Watson 2 Rev.

LTU/NTU
Operating Manual

Document Identification SZ.DOC.W2E.3.pdf

Document Version 1.2
Document Revision 3.11. 2000

Binzstrasse 35 CH-8045 Zurich

Switzerland
CH-1 456 11 11 Fax CH-1 466 92 92
SZ.DOC.W2E.3.pdf LTU/NTU
Version: 1.2 Operating Manual

Version Control

Version of Major changes to previous version

Operating Manual
0.9 Creation, SSt, UFh.
1.0 Revised Version, CTa.

1.1 Description of the Commands: RESET and STOPAL, for the Dual
LTU, CTa.

1.2 Operating voltage range corrected; Nx64 kbit/s, E1, Installation

Guide, CE, Safety, structure according W3/4, remote powering
part, LSs, RAn
TMN Interface and Minirack address features added, URr

Copyright 2000 by Schmid Telecommunication, Zurich, Switzerland. All rights reserved. Reproduction of part or all of
the contents in any form is expressly prohibited without the prior written consent of Schmid Telecommunication.
Schmid Telecommunication has used its discretion, best judgments and efforts in preparing this document. Any
information contained in this document is provided without any warranty of any kind. Schmid Telecommunication
hereby disclaims any liability to any person for any kind of damage. Schmid Telecommunication may make
improvements and/or changes of this document at any time.

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Declaration of Conformity
Watson 2 LTU, E1, Rev.E, with 19” subrack SZ.379.V3 SZ.363.V510, SZ.363.V530
LTU, 2*E1, Rev.E, with 19” subrack SZ.379.V3 SZ.363.V511, SZ.363.V533
NTU, E1, Rev.E , tabletop SZ.364.V510, SZ.364.V530
NTU, nx64, Rev.E, tabletop SZ.364.V580
LTU, 2*E1, Rev.E, minirack SZ.798.V511, SZ.798.V533
NTU, E1, Rev.E, minirack SZ.795.V510, SZ.795.V530
NTU, nx64, Rev.E, minirack SZ.795.V580
REG with housing SZ.372.V3, SZ.371.V3, SZ.371.V2 SZ.372.V2

Manufacturer: Schmid Telecom AG

Binzstrasse 35
CH-8045 Zurich

The products mentioned above comply with the regulations of the following European Directives:
89/336/EEC The compliance of the above mentioned product with the
Directive containing requirements in respect requirements of the directive 89/336/EEC is ensured by
with electro-magnetic compatibility. complete application of the following harmonized European
Standards:
EN 300386-2 (1998)
73/23/EEC The compliance of the above mentioned product with the
Directive containing requirements in respect requirements of the directive 73/23/EEC is ensured by
with safety requirements. complete application of the following harmonized European
Standards:
EN 60950/A4 (1997)
99/5/EEC The compliance of the above mentioned product with the
Directive containing requirements in respect requirements of the directive 99/5/EEC is ensured by
with Radio & Telecommunication Terminal complete application of the following harmonized European
Equipment. Standards:
EN 300386-2 (1998)
EN 60950/A4 (1997)

The compliance of the above mentioned products with the specified requirements of the applicable directives
and harmonized and non-harmonized standards is shown in the following internal and external test reports:
SZ.QDOC.W2E.pdf and W2E_Test_Reports.pdf

CE Label attached to the product(s): on minirack, on tabletop, on 19” subrack (for LTU only)
Issued by: Schmid Telecom AG
Binzstrasse 35
CH-8045 Zurich
Place and date: Zurich, 3.11.2000

Signatures: Signature 1 Signature 2

Dr. Lothar Schultheis Walter Büchel

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Contents

1 The Watson 2 Family................................................................................................................. 1

2 General Information .................................................................................................................. 3

2.1 Important Safeguards ........................................................................................ 3
2.2 Ordering Information.......................................................................................... 5
2.2.1 LTU.................................................................................................... 5
2.2.2 NTU................................................................................................... 5
2.2.3 REG................................................................................................... 6
2.2.4 Accessories........................................................................................ 6
3 Installation Guide ...................................................................................................................... 7
3.1 Preparations ..................................................................................................... 7
3.2 Installing a Watson Modem................................................................................ 7
3.3 Installation Requirements................................................................................... 9
4 Interface Configuration Options...............................................................................................11
4.1 DSL.................................................................................................................11
4.1.1 Master / Slave....................................................................................11
4.1.2 HDSL Operating Modes......................................................................12
4.1.3 Autorestart.........................................................................................13
4.1.4 Time Slot Mapping .............................................................................13
4.2 E1 Interface (2 Mbit/s G.703 / G.704) ................................................................14
4.2.1 Framing.............................................................................................14
4.2.1.1 Transparent Mode ...........................................................................14
4.2.1.2 Framed Mode ITU-T G.704 ..............................................................14
4.2.1.2.1 CRC4.........................................................................................14
4.2.1.2.2 E-bit Insertion .............................................................................15
4.2.2 AIS Generation ..................................................................................15
4.2.3 AIS Detection.....................................................................................15
4.2.4 E1 Clock Modes.................................................................................15
4.2.4.1 Clock Sources .................................................................................15
4.2.4.2 External Clock Mode........................................................................17
4.3 ISDN PRA Interface .........................................................................................18
4.3.1 PRA Mode.........................................................................................19
4.3.2 CRC4 Processing Options ..................................................................19
4.3.2.1 Digital Link without CRC Processing (Option 1) .................................19
4.3.2.2 Digital Link with CRC Processing in the NT1 (Option 2)......................20
4.3.2.3 Digital Link with CRC Processing in the LT and NT1 (Option 3) ..........22
4.3.2.4 Digital Link with CRC Monitoring in the NT1 (Option 4).......................22
4.3.3 Generation of CRC4 Error Notifications to the ET.................................23

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4.4 n x 64kbit/s Interface........................................................................................24

4.4.1 Features............................................................................................24
4.4.2 Configuration .....................................................................................25
4.4.2.1 Time Slot Mapping...........................................................................25
4.4.2.1.1 Terminology ...............................................................................25
4.4.2.1.2 n x 64kbit/s Time Slot Mapping....................................................25
4.4.2.1.3 E1 Time Slot Mapping.................................................................26
4.4.2.2 User Interface Type .........................................................................26
4.4.2.3 Bit Rate...........................................................................................26
4.4.2.4 Clock Mode.....................................................................................26
4.4.2.5 Clock Direction................................................................................28
4.4.2.6 V.54 Loops and Loop Control...........................................................28
4.4.2.6.1 Normal Handshake Operation......................................................28
4.4.2.6.2 Supported V.54 Loops ................................................................29
4.4.2.6.3 Automatic Loop Control through the DTE/DCE Interface ...............29
4.4.2.7 Byte Timing.....................................................................................29
4.5 TMN Interface (Minirack LTU only)....................................................................30
4.5.1 TIA/EIA-485 4-wire Bus ......................................................................30
4.5.2 TIA/EIA-485 2-wire Bus ......................................................................31
4.5.3 TIA/EIA-485 Bus Termination .............................................................33
5 Performance Monitoring ..........................................................................................................35
5.1 Noise Margin ...................................................................................................35
5.2 G.826 Performance Monitoring .........................................................................35
5.2.1 DSL Interface ....................................................................................36
5.2.2 E1 Interface.......................................................................................37
5.2.3 ISDN PRA Interface...........................................................................38
6 Alarms 39
6.1 LEDs...............................................................................................................39
6.1.1 Status LEDs ......................................................................................40
6.1.2 Alarm Conditions ...............................................................................40
6.1.2.1 Local LED.......................................................................................40
6.1.2.2 Remote LED ...................................................................................41
6.2 Alarm Relays ...................................................................................................42
6.2.1 LTU...................................................................................................42
6.2.1.1 Alarm Conditions .............................................................................42
6.2.2 NTU..................................................................................................43
6.2.2.1 Alarm Conditions .............................................................................43
7 Power Concept ........................................................................................................................45
7.1 LTU.................................................................................................................45
7.1.1 Power and Grounding ........................................................................45
7.2 NTU................................................................................................................45
7.2.1 Power and Grounding ........................................................................45
7.2.2 Power Failure Alarm...........................................................................46
7.3 Remote Powering ............................................................................................46
8 Monitor 51
8.1 General ...........................................................................................................51
8.2 Addressing ......................................................................................................51
8.2.1 LTU...................................................................................................51
8.2.2 LTU Minirack.....................................................................................54
8.2.3 NTU..................................................................................................54
8.3 Structure and Organization ...............................................................................54

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8.3.1 Performance Management PM............................................................55

8.3.1.1 G826 Command ..............................................................................56
8.3.1.2 RESETG826 Command ...................................................................61
8.3.2 Fault and Maintenance Management FMM ..........................................61
8.3.2.1 SQ Command .................................................................................62
8.3.2.2 SQ REGn Command .......................................................................62
8.3.2.3 STARTUP Command.......................................................................63
8.3.2.4 STATUS Command .........................................................................64
8.3.2.5 STATUS REGn Command ...............................................................67
8.3.2.6 ALARM Command...........................................................................68
8.3.2.7 ACO Command...............................................................................70
8.3.2.8 LOOP1 Command ...........................................................................70
8.3.2.9 LOOP2 Command ...........................................................................71
8.3.2.10 LOOPREGn Command....................................................................71
8.3.2.11 STARTAL Command .......................................................................71
8.3.2.12 STOPAL Command .........................................................................72
8.3.2.13 TRACETIME Command...................................................................72
8.3.2.14 RESET Command ...........................................................................72
8.3.3 Configuration Management CM...........................................................72
8.3.3.1 CONFIG Command .........................................................................73
8.3.3.2 Configuration Commands.................................................................74
8.3.3.3 DEFAULT Command .......................................................................76
8.3.3.4 REMOTE Command........................................................................81
8.3.3.5 COPY Command.............................................................................82
8.3.3.6 LOCAL Command ...........................................................................82
8.3.4 Accounting Management AM..............................................................82
8.3.5 Security Management SM...................................................................82
8.4 Monitor Commands for the n x 64kbit/s Interface................................................82
8.4.1 Fault and Maintenance Management FMM ..........................................83
8.4.1.1 ALARM Command...........................................................................83
8.4.2 Configuration Management CM...........................................................83
8.4.2.1 CONFIG Command .........................................................................84
8.4.2.2 BITRATE Command .......................................................................85
8.4.2.3 CLOCKMODE Command.................................................................85
8.4.2.4 CLOCKDIR Command.....................................................................85
8.4.2.5 V54LOOPS Command.....................................................................85
8.4.2.6 BYTETIMING Command..................................................................85
8.4.2.7 UIF Command.................................................................................85
8.4.2.8 DEFAULT Command .......................................................................85
8.4.2.9 COPY Command.............................................................................87
8.5 Monitor Commands for LTU Minirack TMN Interface...........................................88
8.5.1 ADDRESS Command.........................................................................88
8.5.2 V11WIRES Command........................................................................90
9 Front and Rear Panel Description ............................................................................................93
9.1 Tabletop NTU, Rear Panel................................................................................94
9.2 Minirack NTU, Front Panel ................................................................................94
9.3 Plug-in LTU, Front Panel...................................................................................96
9.4 Minirack LTU, Front Panel ................................................................................99
10 Connectors’ Description ........................................................................................................101
10.1 DSL Connector ..............................................................................................102
10.2 E1 Connector.................................................................................................103
10.2.1 Impedance 120Ω .............................................................................103
10.2.2 Impedance 75Ω ...............................................................................105
10.3 n x 64kbit/s Connector ....................................................................................105

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10.3.1 User Interface Type ......................................................................... 105

10.3.2 n x 64kbit/s Cables........................................................................... 108
10.3.2.1 V.35 DTE Cable ............................................................................ 108
10.3.2.2 V.35 DCE Cable............................................................................ 109
10.3.2.3 V.36 DTE Cable ............................................................................ 110
10.3.2.4 V.36 DCE Cable............................................................................ 111
10.3.2.5 X.21 DTE Cable ............................................................................ 112
10.3.2.6 X.21 DCE Cable............................................................................ 113
10.4 Monitor Connector (NTU)................................................................................ 115
10.5 Monitor Connector (LTU in Minirack) ............................................................... 115
10.6 48VDC Power Connector (NTU) ....................................................................... 116
10.7 48VDC Supply (Minirack) ................................................................................. 117
10.7.1 Mains Connector (Minirack LTU only)................................................ 117
10.7.2 2048kHz Input (Minirack LTU only) ................................................... 117
10.7.3 TMN Alarms (Minirack LTU only) ...................................................... 118
11 Technical Specifications ........................................................................................................ 119
11.1 Interfaces ...................................................................................................... 119
11.1.1 DSL Line Interface........................................................................... 119
11.1.2 User Interface.................................................................................. 120
11.1.3 Monitor Interface.............................................................................. 121
11.1.4 TMN and Alarm Interface (Minirack LTU Only)................................... 121
11.1.5 The 230/115Vrms and 48V DC Supply of the Minirack............................ 121
11.1.6 External Clock ................................................................................. 122
11.2 Power Supply ................................................................................................ 122
11.2.1 LTU................................................................................................. 122
11.2.2 NTU................................................................................................ 123
11.2.3 REG................................................................................................ 123
11.3 Environment .................................................................................................. 123
11.3.1 Climatic Conditions .......................................................................... 123
11.3.2 Safety ............................................................................................. 123
11.3.3 EMC ............................................................................................... 123
11.4 Physical Dimensions ...................................................................................... 124
11.4.1 LTU................................................................................................. 124
11.4.2 NTU................................................................................................ 124
12 Diagnostics and Troubleshooting.......................................................................................... 125
12.1 Test Loops..................................................................................................... 125
12.2 Hints for Troubleshooting................................................................................ 127
13 Appendix 129
13.1 Abbreviations................................................................................................. 129
13.2 Referenced Documents .................................................................................. 132

Figures
Figure 4-1: Clock Sources..........................................................................................16
Figure 4-2: Synchronous Operation (=”Loop Timing”)...................................................16
Figure 4-3: External Clock Mode.................................................................................17
Figure 4-4: Reference Points of the PRA .....................................................................18
Figure 4-5: Digital Link without CRC Processing ..........................................................20
Figure 4-6: Digital Link with CRC Processing in the NT1 ..............................................21
Figure 4-7: Digital Link with CRC Processing in the LT and NT1 ...................................22

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Figure 4-8: Digital Link with CRC Monitoring in the NT1 ...............................................23
Figure 4-9: TMN bus 4-wire connection for Minirack units.............................................30
Figure 4-10: TMN bus 2-wire connection for Minirack units...........................................31
Figure 4-11: TMN bus 2-wire connection for Plug-in units .............................................32
Figure 4-12: Termination for long TMN bus..................................................................34
Figure 5-13: Regenerator G.826 Performance Evaluation.............................................36
Figure 5-14: E1 G.826 Performance Evaluation ...........................................................37
Figure 5-15: PRA G.826 Performance Evaluation ........................................................38
Figure 7-16: Line feed current vs loop resistance for different NTU power consumptions48
Figure 7-17: LTU powers one REG and one NTU: Line feed current vs loop resistance
two different REG power consumptions.......................................................................48
Figure 7-18: LTU powers two REGs: Line feed current vs loop resistance two different
REG power consumptions..........................................................................................49
Figure 8-19: LTU Interface Addressing Scheme ...........................................................53
Figure 12-20: Standard Test Loops ...........................................................................125
Figure 12-21: Regenerator Loopback........................................................................126
Figure 12-22: Regenerator in Loopback Mode ...........................................................127

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1 The Watson 2 Family

The Watson II family is a 2B1Q based 2-pair HDSL-System. It was designed with
flexibility and modularity in mind. It supports both full and fractional E1 data rates, in
either framed or transparent mode and ISDN Primary-Rate-Access (PRA).
The Line-Termination-Units (LTU) are available as 19′′ subrack card or as minirack
version (only Dual LTU version). The LTU may be configured (jumper) as LTU-L or
LTU-R. The LTU-R is capable of remotely powering a remote NTU-R and a regenerator
(i.e. the LTU-R is a remote power source). The LTU-R is only master configurable,
whereas the LTU-L is both master and slave configurable.
The regenerator has to be remotely powered via the HDSL line and is available with
different housings for outdoor and underground installation.
The Network-Termination-Unit (NTU) is available as a table-top unit or as a minirack
version. The NTU may be configured by a slide switch as either NTU-R or NTU-L. An
NTU-R is remotely powered by an LTU-R, whereas an NTU-L is powered by a
230V/48V mains adapter.
An Alarm Control Unit (ACU) in the subrack enables the connection of the EIA485-bus,
the EIA232 Monitor interface, and the alarm relays.
An optional Control and Management Unit (CMU) in the 19” subrack acts as an SNMP
agent and brings TMN facilities to the system.

