PairGain T1L2F10A User manual

HIGAIN LINE UNIT
PAIRGAIN TECHNOLOGIES, INC.
ENGINEERING SERVICES TECHNICAL PRACTICE
SECTION 150-231-185-05
Model List Number Part Number CLEI Code
HLU-231 8E 150-1111-85 T1L2F10A

Revision History of This Practice 150-231-185-05, Revision 05
ii September 13, 1999 HLU-231 List 8E
REVISION HISTORY OF THIS PRACTICE
© Copyright 1999 PairGain Technologies, Inc.
PairGain andHiGain areregistered trademarks of PairGain Technologies, Inc. All other product namesmentionedin this practice
are used for identification purposes only and may be trademarks or registered trademarks of their respective companies.
Information contained in this document is company private toPairGain Technologies, Inc., and shall not be modified, used, copied,
reproduced or disclosed in whole or in part without the written consent of PairGain.
Information furnished by PairGain Technologies is believed to be accurate and reliable. However, no responsibility is assumed by
PairGain Technologies for its use; nor for any infringement of patents or other rights of third parties which may result from its use.
No license is granted by implication or otherwise under any patent or patent rights of PairGain Technologies. PairGain
Technologies reserves the right to change specifications at any time without notice.
Revision Release Date Revisions Made
01 May 6, 1998 Initial release
02 June 10, 1998 Adjusted table widths, miscellaneous edits
03 December 15, 1998 Modified alarm diagnostics, miscellaneous edits
04 April 7, 1999 Update diagnostic tables
05 September 13, 1999 Troubleshooting screens added

150-231-185-05, Revision 05 Using This Technical Practice
HLU-231 List 8E September 13, 1999 iii
USING THIS TECHNICAL PRACTICE
The following conventions are used in this manual:
•Monospace type indicates screen text, including text you type at a screen prompt.
•Keys you press are indicated by small icons such as . Key combinations to be pressed simultaneously
are indicated with a plus sign as follows: + .
•Three types of messages, identified by icons, appear in text.
For a list of abbreviations used in this document, refer to “Appendix E - Glossary” on page 65.
DOCUMENTATION
If you have comments on this PairGain document, send an email to [e-mail]. Type
the product name and the section number of the document in the subject area of the email message.
INSPECTING THE SHIPMENT
Upon receipt of the equipment:
•Unpack each container and inspect the contents for signs of damage. If the equipment has been damaged in
transit, immediately report the extent of damage to the transportation company and to PairGain. Order
replacement equipment, if necessary.
•Check the packing list to ensure complete and accurate shipment of each listed item. If the shipment is short
or irregular, contact PairGain as described in the Warranty located inside the back cover. If you must store
the equipment for a prolonged period, store the equipment in its original container.
Notes contain information about special circumstances.
Cautions indicate the possibility of equipment damage or personal injury.
The Electrostatic Discharge (ESD) Susceptibility symbol indicates that a device or assembly is
susceptible to damage from electrostatic discharge.
(17(5
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Table of Contents 150-231-185-05, Revision 05
iv September 13, 1999 HLU-231 List 8E
TABLE OF CONTENTS
Overview ____________________________________________________________________________ 1
Features.............................................................................................................................................. 1
Product Enhancements........................................................................................................ 1
Standard Features................................................................................................................ 2
Compatibility..................................................................................................................................... 2
Applications....................................................................................................................................... 2
HiGain Doubler Applications ............................................................................................. 3
Personal Communications System Applications ................................................................ 3
Front Panel __________________________________________________________________________ 4
Installation___________________________________________________________________________ 8
Verification........................................................................................................................................ 9
Verification without a Downstream Device........................................................................ 9
Verification with a Downstream Device............................................................................. 9
Provisioning Requirements ............................................................................................................. 10
Provisioning_________________________________________________________________________ 11
Using the MODE and SEL Buttons................................................................................................. 11
Setting Options through MODE and SEL......................................................................... 11
Resetting to Factory Default Values................................................................................. 12
Displaying System Parameter Settings ............................................................................. 12
Disabling an Alarm........................................................................................................... 12
Loopback Modes............................................................................................................... 12
Using a Maintenance Terminal ....................................................................................................... 13
Connecting to a Maintenance Terminal............................................................................ 13
Accessing the Maintenance Terminal Screens.................................................................. 13
Navigation Keys ................................................................................................. 13
Maintenance Terminal Main Menu.................................................................... 14
Selecting a Maintenance Terminal Function...................................................... 15
System Spans...................................................................................................... 15
Using the Maintenance Terminal Screens....................................................................................... 15
View Span Status Screen .................................................................................................. 15
Span Status Screen without Doublers................................................................. 16
Span Status Screen for Doubler Applications .................................................... 16
Set Clock Screen............................................................................................................... 19
Set Time.............................................................................................................. 19
Set Date............................................................................................................... 20
Update the HRU Time and Date......................................................................... 20

