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General DataComm DeskTop T1 Installation And Operation Instruction Manual

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GDC 048R154-000-01
Issue 1 - October 1997
Installation and Operation
DeskTop T1
Data Service Unit
General DataComm

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Summary of Contents for General DataComm DeskTop T1

  • Page 1 GDC 048R154-000-01 Issue 1 - October 1997 Installation and Operation DeskTop T1 Data Service Unit General DataComm...

  • Page 3: Table Of Contents

    Table of Contents Preface Technical Overview Overview................1-1 DT T1 DSU Features ............1-1 Description ................. 1-2 Fractional T1 Capabilities..........1-2 DTE Interface..............1-3 Installation Overview................2-1 Unpacking and Handling ........... 2-1 Preoperational Check ............2-1 Option Selection..............2-2 Timing Options............2-2 Connections..............
  • Page 4 Table of Contents Monitor ..............3-10 What Are You?............3-12 Tests Overview................4-1 Terminal Interface Test Procedure........4-4 Network QRSS Self Test ........... 4-8 Network Payload Loopback..........4-10 Network Line Loopback ..........4-11 Network Local Test............4-13 Network Local Test with QRSS Self Test ....... 4-13 Network Remote Test ............
  • Page 5 Table of Contents Figures 2-1 Position of Configuration Option Switchbanks..2-3 2-2 Back Panel Connectors ..........2-13 2-3 EIA-530 Interface Daughter Card Installation.... 2-14 3-1 DT T1 Front Panel Controls and Indicators....3-2 3-2 Configuration Screen, with Default Settings ....3-4 3-3 Diagnostics Selection Screen........
  • Page 6 Table of Contents 4-19 Data Path for DTE Digital Loopback ......4-21 4-20 Data Path for DTE Remote Digital Loopback.... 4-22 4-21 DTE Remote Digital Loopback, Front Panel Control............. 4-22 4-20 Data Path for DTE Remote Digital Loopback with Self Test .............. 4-23 4-21 DTE Remote Digital Loopback with Self Test, Front Panel Control.............

  • Page 7: Preface

    Scope This manual describes how to install and configure a General DataComm Desktop T1 Data Service Unit. It is written for installers, service technicians, and users. It assumes a working knowledge of data interfaces, and T1 and Fractional T1 data transmission services.
  • Page 8 NOTE Service and Support General DataComm is committed to providing the service and support needed to install, manage, and maintain your equipment. For information about service programs or for assistance with your support requirements, contact your local Sales Representative or call General DataComm Service at the 24-hour, toll-free number listed below.
  • Page 9 Preface Be ready with the site name and phone number, and a description of the problem. The next available support representative will promptly return your call. Hands-on training courses are provided by GDC Educational Services. Courses range from basic data communications, modems and multiplexers, to complex network and ATM systems and are taught in Connecticut or at a customer location.
  • Page 10 A label on the bottom of the DT T1 enclosure provides the FCC Registration number for the unit. If requested, give this information to the telephone company. To connect the DeskTop T1 DSU to the Public Telephone Network you are required to give the following information to the Telephone Company:...
  • Page 11 Preface SOC (Service Order Code):6.0Y Telephone Company jack type:RJ48C The telephone company may discontinue your service temporarily if the unit causes harm to the telephone network. If possible, you will be notified of such an action in advance. If advance notice is not practical, you will be notified as soon as possible and will be advised of your right to file a complaint with the FCC.
  • Page 12 Preface water pipe system, if present, are connected together. This precaution may be particularly important in rural areas. Users should not attempt to make such connections themselves, but should contact the appropriate electric inspection authority, or electrician, as appropriate. GDC 048R154-000...

  • Page 13: Technical Overview

    DeskTop T1 DSU Features The General DataComm DeskTop T1 Data Service Unit (DSU) is a highly efficient means of transmitting and receiving digital data over a T1 line supplied by a telephone company (Telco) or other service provider.

  • Page 14: Description

    Fractional T1 Capabilities A T1 line's DS1 signal consists of 24 DS0 channels. The DeskTop T1 DSU can be configured to map user data into either consecutive or alternate DS0s to provide rates from 56 Kbps (1 DS0) to 1.536 Mbps (24 DS0s at 64 Kbps each).

