modems MMH2834 LED on the front panel is ON.
  • Page 93 To reconfigure a channel based on your actual channel requirements, enter commands as described in Chapter 5 or Appendix D of this manual. To save new parameters, you must again execute an AT&W command. Downline Load If you are downline loading remote parameters, your 8-position DIP switch SW1 must be in the UP (open) position, refer to the 8-position DIP Switch in the Configuration Chapter (Chapter 3) of this manual.

  • Page 94: Command Modem Operating Procedures

    Command Modem Operating Procedures A wide variety of autodial operations and modem options can be controlled when the command modem is in the command mode. Command modem access commands are described in Chapter 5. Appendix D describes the general AT commands in detail. Table 6-2.
  • Page 95 dialing commands. For example, enter the following to dial a phone number (555-1212) through a switchboard. ATD9,5551212 (hit Return) When a carrier signal is detected, the Connect (1) Result Code is displayed. If no carrier is detected, the No Carrier (3) Result Code is displayed after about 30 seconds.

  • Page 96: Chapter 7 - Troubleshooting

    Chapter 7 - Troubleshooting...

  • Page 97: Introduction

    Introduction The MultiMux is designed to make it easy to operate and maintain. The procedures in this chapter will help isolate any problems you have to a specific component of your network, at which point you will be instructed to call the appropriate personnel or execute commands to adjust operating conditions.

  • Page 98: Test Cables

    Chapter 6 - Operating Procedures retransmits needed to get the data through can indicate a line problem. Comparing the blocks received and receive block errors indicates the same problem from the other end of the link. The comparative numbers that you might encounter could be 10,000 blocks transmitted (or received) with 500 or 1000 retransmits (or receive block errors).
  • Page 99 If you have any problems in performing these procedures, contact the Tech Support department for assistance, refer to Chapter 8. Using the Test Cable MultiMux Internal Composite Note: Used locally before installation to verify operation of entire system except compolsite link. Using the Composite Link Loopback Cable Internal Composite MultiMux...

  • Page 100: Troubleshooting Guide

    Channel Communications (RS232 cabling,synchronous modems, etc.) • MultiMux control units • Synchronous link modems (internal Multi-Tech or external) • Composite link communications line (2-wire or 4-wire leased line with internal or external modems) • Dial-up composite link communications line with internal or external modem •...
  • Page 101 Table 7-1. Troubleshooting Guide The following symptoms are typical of problems you might encounter: • Supervisory Console not communicating with mux command port • Supervisory Console not communicating with command modem • Garbage on Supervisory console screen • Composite Link down with CTS, XMT and REMOTE DWN LEDs ON •...
  • Page 102 Supervisory Console not communicating with mux command port Problem Communications softwarenot installed on Supervisory Console Solution 1. Install communications software on supervisory console, refer to communicaitons software user’s manual for installation. Problem Bad cable or cable connection Solution 1. Check RS 232 cable connections between supervisory console and COMMAND PORT on MultiMux for loose connection or bent pins, refer to Supervisory Console Installation procedures in...
  • Page 103 Composite link down with CTS, XMT and REMOTE DWN LEDs Problem Composite Link cabling Solution 1. If internal composite link modem is installed, check Composite Link cabling for loose connection. 2. If external composite link modem is installed, check composite link cable for loose connection or bent pin.
  • Page 104 Composite link down with CO CTS and REMOTE DWN LEDs Problem External modem settings on remote mux Solution 1. Verify that external modem is set for sync, full duplex and internal clocking. 2. Connect composite link cable between mux and modem.
  • Page 105 Problem Channel devices incorrectly cabled Solution 1. Refer to cabling diagrams of both mux and channel devices. Some channel devices not communicating with MultiMux and composite link up Problem Incorrect channel parameter settings fo rthose channel devices Solution 1. Verify channel parameter settings for those channel devices, refer to Lx command in Chapter 4 to display channel parameters.

  • Page 106: Channel Device Testing

    Channel Device Testing The first step in system testing is to check the operation of the multiplexer network section from each channel device to the MultiMux and back again to the channel device. These procedures will enable you to see that data from the channel device is passing through the MultiMux properly by echoing channel keystrokes through the MultiMux and then displaying them as correct characters on the channel device’s monitor.