150-231-185-05, Revision 05 Table of Contents
HLU-231 List 8E September 13, 1999 v
System Settings Screen......................................................................................................20
Equalization Option.............................................................................................23
BPVT Option.......................................................................................................23
BER Option.........................................................................................................24
DS0 Blocking Option..........................................................................................24
DS1 Line Code Option........................................................................................24
Margin Alarm Threshold Option.........................................................................25
HAIS Option .......................................................................................................25
HDSL Line Voltage Options...............................................................................25
Loopback Mode Screen.....................................................................................................26
Loopback Menu without Doubler.......................................................................27
Loopback Menu for Doubler Applications.........................................................27
Initiating a Loopback ..........................................................................................28
Disabling a Loopback..........................................................................................28
View Performance Data Screen.........................................................................................29
Performance Data Screen without Doubler.........................................................30
Performance Data Screen for Doubler Applications...........................................30
View Performance History Screen ....................................................................................31
Performance History Screen without Doubler....................................................31
Performance History Screen for Doubler Applications ......................................32
View Alarm History Screen ..............................................................................................33
Alarm History Screen without Doubler ..............................................................34
Alarm History Screen for Doubler Applications.................................................34
View System Inventory Screen .........................................................................................35
System Inventory Screen without Doubler .........................................................36
System Inventory Screen for Doubler Applications ...........................................36
View Troubleshooting Screen ...........................................................................................37
Troubleshooting _____________________________________________________________________ 40
System Alarms.................................................................................................................................40
Alarm Option for DLC Feed .............................................................................................41
Retiring System Alarms.....................................................................................................41
Self Test.............................................................................................................................41
Loopback Operation.........................................................................................................................42
Generic Loopback Commands ..........................................................................................42
Special Loopback Commands ...........................................................................................44

Table of Contents 150-231-185-05, Revision 05
vi September 13, 1999 HLU-231 List 8E
Initiating a Manual Loopback Session.............................................................................. 45
Setting the Loopback Time-out Option.............................................................. 45
Initiating a Manual Loopback Session ............................................................... 45
Loopback Test Procedures .............................................................................................................. 46
General Troubleshooting Tips .......................................................................................... 46
GNLB Test Procedures..................................................................................................... 46
A1LB, A2LB, and A5LB Test Procedures....................................................................... 48
A3LB and A4LB Test Procedures .................................................................................... 51
Appendix A - Specifications____________________________________________________________ 52
HDSL Insertion Loss Guidelines..................................................................................................... 53
Power Consumption ........................................................................................................................ 53
Power Consumption without Doublers............................................................................. 53
Power Consumption with Doublers.................................................................................. 54
Maximum Power Dissipation.......................................................................................................... 56
Maximum Current Drain................................................................................................................. 56
HLU-231 List 8E Card Connector ..................................................................................................57
Network Management Control Bus .................................................................................. 57
Fuse Alarm........................................................................................................................ 57
System Alarm Relay Output............................................................................................. 58
Craft Port......................................................................................................................................... 58
Appendix B - Functional Operation _____________________________________________________ 59
Timing ............................................................................................................................................. 59
Ground Fault Detect........................................................................................................................ 60
Appendix C - Compatibility____________________________________________________________ 61
T1 Repeater Shelves and Related Equipment ................................................................................. 61
HiGain Doubler Circuit Deployment .............................................................................................. 61
Appendix D - Product Support _________________________________________________________ 63
Technical Support............................................................................................................................ 63
World Wide Web............................................................................................................................. 63
Returns............................................................................................................................................. 63
Appendix E - Glossary ________________________________________________________________ 65
Certification and Warranty______________________________________________ Inside Back Cover