  • Page 15: Dte Interface

    50% by filling the unused DS0s with ones. DTE Interface The DeskTop T1 DSU provides DTE interface through an ITU-T V.35-compatible port for connection to synchronous serial customer equipment. Examples of customer equipment are Front End Processors (FEPs), Local Area Network (LAN) bridges, video codecs, CAD/CAM workstations, and Group 4 facsimile equipment.

  • Page 16: Equipment List

    Technical Overview Table 1-1 Equipment List Description GDC Part No. GDC DeskTop T1 DSU, 117 V ac, V.35 channel 048A102-005 interface Power Supply Power supply, 19 Vac, 0.6A, 60 Hz wall mount 700-053-002 transformer Cables Interface cable, ITU-T V.35 34-pin male-to-male...

  • Page 17: Installation

    When the test is successfully completed you may proceed to make cable connections to the DSU. The DeskTop T1 DSU should be installed in a ventilated area where the ambient temperature does not exceed 122°F (50°C). Do not install the DSU above other equipment that generates large amounts of heat (e.g., power supplies).

  • Page 18: Option Selection

    Installation If the DeskTop T1 DSU does not check out properly, replace it with a spare, if available, and repeat the test. Do not attempt to repair the DeskTop T1 DSU. For assistance, contact General DataComm Service as described in the Preface.
  • Page 19 Installation Although the network clock is the preferred timing source, the DeskTop T1 DSU provides other timing options for use in applications where a network clock is either not available or not applicable. The flexibility and complexity of the DSU’s timing options require detailed explanations.

  • Page 20: Option Application Notes - Switchbank S13, Csu Characteristics

    Installation Table 2-1 Option Application Notes — Switchbank S13, CSU Characteristics Option Selection Switch Position Description Configuration Soft S13-1 Off* DSU can be configured by a Mode VT100-compatible terminal connected to the Console port. The positions of other switches may not reflect the actual configuration of the unit when this is selected.
  • Page 21 Installation Table 2-1 Option Application Notes — Switchbank S13, CSU Characteristics (Continued) Option Selection Switch Position Description DS-1 Line S13-5 All Off* = These switches control LBO when Build-Out (LBO)/ S13-6 0 dB a DS-1 line interface is selected at DSX-1 S13-7 S13-4.

  • Page 22: Option Application Notes - Switchbank S14, Network Characteristics

    Installation Table 2-2 Option Application Notes — Switchbank S14, Network Characteristics Option Selection Switch Position Description Network B8ZS* S14-1 Off* Selects Bipolar with 8 Zero Substi- Coding tution (B8ZS) encoding for the network side S14-1 Selects Alternate Mark Inversion (AMI) encoding for the network side.
  • Page 23 Installation Table 2-2 Option Application Notes — Switchbank S14, Network Characteristics (Continued) Option Selection Switch Position Description Network Inband Inhibit* S14-5 Off*or On Disables response to in-band T1 Loop S14-6 Off* loop codes Note: Both settings provide the same result. Line S14-5 DSU starts or stops a Line Loop...

  • Page 24: Option Application Notes - Switchbank S15, Dte Characteristics

    Installation Table 2-3 Option Application Notes — Switchbank S15, DTE Characteristics Option Selection Switch Position Description DTE CTS Forced ON* S15-1 Off* CTS forced On Follow RTS S15-1 CTS controlled by RTS DTE DCD Forced ON* S15-2 Off* DCD forced On Follow S15-2 DCD Off when network signal is Out...

  • Page 25: Option Application Notes - Switchbank S10, Dte Characteristics

    Installation Table 2-4 Option Application Notes — Switchbank S10, DTE Characteristics Option Selection Switch Position Description DTE Auto Clock Disable* S10-1 Off* Normal/Invert condition of DTE Invert Receive and Send Clocks controlled by S15-7&8 Enable S10-1 DSU monitors for data/clock mismatches in DTE data, and auto- matically toggles between Normal and Invert conditions to compensate...