  • Page 107: Local Modem And Communications Line Testing

    Local Modem and Communications Line Testing After determining that the channel-device-to-MultiMux portion of the multiplexer network is operating properly, the next steps are to check the operation of the local modem, the communications line and the remote modem. By performing the procedures in Table 7-3, the MultiMux can send data (keystrokes) from the channel device and have the data echoed through the composite link and remote modem back to the channel device’s monitor.
  • Page 108 Place your local MultiMux in normal operating mode by shutting power off and turning it back on. Make sure your 8-position DIP switch SW1 is in the off (closed) position. With the two MultiMuxes in your network set properly, you can now enter data on the keyboard of each channel device and, if the network is operating correctly, the data will be correctly displayed on the channel device monitor.

  • Page 109: Multimux Functional Testing Procedures

    MultiMux Functional Testing Procedures There are tests available on the MultiMux which check various functions within the MultiMux logic. These tests will assist you in trouble shooting problems which are not related to the composite communications channel or local channel devices. The two tests described below will check the non-volatile memory used for parameter storage and internal circuitry, called the Watch-Dog circuitry, which is responsible for keeping the MultiMux functioning normally.
  • Page 110 To check the Watch-Dog circuitry, place the local MultiMux unit in Test Mode 9 (i.e., executing the Watch-Dog Timer Test) by entering the following command: AT&T9 (hit Return) The supervisory console will display the following message: Watch-Dog Timer Test #9 - wait for test indicator to turn off and when the test indicator comes back on, enter “AT”...

  • Page 111: Chapter 8- Service, Warranty, & Technical Support

    Chapter 8- Service, Warranty, & Technical Support...

  • Page 112: Introduction

    The final section explains how to use the Internet. Warranty Multi-Tech Systems, Inc., (hereafter “MTS”) warrants that its products will be free from defects in material or workmanship for a period of two, five, or ten years (depending on model) from date of purchase, or if proof of purchase is not provided, two, five, or ten years (depending on model) from date of shipment.

  • Page 113: Repair Procedures For U.s. And Canadian Customers

    Chapter 8 - Service, Warranty, & Technical Support Repair Procedures for U.S. and Canadian Customers In the event that service is required, products may be shipped, freight prepaid, to our Mounds View, Minnesota factory: A Returned Materials Authorization (RMA) is not required. Return shipping charges (surface) will be paid by MTS.

  • Page 114: Repair Procedures For International Customers (Outside U.s.a. And Canada)

    Customers (Outside U.S.A. and Canada) Your original point of purchase Reseller may offer the quickest and most economical repair option for your Multi-Tech product. You may also contact any Multi-Tech sales office for information about the nearest distributor or other repair service for your Multi-Tech prod- uct.

  • Page 115: Repair Procedures For International Distributors

    Repair Procedures for International Distributors Procedures for International Distributors of Multi-Tech products are on the distributor web site. http://www.multitech.com/PARTNERS/login/ Online Warranty Registration If you have access to the World Wide Web, you can register your Multi-Tech product online at http://www.multitech.com/register/.

  • Page 116: Appendices

    Appendices...

  • Page 117: Appendix A

    Appendix A - ASCII Character/Code/Hex/Decimal Conversion Chart Appendix A ASCII Character Code/Hex/Decimal Conversion Chart CTRL CODE HEX DEC CODE HEX “ & ‘ < > — CODE HEX CODE – HEX DEC...

  • Page 118: Rs232C Interface Specification

    RS232C interface connector. All other pins are unused. The composite side of the mux is configured as a DTE device and the channel sides are DCE devices. MULTI-TECH ASSIGNMENT DESIGNATION *DTE Appendix B - RS232C Interface Specifications...
  • Page 119 Appendix B - RS232C Interface Specifications The computer or terminal should be supplied with a cable terminated with a Cinch DB25P (or equivalent) connector mounted in a Cinch DB51226-1 (or equivalent) hood assembly as specified by the RS232C/ V.24 standard.