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2 General Information

2.1 Important Safeguards

This section describes the safety precautions the user should abide by when operating this
equipment.
• Transport this equipment in its original packaging or by using appropriate materials to
prevent against shock and impact,
• Before setting up this product for operation please make note of the accompanying
environmental requirements.
• Slots and openings in the unit are provided for ventilation. To ensure reliable
operation and to protect it from overheating these slots and openings must not be
blocked or covered.
• Condensation may occur externally or internally if this equipment is moved from a
colder room to a warmer room. When moving this equipment under such conditions,
allow ample time for the equipment to reach room temperature and to dry before oper-
ating.
• Note that normal operation (in accordance with EN 60950) is only possible when the
external housing is left in place (ventilation, fire prevention, and radio interference).
• Before supplying power, verify the power rating identified on the marking label
complies with the local power source.
• Do not allow anything to rest on any of the attached cables and do not locate the
product where persons will walk or trip on the cables.
• Connect this equipment only to an approved, properly grounded, and accessible socket
outlet. To completely turn off this equipment you must remove the power cord from
the system.
• Avoid connecting or disconnecting data lines during lightning storms.
• Follow the accompanying instructions when connecting the required cabling.
• Make sure no foreign objects or liquids come into contact with the internal
components (danger of shock or short circuit).
• In an emergency (e.g., damaged external housing or internal elements, liquid spills)
immediately remove the power cord and notify customer service.
• Electrostatic electricity can damage internal components. Ground yourself before
touching any internal components.

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• Never use water to clean this device. lf water reaches the internal parts, extreme
danger may result to the user or the equipment.
• Never use scouring or abrasive cleaning agents, or agents containing alkaline on
device. Damage of the device‘s exterior may result.

Information for the Technician

• Remove the network cables before opening this equipment or removing the plug-in
units, respectively.

Safety Notices
Do not proceed any of these notices until you have fully understood the implications:

• Caution! Potential hazard that can damage the product.

• Important! Potential hazard that can seriously impair operation.

2.2 Ordering Information

2.2.1 LTU
Model Description Product Number
Plug-in W2 LTU-L/R E1 120Ω SZ.363.V510x
W2 LTU-L/R E1 75Ω SZ.363.V530x
W2 Dual LTU-L/R 2xE1 120Ω SZ.363.V511x
W2 Dual LTU-L/R 2xE1 75Ω SZ.363.V533x
Minirack W2 Dual LTU-L/R 2xE1 120Ω SZ.798.V511x
W2 Dual LTU-L/R 2xE1 75Ω SZ.798.V533x

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2.2.2 NTU
Model Description Product Number
Table-top W2 NTU-L/R E1 120Ω SZ.364.V510x
W2 NTU-L/R E1 75Ω SZ.364.V530x
W2 NTU-L/R nx64 SZ.364.V580x
Minirack W2 NTU-L/R 2xE1 120Ω SZ.795.V510x
W2 NTU-L/R 2xE1 75Ω SZ.795.V530x
W2 NTU-L/R nx64 SZ.795.V580x

Notes:
x = W, as a default for the general version
x = other letter than W standing for customer-specific version

2.2.3 REG
Description Product Number
W2 regenerator unit SZ.372.V2x
W2 regenerator case (open air, ground installation) for 4 REG SZ.372.V3x
W2 regenerator outdoor case IP66, for 1 REG SZ.371.V2x
W2 regenerator outdoor case IP55, for 2 REG SZ.371.V3x

2.2.4 Accessories
Subrack SZ.379.V3W
ACU2R SZ.369.V5W
ACU48R SZ.369.V4F
Nx64kbit/s Cables
V.35 DTE, 3m length SZ.378.0F1.V1
V.35 DCE, 3m length SZ.378.0G1.V1
V.36 DTE, 3m length SZ.378.0H1.V1
V.36 DCE, 3m length SZ.378.0J1.V1
X.21 DTE, 3m length SZ.378.0K1.V1
X.21 DCE, 3m length SZ.378.0L1.V1
AC/DC Adapter, 230V version SZ.378.0A0.V1
AC/DC Adapter, 115V version SZ.378.0A0.V3
DC/DC Adapter, 48/60V SZ.378.0A0.V5

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3 Installation Guide

This chapter gives a brief overview over the necessary steps to install a Watson modem.

3.1 Preparations
Before going to the installation site, check what you need of the following equipment in
addition to the modem:
• AC/DC Power adapter or supply cable (for tabletop or minirack NTU)
• DSL cable
• Network cable
• Monitor cable and terminal
• Mounting material
In case your installation requires special DSL cabling or rack mounting, check what you
need of the following tools:
• Wire stripping tool appropriate for the cable size.
• Crimp tools for connectors
• Screwdrivers

3.2 Installing a Watson Modem

• Unpack and mount the unit safely. Keep chapter "Important Safeguards" in mind
when choosing an appropriate place for tabletops. Miniracks can be mounted in 19"
racks.
• Plug-in units are simply inserted into subracks and will start operation immediately.
Mounting of subracks is described in manual "Installation Manual of Subrack".
• Check the setting of the remote power switch/jumper.
NTU In the default switch position "Rem", the NTU modem is powered via the
xDSL line and will start operation immediately after connection of the
xDSL line. In case the remote LTU modem does not support power feeding,
local power supply is needed for operation. In position "Loc", the NTU
modem is powered locally and needs the power supply connected to
operate.
LTU In the default jumper positions "RPWR A ON", "RPWR B ON", .. the LTU

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modem is powering the remote NTU unit. In jumper position "OFF", the
remote powering function is disabled.

Caution: LTUs must be disconnected from power during change of jumper setting.
See chapter "Power concept"; section "Remote powering" for further information.
• Connect the modem to the network or PC. Plug the appropriate cable to the interface
connector on the unit. Refer to chapter "Connectors' Description" for cable
definitions.
• Connect the modem to the DSL line. If using a preconfigured cable, just connect the
xDSL line with male RJ45 cable into the female RJ45 connector of the modem. If
you need to configure the cable, refer to chapter 10 "Connector Description"; section
"DSL Connector".
• NTUs in remote power mode will start operation immediately with factory default
settings, and further configuration is optional.
• Optional: Connect the power supply. For local power supply of NTUs, connect the
AD/DC power adapter (ordered separately) to the mains and to the unit. The power
adapter is optional for NTUs in remote power mode. Minirack LTUs can be
connected directly to mains, to a 48VDC source or both at the same time. Plug-in units
are powered via the subrack backplane. See chapter "Power concept" for further
information.
• Optional: Configure the unit. Connect a VT100 terminal using the serial monitor
cable to the "Monitor" connector of the unit or of the subrack.
Important: Check DSL mode configuration "master/slave". There must be a "master" unit connected
to a "slave" unit for proper operation. The configuration of a "slave" unit can also be done
via the "master" unit. Refer to chapter "Monitor Operation" for detailed information.
• Check the proper operation. The LED "Local" lights green in normal operation. In
"slave" mode, the LED "Remote" is off, but should light green for normal operation
in "master" mode. See chapter "Alarm Indication" for further information.
Watson modems are generally very easy to install; usually just plugged to the DSL line
and to the network. If more configuration is needed, the operator is supported by
comprehensible menus, default settings, plausibility checks and helpful warning
messages. This way, the operator can easily control the wealth of powerful functions that
Watson modems provide.

3.3 Installation Requirements

Installation of this equipment has to be done by qualified personnel only.
To achieve safety and satisfactory EMC performance, the plug-in LTU has to be inserted
into the subrack. Subrack slots that are not used have to be covered with blanking plates.
The subrack or minirack must be bonded to earth. This is usually achieved by installing
the subrack or minirack into a rack which is connected to the earthing network according
to ETS 300 253.
Additionally, on the subrack an extra earth terminal for connection to the FPE connector
(Functional Protective Earth) is provided.

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4 Interface Configuration Options

The following sections describe the various configuration options. On the plug-in LTU,
the operating modes are configurable via the V.24 monitor interface or via the TMN
interface of the ACU, whereas on the minirack LTU, table-top NTU and minirack NTU,
they are directly configurable via the monitor interface. If the LTU/NTU is slave, it is
also configurable from the master side. Only the remote/local powering has to be
configured via jumpers on the board of the LTU or via slide switches on the NTU.

4.1 DSL
The following configuration options refer to the DSL side and do not affect the user
interface operating mode except in case of Fractional, Partial, or Hot Standby operation.

4.1.1 Master / Slave

To start up a DSL link, one system unit must be configured as master and the other one as
slave. The link start-up procedure is controlled by the master. If both system units are
configured as master or as slave, no start-up will occur.
Usually, the LTU is configured as master and the NTU as slave (default setting).
However, it is possible to set up a DSL link with two LTUs or two NTUs, as long as one
is configured as master and the other one as slave. In these cases, remote powering is not
possible.
Generally, the master-slave permissions are:
• The slave unit has only the permission to change its own configuration locally. It
cannot access nor modify the master unit's configuration or data. Access to the slave
unit's configuration or data is possible via local monitor or via the master unit.
• The master unit has local access as well as remote access to the slave unit. For safety
reasons, only the master / slave configuration and the autorestart option cannot be
altered by the master unit over the DSL link.
When the “Remote” LED on the front panel of the NTU is lit, the system unit is
configured as master.

4.1.2 HDSL Operating Modes

In this section the various operating modes of the HDSL transceiver pairs are described.

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In Fractional, Partial and Hot Standby mode, remote power feeding is not available since
the NTU consumes more power than can be suppled over a single pair on long loops with
high DC resistance.
In Normal mode, there are no restrictions on configuration options.
For Fractional and Partial operation mode, also refer to ETSI TS 101 135, sections 7.4
and 7.5.

Normal Mode:
In Normal mode, startup and operation of the two HDSL channels (pairs) are
synchronized to each other. Therefore, if one of the two HDSL channels fails, both
channels are restarted and data transmission is interrupted until both channels have been
reactivated.

Fractional Mode:
In Fractional mode, only HDSL channel A is in operation while the transceiver of channel
B is switched off. Only time slots TS0-TS17 of the application frame are transmitted
while the unused time slots TS18-TS31 are refilled with all-ones (AIS) at the receive end.

Partial Mode:
In Partial mode, startup and operation of the two HDSL channels (pairs) are not
synchronized to each other. Therefore, if one of the HDSL channels fails, only the failed
channel is restarted while the other channel continues data transmission.
Time slots TS0-TS17 of the application frame are assigned high priority and TS18-TS31
low priority. Therefore, if one of the HDSL channels fails, time slots TS0-TS17 are
dynamically reallocated to the remaining active channel while time slots TS18-TS31 are
filled with AIS until the failed channel has been reactivated.
If the HDSL channel carrying time slots TS0-TS17 fails, high priority data may be
corrupted for a short time only, due to the reallocation procedure. If the HDSL channel
carrying time slots TS18-TS31 fails, high priority data will not be corrupted at all.

Hot Standby Mode:

In Hot Standby mode, startup and operation of the two HDSL channels (pairs) are
performed in the same way as in Partial mode, except that both channels are carrying time
slots TS0-TS17 of the application frame redundantly. The unused time slots TS18-TS31
are filled with all-ones (AIS) at the receive end.
If the active channel fails, the receivers will immediately switch to the standby channel
and application data may be lost for a short time only, due to the reallocation procedure.
If the standby channel fails, only this channel is restarted and no application data will be
lost.

4.1.3 Autorestart
This option enables / disables automatic DSL channel restart according to the ETSI
TS 101 135. This specifies an automatic DSL restart after a 2s loss of DSL
synchronization.

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4.1.4 Time Slot Mapping

User interface time slots are mapped onto the DSL frame according to ETSI TS 101 135.

4.2 E1 Interface (2 Mbit/s G.703 / G.704)

4.2.1 Framing

4.2.1.1 Transparent Mode

In transparent mode, the E1 data will be transmitted without any changes, whereas in
framed mode, the frame / multiframe alignment words and CRC4 bits are regenerated by
the E1 framer.
The “CRC4 “ and “E-bit Insertion” options are not relevant in transparent mode.

4.2.1.2 Framed Mode ITU-T G.704

In framed mode (framing according to ITU-T G.704), the incoming E1 data stream passes
through an E1 framer before entering the DSL section. From the other side, the same
process happens in reverse; the E1 data stream received from the DSL section first passes
through the E1 framer before being transmitted to the E1 network.
The E1 framer operates in Common Channel Signaling (CCS) mode. Time slot 16 and all
national bits are fully transparent.
Consider the “CRC4” and “E-bit Insertion” options when operating in framed mode.

4.2.1.2.1 CRC4
If operating in framed mode, the “CRC4” option can be used to adapt to specific E1
network requirements:
• If enabled, the E1 framer will synchronize on CRC4 multiframes and CRC4 errors
will be reported. In the outgoing E1 signal the framer regenerates the CRC4
multiframe alignment and checksum words. The A-Bit and the Sa-Bits pass
transparently.
• If disabled, the international bits are set to ‘1’ in the outgoing E1 signal. All national
bits are fully transparent. On the receive side, the E1 framer will synchronize on basic
frames only and no CRC4 errors will be reported.

4.2.1.2.2 E-bit Insertion

• If automatic E-Bit generation is enabled, detected CRC4 errors will cause the
assertion of the E-bits.
• If disabled, all E-Bits are set to ‘1’.

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4.2.2 AIS Generation

If this option is enabled, an unframed AIS (all ones) will be transmitted on the E1 side,
irrespective of whether the system is configured in transparent or framed mode.
AIS generation will be activated on the following conditions:
• DSL link to the remote station is not established (loss of signal or loss of frame
alignment on DSL side) or
• remote station is sending AIS-R.
If AIS generation is disabled, no signal will be transmitted on the E1 side if either of
these two conditions occurs.