150-231-185-05, Revision 05 List of Figures
HLU-231 List 8E September 13, 1999 vii
LIST OF FIGURES
1. HLU-231 List 8E Front Panel .........................................................................................................................4
2. Installing the HLU-231 List 8E into a Shelf ...................................................................................................8
3. Maintenance Terminal Main Menu...............................................................................................................14
4. System Spans.................................................................................................................................................15
5. Span Status Screen: No Doubler...................................................................................................................16
6. Span Status Screen: Four Doublers (Span 5) ................................................................................................16
7. Set Clock Screen............................................................................................................................................19
8. System Settings Screen..................................................................................................................................20
9. Loopback Menu: No Doubler........................................................................................................................27
10. Loopback Menu: Four Doublers ...................................................................................................................27
11. NLOC Loopback Mode Reported in the Maintenance Terminal Main Menu..............................................28
12. Performance Data Screen: No Doubler.........................................................................................................30
13. Performance Data Screen: Four Doublers (Span 5)......................................................................................30
14. 31-Day Performance History Screen: No Doubler........................................................................................31
15. 31-Day Performance History Screen: Four Doublers (Span 5).....................................................................32
16. Alarm History Screen: No Doubler...............................................................................................................34
17. Alarm History Screen: Four Doublers (Span 5)............................................................................................34
18. System Inventory Screen: No Doubler..........................................................................................................36
19. System Inventory Screen: Four Doublers......................................................................................................36
20. Troubleshooting Screen for a Doubler Application ......................................................................................37
21. Troubleshooting Screen Describing Circuit Problem....................................................................................37
22. Troubleshooting with Help............................................................................................................................38
23. Troubleshooting with Margin Values............................................................................................................39
24. Troubleshooting with Insertion Loss Values.................................................................................................39
25. Loopback Summary.......................................................................................................................................42
26. Loopback Configurations..............................................................................................................................47
27. HLU-231 List 8E Card-edge Connector........................................................................................................57
28. RS-232 Craft Port Pinouts.............................................................................................................................58
29. HLU-231 List 8E Block Diagram .................................................................................................................59

List of Tables 150-231-185-05, Revision 05
viii September 13, 1999 HLU-231 List 8E
LIST OF TABLES
1.Front-panel Description................................................................................................................................... 5
2.Front-panel Display Messages......................................................................................................................... 6
3.Navigational Keys on the Maintenance Terminal ......................................................................................... 13
4.Maintenance Terminal Screens...................................................................................................................... 14
5.Span Status Fields and Descriptions.............................................................................................................. 17
6.HDSL System Alarms ................................................................................................................................... 18
7.Loopback Messages....................................................................................................................................... 18
8.HLU-231 List 8E System Settings................................................................................................................. 21
9.Loopback Field Messages and Descriptions.................................................................................................. 26
10.Errored and Unavailable Seconds Definitions............................................................................................... 29
11.Alarm History Fields and Descriptions ......................................................................................................... 33
12.HDSL System Alarms ................................................................................................................................... 40
13.Summary of HiGain Loopback Codes........................................................................................................... 43
14.Addressable Repeater Loopback Commands (A1LB, A2LB, A5LB)........................................................... 48
15.Addressable Repeater Loopback Commands (A3LB and A4LB)................................................................. 51
16.HDSL Loss Over Cables................................................................................................................................ 53
17.Power Parameters: No Doubler ..................................................................................................................... 54
18. HLU-231 Power Parameters—Single Doubler (HDU-451 List 1 or 2) ....................................................... 54
19.HLU-231 Power Parameters—Single Doubler (HDU-439 or HDU-437 Lists 1 and 1B) ............................ 54
20.HLU-231 Power Parameters—Single Doubler (HDU-409 List 2)................................................................ 55
21.HLU-231 Power Parameters—Two Doublers (HDU-451 List 3, 4, 3B or 4B) ............................................ 55
22.HLU-231 Power Parameters—Two Doublers (HDU-439 or HDU-437 Lists 1 and 1B).............................. 55
23.HLU-231 Power Parameters—Two Doublers (HDU-409 List 2)................................................................. 55
24.HLU-231 Power Parameters—Three and Four Doublers (HDU-409 List 2)................................................ 56
25.HiGain Doubler Deployment Matrix............................................................................................................. 62