  • Page 120: Appendix C

    Appendix C Cabling Diagrams Channel Cables DCE to Channel cabling (with EIA pass Thru) PIN NO. PIN NO. MultiMux Channel Connector DCE to Channel cabling (without EIA pass Thru) PIN NO. PIN NO. MultiMux Channel Connector DTE to Channel cabling PIN NO.
  • Page 121 Command Port Cables DCE to DTE cabling PIN NO. PIN NO. MultiMux Command Port Connector DCE to DCE cabling PIN NO. PIN NO. MultiMux Command Port Connector Appendix C - Cabling Diagrams CHASSIS GROUND (AA) TRANSMIT DATA (BA) RECEIVE DATA (BB) Device CLEAR TO SEND (CB) (Terminal...
  • Page 122 Composite Link Cabling RS232C/V.24 *Configured Composite Link PIN NO. PIN NO. CHASSIS GROUND (AA) TRANSMIT DATA (BA) RECEIVE DATA (BB) REQUEST TO SEND (CA) External CLEAR TO SEND (CB) Synchronous SIGNAL GROUND (AB) Modem/DSU CARRIER DETECT (CF) Connector TRANSMIT CLOCK (DB) RECEIVE CLOCK (DD) DATA TERMINAL READY (CD) V.
  • Page 123 RJ45 Cabling for Internal DSU Receive Transmit 1 2 3 4 5 6 7 8 Back to Back Mux Cable* 25-PIN CONNECTOR (FEMALE) INT. CLK “DCE” * This cable is used to connect two muxes back to back during testing. The cable is asymmetrical and allows one of the mux's to provide clock to the TxC and RxC pins of the other mux.

  • Page 124: Appendix D

    Appendix D Command Modem Commands Command Description Answer The Answer Mode forces the command modem into answer mode. Entering ATA when in the Command mode will immediately bring the command modem off-hook, out of the command mode and into the On- Line Answer mode, and cause it to retransmit its carrier signal over the phone line.
  • Page 125 Appendix D - Command Modem Commands following it. For example, if you enter ATD5551212 and hit Return, the command modem will dial the number 555-1212. Valid dial characters are 0 through 9, A through D, # , and *. Dial modifiers are: , P R S=x T W ; @ and !. In pulse dialing, non- digit characters have no meaning.
  • Page 126 Appendix D - Command Modem Commands &F Load Command Modem Factory Defaults The Load Command Modem Factory Default &F Command resets the S-Registers and command modem commands to thefactory default values. They are as follows: S-Registers: S0=0, S1=0, S2=43, S3=13, S4=10, S5=8, S6=2, S7=30, S8=2, S9=6, S10=14,S11=95, S12=50, S18=0, S25=5, S26=1, and S28=0.
  • Page 127 Appendix D - Command Modem Commands command. This “read” command enables the software to determine the type of modem with which it is communicating. When ATI or ATI0 (upper case) is entered, the command modem will respond with xxx, with the first two digits indicating model, and the third digit indicating the revision level.
  • Page 128 Appendix D - Command Modem Commands for your dialing. An example of combining pulse and tone dialing could involve a PBX system where 9 had to be pulse-dialed first, then the rest of the number tone-dialed after pausing for a second dial tone. The number would be dialed by entering ATDP9,T5551212 and hitting Return.
  • Page 129 Appendix D - Command Modem Commands SN=xxx S-Register Read or Write The S command can be used to both assign a value to or read the current value of an S-Register. (Refer to Appendix G of this manual for the function of each S-Register.) The format for reading a register is to enter the letter S (upper case) followed by the register number and a question mark ? and then hit...
  • Page 130 Appendix D - Command Modem Commands Vo-1 Result Codes Word or Digit The command modem can display its Result Codes on your supervisory console. These codes can appear either in word(“verbose”) or single digit (“terse”) form. For example, if after dialing, no carrier signal is detected, the result can be displayed either as NO CARRIER or as the digit 3.
  • Page 131 Appendix D - Command Modem Commands You can also choose to completely eliminate the display of all of the Result Codes. This is accomplished by executing the Q command. &V View Active Configuration and User Profiles The View Active Configuration and User Profiles &V command displays the commands and S-Register settings along with the stored telephone numbers.
  • Page 132 Appendix D - Command Modem Commands Wait for Dial Tone The W command causes the command modem to wait up to a specified time for the dial tone to occur. The telephone number is dialed immediately upon dial tone detection. The S-Register S7 value determines the maximum wait time.
  • Page 133 Appendix D - Command Modem Commands dialing where actual dial tones are not detected, instead the command modem relies on timed pauses. The ATX0 enables the basic result codes while the ATX1 enables the extended result codes with call progress disabled on both commands. The ATX2 through ATX4 commands determine whether or not call progress is activated and extended result codes are enabled on each of these...
  • Page 134 Appendix D - Command Modem Commands ATX3 Blind dialing is enabled along with extended result codes. Busy result code is enabled if the busy signal is detected. ATX4 Smart dialing is enabled with extended result codes. Smart dialing provides dial tone and busy signal detection.
  • Page 135 Appendix D - Command Modem Commands specified by the number preceding the delimiter.The following characters are allowed to be stored: 0 through 9, A through D, T P R W # * , ! ; along with the delimiter (=). 0 to 9, A to D, # and * Dial Digits/Characters...
  • Page 136 Appendix D - Command Modem Commands length of the pause of the comma, from two seconds to any other value from 0 up to 255 seconds. This is accomplished by accessing S-Register S8 which we explain in the Command Modem Commands Section.