4.2.3 AIS Detection

If AIS detection is enabled, receiving AIS from the E1 side will cause the following
actions:
• The Non-Urgent alarm will be set active (AIS-S).
• AIS will be transmitted to the remote station by AIS-R.

4.2.4 E1 Clock Modes

4.2.4.1 Clock Sources

The following block diagram shows the possible clock sources for the LTU and the NTU
(Note, that the external clock option is not available for the NTU!). The clock sources are
intended to be references only and do not drive the DSL transmit section physically.
Data rate adaptation between the 2048kHz clock and the DSL transmit clock is achieved
by stuffing / deleting bits in the DSL frames.
The E1 interface clock is never affected by the crystal controlled DSL clock.
INP 2048 kHz

E1 Side DSL Side

External
clock

E1
DSL
Tx 2 Mbit/s Tx Clock Stuff/ Tx
Delete
Internal
Clock
2048 kHz
Clock-
E1
Recovery DSL
Rx
Recovered 2048 kHz Clock Rx

Figure 4-1: Clock Sources

Note: Signals towards the transceiver section are denoted as Tx and signals coming from the
transceiver sections are denoted as Rx.

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As long as the DSL link is not established, the internal clock oscillator is used as clock
source.
The clock sources are automatically switched by the microcontroller, depending on the
actual signal and clock status, which is updated every 100 ms.
The transmit clocks of the two E1 data directions are independent of each other. Both
plesiochronous and synchronous operation modes are possible. Synchronous operation
occurs when the E1 equipment at one end of the DSL link uses the receive clock as
transmit clock, as shown below.
E1 Equipment E1 Equipment

2048 kHz Clock Tx E1 NTU / DSL E1 NTU / Rx

LTU LTU
Rx Tx

Figure 4-2: Synchronous Operation (=”Loop Timing”)

Warning: Do not configure the E1 interfaces at both ends to use the receive clock as transmit clock
except if one DSL equipment is an LTU using the “External Clock” option. Otherwise
there will be no defined clock.

4.2.4.2 External Clock Mode

Tx Rx
DSL
NTU/
2 Mbit/s LTU 2 Mbit/s
LTU

Rx Tx

INP 2048 kHz

Figure 4-3: External Clock Mode

In “External Clock” mode, the 2048kHz input clock is fed directly in the LTU in case of
the minirack or via the ACU clock input in case of the plug-in LTU. The external clock is
used as the E1 reference clock.
If the “External Clock” option is enabled, the primary E1 clock source is the external
clock. If no external clock is present at the 2048kHz clock input, the E1 transmit clock is
used as the clock source. If no signal is received at the E1 port, then the internal clock is
used as the clock source.
If the “External Clock” option is disabled, the primary E1 clock source is the 2Mbit/s
transmit clock. If no signal is received at the E1 port, then the internal clock is used as the
clock source.
The external clock is never used to drive the E1 Rx direction.

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Note: There is neither an external clock input nor a clock output on the NTU side. The E1 Tx
clock rate is defined by the incoming E1 Tx data rate. The Rx clock rate is the recovered
Tx clock rate of the remote side or the local internal clock. The primary E1 Rx clock
source is the recovered 2048kHz clock.

4.3 ISDN PRA Interface

In PRA mode, the DSL modem offers the functions of an ISDN PRA NT1, a LT or a
combination of the functions of NT1 and LT. This makes it possible to use two setups:
• The slave modem at the customer premises is configured as NT1, the master modem at
the central office is configured as LT.
• The slave modem at the customer premises is configured as NT1 & LT. Direct access
to the exchange is established by a bit-transparent DSL-Link. All data, including time
slot 0, from the exchange must be transmitted transparently (also time slot 0) to the
PRA-NTU, therefore the DSL equipment providing the line termination is E1 working
in transparent mode (see Figure 4-4).

T V3 V3'
DSL Link

DSL DSL
NT2/TE NT1 LT XVR XVR ET

Figure 4-4: Reference Points of the PRA

Normally, the PRA-digital section (NT1 and LT) is configured as a digital link with CRC
processing in the NT1 (option 2, according to I.604). However, also the other subscriber
access options described in I.604 Annex A, can be configured. One of the DSL system
units must be configured as master and the other as slave. Normally, the LTU (or the
NTU, respectively) at the exchange is configured as the master on the DSL link, and the
PRA-NTU as slave.
The equipment described above provides an access digital section for ISDN primary rate
at 2048kbit/s. The 120Ω port (or optionally the 75Ω In/Out BNC) is the user/network-
interface for primary rate access, which is denoted as T reference point in ISDN
terminology. The equipment at the user side of the T reference point, which may be TE1,
TA or NT2, is termed TE or NT2 in the normative references. Therefore, it is denoted as
NT2/TE in this document. The interface towards the exchange, which will be abbreviated
ET in the following, is the V3 reference point.

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4.3.1 PRA Mode

The modem can work as NT1, LT or NT1 and LT combined.

4.3.2 CRC4 Processing Options

In addition to the usual PRA operation with CRC4 processing in both directions, the PRA
interface also offers other modes of operation. Following ITU-T Rec. I.604 Annex A,
three subscriber access options for a digital link are supported. The PRA interface can be
configured to work either as a digital link without CRC processing (option 1), a digital
link with CRC processing in the NT1 (option 2) or a digital link with CRC monitoring
only in the NT1 (option 4). A digital link with CRC processing in the LT and NT1 is
possible by using an DSL link consisting of an NT1 and an LT, both configured with
CRC processing on.

4.3.2.1 Digital Link without CRC Processing (Option 1)

In this mode, transparent transmission between the ET and the NT2/TE is possible. There
is no CRC4 processing in the PRA-NTU; the CRC processing is only done in the ET and
the NT2/TE.
When loss of incoming signal is detected on either side, AIS is transmitted at the opposite
side.
The detection of events and the state information are still valid as in normal PRA
operation mode (option 2).
Depending on the distribution of NT1 and LT functionality, two setups are possible for
option 1:
• The master is E1 configured transparent, AIS-generation on and AIS-detection off; the
slave is PRA NT1 & LT, CRC4 processing off.
• The master is PRA LT with CRC4 processing off, the slave is PRA NT1 with CRC4
processing off.

Note: For proper operation in Option 1, the equipment at the customer side (NT2) and at the
central office side (ET) must be in CRC4 framed mode.

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NT2 ET

R RX
M TX
G
L

Digital Link

TX RX L
G M
R

T V3'
L Local CRC error information
R Remote CRC error information Mandatory
M CRC Monitor Optional
G CRC Generator

Figure 4-5: Digital Link without CRC Processing

4.3.2.2 Digital Link with CRC Processing in the NT1 (Option 2)

This is the usual PRA operating mode as described in ETS 300 233 and ITU-T Rec.
G.962 Annex B. The PRA interface is intended to be used in this mode.

NT2 NT1 LT ET

R
R RX
G L G
M M
L

L L
TX
G M G M R
R
Digital Link
T V3'

L Local CRC error information

R Remote CRC error information Mandatory
M CRC Monitor Optional
G CRC Generator

Figure 4-6: Digital Link with CRC Processing in the NT1

CRC4 is generated towards the NT2/TE and towards the ET and monitored at both sides
of the NT1. When a block with a CRC4 error is received from the NT2/TE, CRC4 error

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information is transmitted towards the NT2/TE (via E-bits) and optionally towards the ET
(via Sa6-bits). When a block with a CRC4 error is received from the ET, error
information is transmitted towards the ET (via E-bits). CRC4 errors detected at the T
reference point of the NT2/TE are reported to the NT1 (via E-bits) and optionally towards
the ET (via Sa6-bits). CRC4 errors detected at the V3 reference point of the ET are
reported to the NT1 (via E-bits). Loopback 1 and 2 control facilities and monitoring of
defect conditions are implemented according to ETS 300 233.
Depending on the distribution of NT1 and LT functionality, two setups are possible for
option 2:
• The master is E1 configured transparent, AIS-generation on and AIS-detection off; the
slave is PRA NT1 & LT, CRC4 processing on.
• The master is PRA LT with CRC4 monitoring on, the slave is PRA NT1 with CRC4
processing on.

4.3.2.3 Digital Link with CRC Processing in the LT and NT1 (Option 3)
In this mode, the NT1 behaves like in option 2. The LT is not transparent, but has CRC4
generation and monitoring in both directions. This option is not possible when using
combined NT1 & LT mode, the setup for option 3 is:
• The master is PRA LT with CRC4 processing on, the slave is PRA NT1 with CRC4
processing on.

NT2 NT1 LT ET

R R
R RX
G L G L G
M M M
L

L L L
TX
G M G M G M R
R R
Digital Link
T V3'

L Local CRC error information

R Remote CRC error information Mandatory
M CRC Monitor Optional
G CRC Generator

Figure 4-7: Digital Link with CRC Processing in the LT and NT1

4.3.2.4 Digital Link with CRC Monitoring in the NT1 (Option 4)

CRC4 multiframe alignment and checksum words are not regenerated in both directions,
i.e. data will be transmitted without changes in both directions. However, blocks with
CRC4 errors received from the NT2/TE and the ET will be detected and monitored by the
G.826 performance management functions of the NTU monitor.
When loss of signal or loss of frame alignment is detected at either side, AIS is
transmitted at the opposite side.

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The detection of events and the state information are still valid as in normal PRA
operation mode (option 4).

NT2 NT1 LT ET

R RX
G
M M
L

SU SN

L
TX
G M M R

Digital Link
T V3'

L Local CRC error information

R Remote CRC error information Mandatory
M CRC Monitor
G CRC Generator Optional
SN Storage for network side monitor
SU Storage for user side monitor

Figure 4-8: Digital Link with CRC Monitoring in the NT1

Depending on the distribution of NT1 and LT functionality, two setups are possible for
option 1:
• The master is E1 configured transparent, AIS-generation on and AIS-detection off; the
slave is PRA NT1 & LT, CRC4 monitoring on.
• The master is PRA LT with CRC4 processing off, the slave is PRA NT1 with CRC4
monitoring on.

4.3.3 Generation of CRC4 Error Notifications to the ET

For enhanced maintenance capabilities, CRC4 errors detected at the interface at the T
reference point may optionally be reported to the ET (see ETS 300 233 section 8.3 and
table 4 of ITU-T Rec. G.962 section B.5 and table B.2). CRC blocks in error detected at
the T reference point of the NT1 as well as CRC error indications received from the
NT2/TE in the E-bits are reported to the ET by using the Sa6-bits. An ET applying
asynchronous detection of the Sa6-bits (no synchronization of the Sa6-bits to the sub-
multiframe) will misinterpret such CRC4 error reports from the NT1 with other defect
indications, e.g. loss of power at NT1 or FC4. Therefore, this Sa6-bits indication can be
disabled.
• If the CRC4 error notification in Sa6 is enabled, Sa6=0001 indicates an E-bit received
from the NT2/TE, Sa6=0010 indicates a CRC4 error detected at the T reference point
of the NT1, and Sa6=0011 indicates the simultaneous occurrence of both errors.
• If disabled, Sa6 is always 0000 in normal operation state.
As sending of Sa-bits requires regeneration of the CRC4 frames in the NT1, this option is
only activated when option 2 (Digital link with CRC processing in the NT1) is selected.

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4.4 n x 64kbit/s Interface

This chapter describes the configuration options and alarms related to the n x 64kbit/s
user interface.

4.4.1 Features
• The n x 64kbit/s interface is software-configurable between V.35, V.36 and X.21.
• The bit rate can be selected in steps of 64kbit/s from 64kbit/s up to 2048kbit/s
(n x 64kbit/s, n=1…32)
• Independent receive and transmit clocks for V.35 and V.36.
• Codirectional (from equipment connected to n x 64kbit/s port) and contradirectional
(clock generated by internal reference of from receive clock recovery) transmit clocks
are possible.
• Detection for loss of clock and clock rate mismatch in codirectional clock mode.
• Standard SubD25 connector (ISO 2110 for V.35, RS-530 for V.36, proprietary for
X.21) for DCE operation, other connectors (ISO 2593 for V.35, ISO 4902 for V.36,
ISO 4903 for X.21) both for operation as DCE or DTE are available by means of
adapter cables.
• Loop 1 and Loop 2 supported, for V.35 and V.36 they can also be controlled by
circuits 140 (RL) and 141 (LL), according to V.54.
• Support for byte timing (circuit B) in X.21 mode.
• Mixed mode n x 64kbit/s - E1, n x 64kbit/s - Ethernet possible.

4.4.2 Configuration

4.4.2.1 Time Slot Mapping

4.4.2.1.1 Terminology
In the following, time slot numbers 0 to 31 denote the positions where E1 time slots 0 to
31 are mapped to the DSL frame according to TS 101 135.
The n x 64kbit/s bandwidth is the bit rate which is available for the n x 64kbit/s interface
• for equipment with both E1 and n x 64kbit/s interface: the n x 64kbit/s bit rate,
• for equipment with configurable DSL line rate and no E1 interface: the DSL line rate -
16kbit/s,
• for equipment with fixed DSL rate and no E1 interface: 32 × 64kbit/s.
The E1 bandwidth is the bit rate which is available for the E1 interface,
• for equipment with both E1 and n x 64kbit/s interface: the E1 bit rate,

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• for equipment with configurable DSL line rate and no n x 64kbit/s interface: the
DSL line rate - 16kbit/s,
• for equipment with fixed DSL rate and no n x 64kbit/s interface: 32 × 64kbit/s.
The mapping of the n x 64kbit/s data to the time slots 0 to 31 depends on the n x 64kbit/s
bit rate configured and n x 64kbit/s bandwidth. The mapping of the E1 data to the time
slots 0 to 31 depends on the E1 bandwidth.

4.4.2.1.2 n x 64kbit/s Time Slot Mapping

With an n x 64kbit/s bandwidth of 32 × 64kbit/s, the time slots are filled as follows
(depending on the n x 64kbit/s bit rate n):
• for n ≤ 15, time slots 1 to n are filled with n x 64kbit/s; the unused time slots are filled
with all ones data,
• for 16 ≤ n ≤ 30, time slots 1 to 15 and 17 to n+1 are filled with n x 64kbit/s data
(time slot 16 is skipped); the unused time slots are filled with all ones data,
• for n = 31, time slots 1 to 31 are filled with n x 64kbit/s data,
• for n = 32, time slots 0 to 31 are filled with n x 64kbit/s data.

4.4.2.1.3 E1 Time Slot Mapping

A mixed mode connection is a link between a modem using an E1 / PRA interface and a
modem using an n x 64kbit/s or Ethernet interface. The n x 64kbit/s / Ethernet data is
available in n E1 time slots:
• for n ≤ 15, time slots 1 to n,
• for 16 ≤ n ≤ 30, time slots 1 to 15, 17 to n+1,
• for n = 31, time slots 1 to 31,
• for n = 32, time slots 0 to 31.

4.4.2.2 User Interface Type

The interface mode can be set to V.35, V.36 or X.21.

4.4.2.3 Bit Rate

The bit rate can be selected in the range of 64kbit/s up to 2048kbit/s in steps of 64kbit/s
(n = 1..32).