150-231-185-05, Revision 05 Overview
HLU-231 List 8E September 13, 1999 1
OVERVIEW
The PairGain®HiGain®Line Unit HLU-231 List 8E is the Central Office (CO) side of a repeaterless
T1 transmission system. When used in conjunction with a HiGain Remote Unit (HRU), the system provides
1.544 Mbps transmission on two unconditioned copper pairs over the full Carrier Service Area (CSA) range. The
CSA includes loops up to 12,000 feet of24 AWG or 9,000 feet of 26 AWG wire, including bridged taps. This line
unit can be used with HiGain Doubler Units (HDUs) to extend reach.
FEATURES
Product Enhancements
•Five-span range with four doublers (60 kft, 24 AWG)
•Four line-powered spans (three doublers and one remote)
•Reduced power consumption
•Customer Disconnect Indicator (CDI) option
•Ultra-low wander (Stratum 1 compliant)
•Low line-power option (-140 Vdc) for circuits with a single doubler
•Selectable Power Feed (PWRF) modes: Auto, High, Low and Disabled
•HDSL grounded loop detection
•Bipolar Violation Transparency (BPVT) options
•Bit Error Rate (BER) alarm options
•HRU loopback screen
•Inventory and troubleshooting screens
•Loss of Signal/Alarm Indicator Signal (LOS/AIS) payload alarm option
•Remote Loss of Signal (RLOS) disable alarm option
•Digital Data Service (DDS) latching loopback option
•Supports HRU-411 in PCS applications
•Default setting screen option
•Payload (PL) or HiGain (HG) loopback source identification
•Remote Provisioning

Overview 150-231-185-05, Revision 05
2 September 13, 1999 HLU-231 List 8E
Standard Features
•Selectable DS1 pre-equalizer
•Front-panel features:
–Four-character status display
–DS1 splitting and bridging access
–Status LED
–RS-232 craft port for connection to a maintenance terminal (ASCII terminal or a PC running a terminal
emulation program)
•Compatible with SXSS shelves, and equivalent
•Selectable loopback activation codes
•Network Management and Administration (NMA) interface
•Lightning and power cross protection on HDSL interfaces
•Full duplex 2B1Q HDSL transmission on two pairs at 784 kbps
•Margin threshold alarm
COMPATIBILITY
The HLU-231 List 8E is designed to be mounted in 220 mechanics shelves. For a list of compatible shelves, see
“Appendix C - Compatibility” on page 61.
All generations of HiGain HLU and HRU modules are compatible with each other. To take advantage of the
enhanced features of newer HiGain doublers, refer to “HiGain Doubler Circuit Deployment” on page 61.
APPLICATIONS
HiGain systems provide a cost-effective, easy-to-deploy method for delivering T1 High Capacity Digital Service
(HCDS) over metallic pairs.
•The service is deployed over two unconditioned, non-loaded copper pairs, yet it demonstrates a quality that
is competitive with fiber optics.
•Conventional, in-line, T1 repeaters are not required.
•Cable pair conditioning, pair separation and bridged tap removal are not required.
In general, HiGain systems:
•Operate with any number of other T1, POTS, Digital Data Service (DDS) or other HiGain systems sharing
the same cable binder group
•Can be used with customers requiring DS1 service on a temporary or permanent basis
•Provide a means of quickly deploying service in advance of fiber-optic transmission systems.
With a HiGain system, service can be provided within hours. Fiber-optic systems can be installed incrementally
and cut-over from the installed HiGain system when convenient to do so.