  • Page 137: Appendix E Command Modem S-Register Function

    Appendix E - Command Modem S-Register Functions Appendix E Command Modem S-Register Function Number of Rings Until Modem Answers Unit: 1 ring Range: 0-255 Default: Description: SO defines how many rings the command modem will wait before answering an incoming call. Default value is zero rings (Decimal 0), which means the Auto-Answer feature is enabled.
  • Page 138 Appendix E - Command Modem S-Register Functions Return Character Unit: ASCII Character Range: 0-127 Default: Description: Defines the character recognized as Carriage Return (RETURN) or “Enter”. Default setting is CTRL-M (Decimal 13), which is the aSCII code for the Return key on most key boards. May be set for any ASCII character.
  • Page 139 Appendix E - Command Modem S-Register Functions the telephone line. the minimum time is two seconds (Decimal 2) and is the factory default setting. Values greater than 2 seconds may be necessary if trouble is encountered getting dial tones. Time for Carrier (Abort Timer) Unit: 1 second Range:...
  • Page 140 Appendix E - Command Modem S-Register Functions Carrier Loss Disconnect Delay Time Unit: 100 mSec. Range: 1-255 Default: Description: Sets the time a carrier signal must be lost before the modem disconnects. The S10 default setting is 1.4 seconds or 14 units (Decimal 14) where each unit is 0.1 second.
  • Page 141 Appendix E - Command Modem S-Register Functions S19Not Used S20Not Used S21Reserved S22Reserved S23Reserved Sleep Mode Inactivity Timer Unit: Sec. Range: 0-255 Default: Description: S24 is used to set the amount of time the modem may be inactive before it will enter the sleep mode. The range of S24 is 0 to 255.

  • Page 142: Appendix F

    Appendix F Flow Control Background Flow control refers to the techniques used by computer devices and multiplexers to stop and restart the flow of data from each other. Flow control is necessary so that a channel device does not receive more data than it can handle or vice versa (the MultiMux receives more data than its buffers can accommodate).
  • Page 143 minicomputer so that the mux’s buffer capacity is not exceeded. We chose Xon/Xoff flow control for this example and are setting pace ON for all channel devices. NODE 1 NODE 1 Channel Channel Link Link Mini- Mini- Computer Computer MiniComputer Flow Control In the example below, the flow control on the minicomputer works as follows: Channel...
  • Page 144 Appendix D - Command Modem Commands so the mux sends a start data Flow Control (ON) signal to the mini. D. Data from the mini again flows through the channel. Printer pacing and Flow Control The example below shows how Pacing and Flow Control work on a printer.

  • Page 145: Appendix G

    Appendix G MMH2834 S-Registers Introduction This section covers the MMH2834 memory (option) registers called S- Registers, where certain MMH2834 modem and command mode configurations are stored. Each S-Register is assigned a number (S0, S1, S2, etc.). Use the S command to read and/or change the value stored in an S-Register (ATSr? to read and ATSr= to change S-Register values).
  • Page 146 Pause Time for Comma Unit: 1 second Range: 0-255, 4-255**, 4-7*** Default: 2, 4**, 4*** Description: S8 sets the length of the pause caused by a comma inserted in a dialing command. The default setting is two seconds, (or two units Decimal 2) or four seconds, where each unit is one second. S8 may be set for up to 255 seconds.
  • Page 147 Remote Configuration Escape Character Unit: ASCII Character Range: 0-127 Default: 37 (%) Description: S13 defines the remote configuration escape character (which becomes your modem’s remote configuration character). The default is three percent symbols (%%%). When the S13 character is entered three consecutive times from a remotely connected site, your modem responds with its Remote Configuration procedure.