4.4.2.4 Clock Mode

Previous versions of n x 64kbit/s interfaces from Schmid Telecommunication used the
same clock to receive and to transmit data. A phase difference was allowed, but the clock
frequencies had to be nominally equal. This led to a few restrictions when configuring the
n x 64 kbit/s port. Note, that these restrictions still apply when using old equipment
together with new equipment. In that case, follow the configuration instructions in the
previous manual.
For V.35 and V.36, the receive and the transmit clock are independent. The receive clock
is always the recovered remote clock. The clock mode configuration applies only to the
transmit clock. For X.21, there is only one clock (circuit S) to receive and transmit, the

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clock mode determines the source of that single clock; however, in the codirectional
n x 64 port clock mode, X is used as a codirectional transmit clock and S is used only as
receive clock. In the following section the clock which can be selected by the clock mode
is denoted as “transmit clock”.
The clock mode determines in most cases, whether the transmit clock is codirectional (it
has the same direction as the transmit data, i.e. it is an input signal) or contradirectional (it
has the contrary direction of the transmit data. i.e. it is an output signal).
These clock modes are possible:
• n x 64 port: The transmit clock is the codirectional clock coming from the equipment
connected to the n x 64kbit/s port (circuit 113, X).
• E1 port: The transmit clock is generated from the transmit clock used at the E1 port.
The 2048kHz E1 clock is fractionally synthesized to the bitrate configured and
available at the contradirectional transmit clock output (circuit 114).
• Internal: The transmit clock is generated from the internal reference clock
(contradirectional, circuit 114).
• Remote: The transmit clock is the recovered remote clock, i.e. the same clock as the
receive clock (115) at the V.35 and V.36 interface (contradirectional, circuit 114).
The clock mode to be used depends on the individual network configuration:
• n x 64kbit/s - n x 64kbit/s connection: First, it should be checked whether the
equipment connected to the n x 64kbit/s port uses a transmit clock output or input. In
the first case, the codirectional nx64 port mode can be used. In the latter case, one of
the contradirectional clock modes should be used. The internal clock mode should be
suitable in most cases, the remote clock can be used if the receive and transmit clocks
have to be equal.
As the contradirectional X.21 clock modes use only one clock, these configurations
are possible: n x 64 Port - n x 64 Port, n x 64 Port - Remote, Internal - Remote.
• n x 64kbit/s - E1 connection: The clock mode can be selected as in the previous case.
• n x 64kbit/s - Ethernet connection: Ethernet modems have the same restrictions as
prior n x 64kbit/s equipment: The receive and the transmit clocks have to be equal.
Therefore the network can have only one system clock. The Ethernet NTU will
provide the clock when it is configured as master. Then the n x 64kbit/s clock mode
has to be remote. When the Ethernet NTU is slave and the n x 64kbit/s NTU/LTU
master, the clock must be determined by the n x 64kbit/s equipment, i.e. its clock
mode must be internal or local port.
It is recommended to have at least one clock reference. So one should not use remote
clock mode at both ends. You should not choose remote clock mode either if the remote
modem is E1 and the E1 equipment connected to the remote E1 port uses loop timing (i.e.
it uses the received clock as transmit clock).

4.4.2.5 Clock Direction

In most cases, the clock direction depends on the clock mode and cannot be configured.
An exception is E1 port clock mode: In this case codirectional or contradirectional clock
direction can be configured. However, in almost all cases, a contradirectional clock
should be used. A codirectional clock can only be used, if it has the same reference as the
E1 transmit signal (i.e. its rate is nominally equal to n/32 of the E1 rate).

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A clock direction configuration is also possible for last-generation NTUs which are
equipped with two n x 64kbit/s interfaces working in local port 1 or 2 clock mode. Then it
can be selected whether the other port uses also a codirectional clock (both codirectional
clocks must have the same reference).

4.4.2.6 V.54 Loops and Loop Control

As the X.21 interface provides only the control interchange circuits C and I, most of the
features described afterwards are only applicable for V.35 and V.36, but not for X.21.

4.4.2.6.1 Normal Handshake Operation

When no loopback is established, the control circuits perform this handshake protocol:
• 105 (RTS Request to send; X.21: C): Input from DTE. For X.21, C = OFF will cause a
DTR alarm.
• 106 (CTS Ready for sending,; X.21: I): Is set ON when an DSL connection is
established and 105 = ON is detected.
• 107 (DSR Data set ready): Is set ON when an DSL connection is established.
• 108 (DTR Data terminal ready): Input from DTE. For V.35 and V.36, 108 = OFF will
cause a DTR alarm.
• 109 (RLSD Data channel received line signal detector): Is set ON when an DSL
connection is established.
• 140 (RL Loopback / Maintenance test): Input from DTE; will be set OFF in normal
mode.
• 141 (LL Local loopback): Input from DTE; will be set OFF in normal mode.
• 142 (TM Test indicator): Is set OFF in normal mode.

4.4.2.6.2 Supported V.54 Loops

ITU-T recommendation V.54 defines four test loops. Loops 2 and 3 correspond to DSL
loopbacks 2 and 1. The interchange circuits are set in the following way:
• V.54 Loop 3
Local loop established in the DCE, i.e. DSL loopback 1 in an n x 64kbit/s NTU/LTU.
These output interchange circuits are set: 107 = ON and 142 = ON
• V.54 Loop 2
Loop in remote DCE, i.e. DSL loopback 2 in the remote (slave) NTU/LTU.
These output interchange circuits are set:
− Master: 107 = ON and 142 = ON
− Slave: 104 (received data) = 1, 106 = OFF, 107 = OFF, 109 = OFF and 142 = ON.

4.4.2.6.3 Automatic Loop Control through the DTE/DCE Interface

Automatic control through the interface is achieved by using circuits 140 and 141:
• 140 = ON and 141 = OFF ⇒ V.54 loop 2 (DSL loopback 2)
• 140 = OFF and 141 = ON ⇒ V.54 loop 3 (DSL loopback 1)

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This automatic loop control can be switched on/off using the “V54LOOPS” configuration
option.
The interface on the user side can be a DTE or a DCE. To connect them to the interface
port, the V.35 DTE or V.35 DCE cable must be used.

4.4.2.7 Byte Timing

In the X.21 mode, the byte timing circuit B according to X.24 can be activated
(configuration option “BYTETIMING”). As the circuits B (byte timing) and X
(codirectional transmit clock) share the same pins on the 15-pin ISO 4903 connector,
separate cables have to be used for these cases.

4.5 TMN Interface (Minirack LTU only)

The Telecommunication Management Network (TMN) is connecting the Management
Center (MC), Agent Elements (AEs) and Modems. Towards the MC the network is based
on a X.25 or a LAN connection. Between AE and modems this network is established by
means of a serial, asynchronous bus with differential (balanced) line transmission
according to TIA/EIA-485 standard. Independent if the bus is set-up by a 2- or 4-wire
connection the bus communication between Common Management Unit (CMU) and the
Line Termination Units (LTUs) is always operating in half-duplex mode. The CMU is
representing the Agent Element and is working as bus master on the EIA-485 side. The
LTUs are representing the modem and work as bus slaves on the EIA-485 side.

4.5.1 TIA/EIA-485 4-wire Bus

The default TMN communication between Minirack versions of CMU and LTU is using
a 4-wire transmission with different pairs for receive and transmit direction.
This bus system requires a crossing of RX and TX signals between CMU and LTU.
Tx A
Tx B TMN
CMU MR Interface

Rx A
Rx B

X.25
or LAN Tx A Tx B Rx A Rx B Tx A Tx B Rx A Rx B Tx A

…
LTU MR LTU MR LTU MR
Management
Center

Figure 4-9: TMN Bus 4-Wire Connection for Minirack Units

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4.5.2 TIA/EIA-485 2-wire Bus

TMN communication can be established via an EIA-485 2-wire connection as well. In
this case no crossing of signals between CMU and LTU is required.

Management
X.25 Center
or LAN

CMU MR LTU MR LTU MR

…
Rx A Rx B Tx B Tx A Tx A Tx B Rx A Rx B Tx A Tx B Rx A Rx B

Figure 4-10: TMN Bus 2-Wire Connection for Minirack Units

A Plug-in version of the CMU is available as well. Due to the fact maximum 32 units can
be connected to an EIA-485 bus, 1 CMU is able to handle more than the 12 LTUs located
in one subrack. The extension of the TMN bus in the backplane towards a second subrack
is realized by means of the Alarm Control Unit (ACU).

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Management
Center
X.25
or LAN

Front
Connector Tx A Tx B Rx A Rx B
LTU CMU ACU
Backplane
Connector Tx B Rx A Rx B … Tx A Tx B Rx A Rx B Tx A Tx B Rx A Rx B

EIA-485
Backplane
Bus

Subrack 0

Front
Connector Tx A Tx B Rx A Rx B
LTU LTU ACU
Backplane
Connector Tx B Rx A Rx B … Tx A Tx B Rx A Rx B Tx A Tx B Rx A Rx B

EIA-485
Backplane
Bus

Subrack 1

Figure 4-11: TMN Bus 2-Wire Connection for Plug-in Units

Limitation: Plug-in versions of CMU, ACU and LTU support 2-wire connection only

In case of a single subrack configuration and if no external alarm indications have to be

controlled, an ACU is not needed in the subrack. But direct access for configuration of
LTUs via the monitor interface on a local craft terminal is not possible without an ACU.

4.5.3 TIA/EIA-485 Bus Termination

In order to achieve highly reliable connections with a minimum of reflections, a
termination with 120Ω is required at both ends of the bus by the TIA/EIA-485 standard.
A bus termination is not imperative when transmission is applied over short distances
(< 1m) and with signalling rates …200 kbps.

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The TMN bus communication is running with a signalling rate of 5 kbps. Due to this fact
a termination is required only if TMN bus is extended via cable over long distances and
especially if different reference ground levels are applied at both ends of the bus
(different racks).
Plug-in versions of ACU and CMU offer jumpers to connect a simple 120 Ω parallel
termination to both differential wire pairs of the TMN bus.
ACU Plug-in: Closing J4 and J5 will activate the termination.
CMU Plug-in: Closing jumper ST4 and ST5 will activate the termination.
More for reasons of avoiding excessive ground currents than for signal quality, the
grounding configuration for the signal return path shown in Figure 4-12 is recommended
for a TMN bus connections with different ground levels at both ends.

Tx A Tx A
CMU MR LTU MR
ZT ZT
Tx B Tx B
ZG ZG
SGND … SGND
Rx A Rx A
ZG = ZT = 100 Ω
ZT ZT
Rx B Rx B

Tx ATx B Rx ARx B
… Logic Ground 2
Logic Ground 1 LTU MR

Figure 4-12: Termination for Long TMN Bus

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5 Performance Monitoring

The transmission performance of a DSL link can be monitored in two different ways. The
DSL signal quality is typically used during installation and maintenance procedures,
whereas the G.826 error performance parameters are intended to be used for long term
evaluation of an operating DSL link. Refer also to the “SQ” and “G826” monitor
commands described in the “Monitor Operation” chapter.

5.1 Noise Margin

The Noise Margin (NM) provides qualitative performance information according to
TS 101 135 of a specific loop and is an effective maintenance tool to determine
inadequate or bad cable pairs.
A NM of 0dB, in presence of Gaussian noise would yield an expected Bit-Error-Ratio of
10-7.

5.2 G.826 Performance Monitoring

The G.826 error performance parameters provide quantitative performance information
of a specific loop. They are intended to be used for long term evaluation of operating
DSL links.
The evaluation of the G.826 error performance parameters is based on CRC (Cyclic
Redundancy Check) error detection: The estimation of a bit-error rate is not within the
scope of the G.826 calculations.

5.2.1 DSL Interface

On the DSL side, six CRC6 check bits are generated per DSL frame for each channel and
direction. For signaling detected block-errors in the return direction, the FEBE-bits are
used. The DSL G.826 performance of the opposite unit is calculated according to these
FEBE-bits.
CRC6 errors are used by the software to count the block-errors of the respective DSL
channel and to evaluate its error performance according to ITU-T G.826.
The regenerator also monitors received DSL frames from the LTU (REG-R side) and
from the NTU (REG-C side) using CRC6. Detected CRC errors are reported to both
stations using the RRBE (errors detected at LTU side) and RCBE (errors detected at NTU
side) bits. These bits are used to calculate the G.826 performance of the regenerator.

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In case of severe impairments on the second section (REG - NTU), the G.826
performance of the first section is likely to be degraded due to the regenerator’s strict
coupling of the received and transmitted DSL frames. Whenever one of the regenerator’s
receivers recovers frame-alignment, the transmitter that passes on these HDSL frames
will immediately adjust the frame start to the recovered frame-timing. As a result, a
disturbed REG-NTU section will cause occasional LFAs at the LTU side and, as a
consequence, degrade the LTU’s G.826 performance (based on CRC6 and RRBE).
NTU Regenerator LTU
CRC6 CRC6 CRC6 CRC6

RCBE

Gen. Test Gen. Test

G.826 G.826
Evaluation
HDSL HDSL Evaluation

CRC6, FEBE, CRC6, FEBE,

RRBE, RCBE Test Gen. Test Gen. RRBE, RCBE

RRBE

Figure 5-13: Regenerator G.826 Performance Evaluation

5.2.2 E1 Interface
Slave Master
CRC4 CRC6 CRC6 CRC4

TX RX
Test Gen. Test Gen.

G.826 G.826 E1
E1 CRC4/E-bit
Evaluation
CRC6/FEBE DSL CRC6/FEBE
Evaluation
CRC4/E-bit

Gen. Test Gen. Test

RX TX

Figure 5-14: E1 G.826 Performance Evaluation

On the E1 side, four CRC4 check bits are generated per sub-multiframe (SMF) and
compared with the corresponding CRC4 bits in the following SMF. If they do not match,
the CRC4 error counter is incremented. The opposite station is informed of detected
CRC4 errors by setting E-bits in the transmitted frames. At the same time, the E-Bits
from the opposite station are counted and can be used for performance-monitoring.
For the E1 interface, calculations according to G.826 are only possible in framed mode
with CRC4 option enabled. In framed mode with CRC4 option disabled only FAS-errors
are detected.

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5.2.3 ISDN PRA Interface

Slave (NTU-PRA) Master (LTU or NTU-E1 transp.)

CRC4_T CRC4_V3 CRC6 CRC6

TX CR CR RX
Test CR CR Gen. Test
C4/
Gen. C6/ C6/
C4/
E- FE FE
E-
Bit G.826 Bit BE DSL BE
G.826 ET
TE Evaluation Channels A & B Evaluation

Gen. Test Test Gen.

RX TX

Figure 5-15: PRA G.826 Performance Evaluation

When the PRA interface is working with CRC4 processing or monitoring (options 2 and
4) four CRC4 check bits are generated per sub-multiframe (SMF) received from the ET
and the NT2/TE and compared with the corresponding CRC4 bits in the following SMF.
If they do not match, the corresponding CRC4 error counter is incremented. At the same
time, the E-Bits from the ET and the NT2/TE are counted and can be used for
performance-monitoring.
For the PRA interface, calculations according to G.826 are only possible when CRC4
processing or monitoring is selected.

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6 Alarms

6.1 LEDs
The two LEDs ′Status Local′ and ′Status Remote′ are used to display normal operation
condition and alarm condition. Each LED can be green, amber, or red according to the
following table.