  • Page 26: Option Application Notes - Switchbanks S11 & S12, Ds0 Assignments

    2-10 Installation Table 2-5 Option Application Notes — Switchbanks S11 & S12, DS0 Assignments Option Selection Switch Position Description Starting DS0 1* — 24 S11-4 Default: Selects lowest numbered DS0 S11-5 in the group that conveys All Off = DS0 1 S11-6 channel data.
  • Page 27 Installation 2-11 Table 2-6 DTE Data Rate Selection — Switchbank S12 Rate* # of S12-4 S12-5 S12-6 S12-7 S12-8 DS0s** 1344/1536 Default Setting 56/64 112/128 168/192 3 (1/8) 224/256 280/320 336/384 6 (1/4) 392/448 448/512 504/576 9 (3/8) 560/640 616/704 672/768 12 (1/2) 728/832...

  • Page 28: Dte Starting Ds0 Selections - Switchbank S11

    2-12 Installation Table 2-7 DTE Starting DS0 Selections — Switchbank S11 Starting DS0 S11-4 S11-5 S11-6 S11-7 S11-8 Default Setting GDC 048R154-000...

  • Page 29: Connections

    Refer to Table 1-1 for the appropriate interface cable. Refer to Appendix B for interface pin/signal assignments. Network Connection Connect the network (T1 line) to the DeskTop T1 DSU as described below. The Telco continuously monitors the T1 link and the equipment connected to it.
  • Page 30 2-14 Installation For Canadian installations only, a special cable is required for the network connection. Use GDC cable P/N 022H020 (RJ48C to DB15F) to connect the network port to the T1 NOTE line. The network port interface is an RJ48C jack located on the rear panel. You must use either GDC cable P/N 022H024-XXX (RJ48C plug-to- plug) or 022H021-XXX (RJ48C plug-to-terminal lugs) to connect the T1 line to the DSU.

  • Page 31: Primary Power Connection

    19 Vac, 0.6A, at 60 Hz. The outlet that provides ac power should not be under switch control. The DeskTop T1 DSU should be powered by the same ac source as the customer equipment connected to it. Use of the same ac source will prevent large circulating currents caused by differences in ground potential.
  • Page 32 2-16 Installation Use of a terminal is optional. Configuration can be accomplished entirely by means of the hardware switches on the pc card. GDC 048R154-000...

  • Page 33: Operation

    Controls and Indicators Figure 3-1 illustrates the DeskTop T1 DSU front panel and explains the function of each control and indicator. The four switches on the front panel are momentary action pushbuttons.
  • Page 34 Selects between Self Test pattern generator/checker On (LED On) and Off (LED Off) LL (Red LED & Switch) Controls Line Loopback Test RL (Red LED & Switch) Controls Remote Loopback Test Figure 3-1 DeskTop T1 Front Panel Controls and Indicators GDC 048R154-000...

  • Page 35: Terminal Interface

    Operation Terminal Interface When you connect a VT100-compatible terminal to the DSU back panel Console Port it provides on-screen interface functions for configuration, diagnostics, status monitoring, and display of information concerning the unit. To access the terminal interface, connect a VT100-compatible terminal as described in Chapter 2, Installation, and press the Enter key.

  • Page 36: Configuration Screen, With Default Settings

    Operation DT T1 Configuration [0] Return to Main Menu Unit is under Software Control [1] Network Framing: [2] Network Coding: B8ZS [3] Network Line Type: DS-1 [4] Network Line Buildout: Manual 0dB [5] Network ESF Mode: ANSI T1.403 [6] Network Timing: Receive [7] Network Inband Loop: Inhibit...
  • Page 37 For more detailed descriptions of the individual option settings and their effects on operation of the DSU you can consult Tables 2-1 through 2-5 in Chapter 2, Installation. Table 3-1 DeskTop T1 Configuration Option Settings Option Potential Settings [0] Return to Main Menu...
  • Page 38 Operation Table 3-1 DeskTop T1 Configuration Option Settings (Continued) Option Potential Settings [4] Network Line Buildout: Manual 0 dB [4] is Line Buildout when Line Manual -7.5 dB Type is DS-1 Manual -15 dB Manual -22.5 dB Auto [4] Network Pre-Equalization:...
  • Page 39 Operation Table 3-1 DeskTop T1 Configuration Option Settings (Continued) Option Potential Settings [B] DTE Allocation: Consecutive Alternate [C] DTE CTS Control: Forced ON Follow RTS [D] DTE DCD Control: Forced ON Follow OOF [E] DTE DSR Control: Forced ON Follow LOS...