150-231-185-05, Revision 05 Overview
HLU-231 List 8E September 13, 1999 3
HiGain Doubler Applications
For applications without doublers, the HLU-231 is directly connected to the HRU by the two HDSL cable pairs.
The HLU-231 List 8E is compatible with all HiGain HRUs.
For doubler applications, one to four doublers may be used in the HDSL loops between the HLU and HRU.
•If the HRU is line-powered, the HLU-231 List 8E can power three doublers and the remote unit (HRU-402
or HRU-411) for a total of four spans.
•If the HRU is locally powered, the HLU can power up to four doublers for a total of five spans.
Personal Communications System Applications
The HLU-231 List 8E is required for Personal Communications System (PCS) applications that use the
HRU-411. The HRU-411 has an onboard 130 Vdc, 8.5 W power supply that can power the 200 mW PCS remote
radio ports. The line unit recognizes the HRU-411 (if CPE POWER switch is set to ON) and performs the
following two functions required by the HRU-411 to bring up the NEC radio port:
•Increases the HDSL line voltage to its high ±112 Vdc level with the PWRF option set to AUTO
•Enables HRU-411 to turn on its 130 Vdc radio port supply
These extended ranges are only available when using the HDU-409, HDU-404 or HDU-407
micro-doublers with the HRU-411 or HRU-402. Older doublers (HDU-451, HDU-439 and HDU-437)
cannot be used in circuits with more than two doublers in any line or local power system. For
compatibility guidelines on mixing newer doublers with older HRU and HLU models, refer to
“HiGain Doubler Circuit Deployment” on page 61.
For additional information about associated HiGain equipment, refer to the respective HiGain
technical practice (see “Appendix D - Product Support” on page 63).

Front Panel 150-231-185-05, Revision 05
4 September 13, 1999 HLU-231 List 8E
FRONT PANEL
The HLU-231 List 8E front panel is shown in Figure 1. The front-panel components are described in
Table 1 on page 5. For pinout diagrams of the HLU card-edge connector and the craft port, refer to
“Appendix A - Specifications” on page 52.
Figure 1. HLU-231 List 8E Front Panel

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HLU-231 List 8E September 13, 1999 5
Table 1. Front-panel Description
Front-panel Feature Function
Front-panel display Displays four-character status, provisioning, and alarm system messages.The front-panel display
illuminates when power is initially applied. To conserve power the display only remains on for
4 minutes. Using the MODE or SEL buttons reactivates the display and restarts the 4-minute timer.
Refer to Table 2 on page 6 for a listing of the four-character messages.
System option buttons
(MODE and SEL)
Permits the user options to be monitored and modified without the need of a maintenance terminal.
Used to initiate all HiGain loopbacks and to display DSX-1 line parameters and line unit identity.
Status LED The status LED can report the following conditions:
Green Normal operation
Flashing green HDSL loop acquisition
Red Fuse Alarm
Flashing red System alarm
Yellow Self Test is in process or an HLU-231 List 8E Customer Remote Loopback (CREM) or a Network
Local Loopback (NLOC) is in effect.
Flashing yellow HLU-231 List 8E is Armed to respond to Intelligent Repeater Loop (ILR) codes.
DSX-1 access jacks (DS1
Cross-connect frame)
XMT is the Transmit jack and RCV is the Receive Jack for spanning and bridging
SPAN Provides splitting jack access to (XMT) and from (RCV), the HDSL span at the DSX-1 interface.
Breaks the XMT and RCV paths to permit test signal insertion and retrieval.
BRG Provides non-intrusive bridging jack access to (XMT) and from (RCV) the HDSL span at the DSX-1
interface. Allows the two T1 payloads to be monitored.
Craft (RS-232) port Provides bidirectional communication between the unit and an external terminal to allow
configuration and performance monitoring through the Maintenance Terminal screens.
CLEI and ECI bar code label Provides the human-readable Common Language Equipment Identifier (CLEI) code number and the
Equipment Catalog Item (ECI) bar code number.
List number Identifies the version of the HLU-231.
Retaining latch Retains the card in the shelf when pulled up and extracts the card from the shelf when pulled down.
Configuration number Contains either a five or six-digit warranty configuration number or a stand-alone two or three-digit
configuration number as follows:
Digit 1 - Last digit of shipment year
Digits 2 and 3 - Shipment month
Digits 4, 5, and 6 - Configuration number
The configuration number can also be found on a small bar label that contains the Julian date code
and part number. This gummed label may be affixed to the PC board or to the front panel.