  • Page 148: Appendix H

    Appendix H - Dial Back-up Appendix H Dial Back-up The dialing associated with the MMH2834, when in leased line with dial- back mode, involves placing a call from the originating MMH2834 due to a leased line failure. After a preset period of time, determined by S-Register S18 (refer to Appendix I for a description of the S-Registers), the MMH2834 automatically tries to restore the leased line.

  • Page 149: Appendix I

    Appendix I Testing Your MMH2834 I.1 Introduction Each time power is applied to a MultiMux with an internal MMH2834 modem, the MMH2834 performs an automatic self- test to ensure proper operation. The MMH2834 also has three diagnostic test features: Local Analog Loopback, Digital Loopback (remote/automatic) and Digital Loopback (local/manual).

  • Page 150: Local Analog Loopback Test/V.54 Loop 3

    Local Analog Loopback Test/V.54 Loop 3 In this test, data from your computer or terminal is sent to your modem's transmitter, converted into analog form, looped back to the receiver, converted into digital form and then received back at your monitor for verification.

  • Page 151: Digital Loopback Test/V.54 Loop 2 (Loc/Man)

    I.3 Digital Loopback Test/V.54 Loop 2 (Loc/Man) In this test, your modem must be On-Line with another modem that can respond to a request for Digital Loopback, such as another MMH2834. The Digital Loopback Test is an on-line test that loops data sent from one modem across the phone line to another modem, then back to the first modem.
  • Page 152 maintaining the pseudo On-line mode with the remote modem. 4. Type ATU3 from the local PC and hit ENTER. Once you receive an OK message from your modem (if responses are enabled), the local modem is placed in Digital Loopback mode. 5.

  • Page 153: Digital Loopback Test/V.54 Loop (Rem/Auto)

    Digital Loopback Test/V.54 Loop (Rem/Auto) In this test, your modem must be On-line with another modem set up to respond to a request for Digital Loopback, such as another MMH2834. With the MMH2834, this ability to respond is controlled by the &T command.
  • Page 154 4. Type ATU2 and hit ENTER. The local modem responds to this command by transmitting an unscrambled marking signal, which causes the remote modem to place itself in Digital Loopback mode. Then the local modem exits Command mode and enters pseudo On- line mode.

  • Page 155: Synchronous Mode Testing

    Appendix I - Testing Your MMH 2834 I.5 Synchronous Mode Testing The following tests must be run with your modem in Synchronous mode. The test procedures for Synchronous mode are different from those for Asynchronous mode. In Synchronous mode, you cannot access the modem’s AT commands.

  • Page 156: Local Analog Loopback Test (Sync Mode)

    I.6 Local Analog Loopback Test (Sync Mode) This test diagnoses the connection between your MMH2834 and your computer or terminal. In Local Analog Loopback Test mode, data entered at the local computer or terminal are sent through the local modem’s transmit and receive circuits (much like entering an ATU or ATU1 command in Asynchronous mode).

  • Page 157: Digital Loopback Test (Loc/Man) Sync Mode

    I.7 Digital Loopback Test (Loc/Man) Sync Mode This test must be run when you have a data connection with another modem. If a Local Analog Loopback Test resulted in errors, and this test passes without errors, then the problem exists in your computer-to- modem connection.

  • Page 158: Digital Loopback Test (Rem/Auto)(Sync Mode)

    I.8 Digital Loopback Test (Rem/Auto)(Sync Mode) This test must be run when you have a data connection with another modem. In this test, data is passed to the remote modem and is looped back to the local modem (as if an ATU2 command was issued in Asynchronous test mode), as shown in Figure I-6.

  • Page 159: Appendix J - Internal Mmh2834 Composite Link Modem Commands

    Appendix J - Internal MMH2834 Composite Link Modem Commands Appendix J - Internal MMH2834 Composite Link Modem Commands J.1 Introduction Before the internal MMH2834 composite link modem commands can be entered, access to the modem has to be activated using the composite link access (#CLA1) command.
  • Page 160 Appendix J - Internal MMH2834 Composite Link Modem Commands MMH2834 Modem Configure &Q Command Responses (Section J.1.5) MMH2834 Modem &T Condition Phone Line (Section J.1.6) MMH2834 Modem &D RS232C Interface (Section J.1.7) MMH2834 Modem Configure Error Correction (Section J.1.8) MMH2834 Modem &BS Compression &...
  • Page 161 Appendix J - Internal MMH2834 Composite Link Modem Commands MMH2834 Modem Read and Assign S-Register Values (Appendix G) MMH2834 #CBN Remote Configuration & Callback #RCBNxx Security MMH2834 Modem Test &T (Appendix I)) Read Current S-Register Value Assign S-Register Value Passwords for Callback Phone Numbers Callback Security Enable/Disable Change LOGIN Password Erase Password...