  • Page 40: Diagnostics

    Operation Diagnostics The terminal interface DeskTop T1 Diagnostics function supports two screens: one by which you select and initiate tests on the DSU, and one that displays test results. The results screen also contains the control function for ending a test.

  • Page 41: Diagnostics Selection Screen

    Operation DT T1 Diagnostics [0] Return to Main Menu [1] Select LL Mode: Unilateral [2] Start Network QRSS Self Test [3] Start Network Payload Loopback [4] Start Network Line Loopback [5] Start Network Local Test [6] Start Network Local Test with QRSS Self Test [7] Start Network Remote Test [8] Start Network Remote Test with QRSS Self Test [9] Select DTE Self Test Pattern:...

  • Page 42: Monitor

    "NO SYNC"; displays only while a Self Test is selected Figure 3-4 Diagnostics Results Screen Monitor The terminal interface DeskTop T1 Monitor function displays a screen of status information concerning DTE interface signals and alarm conditions. Figure 3-5 illustrates the Monitor screen.

  • Page 43: Monitor Screen

    Operation 3-11 or Off condition. The Alarm Status portion of the screen displays the current status, INACTIVE or ACTIVE, of the nine alarm conditions that the DSU can report. Definitions of the alarm conditions appear in Appendix D, Alarm Definitions. When you are done viewing the Monitor screen, type 0 to return to the Main Menu.

  • Page 44: What Are You

    3-12 Operation What Are You? The terminal interface DeskTop T1 What Are You? function displays a screen of information that identifies the unit, its firmware revision level, and the type of DTE interface installed in it. Figure 3-6 illustrates the What Are You? screen.

  • Page 45: Overview

    4 Diagnostics Overview This chapter describes the test functions of the DeskTop T1 DSU and provides instructions for their use. There are three ways to control tests locally: • Terminal Interface Diagnostics Selection screen enables you to command all DSU tests •...
  • Page 46 Inband loop codes received from the remote site DSU take precedence over local diagnostic functions. If a locally initiated test is running when a loop code is received, the DeskTop T1 DSU terminates the test and performs the remote loopback.

  • Page 47: Fault Isolation Procedure

    Diagnostics Start Perform Network Local Test with QRSS Self Test Pass Fail Pass Perform Network Local Test Local DSU Problem Fail Perform Network Remote Local Equipment or Pass Fail Pass Test, or Network Remote Equipment-to-DSU Test with Self Test, with Connection Problem Fail remote configured for Line...

  • Page 48: Terminal Interface Test Procedure

    Diagnostics Tests can be used at the time of installation or whenever operation of the DSU must be checked. You can also use these tests as an aid in isolating problems in the data communications system (refer to Figure 4-1, Fault-Isolation Procedure). Terminal Interface Test Procedure All tests that you perform by means of the terminal interface involve the same basic procedure, which is described below.
  • Page 49 Loopbacks. 2. Select [2] DIAGNOSTICS from the terminal interface Main Menu. The DSU responds by displaying the DeskTop T1 Diag- nostics Selection screen, as shown in Figure 4-1. 3. Make any preliminary setups required for the test you intend to perform.
  • Page 50 Diagnostics A.The DSU must be optioned for Soft Configuration mode in order for you to perform LL Mode or DTE Self Test Pattern selection from the Diagnostics Selection screen. If NOTE you attempt either selection while the DSU is in Hard Configuration mode, the screen displays a message that the function is not available.

  • Page 51: Diagnostics Results Screen

    Diagnostics an intentional error as check on the error detector when run- ning a self test. [3] Reset Counters clears both the Bit Errors count and the Test Duration. DT T1 Diagnostics [0] Return to Main Menu [1] Stop Test [2] Inject Single Bit Error (ST only) [3] Reset Counters Current Test:...