6.1.1 Status LEDs

Status Local LED Remote LED
Power failure off off
Hardware - / Software failure blinking off
Normal operation (Master mode) green green
Normal operation (Slave mode) green off
Non-urgent alarms(Local / remote) amber amber (off for slave)
Urgent alarms (Local / remote) red red (off for slave)
Regenerator alarm or Loopback amber red
(Master mode)

6.1.2 Alarm Conditions

6.1.2.1 Local LED

An alarm condition is displayed with the Local LED if one of the following conditions
occurs:
Urgent alarm (red):
• Hardware or software failure (blinking)
• Loss of signal / frame alignment on the DSL side, depending on the DSL operating
mode:

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DSL operating mode Alarms

Normal LOS/LFA-A or LOS/LFA-B
Fractional LOS/LFA-A
Partial LOS/LFA-A and LOS/LFA-B
Hot Standby LOS/LFA-A and LOS/LFA-B
• DSL block-error-rate according G.826 ≥ 30% (BER-H,BER-REG-H)
• LTU only: overcurrent detected in remote power feeding circuit (CLDET-A,
CLDET-B)
Non-urgent alarm (amber):
• DSL block-error-rate according G.826 > 15% (BER-L)
• Either Loop 1, Loop 2, Analog Loopback, or the Regenerator Loopback is active
(LOOP1, LOOP2, ALB, LOOPREG)
• Receiving regenerator alarm (REG-A, REG-B), indicating second section (REG-NTU)
has not yet started and/or Regenerator Loopback is active (Master mode)
• Alarm cut off is activated (ACO)
E1 Interface:
• Loss of signal or frame alignment on the E1 side (LOS-S, LFA-S)
• Loss of external clock (EXT-LOC, in external clock mode only)
• Receiving AIS on E1 side (AIS-S)
• Excessive block error rate on E1 side (BER-S)
PRA Interface:
• Loss of signal at the T reference point (LOS-S)
• Loss of frame at the T reference point (LFA-S)
• Receiving AIS at the T reference point (AIS-S)
• Loss of frame at the V3 reference point (LFA-V3)
• Receiving AIS at the V3 reference point (AIS-V3)
n x 64kbit/s Interface:
• Loss of codirectional clock or clock rate mismatch (clock mode: n x 64 port) on the n
x 64kbit/s side (LOC),
• Data Terminal Ready (DTR, circuit 108/2) on the n x 64kbit/s port is detected as
'OFF'. For X.21, the control-signal (C) is represented by DTR.
• The loops 1 and 2 can be controlled by the circuits 140 (RL) and 141 (LL), thus the
alarms LOOP1 and LOOP2 can also be caused by the n x 64kbit/s interface
Displaying an urgent alarm has a higher priority than displaying a non-urgent one, i.e. an
amber alarm will be “overwritten” by a red alarm.

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6.1.2.2 Remote LED

The remote LED is an image of the local LED of the remote slave station (see previous
LED-table for exceptions). When configured as “slave” no remote access is possible, so
the remote LED is turned off.

6.2 Alarm Relays

6.2.1 LTU
There are two concepts for signaling the alarm status of the LTU in the subrack.
Each LTU has an open collector alarm output working on a common signaling line. The
ACU2R gives consolidated alarm signals to the sum alarm relays “Urgent” and “Non-
urgent”.
The alarm status is also analyzed by the ACU48R via the internal monitor bus to poll
each of the possible 24 (=12 dual) LTUs within the subrack and to signal the alarm status
to two alarm relays “Urgent” and “Non-urgent” specific for each LTU.
Under normal LTU power conditions the two output stages of each LTU are controlled by
its microcontroller. In case of a power failure on an LTU, both the “Urgent” and “Non-
urgent” alarms will be activated on the ACU. (The ACU generates an auxiliary +5 VDC
which is used to pull-up the open collector alarm output stages of the LTUs.)

6.2.1.1 Alarm Conditions

Urgent Alarm:
• At least one of the LTU – LEDs displays a red alarm
• Power failure of any one of the LTUs
• Power failure of the auxiliary +5VDC auxiliary supply on the ACU
• Power failure of both –48VDC supplies

Non-urgent Alarm:
• At least one of the LTU – LEDs displays an amber alarm and none of the LTU –
LEDs displays a red alarm
• Power failure of any one of the LTUs
• Power failure of the auxiliary +5VDC auxiliary supply on the ACU
• Power failure of one of the –48 VDC supplies
Note: The E1 LTU/NTU must be configured as master and the n x 64kbit/s NTU as slave when
the line rate is lower than 2064kbit/s.

6.2.2 NTU
The two alarm relays “Urgent” and “Non-urgent” are located on the NTU, the alarm
contacts are available on the monitor connector.

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6.2.2.1 Alarm Conditions

Urgent Alarm:
• At least one of the NTU - LEDs is red
Non-urgent Alarm:
• At least one of the NTU - LEDs is amber and none of the NTU - LEDs is red

Note: If alarm cut off is activated (ACO = on), the alarm relays are disabled.

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7 Power Concept

7.1 LTU

7.1.1 Power and Grounding

Each plug-in LTU is fed via subrack backplane with (dual) -48VDC (referenced to 0VDC of
the exchange battery), whereas the minirack LTU is fed via an internal power supply unit.
The LTU generates the used voltages onboard.
The ground reference of all voltages on the secondary side of the LTU’s DC/DC-
converter are tied to FPE (Functional Protective Earth).
Additionally, the plug-in LTU is fed over the backplane with an auxiliary +5VDC supply
(referenced to ground) generated on the ACU. The only purpose of this voltage is to drive
the alarm circuitry on each LTU, even in the case of a failure of the LTU's onboard
DC/DC-converter.
In case of a failure of the LTU's onboard power supply, both LEDs on the front panel will
be extinguished.

7.2 NTU

7.2.1 Power and Grounding

The ground of an NTU is typically floating when referenced to earth. If an NTU is
equipped with an E1 or n x 64kbit/s user interface, the shields / signal ground of the
cables are coupled to the ground of the NTU.
Powering of the NTU unit can be selected by a slide switch located on the rear side of the
housing:
• Remote powering from the LTU over the DSL line or
• Local powering by an external AC/DC or DC/DC adapter
The position of the switch can be changed by means of a small screw driver. Before
operating the switch, the DSL line connector and the mains adapter connector should be
removed.

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The supply voltage input is protected against reversal of polarity but not fused.
Appropriate fusing has to be done externally. AC/DC adapters from SZ are
recommended.
Caution: A 48VDC battery supply must not be connected directly to the “AC/DC adapter”
connector! High voltage transients from the DSL line may damage other equipment
connected to the battery. A DC/DC converter with 4kV transient isolation voltage should
be used in this case.

7.2.2 Power Failure Alarm

In case of a failure of the NTU's power supply, both LEDs will be extinguished.
The two DSL overhead bits ps1 and ps2 inform the remote LTU about the status of the
NTU power supply. If the NTU is remotely powered, ps1 is set to 1. If the NTU is locally
powered, ps2 is set to 1; if the supply voltage drops below 40.5VDC, ps2 is set to 0 to
inform the remote station about the dying local power supply of the NTU.

7.3 Remote Powering

Remote power feeding is supported. The remote NTU-R and the regenerator can be fully
powered over the DSL twisted wire-pairs from the LTU-R. The remote power feeding
concept has the following characteristics:
• Per pair remote feeding (no “phantom”-circuit)
• Cross-wiring tolerant
• Power feeding voltage within TNV-Limits (max. 120VDC)
• Independent current limiters on a per pair basis (microcontroller - controlled)
• Tolerant against micro-interruptions
• Automatic system restart after power failure
• Protection according to ITU-T Rec. K.20
The remote power voltage of 120VDC is generated locally on each LTU-R and is
referenced to earth. In case of overvoltage ( |U| > 120VDC), the unit is immediately
shutdown within 100ms and can be reactivated only after an interruption of at least
500ms of its -48VDC supply / supplies. The LTU is able to feed up to 60mADC over each
DSL pair.
Depending on the DC - loop resistance, the remote power voltage at the NTU-R may be
far below 120VDC. The lowest acceptable voltage is approximately 65VDC.
The ability of providing remote power to the DSL line can be permanently switched off
by placing the 4-fold R/L jumpers located on the PCB from position "RPWR A ON",
"RPWR B ON",...” into the “OFF” position. In this case, the DSL line interface is
disconnected from the remote power circuitry and it behaves like the DSL interface of a
NTU, i.e. it is floating.
Caution: If changing the remote powering condition the LTU must not be connected to the power
supply. For the LTU in minirack the external power supply should be disconnected first
before opening the cover!

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Remote powering depends strongly on the power consumption of the NTU or REG
(which in turn depends slightly on the supply voltage) as well as the loop resistance (wire
diameter and cable length).

Remote Powering of 2p NTU, U 0 =113V

0.03

0.028

0.026 P=2.75 W
0.024
P=2.5 W
Line Feed Current (A)

0.022

0.02

0.018

0.016

0.014

0.012

0.01
0 500 1000 1500 2000 2500 3000
Loop Resistance (Ohm)
Figure 7-16: Line feed current vs loop resistance for different NTU power consumptions

Remote Powering of 2p REG + NTU, U 0=113V

0.06

0.055
current limit = 55mA
P1=3.8 P2=2.75 W
0.05
P1=3.3 P2=2.5 W
Line Feed Current (A)

0.045

0.04

0.035

0.03

0.025

0.02
0 100 200 300 400 500 600 700 800 900 1000
Loop Resistance (Ohm)
Figure 7-17: LTU powering one REG and one NTU: Line feed current vs loop resistance
two different REG power consumptions

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Remote Powering of 2p REG + REG, U 0 =113V

0.07

0.065

0.06
P1=3.8 P2=3.8 W
Line Feed Current (A)

0.055
current limit = 55mA
P1=3.3 P2=3.3 W
0.05

0.045

0.04

0.035

0.03
0 100 200 300 400 500 600 700 800 900 1000
Loop Resistance (Ohm)

Figure 7-18: LTU powering two REGs: Line feed current vs loop resistance two different
REG power consumptions

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8 Monitor

8.1 General
The units can be connected to a terminal or a PC with a terminal emulation in order to
monitor relevant events and to display additional information such as signal quality of the
DSL link or the G.826 error performance parameters. In addition, full system
configuration and fault localization can be done over the monitor interface.
The terminal for monitoring should be VT100 compatible and be configured as follows:
• 9600 baud, asynchronous
• 8 bits, no parity, one stop bit
• XON/XOFF enabled
• No new line on carriage return (i.e. no line feed on carriage return)

8.2 Addressing

8.2.1 LTU
There is a point / multipoint TTL-bus (9600 baud) on the subrack's backplane.The TTL to
RS-232 level conversion is done on the ACU where the monitor connector is located.
In order to re-enable communication of LTUs occasionally left in XOFF state, it is
recommended to start each session with Ctrl-Q (=XON) followed by an ECHO
command.
At any one time, only one of the LTUs in the subrack can be logically connected to the
monitor interface. The appropriate LTU interface is addressed (i.e. selected) according to
its physical position in the subrack, starting with the leftmost slot number 01 and
ascending rightwards to number 12. If one LTU supports a second interface, it may be
addressed by adding 12 to the address of the first interface.
To select the first interface on the LTU in slot number SN, just type “%SN“ at the
terminal, even in the case it does not show any prompt. (e.g. to select the LTU in slot 01,
type “%01”). To select the second interface (optional) in the same slot number, just type
“%(SN+12)” at the terminal.

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Single LTU Interface Addressing Scheme

Unit LTU LTU LTU LTU LTU LTU LTU LTU LTU LTU LTU LTU ACU PSB

First Interface
Address 01 02 03 04 05 06 07 08 09 10 11 12 ACU

Subrack

Dual LTU Interface Addressing Scheme

Unit LTU LTU LTU LTU LTU LTU LTU LTU LTU LTU LTU LTU ACU PSB

First Interface
Address 01 02 03 04 05 06 07 08 09 10 11 12 ACU

Second Interface
Address 13 14 15 16 17 18 19 20 21 22 23 24

Subrack

Figure 8-19: LTU Interface Addressing Scheme

To see which units in a rack are available, you can use the “ECHO” command. Each
present unit will respond with its associated slot number (%SN).
The response could be : %01 %03 %08 %10 %11 %12 %15

Note: Each command must be terminated by a carriage return.

8.2.2 LTU Minirack

For Minirack versions of the LTU, the address number of the DSL interface can be set
manually by monitor commands in the Configuration Management (CM) menu. After
power-up of a Minirack LTU the local monitor main menu appears always with the first
DSL system activated (behaviour like a NTU).
Address numbers in range 1-127 can be set independently to the different DSL systems of
a LTU.

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8.2.3 NTU
There is no need of addressing for a point-to-point connection.

8.3 Structure and Organization

The structure and organization of the monitor menu is adapted to ITU-T M.3400 for
TMN with its five sub-sets.

Sub-set Short-form
Performance management PM
Fault and maintenance management FMM
Configuration management CM
Accounting management AM
Security management SM

Since accounting management is not supported, AM is not in the monitor's main menu.

Watson II
E1 Monitor V4.2
Copyright (C) 95,98,99 by Schmid Telecom AG Zuerich, Switzerland

+------------------------+
| Main Menu |
+------------------------+

1. Performance management (PM)

2. Fault and maintenance management (FMM)
3. Configuration management (CM)
4. Security management (SM)
5. Exit

LTU_04> Select [1..5]:

To select the desired sub-menu, type the appropriate number.

Notes:
The “Exit” command, number 5, is only available on the LTU. To address another LTU,
type ”%SN”.

8.3.1 Performance Management PM

The G.826 error performance parameters are intended to be used for long term evaluation
of operating DSL links (see chapter “Performance Monitoring”).

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03:33:10 Performance management activated

type <M> to return to MAIN, or <H> for HELP information

Type <H> and the monitor lists all available commands in the performance sub-menu:

LTU_04_PM> H
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
G826 Display HDSL G.826 parameter
G826 C Display HDSL G.826 parameter continuously
G826 E1 Display local E1 G.826 parameter
G826 E1 C Display local E1 G.826 parameter continuously
G826 REGn Display regenerator G.826 parameter
G826 REGn C Display regenerator G.826 parameter continuously
RESETG826 Reset G.826 error performance parameter
M(AIN) Return to main menu
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_04_PM>

8.3.1.1 G826 Command

The G826 command displays the ITU-T G.826 error performance parameters on the DSL
line side of the local and remote DSL unit:

LTU_04_PM> G826
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
G.826 Error Performance : CRC6 A CRC6 B FEBE A FEBE B
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Errored blocks : 00000000 00000000 00000000 00000000
Errored seconds : 00000000 00000000 00000000 00000000
Severely errored seconds : 00000000 00000000 00000000 00000000
ESR [%] : 0.00 0.00 0.00 0.00
SESR [%] : 0.00 0.00 0.00 0.00
BBER [%] : 0.00 0.00 0.00 0.00
Available time : 00624483 00624483 00624483 00624483
Unavailable time : 00000024 00000024 00000024 00000024
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_04_PM>

Definitions:
1. CRC6: Cyclic redundancy check indicating errored blocks are being received on the
local DSL side.
2. FEBE: Far end block error indicating errored blocks are being received on the remote
DSL side.
3. Errored block (EB): A block in which one or more bits are in error.
4. Errored seconds (ES): A one second period with one or more errored blocks. SES
defined below is a subset of ES.
5. Severely errored second (SES): A one second period which contains >=30% errored
blocks.
6. Background block error (BBE): An errored block not occurring as part of an SES.