Front Panel 150-231-185-05, Revision 05
6 September 13, 1999 HLU-231 List 8E
Table 2 lists the front-panel display messages. The four-character displays reports the code of a pertinent alarm,
loopbackor diagnostic message, insome cases followedby a second four-character messagethat modifiesthe first
message with a value or current configuration setting.
Table 2. Front-panel Display Messages
Message Full Name Description
ALARM MESSAGES
ACO Alarm CutOff A system alarm has occurred, and has been retired to an ACO
condition by pressing the SEL button on the HLU front panel.
ALRM Alarm Condition A system alarm condition is in effect.
BER Bit Error Rate A system BER alarm is in effect.
LLOS Local Loss of Signal Indicates that no signal is detected at the T1 input to the HLU.
Causes a system alarm.
LOSW Loss of Sync Word Indicates that one of the HDSL loops has lost sync. Causes a system
alarm.
MAL1 or MAL2 Margin Alarm Loop 1 or Loop 2 The margin on HDSL Loop 1 or Loop 2 has dropped below the
threshold (1 to 15 dB) as set by the operator.
RLOS Remote Loss of Signal Indicates that no signal is detected at the DS1 input to the HRU.
Causes a system alarm.
LOOPBACK MESSAGES
CDUn?Customer Doubler nLoopback Query to initiate loopback at doubler n to CI, where nis the number
of the doubler.
CLOC Customer Local Loopback Signal from customer is looped back to the customer at the HRU.
CREM Customer Remote Loopback Signal from customer is looped back to the customer at HLU-231.
NDUn?Network Doubler nLoopback Query to initiate loopback at doubler n to network, where nis the
number of the doubler.
NLOC Network Local Loopback DSX-1 signal is looped back to DSX-1 at the HLU.
NREM Network Remote Loopback DSX-1 signal is looped back to DSX-1 at the HRU.
SMJK Remote SmartJack Loopback Signal from DSX-1 is looped back at the HRU by the HRU SmartJack
module.
DIAGNOSTIC MESSAGES
1=xx or 2=yy HDSL Loop Margins Indicates the power of the received HDSL signal on each loop
relative to noise. Any value of 06 dB or greater is adequate for
reliable system operation.
ACQ1 or ACQ2 Acquisition 1 or Acquisition 2 The multiplexers of the HLU and the HRU or first doubler are trying
to establish synchronization over Loops 1 or 2 of Span 1.
AnL1 or AnL2 Acquisition nLoop 1 or
Acquisition n Loop 2
The multiplexers of the two devices on Span nare trying to establish
synchronization with each other on Loops 1 or 2, where nis the
number of the span.
ARM HiGain System Armed Armed to respond to Intelligent Repeater Loop Codes.
BAD RT? No response from HRU The HLU does not receive any response from the HRU. Therefore,
the integrity of the HRU or the two HDSL loops (they may be open)
is questionable.
CODE xxxx Line Code: AMI, B8ZS, AUTO The line code that HLU-231 List 8E is receiving at its DSX-1
interface, if the DS1 option is set to AUTO. Otherwise, it mimics
either of the other two DS1 line code settings, Alternate Mark
Inversion (AMI) or Bipolar with 8-zero Substitution (B8ZS).
Displayed during System Settings review mode.

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HLU-231 List 8E September 13, 1999 7
DS0 DS0 Blocked Channels Indicates status of DS0 blocked channels. NONE indicates no
channels are blocked. BLK indicates some channels are blocked.
FERR Framing Bit Error Framing bit error occurred at HLU T1 input.
FRM xxxx Frame: SF, ESF, UNFR, NONE Defines the type of frame pattern being received from the DSX-1:
SuperFrame (SF), Extended SuperFrame (ESF), Unframed (UNFR),
or NONE. Displayed during System Settings review mode.
H1ES or H2ES HDSL CRC Error Channel 1 or
Channel 2
HDSL Loop 1 or Loop 2 CRC error.
nHDU Number of Doublers This message indicates the number (n) of doublers in the circuit.
INSL, then xxDB Maximum Insertion Loss The maximum Insertion Loss message (INSL) appears followed by
xxDB, where xx is the maximum insertion in dB of all spans and
loops.
LBPV Local Bipolar Violation A bipolar violation has been received at the T1 input to the HLU-231.
LIST xxxx HLU-231 List Number The software list number (xxxx) appears during the System Settings
review mode. Press the MODE button for 3 seconds to display the
list number.
MNGD Managed The HLU is under control of the HMU-319 network management
unit. In this state, the front-panel craft port and push buttons are
disabled.
PWR FEED GND Power Feed Ground One of the HDSL loops has been grounded.
PWR FEED ON Power Feed On Indicates that the HDSL loops are not grounded or shorted.
PWR FEED OFF Power Feed Off HDSL span power has been turned off by setting the PWFD option
to DIS, or HDSL span power has been turned off by use of the
A1LB/A2LB/A5LB Intelligent Office Repeater (IOR) Power Down
code.
PWRF SHRT Power Feed Short Indicates a short between the two HDSL pairs. This same message
can occur with an HRU that is drawing the correct amount of power
over good cable pairs but cannot communicate with the HLU.
SELF TEST Self Test The HLU is in a self-test mode. This occurs every power On/Off
cycle.
SIG1 or SIG2 Signal 1 or Signal 2 The transceivers of the HLU and HRU or first doubler are trying to
establish contact with each other on Loop 1 or Loop 2 of Span 1.
SnL1 or SnL2 Signal nLoop 1 or Loop 2 The transceivers of the two devices on Span nare trying to establish
contact with each other on Loop 1 or Loop 2, where nis the number
of the span.
TLOS Transmit Loss of Signal DSX-1 signal is looped back to the DSX-1 interface at the HRU. HRU
is in a logic loopback state caused by a loss of its DS1 input from
the CI, if enabled at the HRU by its TLOS switch option.
VER xxxx HLU-231 Version Number The software version number (xxxx) appears during the System
Settings review mode. Press the MODE button for 3 seconds to
display the software version.
Table 2. Front-panel Display Messages (Cont.)
Message Full Name Description