  • Page 52: Network Qrss Self Test

    Diagnostics Network QRSS Self Test The Network QRSS Self Test function provides test pattern generation and checking that involves the network interface while excluding the DTE interface. The pattern it provides is a quasi-random signal (QRSS). The Network QRSS Self Test function appears three times in the terminal interface Diagnostics Selection menu: once by itself and twice in combination with loopback tests.

  • Page 53: Data Path For Network End-To-End Self Test

    Diagnostics DeskTop T1 DSU DeskTop T1 DSU Network Network Interface Interface Interface Network Interface TPG – Test Pattern Generator TPC – Test Pattern Checker Figure 4-4 Data Path for Network End-to-End Self Test 3. TM, T1, and ST indicators are On during the test.

  • Page 54: Network Payload Loopback

    4-10 Diagnostics Network Payload Loopback The Network Payload Loopback function provides a data path for a test signal that is originated and checked at the remote site. The Payload Loopback, illustrated in Figure 4-6, loops back onto the T1 line only the receive DS0s that carry DTE channel data. The loopback occurs at a point within the DSU at which the data has already passed through most of the network interface circuitry.

  • Page 55: Network Line Loopback

    Diagnostics 4-11 Network Payload Loopback DeskTop T1 DSU DTE or Network other Interface Interface Network signal source Network Payload Loopback can be commanded from front panel by running DTE Local Loopback with DSU optioned for bilateral loopbacks (switch S10-4). Figure 4-6 Data Path for Network Payload Loopback...

  • Page 56: Data Path For Network Line Loopback

    4-12 Diagnostics Network Line Loopback DeskTop T1 DSU DTE or Network other Interface Interface Network signal source When DSU is optioned for bilateral loopbacks (switch S10-4) a DTE Local Loopback is also initiated when Network Line Loopback is commanded. Figure 4-7 Data Path for Network Line Loopback 3.

  • Page 57: Network Local Test

    T1 line. Error detection and reporting is entirely the responsibility of the external device that supplies the test signal. To initiate the loopback from the Diagnostics Selection screen, select [5] Start Network Local Test. DeskTop T1 DSU DTE or Network other...

  • Page 58: Network Remote Test

    T1 line and the DTE. It does not check the channel interface to the DTE. To initiate the test from the Diagnostics Selection screen, select [6] Start Network Local Test with QRSS Self Test. DeskTop T1 DSU Network Interface Interface TPG –...

  • Page 59: Data Path For Network Remote Test

    To initiate the test from the terminal interface Diagnostics Selection screen, select [7] Start Network Remote Test. Figure 4-12 shows the switches and indicators that are involved when you command a Network Remote Test from the front panel. DeskTop T1 DSU DeskTop T1 DSU DTE or Network...

  • Page 60: Network Remote Test With Qrss Self Test

    [8] Start Network Remote Test with QRSS Self Test. Figure 4-14 shows the switches and indicators that are involved when you command a Network Remote Test with QRSS Self Test from the front panel. DeskTop T1 DSU DeskTop T1 DSU Network Network Interface...

  • Page 61: Dte Self Test

    2047-bit or a 511-bit pattern. You can select the pattern by means of hardware switch S10-3 or by means of the terminal interface DeskTop T1 Diagnostics Selection screen, [9] Select DTE Self Test Pattern . The DTE Self Test function can be initiated from two selections in the terminal interface Diagnostics Selection menu: once by itself and once in combination with a loopback test.

  • Page 62: Data Path For Dte End-To-End Self Test

    Remember that when you initiate the test from the front panel the only display of results is the TM indicator flashing in response to detected errors. The terminal interface Diagnostics Results screen does not display the results of tests initiated from the front panel. DeskTop T1 DSU DeskTop T1 DSU Network Network...

  • Page 63: Dte Local Loopback

    Diagnostics 4-19 3. TM and ST indicators are On during the test. TM flashes to indicate detect- ed errors. General Data- SD RD OOF LOS BPV ALM TM T1 Comm DeskTop 1. T1 indicator must be Off; press T1 switch if indicator is On. 2.

  • Page 64: Data Path For Dte Local Loopback

    4-20 Diagnostics DTE Local Loopback DeskTop T1 DSU DTE or Network other Interface Interface Network signal source When DSU is optioned for bilateral loopbacks (switch S10-4) a Network Payload Loopback is also initiated when DTE Local Loopback is commanded. Figure 4-17 Data Path for DTE Local Loopback 3.