  • Page 162: Dialing Action Commands

    Appendix J - Internal MMH2834 Composite Link Modem Commands J.1.1 Dialing Action Commands Dial The letter D in a command causes the MMH2834 to dial the Command telephone number immediately following it. For example, if you enter ATD5551212 and hit RETURN, the MMH2834 dials the number 555-1212.
  • Page 163 Appendix J - Internal MMH2834 Composite Link Modem Commands RETURN. Do not include the letter D in this command, or the stored number will be erased (also see Section J.1.3., on Phone Number Memory Commands). An alternate method of causing the MMH2834 to Dialing automatically dial is DTR Dialing.

  • Page 164: Dial Modifier Commands

    Appendix J - Internal MMH2834 Composite Link Modem Commands J.1.2 Dial Modifier Commands Pulse or Tone Dial The MMH2834 dials numbers using either pulse or tone dialing, or a combination of both methods. Pulse dialing is a method used by rotary-dial telephones, which involves the timed opening and closing of line relay.
  • Page 165 Appendix J - Internal MMH2834 Composite Link Modem Commands Long Space When two modems are connected in Normal mode (i.e. Disconnect withouterror correction) there is no "polite" means of requesting a disconnect. A link disconnect request packet is sent under reliable connections. As a result some "garbage" may be received when a hangup command is issued.
  • Page 166 Appendix I - Testing Your MMH 2834 message. Hitting any key also aborts the $ command. The following is an example of this command: ATDT1028806127853500 $123456789 (access/phone number) (credit card number) Quiet Answer The @ command causes the MMH2834 to wait before processing the next symbol in the dialing string.

  • Page 167: Phone Number Memory Commands

    Appendix J - Internal MMH2834 Composite Link Modem Commands J.1.3 Phone Number Memory Commands Storing Phone A telephone number and command line of up to sixty Numbers characters may be stored in the MMH2834’s number memory. As many as ten of these numbers may be stored. D...N Each number will be given a name, using the codes N0, N1, N2 up to N9.
  • Page 168 Appendix J - Internal MMH2834 Composite Link Modem Commands shown below. All digits and command letters will be shown. The number’s “name” (0 thru 9) is shown first, followed by the complete dialing command and telephone number as originally entered. Simply enter ATL and hit RETURN to display these numbers on your video screen or printer.

  • Page 169: Configuration And Default Storage Commands

    Appendix J - Internal MMH2834 Composite Link Modem Commands J.1.4 Configuration and Default Storage Commands Store Configuration The MMH2834 can store configuration parameters and & S-Register S-Register values in its non-volatile read/write Random Parameters in Access Memory (RAM) memory. The &W command does Non-Volatile this which prevents any reconfiguration from being lost on Memory...
  • Page 170 Appendix J - Internal MMH2834 Composite Link Modem Commands Async/Sync This command can be used to set the on-line mode to either Mode synchronous or asynchronous. AT&M0 will set the MMN2834 Switching to Asynchronous mode, and all communications will be &M Asynchronous, in both On-line and Command modes.

  • Page 171: Command Response (Result Code) Commands

    (enable Result Codes) is automatically selected. Result Codes The MMH2834 gives you a choice between the Multi-Tech (“Multi-Tech” or Result Codes, and Result Codes that more closely match the “Standard AT”) standard AT command set responses.
  • Page 172 Appendix J - Internal MMH2834 Composite Link Modem Commands AT&Q0 selects Multi-Tech responses with Reliable/ Compression modifiers. With this command, the terse result code for CONNECT 2400 is 9. TERSE * When error correction is used, the word RELIABLE (verbose) or the letter R (terse) is added to these responses.
  • Page 173 Appendix J - Internal MMH2834 Composite Link Modem Commands Call Progress combinations related to these methods. You can choose to Selection have certain responses suppressed, or whether or not you want speed indications along with the CONNECT responses. You can also pick and choose certain responses in order to match up with “Standard AT”...
  • Page 174 Appendix J - Internal MMH2834 Composite Link Modem Commands Five different X commands are available (X0 through X4), with five different effects on the MMH2834’s Result Codes. Provides the basic (short) result codes and provides “dumb” dial capabilities. Provides the extended result codes and provides “dumb” dial capabilities.