Installation 150-231-185-05, Revision 05
8 September 13, 1999 HLU-231 List 8E
INSTALLATION
Figure 2. Installing the HLU-231 List 8E into a Shelf
1Slide the HLU-231 into the card guides of the desired slot, then push the unit back until it touches the
backplane card-edge connector and the retaining latch on the front panel opens (Figure 2).
2Place your thumbs on the HLU-231 front panel and push the HLU-231 into the card-edge connector until the
retaining latch closes. This indicates that the card is properly seated.
Upon receipt of the equipment, visually inspect the contents for signs of damage. If the
equipment has been damaged in transit, immediately report the extent of damage to the
transportation company and to PairGain Technologies.
When installing an HLU in a chassis, be sure to wear an antistatic wrist strap. Avoid touching
components on the circuit board.

150-231-185-05, Revision 05 Installation
HLU-231 List 8E September 13, 1999 9
VERIFICATION
Once the HLU-231 is installed, verify that it is operating properly. To do this, you need to monitor the following:
•Status LED
•Status messages reported by the front-panel display (see Table 2 on page 6)
Verification without a Downstream Device
If there is no downstream device installed:
1Verify that the HLU powers up. (The front-panel display illuminates and reports four-character status
messages. See Table 2 on page 6 for a list of messages.)
2Verify that the HLU attempts to communicate with downstream devices. Even if a downstream device is not
present, the following events should occur:
aThe front-panel display reports four-character status messages.
bThe HLU enters self-test mode (Status LED is yellow).
cThe HLU again attempts communication with downstream devices, repeating events athrough buntil a
downstream device is detected.
Verification with a Downstream Device
If a downstream device has been installed:
1Verify the HLU powers up. (The front-panel display illuminates and reports status messages.)
2Verify the HLU attempts to communicate with downstream devices (status LED flashes green). One of the
following occurs:
•If downstream devices are successfully identified and the HDSL loops synchronize, the HLU status LED
will be a steady green. The HLU reports normal margin messages on the front-panel display.
•If downstream devices are not successfully identified, the HLU reports four-character status messages
and enters self-test mode. The HLU successively:
–enters self-test mode
–completes self-test mode
–attempts communication again
–reports four-character status messages
The HLU repeats this cycle until a downstream device is detected.
3If there is more than one span, verify that each subsequent span synchronizes normally by monitoring the
front-panel display messages.
4If a remote unit is installed, verify that the last span synchronizes normally. The HLU status LED should be
a steady green, and the front-panel display should report normal margin messages.
5Verify that a valid T1 signal has been applied to the HLU and the HRU.
•If no T1 signal is being applied to either the HLU or the HRU inputs, then the appropriate T1 alarms
(LLOS or RLOS) are observed on the front-panel display and the status LED flashes red.
•If a valid T1 signal is being supplied to the HLU and HRU, then T1 alarm indications should be absent
and the status LED should be a steady green.