  • Page 65: Dte Digital Loopback

    DTE interface. You can command the loopback only by means of the terminal interface DeskTop T1 Diagnostics Selection screen. To initiate the loopback from the terminal interface DeskTop T1 Diagnostics Selection screen, select [C] Start DTE Digital Loopback.

  • Page 66: Data Path For Dte Remote Digital Loopback

    DTE Remote Digital Loopback from the front panel. You can also command the test by means of DTE interface pin BB when the DTE Test Leads configuration option is enabled (switch S10-2 On). DeskTop T1 DSU DeskTop T1 DSU DTE or Network...

  • Page 67: Dte Remote Digital Loopback With Self Test

    [E] Start DTE Remote Digital Loopback with Self Test. Figure 4-23 shows the switches and indicators that are involved when you command a DTE Remote Digital Loopback with Self Test from the front panel. DeskTop T1 DSU DeskTop T1 DSU Network Network Interface...

  • Page 68: Dte Remote Digital Loopback With Self Test, Front Panel Control

    4-24 Diagnostics 3. TM, ST, and RL indicators are On during the test. TM flashes to indicate detect- ed errors. General Data- SD RD OOF LOS BPV ALM TM T1 Comm DeskTop 1. T1 indicator must be Off; press T1 switch if indicator is On.
  • Page 69 A Technical Characteristics Item Characteristic Physical PC card assembly in enclosure Height 1.4 in. (36 mm) Width 7.4 in. (188 mm) Depth 11.0 in. (279 mm) Weight 1 lb. (0.45 kg) Shipping weight 2 lb. (0.9 kg) Environmental Temperature Operating 32°...
  • Page 70 Technical Characteristics Item Characteristic Electrical (Continued) Data rates N x 64 kbps or N x 56 kbps (N = 1 to 24); maximum aggregate (payload) rate of 1,536,000 bps (1,544,000 bps in unframed mode) Communication line T1 digital carrier (non-loaded, stag- gered-twist ABAM, PIC, or pulp-insu- lated exchange-type cable, 19 to 26 gauge)
  • Page 71 Technical Characteristics Item Characteristic Electrical (Cont.) Timing source Internal clock, external clock, slave (received timing loopback) Network receiver Operating range 0 to 30 dB of cable loss at 772 kHz (relative to 3.0V launch pulse) Input impedance 100 Ohm Jitter tolerance Conforms to specifications defined in AT&T PUB 62411, December 1988 Longitudinal balance...
  • Page 72 Technical Characteristics Item Characteristic Electrical (Cont.) Consecutive zeros 8 x (N+1) when configured for AMI, enforcement consecutive, N x 64, framed; or AMI, unframed Keep Alive signal Type 1 (consecutive, framed ones fill- ing the unused bandwidth) Framing format D4 Superframe, AT&T 54016 Extended Superframe (ESF), ANSI T1.403 ESF with automatic...
  • Page 73 B Interface Signals Table B-1 ITU-T V.35 34-Pin Pin No. Function Direction Frame Ground, AA Send Data (a), BA To DSU Send Data (b), BA To DSU Rcv Data (a), BB From DSU Rcv Data (b), BB From DSU RTS, CA To DSU CTS, CB From DSU...
  • Page 75 (Timing is embedded in the data stream on the network port, but is provided on a separate lead in the DTE interface.) The network clock is the preferred timing source, but the DeskTop T1 DSU supports other timing options as well, for use in applications where timing from the network clock is either not available or not applicable.
  • Page 76 DTE Split Timing, a combination of Receive Timing and DTE Timing. One thing is common to all DeskTop T1 DSU timing options: the DSU uses the clock it recovers from network receive data to clock data into the receive buffer and to provide the channel receive clock signal for the channel.
  • Page 77 The data rate on the network port is 1.544 Mbps. On the DTE port, however, the data rate may be from 56 Kbps to 1.536 Mbps (1.544 Mbps when using unframed mode). The DeskTop T1 DSU compensates for the difference in data rates by translating the clock frequency when passing it from one port to another.
  • Page 78 Select Receive Timing when using the DeskTop T1 DSU in a network (or with a device at the remote end) that supplies the clock, as in a DACS (Digital Access and Cross-connect System) network.