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7. Errored second ratio (ESR): The ratio of ES to total seconds in available time during a
fixed measurement interval.
8. Severely errored second ratio SESR: The ratio of SES to total seconds in available
time during a fixed measurement interval.
9. Background block error ratio (BBER): The ratio of errored blocks to total blocks
during a fixed measurement interval, excluding all blocks during SES and unavailable
time.
Options:
C: Updates the G.826 parameters continuously

REGn: The G826 REGn command displays the ITU-T G.826 error performance
parameter of the nth regenerator:

LTU_04_PM> G826 REG1

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
G.826 Error Performance : RRBE1 A RRBE1 B RCBE1 A RCBE1 B
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Errored Blocks : 00000000 00000000 00000000 00000000
Errored seconds : 00000000 00000000 00000000 00000000
Severely errored seconds : 00000000 00000000 00000000 00000000
ESR [%] : 0.00 0.00 0.00 0.00
SESR [%] : 0.00 0.00 0.00 0.00
BBER [%] : 0.00 0.00 0.00 0.00
Available time : 00000221 00000221 00000206 00000206
Unavailable time : 00000027 00000027 00000042 00000042
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_04_PM>
1. RRBEn: nth Regenerator remote block errored indicating error blocks are being
received on the REG-R (LTU) side of the regenerator.
2. RCBEn: nth Regenerator central block errored indicating error blocks are being
received on the REG-C (NTU) side of the regenerator.

E1: The G826 E1 command displays the ITU-T G.826 error performance
parameters on the E1 2Mbit/s side. This command is only available if framed
mode is enabled.

If CRC4 mode is on, the following parameters are displayed:

LTU_04_PM> G826 E1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
G.826 Error Performance : CRC4 E-Bit
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Errored Blocks : 00000000 00000000
Errored seconds : 00000000 00000000
Severely errored seconds : 00000000 00000000
ESR [%] : 0.00 0.00
SESR [%] : 0.00 0.00
BBER [%] : 0.00 0.00
Available time : 00524129 00524129
Unavailable time : 00000024 00000024
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_04_PM>

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If CRC4 mode is off, the following parameters are displayed:

LTU_04_PM> G826 E1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
G.826 Error Performance : FAS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Errored blocks : 00000000
Errored seconds : 00000000
Severely errored seconds : 00000000
ESR [%] : 0.00
SESR [%] : 0.00
BBER [%] : 0.00
Available time : 00009841
Unavailable time : 00000024
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_04_PM>

Definitions:
1. CRC4: Cyclic redundancy check indicating errored sub-multiframes received on the
local 2Mbit/s E1 side.
2. E-bit: CRC-4 indication bit denoting received errored sub-multiframes on the 2Mbit/s
E1 side.
3. FAS: Errored Frame Alignment Signal received on the 2Mbit/s E1 side. The criteria
for severely errored seconds (SES) is 28 FAS-Errors per second (in accordance to
G.821).
In PRA mode, the G826 E1 command displays the ITU-T G.826 error performance
parameters on the PRA 2Mbit/s:

LTU_04_PM> G826 E1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
G.826 Error Performance : CRC4_T E-Bit_T CRC4_V3 E-Bit_V3
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Errored Blocks : 00000000 00000000 00000000 00000000
Errored seconds : 00000000 00000000 00000000 00000000
Severely errored seconds : 00000000 00000000 00000000 00000000
ESR [%] : 0.00 0.00 0.00 0.00
SESR [%] : 0.00 0.00 0.00 0.00
BBER [%] : 0.00 0.00 0.00 0.00
Available time : 00524129 00524129 00524107 00524107
Unavailable time : 00000024 00000024 00000046 00000046
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_04_PM>

Definitions:
1. CRC4_T: Cyclic redundancy check indicating errored sub-multiframes received at the
NT1 side of the T reference.
2. E-Bit_T: CRC-4 indication bit indicating received errored sub-multiframes at the
NT2/TE side of the T reference point.
3. CRC4_V3: Cyclic redundancy check indicating errored sub-multiframes received at
the NT1 side of the V3 reference point.

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4. E-Bit_V3: CRC-4 indication bit indicating received errored sub-multiframes at the ET

side of the V3 reference point.
Note: The G826 E1 command is only available if option 2 (CRC4 processing) or option 4
(CRC4 monitoring) is selected in the configuration.

8.3.1.2 RESETG826 Command

The RESETG826 command sets the G.826 error performance parameters back to zero.

LTU_04_PM> RESETG826
04:35:30 G.826 error performance parameter reset
LTU_04_PM>

8.3.2 Fault and Maintenance Management FMM

04:41:20 Fault and maintenance management activated
type <M> to return to MAIN, or <H> for HELP information
Type <H> and the monitor lists all available commands in the fault and maintenance
sub-menu:

LTU_04_FMM> H
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SQ Turn HDSL signal quality trace on/off
SQ REGn Turn regenerator signal quality trace on/off
STARTUP Turn HDSL transceiver startup trace on/off
STATUS Display local system status
STATUS R Display remote system status
STATUS REGn Display regenerator status
ALARM Display local alarm status
ALARM R Display remote alarm status
ALARM T Turn alarm trace on/off
ACO [ON,OFF] Activate / deactivate alarm cutoff
LOOP1 [ON,OFF] Activate / deactivate local loopback
LOOP2 [ON,OFF] Activate / deactivate remote loopback
LOOPREGn [ON,OFF] Activate / deactivate regenerator loopback
STARTAL Start analog loopback
STOPAL Stop analog loopback
TRACETIME [1..20] Change trace time (1..20 seconds)
RESET Reset system
RESET R Reset remote station
M(AIN) Return to main menu
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_04_FMM>

8.3.2.1 SQ Command
The SQ command allows the user to turn the signal quality trace on and off:

LTU_04_FMM> SQ
04:53:30 HDSL signal quality trace on
04:53:30 HDSL noise margin: local A: --.- B: --.- / remote A: --.- B: --.- dB
04:54:30 HDSL noise margin: local A:+19.5 B:+19.5 / remote A:+19.5 B:+19.5 dB

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04:55:30 HDSL noise margin: local A:+19.5 B:+19.5 / remote A:+19.0 B:+19.5 dB
LTU_04_FMM> SQ
04:56:30 HDSL signal quality trace off
LTU_04_FMM>

Note: If configured as master, both local and remote signal quality (signal quality at remote
station) are reported; if configured as slave, only the local signal quality is reported. The
master periodically reads the signal quality from the remote station via EOC. If no valid
signal quality value was able to be communicated from the slave to the master since the
last trace output, “--.-” will appear instead of the signal quality value.

8.3.2.2 SQ REGn Command

The SQ REGn command allows the user to toggle the signal quality trace of the
nth regenerator on and off:

LTU_04_FMM> SQ REG1
05:07:40 regenerator (1) signal quality trace on
05:07:40 REG1 noise margin: REG-R A: --.- B: --.- / REG-C A: --.- B: --.- dB
05:08:40 REG1 noise margin: REG-R A:+20.0 B:+19.5 / REG-C A:+19.0 B:+19.0 dB
05:09:40 REG1 noise margin: REG-R A:+19.5 B:+19.5 / REG-C A:+19.5 B:+19.0 dB
05:10:40 REG1 noise margin: REG-R A:+19.5 B:+19.5 / REG-C A:+19.5 B:+19.5 dB
05:11:40 REG1 noise margin: REG-R A:+19.0 B:+19.0 / REG-C A:+19.5 B:+19.0 dB
LTU_04_FMM> SQ REG1
05:11:70 regenerator (1) signal quality trace off
LTU_04_FMM>

Note: This command is available on LTU-R only. It periodically reads the signal quality from
the regenerator via EOC. If no valid signal quality value was communicated from the
regenerator to the master since the last trace output, “--.-” will appear instead of a signal
quality value. Also, the activation of the regenerator loopback will force the REG-C
values to appear as “--.-”.

8.3.2.3 STARTUP Command

The STARTUP command allows the user to turn the startup trace on and off, in order to
observe the LTU and NTU activation state diagram transitions. The activation state
diagram transitions are conforming to ETSI TS 101 135. Note that in case of a
regenerated DSL link, no activation state diagram transitions for the regenerator-NTU
link can be monitored.

LTU_04_FMM> STARTUP
00:03:60 HDSL transceiver startup trace on
00:03:60 A - INACTIVE : transmit SILENT
00:03:60 B - INACTIVE : transmit SILENT
00:03:80 A - ACTIVATE_1 : transmit S0
00:03:80 B - ACTIVATE_1 : transmit S0
00:05:80 A - ACTIVATE_2 : signal detected
00:05:80 B - ACTIVATE_2 : signal detected
00:15:90 A - ACTIVATE_3 : transmit S1
00:15:90 B - ACTIVATE_3 : transmit S1
00:20:00 A - ACTIVATE_4 : transmit S1

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00:20:00 B - ACTIVATE_4 : transmit S1

00:24:10 A - ACTIVATE_5 : final transceiver mode
00:24:10 B - ACTIVATE_5 : final transceiver mode
00:24:30 A - ACTIVE_RX : receive ready
00:24:30 B - ACTIVE_RX : receive ready
00:24:50 A - ACTIVE_TX_RX : transmit/receive 2B1Q data
00:24:50 B - ACTIVE_TX_RX : transmit/receive 2B1Q data
LTU_04_FMM>

8.3.2.4 STATUS Command

The STATUS command displays the actual system status:

LTU_04_FMM> STATUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local System Status V4.2
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SYNC-A: 02 PID-A: 01 LOSD-A: 00 HRP-A: 01 RPF-A: 01 RPS-A: 02
SYNC-B: 02 PID-B: 02 LOSD-B: 00 HRP-B: 01 RPF-B: 01 RPS-B: 02
MAIN : A
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_04_FMM>
Definitions (shown for loop A; loop B similar):

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Parameter Status Meaning

SYNC-A Status of DSL synchronisation state machine of loop A
according to ETSI TS 101 135.
00 Out of Sync State
02 In Sync State
Note: This parameter does NOT suffice as an indication for
an established DSL link.
PID-A Pair Identification of Loop A according to ETSI TS 101 135.
00 No PID information available
01 Identification Pair No. 1
02 Identification Pair No. 2
Note: If PID-A is 02 and PID-B is 01 on the Slave side, then
Pair A and Pair B between master and slave units are
crossed. At the Master side, PID-A is always = 01 and PID-B
= 02.
LOSD-A Status of LOSD-bit in DSL frame according to ETSI
TS 101 135.
-- No LOSD information available
No signal at application interface of remote station (either
00 LTU or NTU)
Application interface signal of remote station is o.k.
01
HRP-A Status of HRP-bit in DSL frame according to ETSI
TS 101 135.
-- No HRP information available
or 00 Regenerator present
01 No regenerator present
NRA-A
Number of Regenerators available.
RPF-A Remote power feeding status.
00 Remote power feeding on loop a switched off
01 Remote power feeding on loop a switched on
Note: If the LTU is configured with remote power on but RPF
is off, the current limit detector has switched off the remote
power feeding.

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RPS-A Status of ps1 and ps2 bit in DSL frame according to ETSI
TS 101 135:
ps1
-- -
00 0
01 0
02 1
03 1
MAIN DSL master loop
A Loop A
B Loop B
PRA (PRA Current state of the digital section (DS) according to
mode only) ETS 300 233 section 9.4 (only the states possible in
NT1 & LT mode are displayed).
00 NTU dying
01 NTU dying & FV3/FC5
02 NTU dying & FC4
03 NTU dying & FC4 & FV3/FC5
04 NTU dying & AIS
05 NTU dying & AIS & FC4
06 Normal function
07 FC4
08 FV3/FC5
09 FV3/FC5 & FC4
10 Loopback 1
11 Loopback 1 & FC4
12 Loopback 2
13 Loopback 2 & FC4
14 Loopback 1 & NTU dying
15 Loopback 1 & NTU dying & FC4
16 Loopback 2 & NTU dying
17 Loopback 2 & NTU dying & FC4
18 AIS
19 AIS & FC4

Note: With an LTU-L, the RPF and RPS will always display 00.
Options:
R Displays the status of the remote station (supported by master only)

8.3.2.5 STATUS REGn Command

This command is only available on the LTU-R and reads the status of the nth regenerator
over EOC.

LTU_04_FMM> STATUS REG1

05:50:10 reading status from regenerator (1)
LTU_04_FMM>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Regenerator Status (1) V1.3

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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SYNC-RA: 02 SYNC-CA: 02 SQ-RA:+19.5 SQ-CA:+19.0
SYNC-RB: 02 SYNC-CB: 02 SQ-RB:+19.0 SQ-CB:+19.0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_04_FMM>

Definitions (shown for loop A; loop B similar):

Parameter Status Meaning
SYNC-RA Status of DSL synchronisation state machine of loop A at
REG-R (LTU) side of regenerator according to ETSI
TS 101 135.
00 Out of Sync State
02 In Sync State
Note: This parameter does NOT suffice as an indication
for an established DSL link.
SYNC-CA Status of DSL synchronisation state machine of loop A at
REG-C (NTU) side of regenerator, state coding as above.
SQ-RA Signal quality of loop A at REG-R (LTU) side of
regenerator [dB].
SQ-CA Signal quality of loop A at REG-C (NTU) side of
regenerator [dB].

Note: This command is available on the LTU-R only.

During regenerator loopback, the status of SYNC-CA and SYNC-CB shows ‘02’ due to
the loopback location inside the regenerator.

8.3.2.6 ALARM Command

The ALARM command displays the actual alarm status:
LTU_04_FMM> ALARM
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Alarm Status
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LOS-S: on LOS/LFA-A: off BER-H: off LOOP1: off CLDET-A: off
LFA-S: off LOS/LFA-B: off BER-L: off LOOP2: off CLDET-B: off
AIS-S: off EXT-LOC : off AIS-R: on ACO : off
BER-S: off ALB : off
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Regenerator Alarm Status

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
REG1-A: off REG1-B: off BER-REG1: off LOOPREG1: off
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_04_FMM>

Options:
R Displays the status of the remote station (supported by master only)
T Turns alarm trace on / off

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Definitions:
LOS-S: Loss of signal at subscriber (E1) side
LFA-S: Loss of frame alignment at subscriber (E1) side
AIS-S: AIS (Alarm Indication Signal) detected at subscriber (E1) side
BER-S: Excessive Block Error Rate on subscriber side
If CRC4 enabled : BER-S = on if more than 805 CRC4 Errors per
second.
If CRC4 disabled : BER-S = on if more than 28 FAS Errors per second.
EXT-LOC: Loss of external clock

LFA-V3 Loss of frame alignment at V3-reference point (PRA mode)

AIS-V3 Alarm indication signal at V3-reference point (PRA mode)

LOS/LFA-A Loss of signal or frame alignment at DSL loop A

LOS/LFA-B: Loss of signal or frame alignment at DSL loop B

BER-REG-H: DSL block error rate at regenerator according to G.826 ≥ 30%

BER-REG-L: DSL block error rate at regenerator according to G.826 > 15%

BER-H: DSL block-error-rate according G.826 ≥ 30%

BER-L: DSL block-error-rate according G.826 > 15%
AIS-R: Alarm indication from remote station
LOOP1: DSL test loop 1 active
LOOP2: DSL test loop 2 active
ACO: Alarm cutoff
ALB: Analog loopback

CLDET-A: Current limit detection at loop A

CLDET-B: Current limit detection at loop B
REG-A: Alarm indication from regenerator at loop A
or regenerator loopback active
REG-B: Alarm indication from regenerator at loop B
or regenerator loopback active
LOOPREG: Regenerator loopback active

8.3.2.7 ACO Command

The ACO (Alarm Cut Off) command enables or disables the alarm relays. When ACO is
'on', all alarms are disabled and the alarm-relays are inactive. The local alarm LED
signalizes a non-urgent alarm.