  • Page 175: Phone Line Conditioning Commands

    Appendix J - Internal MMH2834 Composite Link Modem Commands J.1.6 Phone Line Conditioning Commands Enable or Disable The MMH2834 has several self-test features (covered in Recognition Appendix J). The tests are activated with different U commands, of Remote such as ATU1, and so forth. The &T command is a phone line Digital Loop Signal conditioning command that enables or disables the modem's &T ability to recognize the Remote Digital Loop (RDL) test signal.

  • Page 176: Rs232C Interface Control Commands

    Appendix J - Internal MMH2834 Composite Link Modem Commands J.1.7 RS232C Interface Control Commands Data Terminal Data Terminal Ready (DTR) on pin 20 of the RS232C interface Ready Control is required in order for the MMH2834 to operate. A high DTR signal tells the modem that the device to which it is connected &D is active, or "ready"...

  • Page 177: Error Correction Commands

    Appendix J - Internal MMH2834 Composite Link Modem Commands J.1.8 Error Correction Commands You can use AT commands to place your MMH2834 one of three V.42 (error correction) modes of operation. V.42 Mode Select The V.42 standard implements both MNP Class 3 & 4 and LAP-M error correction methods.
  • Page 178 Appendix J - Internal MMH2834 Composite Link Modem Commands Enable/Disable In Auto-Reliable mode, the modem is given four seconds to Auto-Reliable establish a Reliable connection. If a single CARRIAGE RETURN Fallback Character is received from the remote modem during this four second period, the Auto-Reliable modem assumes that the remote modem is not in Reliable mode and drops to Normal mode.

  • Page 179: Compression And Maximum Block Size Commands

    Appendix J - Internal MMH2834 Composite Link Modem Commands J.1.9 Compression and Maximum Block Size Commands Data Compression The data compression (&E14) command enables data compression. Maximum The maximum size of Reliable mode data blocks can be controlled Block Size with the &BS command.

  • Page 180: Speed Conversion Commands

    Appendix J - Internal MMH2834 Composite Link Modem Commands J.1.10 Speed Conversion Commands Speed conversion is a necessary part of data compression since data must be presented to the modem faster than it can handle data, if data compression is to be effective. Speed conversion allows the MMH2834 to communicate at one speed over the phone line, and at another speed at the RS232C interface.
  • Page 181 MMH2834 can achieve throughputs approaching 115.2K (depending on line quality and file content). If you presently do not have a 16550 UART in your PC, we recommend that it be replaced with a Multi-Tech high speed Intelligent Serial nterface (ISI) card.

  • Page 182: Immediate Action Commands

    Appendix J - Internal MMH2834 Composite Link Modem Commands J.1.11 Immediate Action Commands Help Screens The Help command is designed to give you short explanations on how to use each MMH2834 command. The Help command can be quite useful if your manual is not handy and you are in the middle of a communications session.
  • Page 183 Appendix J - Internal MMH2834 Composite Link Modem Commands current on-line condition (e.g., Link Type, Line Speed, Serial Speed, Type of Error Correction/Data Compression, Number of past Retrains,etc.). An example of L8 listing is shown below: ATL8 ****** ONLINE DIAGNOSTICS LINK TYPE LINE SPEED SERIAL SPEED...