  • Page 79 Stratum 4, Level II clock, as defined in AT&T Technical Reference 62411.) The remote DSU uses this as its timing reference (3) and loops it back to the DeskTop T1 DSU (4). The DeskTop T1 DSU recovers the receive T1 clock from the network receive T1 data and uses it to clock T1 data into the receive buffer (5).
  • Page 80 DSU DTEl interface provides its own channel transmit clock signal (1) on the appropriate interface lead. The DeskTop T1 DSU translates (2) this clock to provide the send timing source for T1 data output from the transmit buffer (3) to the network.
  • Page 81 Select DTE Timing when using the DeskTop T1 DSU in a private network with the customer equipment supplying the clock. Select the appropriate timing option for the customer equipment: The DeskTop T1 DSU expects external timing on the DTE interface Ext Clk lead.
  • Page 82 DTE Timing, the customer equipment on the channel interface provides the other timing source, its own channel transmit clock signal (5) on the appropriate interface lead, but the DeskTop T1 DSU uses it for nothing else. Select DTE Split Timing when there are timing sources provided by both the network and the customer equipment.
  • Page 83 Clock Figure C-4 DTE Split Timing Typical Network Applications Although you can use the DeskTop T1 DSU in various network configurations with different types of equipment, the following simple applications illustrate the fundamental reasoning you use to select the appropriate timing option.
  • Page 84 Internal Timing for the master or host end, and select Receive Timing for the other, as shown in Figure C-5 A. In this example, the DeskTop T1 DSU at Site A is configured for Internal Timing, making it the timing source.
  • Page 85 AAAA AAAA AA AA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AA AA Site A Site B AA AA AA AA DeskTop T1 DeskTop T1 AA AA AA AA Timing Timing Option: Option: AA AA Terminal Receive AA AA...
  • Page 87 D Alarm Definitions Overview This appendix describes the DeskTop T1 DSU alarms that can appear on the terminal interface Monitor screen Alarm Status display: Network OOF (Network Out of Frame) Network LOS (Network Loss of Signal) Network USS (Network Unavailable Signal State)
  • Page 88 Alarm Definitions Network Unavailable Signal State A Network Unavailable Signal State (NETWORK USS) alarm event occurs when 10 consecutive severely errored seconds occur. It ends when the DSU has processed 10 consecutive seconds of data without the occurrence of a severely errored second. Network Alarm Indication Signal A Network Alarm Indication Signal (NETWORK AIS) alarm event occurs when the DSU receives an AIS from the network.
  • Page 89 Alarm Definitions Configuration Error A Configuration Error (CONFIG ERROR) alarm indicates that the DSU has detected one of the following conditions: • The checksum computed by the DSU for its configuration does not match the one it stored at the time the configuration was performed.
  • Page 91 Index Back Panel Connectors 2-13 Configuration Option Settings Configuration Options CSU Characteristics DS0 Assignments 2-10 DTE Characteristics Network Characteristics Configuration Screen Controls and Indicators Data Rate Selection 2-11 Diagnostics Results Screen 3-10 Diagnostics Selection Screen DTE Digital Loopback 4-21 DTE Interface Port Connection 2-13 DTE Interface DTE Local Loopback...
  • Page 92 Index Preoperational Check Primary Power Connection 2-15 Starting DS0 Selections 2-12 Terminal Connection 2-15 Terminal Interface Configuration Screen Diagnostics Screen Monitor Screen 3-10 Test Procedure What Are You? Screen 3-12 Timing Options Unpacking and Handling What Are You? Screen 3-12 GDC 048R154-000...
  • Page 93 Trademarks and Patents General DataComm, the General DataComm logo and the following are trademarks of General DataComm, Inc. in the United States and other countries: ACCULINE, ANALOOP, AUTOFRAME, BERT 901, DATA- COMM SECURE-PAK, DATALOOP, DIGIDIAL, ENmacs, FASTPRO, FIRST RESPONSE, GDC, GDC APEX, GENERAL DATACOMM...
  • Page 94 General DataComm...

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