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LTU_04_FMM> ACO ON
11:03:10 alarm cutoff activated
LTU_04_FMM> ACO OFF
11:11:70 alarm cutoff deactivated

8.3.2.8 LOOP1 Command

The LOOP1 command starts the local loopback:

LTU_04_FMM> LOOP1 ON
01:10:50 Loop 1 activated
LTU_04_FMM>

8.3.2.9 LOOP2 Command

The LOOP2 command starts the remote loopback:

LTU_04_FMM> LOOP2 ON
01:10:50 Loop 2 activated at remote station
LTU_04_FMM>

Note: The remote loopback is only possible from master side.

8.3.2.10 LOOPREGn Command

The LOOPREGn command starts the loopback in the nth regenerator:

LTU_01_FMM> LOOPREG1 ON
29:25:70 regenerator (1) loopback activated
LTU_01_FMM>

Note: This command is available on LTU-R only.

8.3.2.11 STARTAL Command

The STARTAL command starts the analog loopback:

LTU_04_FMM> STARTAL
01:04:00 analog loopback started
LTU_04_FMM>

Notes:
• The system unit must be configured as master for analog loopback operation.
• Detach the DSL line before starting the analog loopback. If the analog loopback is
started while a remote station is attached to the DSL line, the remote station signal
will interfere with the loopback signal, causing bit errors on the E1 side.
• To return to normal operation, restart the system either by power up or RESET
command or use the STOPAL command.

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8.3.2.12 STOPAL Command

The STOPAL command stops the analog loopback

LTU_04_FMM> STOPAL
02:04:00 analog loopback stopped
LTU_04_FMM>

8.3.2.13 TRACETIME Command

The TRACETIME command allows the user to change the trace display repetition time
(range: 1 .. 20 sec):

LTU_04_FMM> TRACETIME 3
04:10:30 trace time changed to 03 sec
LTU_04_FMM> TRACETIME 1
04:20:10 trace time changed to 01 sec
LTU_04_FMM>

8.3.2.14 RESET Command

By typing RESET, the system unit will be restarted.

LTU_04_FMM> RESET
05:06:10 system reset

Option:
R Resets the remote station (supported by master only)
Note: On a Dual LTU both systems will be reset.

8.3.3 Configuration Management CM

02:26:00 Configuration management activated

Type <M> to return to MAIN, or <H> for HELP information

Type <H> and the monitor lists all available commands in the configuration sub-menu:

LTU_04_CM> H
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CONFIG Display local configuration
G704 [ON,OFF] Set framed mode / transparent mode
CRC4 [ON,OFF] Set CRC4 mode on/off
EBIT [ON,OFF] Set automatic E-Bit insertion on/off
AISGEN [ON,OFF] Set AIS generation on/off
AISDET [ON,OFF] Set AIS detection on/off
EXTCLK [ON,OFF] Set external clock mode on/off
UIF [E1,PRA] Set user interface type
POWER [ON,OFF] Set remote powering on/off
MASTER [ON,OFF] Set HDSL master mode / slave mode
RESTART [ON,OFF] Set autorestart on/off
MODE [N,F,P,H] Set HDSL operating mode
DEFAULT [0..2] Set default configuration
REMOTE Activate remote configuration

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M(AIN) Return to main menu

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_04_CM>

Notes:
• The MASTER command is valid on the LTU-L only.
• The POWER command is valid on the LTU-R only.
• The UIF type command selects only equipped user interfaces.

8.3.3.1 CONFIG Command

The CONFIG command displays the configuration of the unit:

LTU_04_CM> CONFIG
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Configuration Id : 2 Mbit/s G.703
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2 Mbit/s
Framing : ITU-T G.704
CRC4 : On
E-Bit Insertion : On
AIS Generation : On
AIS Detection : On
External Clock : Disabled
HDSL
Master/Slave : Master
Autorestart : Enabled
Operating Mode : Normal
Channel A : On
Channel B : On
Remote Powering : On
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_04_CM>

Notes:
• To display the remote configuration (supported by master only) see REMOTE
command in section “REMOTE Command”.
• After each configuration change, the new configuration is automatically displayed.
• The remote powering option will be displayed for the LTU-R only.

8.3.3.2 Configuration Commands

E1 Interface
G704: Set framed mode / transparent mode.
CRC4: Set CRC4 mode on / off.
EBIT: Set automatic E-Bit insertion on / off.
AISGEN: Set AIS generation on / off.
AISDET: Set AIS detection on / off.

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EXTCLK: Set external clock mode on / off.

UIF: Set the user interface type to E1 or PRA.

PRA Interface
PRA: Select the ISDN PRA functional entities of the modem:
OFF: No PRA function (transparent transmission)
NT1LT: Both NT1 and LT
LT: Only LT
NT1: Only NT1
CRC4: Set CRC4 processing option (Subscriber access option):
1: Digital Link without CRC4 Processing
2: Digital Link with CRC4 Processing
3: Option 3 is not available
4: Digital Link with CRC4 Monitoring
This configuration selects the subscriber access option of the
whole digital section (NT1 and LT) only if PRA Mode NT1 &
LT is selected. If NT1 and LT functions run on different modems,
the CRC4 settings of both modems determine the access option
(see description of PRA configuration options).
CRC4SA6: Set generation of CRC4 error notifications to the ET on / off
(applies only to NT1).
UIF: Set the user interface type to E1 or PRA.

DSL Interface
POWER: Set remote powering on / off.
MASTER: Set DSL master mode / slave mode.
Note:
One unit must be configured as Master (DSL-side) and the
other as Slave.
The master/slave configuration affects the whole unit, i.e. both
modem of a Dual LTU.
RESTART: Set autorestart on / off.

MODE: Set HDSL operating mode: Normal, Fractional, Partial, Hot

Standby.
Partial and Hot Standby operation are not available if remote
power feeding is switched on.

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8.3.3.3 DEFAULT Command

The DEFAULT command sets a default configuration. Three default-settings are
available:

LTU_01_CM> DEFAULT 0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Configuration Id : 2 Mbit/s G.703
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2 Mbit/s
Framing : Transparent
CRC4 : --
E-Bit Insertion : --
AIS Generation : On
AIS Detection : On
External Clock : --
HDSL
Master/Slave : Master
Autorestart : Enabled
Operating Mode : Normal
Channel A : On
Channel B : On
Remote Powering : On
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_01_CM>

LTU_01_CM> DEFAULT 1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Configuration Id : 2 Mbit/s G.703
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2 Mbit/s
Framing : CCITT G.704
CRC4 : On
E-Bit Insertion : On
AIS Generation : On
AIS Detection : On
External Clock : Disabled
HDSL
Master/Slave : Master
Autorestart : Enabled
Operating Mode : Normal
Channel A : On
Channel B : On
Remote Powering : On
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_01_CM>

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LTU_01_CM> DEFAULT 2
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Configuration Id : 2 Mbit/s G.703
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2 Mbit/s
Framing : Transparent
CRC4 : --
E-Bit Insertion : --
AIS Generation : On
AIS Detection : Off
External Clock : --
HDSL
Master/Slave : Master
Autorestart : Enabled
Operating Mode : Normal
Channel A : On
Channel B : On
Remote Powering : On
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_01_CM>

In PRA mode, the default configurations give standard settings for each PRA mode (LT,
NT1, NT1 & LT):

NTU_CM> DEFAULT 0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Configuration Id : ISDN PRA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PRA
PRA Mode : LT
Access Option : Monitoring on
CRC4 Error->Sa6 : --
HDSL
Master/Slave : Slave
Autorestart : Enabled
Operating Mode : Normal
Channel A : On
Channel B : On
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NTU_CM>

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NTU_CM> DEFAULT 1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Configuration Id : ISDN PRA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PRA
PRA Mode : NT1
Access Option : Processing on
CRC4 Error->Sa6 : On
HDSL
Master/Slave : Slave
Autorestart : Enabled
Operating Mode : Normal
Channel A : On
Channel B : On
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NTU_CM>

NTU_CM> DEFAULT 2
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Configuration Id : ISDN PRA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PRA
PRA Mode : NT1 & LT
Access Option : Processing on
CRC4 Error->Sa6 : On
HDSL
Master/Slave : Slave
Autorestart : Enabled
Operating Mode : Normal
Channel A : On
Channel B : On
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NTU_CM>

The factory setting can be loaded using the “DEFAULT 2” command. All DSL LTUs and
NTUs are delivered with this configuration (LTUs as master, NTUs as slave).

Note: The Master/Slave and Remote Powering settings are not affected by the
DEFAULT Command.

8.3.3.4 REMOTE Command

The REMOTE Command enables the remote configuration:

LTU_01_CM> REMOTE
11:32:50 remote configuration activated

Type <H> and the monitor lists all the available commands on the remote side:

LTU_01_CM_REMOTE> H
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CONFIG Display remote configuration
G704 [ON,OFF] Set framed mode / transparent mode
CRC4 [ON,OFF] Set CRC4 mode on/off
EBIT [ON,OFF] Set automatic E-Bit insertion on/off

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AISGEN [ON,OFF] Set AIS generation on/off

AISDET [ON,OFF] Set AIS detection on/off
UIF [E1,PRA] Set user interface type
COPY Copy local configuration to remote station
LOCAL Return to local configuration
M(AIN) Return to main menu
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_01_CM_REMOTE>

Note: The REMOTE command is only possible from master side.

8.3.3.5 COPY Command

The COPY command sets the remote configuration equal to the local.

8.3.3.6 LOCAL Command

The LOCAL command switches back to the local configuration:

8.3.4 Accounting Management AM

Accounting management is not supported.

8.3.5 Security Management SM

Security management is not supported.

8.4 Monitor Commands for the n x 64kbit/s Interface

This section deals only with n x 64kbit/s specific monitor commands.

8.4.1 Fault and Maintenance Management FMM

8.4.1.1 ALARM Command

NTU_FMM> ALARM
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Alarm Status
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
DTR-1: on LOS/LFA-A: on BER-H: off LOOP1: off
DTR-2: off LOS/LFA-B: on BER-L: off LOOP2: off
LOC : off AIS-R: off ACO : off
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NTU_FMM>
These alarms are related to the n x 64kbit/s interface:
DTR: Status of DTR (Data Terminal Ready) Handshake Signal. For X.21, the
Control-signal (C) is represented by DTR.
DTR Signal is detected as ‘ON’ (Status: off)
DTR Signal is detected as ‘OFF’ (Status: on)

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LOC: Loss Of Clock (When Local Clock mode is selected). LOC is also active when
the incoming clock bit rate is not equal to the programmed bit rate (n).
Clock master present with correct bit rate (Status: off)
Clock master not present and/or bit rate mismatch (Status: on)

8.4.2 Configuration Management CM

NTU_CM> H
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CONFIG Display local configuration
BITRATE n1 n2 Set bitrate (n x 64 kbit/s) of Port 1 and 2:
n1,n2 = [0..32]
CLOCKMODE [0..3] Select clock source:
0=Port 1, 1=Port 2, 2=internal, 3=remote
CLOCKDIR dir1 dir2 Set clock direction of Port 1 and 2:
0=codir, 1=contradir
V54LOOPS [ON,OFF] Set V.54 loop control on/off
UIF [V35,V36,X21] Set user interface type
MASTER [ON,OFF] Set HDSL master mode / slave mode
RESTART [ON,OFF] Set autorestart on/off
DEFAULT [0..2] Set default configuration
M(AIN) Return to main menu
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NTU_CM>

8.4.2.1 CONFIG Command

The CONFIG command displays the configuration of the NTU unit (e.g. V.35):

NTU_CM> CONFIG
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Configuration Id : nx64 kbit/s V.35
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
V.35
Bitrate Port 1 : 32 x 64 = 02048 kbit/s
Bitrate Port 2 : Off
Clock Mode : Remote
Clockdir Port 1 : Contradirectional
Clockdir Port 2 : Contradirectional
V.54 Loops : Disabled
HDSL
Master/Slave : Slave
Autorestart : Enabled
Operating Mode : Normal
Channel A : On
Channel B : On
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NTU_CM>

8.4.2.2 BITRATE Command

Set bit rate (n x 64kbit/s) of Port 1 and Port 2: n1, n2 = [0..32]
To turn off the port the bit rate must be 0. Example n1= 32, n2 = 0.
The command for this example will be:

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NTU_CM> BITRATE 32 0

8.4.2.3 CLOCKMODE Command

Select clock source: 0=Port 1, 1=Port 2, 2=internal, 3=remote.

8.4.2.4 CLOCKDIR Command

Set clock direction of Port 1 and 2: 0=codirectional, 1=contradirectional.
In most cases, the clock direction is implicitly set by the clock mode.

8.4.2.5 V54LOOPS Command

Select whether it is possible to switch loop 1 and 2 using the control circuits 140 (RL) and
141 (LL). This command is only available in V.35 and V.36 modes.

8.4.2.6 BYTETIMING Command

Select if circuit B for byte timing is used in X.21 mode. Note that to use the byte timing
you need the appropriate cable and cannot use the codirectional transmit clock.

8.4.2.7 UIF Command

Select the interface type: V35 = V.35, V36 = V.36, X21 = X.21.

8.4.2.8 DEFAULT Command

The DEFAULT command sets a default configuration.
Three default settings are available for the n x 64kbit/s interface:

NTU_CM> DEFAULT 0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Configuration Id : nx64 kbit/s V.35
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
V.35
Bitrate Port 1 : Off
Bitrate Port 2 : Off
Clock Mode : Remote
Clockdir Port 1 : Contradirectional
Clockdir Port 2 : Contradirectional
V.54 Loops : Disabled
HDSL
Master/Slave : Slave
Autorestart : Enabled
Operating Mode : Normal
Channel A : On
Channel B : On
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NTU_CM>

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NTU_CM> DEFAULT 1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Configuration Id : nx64 kbit/s V.35
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
V.35
Bitrate Port 1 : Off
Bitrate Port 2 : Off
Clock Mode : Internal
Clockdir Port 1 : Contradirectional
Clockdir Port 2 : Contradirectional
V.54 Loops : Disabled
HDSL
Master/Slave : Slave
Autorestart : Enabled
Operating Mode : Normal
Channel A : On
Channel B : On
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NTU_CM>

NTU_CM> DEFAULT 2
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Configuration Id : nx64 kbit/s V.35
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
V.35
Bitrate Port 1 : Off
Bitrate Port 2 : Off
Clock Mode : Remote
Clockdir Port 1 : Contradirectional
Clockdir Port 2 : Contradirectional
V.54 Loops : Disabled
HDSL
Master/Slave : Slave
Autorestart : Enabled
Operating Mode : Normal
Channel A : On
Channel B : On
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NTU_CM>

8.4.2.9 COPY Command

The COPY command sets the remote configuration equal to the local and is only
available in the remote configuration menu.