  • Page 184: Glossary

    Glossary...
  • Page 185 AC (Alternating Current): A power source whose signal crosses a reference voltage (usually called ground or zero). Alternating between a maximum and minimum voltage, AC may also be referred to as a bipolar signal. Contrast with DC. ACK (ACKnowledgement code) (pro- nounced "ack"): A communications code sent from a receiving modem to a transmitting modem to indicate that it is ready to accept...
  • Page 186 Baud: Baud is rate, the signalling rate of a line, the switching speed, or the number of transitions (voltage or frequency changes) that are made per second. Transmission speeds are often expressed in baud, though bits per second is more accurate. The speed at which your computer talks to your modem.
  • Page 187 Circuit switching: The temporary connec- tion of two or more communications channels using a fixed, non-shareable path through the network. Users have full use of the circuit until the connection is terminated. Clock: A timing signal generated by an oscillating circuit which is used to synchronize data transmissions.
  • Page 188 DTMF (Dual-Tone MultiFrequency): A generic push-button concept made popular by AT&T TouchTone. Decibel (dB): A unit of measurement for signal strength based on logarithmic incre- ments. A decibel is a relative measurement that is derived from an initial reference level and a final observed level.
  • Page 189 of a graphical document and, therefore, cannot be accurately interpreted according to any character code. Firmware: A category of memory chips that hold their content without electrical power, they include ROM, PROM, EPROM and EEPROM technologies. Firmware becomes "hard software" when holding program code. Flash Memory: A memory chip that holds its content without power, but must be erased in bulk.
  • Page 190 Mid-range computer: A term coined by IBM referring to any of their Advanced Business Systems computers. This product line was originally called their mini-computers, but as the number of supported users approached mainframe capabilities, the term "mid-range" caught on. Mnemonics: A term assigned to a complex idea, value, or list of information which is found to be representative of that information.
  • Page 191 Phase: The timing of a signal based upon the starting point of each cycle in another signal. To be detected phase requires the comparing of two signals. If the cycle of two signals begin at the same point, they are said to be "in-phase".
  • Page 192 a conversion chip called a "UART" which translates between internal parallel and external serial formats. Switched Line: In communications, a physical channel established by dynamically connecting one or more discreet segments. This connection lasts for the duration of the call after which each segment may be used as part of a different channel.

  • Page 194: Index

    Index Symbols &T command, 154 14.4, 9.6, 48, 24 Composite Link Speed Indicators, 37 56, 19.2 Composite Link Speed Indicators, 38 Abort Timer S7, 140 Aggregate, 11 Analog Loop Mode Test (&T4), 87 Answer Mode, 178 Async Command (#ASYNC), 79 ASYNC LINK Indicator, 39 Async/Sync Mode Switching (&M), 171...
  • Page 195 Command Port Cables, 122 COMMAND PORT Connec- tor, 15, 40 Command Sum- mary, 53, 54, 55, 56, 57 Communications, 13 Composite Link, 13, 20 Composite Link Access Command (#CLA), 79 Composite Link Cabling, 47 COMPOSITE LINK DIGITAL DSU Connector, 15 COMPOSITE LINK EXTERNAL RS232C/V.35 Connector, 47 Composite Link Format Com-...
  • Page 196 esult Codes (Basic Extended) and Call Progress (, 173 Extended Result Codes, 175 EXTERNAL COMPOSITE LINK RS232C/V.35 Connector, 16 Facility Interface Codes (FIC), 21 “fallback”, 176 Fallback Modes When On-Line (#F), 176 Flash On Hook (!), 166 Flow Control Background, 143 Flush Timer Value Command (#FT), 74 Front and Rear Panel Descrip-...
  • Page 197 MiniComputer Flow Control, 144 Modem Baud Rate ($MB), 181 Modem Configuration Select Com- mand ($MC), 81 Modem Reset (Z), 170 "Multi-Tech"/"Standard AT" Result Codes (&Q), 172 MultiMux Functional Testing Proce- dures, 110 MultiMux Operating Procedures, 91 Mux Clock Command ($MUXCL), 78...
  • Page 198 Response Time Control, 17 Response Time Priority Command (R0-R3), 70 Result Codes Enable/Disable and No Response (Q), 172 Retransmit Count ($R), 179 Return Character, 139 S3, 139 Return to Command Mode After Dial Execution (;), 166 Ringer Equivalence Number (REN), 21 Rings Which Have Occurred S1, 138 RJ45 Cabling for Internal DSU, 124...
  • Page 199 Universal Channel Parameters (C0) Command, 65 Unpacking, 46 V.35 indicator, 36 V29/V33 Indicator, 39 Wait for New-Dial-Tone (W), 166 Wait Time for Dial Tone, 139 S6, 139 Wait Time for Dial Tone (S6), 146 Watch-Dog Timer Test Mode (&T9), 88 Word Length Select Command (WL5-8), 71 Write Configurations to Modem...
  • Page 200 S000315A...

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