Installation 150-231-185-05, Revision 05
10 September 13, 1999 HLU-231 List 8E
PROVISIONING REQUIREMENTS
Refer to “Provisioning” on page 11 for information about using the MODE and SEL buttons or the Maintenance
Terminal screens to configure the HLU. While the MODE and SEL buttons can be used to manually accomplish
some provisioning tasks, such as setting system options, the Maintenance Terminal screens (available when you
connect a PC to the craft port) can handle all provisioning tasks. Tasks that you need to complete are:
1Set the time and date (see “Set Clock Screen” on page 19).
2Set the circuit IDs (see “View System Inventory Screen” on page 35).
Assuming that the HLU has been successfully installed and provisioned, youshould do the followingto ensure an
accurate Alarm History and Performance History.
1Clear the Span Status, Performance Data, and Performance History screens. This can be accomplished by
pressing (clear) at the Span Status screen (see “View Span Status Screen” on page 15).
2Clear the Alarm History screens (see “View Alarm History Screen” on page 33).
&

150-231-185-05, Revision 05 Provisioning
HLU-231 List 8E September 13, 1999 11
PROVISIONING
This is a reference section for HLU provisioning. There are two methods for provisioning the HLU-231 List 8E:
•Use the MODE and SEL buttons on the front panel of the HLU to:
–set system options
–reset the HLU to its factory default settings for system options
–display system option settings (scroll mode)
–select system loopbacks
•Use a maintenance terminal (ASCII terminal or a PC running terminal emulation software) connected to the
HLU craft port to access the Maintenance Terminal Main Menu (Figure 3 on page 14). This gives you full
access to all HLU status, history, inventory, and provisioning screens.
USING THE MODE AND SEL BUTTONS
Setting Options through MODE and SEL
To provision the HLU-231 List 8E through the MODE and SEL buttons on the front panel:
1Press the MODE button for 2 seconds and then release it. The front-panel display alternately shows the first
system parameter and its current setting.
2Press the SEL button to step through all possible settings (one at a time) of the selected parameter.
3After the desired setting has been selected, press the MODE button. This updates the current displayed
parameter to the selected setting, and then advances to the next configurable parameter. After the last
parameter has been selected, a CONF NO message appears on the front-panel display.
4Do one of the following:
•To cancel the session without saving the requested parameter changes, press the MODE button or, do
nothing. (After 30 seconds, the display returns to its normal mode without saving the new changes.)
•To accept the requested parameter changes, press the SEL button. (A CONF YES message displays, and
the display returns to its normal mode after saving the new changes.)
No dip switches or jumpers are required to provision the HLU-231 as it contains a non-volatile
RAM (NVRAM) which stores the system option settings. System option settings are retained if
shelf power is lost or if the HLU-231 is unplugged.

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12 September 13, 1999 HLU-231 List 8E
Resetting to Factory Default Values
All user options (Table 8 on page 21) can be set to the factory default values using the MODE and SEL buttons.
To set the user options to their default values:
1Press the SEL button for 6 seconds until the following message appears:
DFLT NO
2Press the SEL button while the DFLT NO message is displayed.
The message changes to DFLT YES indicating the factory default values are now in effect and the display
returns to the normal mode.
To terminate the DFLT mode without setting the factory default values, do one of the following:
•Press the MODE button to return to the normal display mode
•Wait 30 seconds for the unit to return to the normal display mode.
Displaying System Parameter Settings
To scroll throughthe current settings of all system parameters, press the MODE button for 3 or more seconds. The
following parameters are displayed:
•HLU software version number
•HLU List number
•Type of frame pattern being received from the DSX-1
•Line code of the signal being received from the DSX-1 (see note)
•HDSL power level setting
•All user-configured parameter settings
Disabling an Alarm
If the system is in a Minor alarm state, the alarm relay can be disengaged by pressing the SEL button. This turns
off the Alarm Cut-off (ACO) indication.
Loopback Modes
See “Loopback Operation” on page 42 for instructionson using the MODE and SEL buttons to activate loopbacks.
The line code parameter is the actual DSX-1 line code being received by the HLU if the DSX-1
code pattern is set to AUTO. Otherwise, the line code parameter mimics either of the other two
line code settings, Alternate Mark Inversion (AMI) or Bipolar with 8-Zero Substitution (B8ZS).