8.5 Monitor Commands for LTU Minirack TMN Interface

For Minirack versions of the LTU, the address number of the DSL interface can be set
manually by monitor commands in the Configuration Management (CM) menu.
After power-up of a Minirack LTU always the local monitor main menu appears with the
first DSL system activated (behaviour like a NTU).

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Address numbers in range 1-127 can be set independently to the different DSL systems of
a LTU.
The alternatives of running the TMN communication on a 2- or 4-wire bus can be
selected in the CM menu as well. The list below shows the available commands in the
Configuration Management menu of a Minirack LTU.
RESET command, DEFAULT command or power down has no influence on settings
made for the TMN interface.

LTU_10_CM> H
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CONFIG Display local configuration
G704 [ON,OFF] Set framed mode / transparent mode
CRC4 [ON,OFF] Set CRC4 mode on/off
EBIT [ON,OFF] Set automatic E-Bit insertion on/off
AISGEN [ON,OFF] Set AIS generation on/off
AISDET [ON,OFF] Set AIS detection on/off
EXTCLK [ON,OFF] Set external clock mode on/off
POWER [ON,OFF] Set remote powering on/off
RESTART [ON,OFF] Set autorestart on/off
MODE [N,F,P,H] Set HDSL operating mode
ADDRESS [1..127] Set address
V11WIRES [2,4] Set number of V.11 wires
DEFAULT [0..2] Set default configuration
REMOTE Activate remote configuration
M(AIN) Return to main menu
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_10_CM>

8.5.1 ADDRESS Command

The ADDRESS command allows the user to assign an address number in the range
between 1–127 to the current DSL interface of a Minirack LTU.

LTU_02_CM> ADDRESS 4
01:19:40 Address set to 04
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Configuration Id : nx64 kbit/s V.35
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
V.35
Bitrate Port 1 : 32 x 64 = 02048 kbit/s
.
.
.
HDSL
Line Rate : 02064 kbit/s
Master/Slave : Master
Autorestart : Enabled
Remote Powering : On
TMN
Address : 04
V.11 wires no. : 04
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_04_CM>

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Note: For a Dual LTU Minirack it is possible to assign a higher interface address number to
DSL system A than to DSL system B.
For Plug-in LTUs the lowest interface number is always assigned to DSL system A and
the pins with appropriate designation on the DSL connector of type RJ-45.

Note: Carefully note already used interface address numbers. No automatic protection against
multiple LTUs assigned to the same interface address number can be applied in a set-up
with several Minirack LTUs.
Two interfaces with same address number on the TMN bus will cause malfunction and the
units will not be accessible by the TMN application SW.

Limitation: Both DSL systems of a Dual LTU can be addressed freely. But possible addresses are
limited to the address ranges 01 - 12 and 33 – 44 by the Small Network Management
Protocol (SNMP) used for communication with the Management Centre.

8.5.2 V11WIRES Command

The V11WIRES command allows to switch between 2- or 4-wire communication on the
TMN interface (EIA-485 bus).

LTU_03_CM> V11WIRES 2
23:34:90 V.11 wires set to 02
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Local Configuration Id : nx64 kbit/s V.35
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
V.35
Bitrate Port 1 : 32 x 64 = 02048 kbit/s
.
.
.
HDSL
Line Rate : 02064 kbit/s
Master/Slave : Master
Autorestart : Enabled
Remote Powering : On
TMN
Address : 03
V.11 wires no. : 02
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LTU_03_CM>

Note: 4-wire communication is recommended for Minirack configurations.

Note: 4-wire communication requires a crossing of Rx and TX signals between CMU and LTU.
2-wire communication uses only Rx A and Rx B wires without any crossing.

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9 Front and Rear Panel Description

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9.1 Tabletop NTU, Rear Panel

E1 120Ω

E1 75Ω

nx64kbit/s

9.2 Minirack NTU, Front Panel

E1 120Ω

E1 75Ω

nx64kbit/s

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9.3 Plug-in LTU, Front Panel

E1 120Ω E1 75Ω Dual 2*E1 120Ω Dual 2*E1 75Ω

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9.4 Minirack LTU, Front Panel

Dual 2* E1 120Ω,

Dual 2* E1 75Ω,

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10 Connectors’ Description

10.1 DSL Connector

Type: RJ45-8

Front View
1 8 RJ45-8

NTU and LTU LTU (Dual)

Pin Signal Description Signal Description
1 NC - LD.a Loop D, tip
2 Shield DSL cable shield (optional) LD.b Loop D, ring
3 LB.a Loop B, tip LB.a Loop B, tip
4 LA.a Loop A, tip LA.a Loop A, tip
5 LA.b Loop A, ring LA.b Loop A, ring
6 LB.b Loop B, ring LB.b Loop B, ring
7 Shield DSL cable shield (optional) LC.a Loop C, tip
8 NC - LC.b Loop C, ring

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10.2 E1 Connector

10.2.1 Impedance 120Ω

LTU: 1 5

Type: SubD9 male (Front View)

6 9
Pin Signal Description
1 RXa E1 120Ω Output (wire A)
2 FPE Functional Protective Earth (cable shield RX)
3 NC -
4 FPE Functional Protective Earth (cable shield TX)
5 TXa E1 120Ω Input (wire A)
6 RXb E1 120Ω Output (wire B)
7 NC -
8 NC -
9 TXb E1 120Ω Input (wire B)

Dual LTU: 1 8

Type: SubD15 male (Front View)

9 15
Pin Signal Description
1 RX1a E1 120Ω Output 1 (wire A)
2 FPE Functional Protective Earth (cable shield RX)
3 TX1a E1 120Ω Input 1 (wire A)
4 FPE Functional Protective Earth (cable shield TX)
5 FPE Functional Protective Earth (cable shield RX)
6 RX2a E1 120Ω Output 2 (wire A)
7 FPE Functional Protective Earth (cable shield TX)
8 TX2a E1 120Ω Input 2 (wire A)
9 RX1b E1 120Ω Output 1 (wire B)
10 NC -
11 TX1b E1 120Ω Input 1 (wire B)
12 NC -
13 RX2b E1 120Ω Output 2 (wire B)
14 NC -
15 TX2b E1 120Ω Input 2 (wire B)

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NTU: 13 1

Type: SubD25 female (Front View)

25 14
Pin Signal Description
1 GND E1 – Ground
6 RXa E1 120Ω Output (wire A)
7 GND E1 – Ground
8 TXa E1 120Ω Input (wire A)
19 RXb E1 120Ω Output (wire B)
21 TXb E1 120Ω Input (wire B)

10.2.2 Impedance 75Ω

Type: BNC 75Ω

10.3 n x 64kbit/s Connector

10.3.1 User Interface Type

A female SubD25 connector is used for all modes. The table below depicts the pin-out of
the connector for the different modes (according to RS-530, ISO 2110) and the signal
levels used for the signals.

13
25
Front View
SubD25, female

14
1

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ITU-T Number Signal Level

Pin Nr. i/o V.35 V.36 X.21 V.35 V.36 X.21
1 FGND FGND FGND
2 i 103A 103A TA V.35 V.11 V.11
3 o 104A 104A RA V.35 V.11 V.11
4 i 105 105A CA V.28 V.11 V.11
5 o 106 106A IA V.28 V.11 V.11
6 o 107 107A V.28 V.11
7 102 102 G
8 o 109 109A V.28 V.11
9 o 115B 115B BB V.35 V.11 V.11
10 o 109B V.11
11 i 113B 113B XB V.35 V.11 V.11
12 o 114B 114B SB V.35 V.11 V.11
13 o 106B IB V.11 V.11
14 i 103B 103B TB V.35 V.11 V.11
15 o 114A 114A SA V.35 V.11 V.11
16 o 104B 104B RB V.35 V.11 V.11
17 o 115A 115A BA V.35 V.11 V.11
18 i 141 141 V.28 V.10
19 i 105B CB V.11 V.11
20 i 108/2 108/2A BIA V.28 V.11 V.11
21 i 140 140 V.28 V.10
22 o 107B V.11
23 i 108/2B BIB V.11 V.11
24 i 113A 113A XA V.35 V.11 V.11
25 o 142 142 V.28 V.10

The ITU-T Numbers are according to ITU-T V.24 (V.35, V.36) and ITU-T X.24 (X.21):
ITU-T Number Description From To
DCE DCE
102, G, SGND Signal Ground
103, T Transmitted data x
104, R Received data x
105, C Request to send x
106, I Clear to send x
107 Data set ready x
108/2 Data terminal ready x
109 Data channel received line signal detector x
113, X Codirectional transmit clock, the transmitted data will be sampled x
with the rising edge.
114 Contradirectional transmit clock, the transmitted data will be sampled x
with the rising edge.
115, S Receive clock, the received data will be sampled with the rising x
edge.
140 Remote loopback x
141 Local loopback x
142 Test Mode x
B Byte timing, OFF during the first half of the last bit of a byte. x
BI Byte timing input (proprietary designation) x

The interface is of type DCE, use the appropriate adapter cable for a DTE connector or
the standard connectors ISO 2593 for V.35, ISO 4902 for V.36, ISO 4903 for X.21.

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10.3.2 n x 64kbit/s Cables

10.3.2.1 V.35 DTE Cable

B A A B
D C C D
E E F
H H
L L
R
N
P P
N
R V.35/ISO 2593
T S S T
V
X
U
W W
U
X
V 34 Pin Connectors
Y
AA

NN NN

male female

Connector Type : 34 pin (ISO 2593), female

ITU-T Pin Assignment 34 pin female Pin Assignment 25 pin male
Number (a/b) (a/b)
FGND A 1
SGND B 7
103 P/S 2/14
104 R/T 3/16
105 C 4
106 D 5
107 E 6
108 H 20
109 F 8
113 U/W 24/11
114 Y/AA 15/12
115 V/X 17/9
140 N 21
141 L 18
142 NN 25

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10.3.2.2 V.35 DCE Cable

Connector Type : 34 pin (ISO 2593), male

ITU-T Pin Assignment 34 pin male Pin Assignment 25 pin male

Number (a/b) (a/b)
FGND A 1
SGND B 7
103 P/S 3/16
104 R/T 2/14
105 C 5
106 D 4
107 E 20
108 H 6
109 - -
113 U/W 17/9
114 - -
115 V/X 24/11
140 N 25
141 L 25
142 NN 18

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10.3.2.3 V.36 DTE Cable

19 1
37 20
V.36/ISO 4902
37 Pin Connectors

20 37
1 19

male female
Connector Type : 37 pin (ISO 4902), female

ITU-T Pin Assignment 37 pin female Pin Assignment 25 pin male

Number (a/b) (a/b)
FGND 1 1
SGND 19 7
SGND(a) 37 7
SGND(b) 20 7
103 4/22 2/14
104 6/24 3/16
105 7/25 4/19
106 9/27 5/13
107 11/29 6/22
108 12/30 20/23
109 13/31 8/10
113 17/35 24/11
114 5/23 15/12
115 8/26 17/9
140 14 21
141 10 18
142 18 25

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10.3.2.4 V.36 DCE Cable

Connector Type : 37 pin (ISO 4902), male

ITU-T Pin Assignment 37 pin male Pin Assignment 25 pin male

Number (a/b) (a/b)
FGND 1 1
SGND 19 7
SGND(a) 37 7
SGND(b) 20 7
103 4/22 3/16
104 6/24 2/14
105 7/25 5/13
106 9/27 4/19
107 11/29 20/23
108 12/30 6/22
109 - -
113 17/35 17/9
114 - -
115 8/26 24/11
140 14 25
141 10 25
142 18 18

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10.3.2.5 X.21 DTE Cable

8 1
15 9
X.21/ISO 4903
15 Pin Connectors

9 15
1 8

male female
Connector Type : 15 pin (ISO 4903), female

ITU-T Pin Assignment 15 pin female Pin Assignment 25 pin male

Number (a/b) (a/b)
FGND 1 1
G 8 7
S 6/13 15/12
R 4/11 3/16
T 2/9 2/14
C 3/10 4/19
I 5/12 5/13
B 7/14 17/91)
BI (7/14) 1) 20/231)
Note:
1) Pins 17-20 and 9-23 have to be connected inside the 25 pin connector.

Alternatively, when the codirectional clock X is used, but no byte clock, this cable can be
used:
ITU-T Pin Assignment 15 pin female Pin Assignment 25 pin male
Number (a/b) (a/b)
FGND 1 1
G 8 7
S 6/13 15/12
R 4/11 3/16
T 2/9 2/14
C 3/10 4/19
I 5/12 5/13
X 7/14 24/11

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10.3.2.6 X.21 DCE Cable

Connector Type : 15 pin (ISO 4903), male

ITU-T Pin Assignment 15 pin male Pin Assignment 25 pin male

Number (a/b) (a/b)
FGND 1 1
G 8 7
S 6/13 24/11
R 4/11 2/14
T 2/9 3/16
C 3/10 5/13
I 5/12 4/19
B 7/14 20/23

Alternatively, when the codirectional clock X is used, but no byte clock, this cable can be
used:
ITU-T Pin Assignment 15 pin female Pin Assignment 25 pin male
Number (a/b) (a/b)
FGND 1 1
G 8 7
S 6/13 24/11
R 4/11 2/14
T 2/9 3/16
C 3/10 5/13
I 5/12 4/19
X 7/14 15/12

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10.4 Monitor Connector (NTU)

Type: SubD9 female (Front View)
5 1

9 6
Pin Signal Description
1 NC -
2 TXD RS-232 Transmit Data
3 RXD RS-232 Receive Data
4 ALACOM Common contact of Alarm relay
5 SGND RS-232 Signal Ground
6 DA_NC Urgent-Alarm contact, normally closed
7 DA_NO Urgent-Alarm contact, normally open
8 ND_NC Non Urgent-Alarm contact, normally closed
9 ND_NO Non Urgent-Alarm contact, normally open

10.5 Monitor Connector (LTU in Minirack)

Type: SubD9 female (Front View)
5 1

9 6
Pin Signal Description
1 SGND RS-232 Signal Ground
2 TXD RS-232 Transmit Data
3 RXD RS-232 Receive Data
4 NC
5 SGND RS-232 Signal Ground
6 NC
7 NC
8 NC
9 NC

Use a standard RS-232 cable female - male (SubD9) for connection to a computer or
terminal.

10.6 48VDC Power Connector (NTU)

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Type: Molex Minifit Junior, safety approved connector to the line adapter with snap-in
characteristic.

4 3
Frontview
Molex-Type Power Connector
2 1

Pin Signal Description

1 -PWR Negative power supply terminal for mains adapter
2 PROT Connected to the center taps of the gas absorbers at
the DSL line input
3 NC Not connected
4 +PWR Positive power supply terminal for mains adapter

10.7 48VDC Supply (Minirack)

Type: Molex, safety approved connector to the line adapter with snap-in characteristic.

4 3
Frontview
Molex-Type Power Connector
2 1

Pin Signal Description

1 NC Not connected
2 NC Not connected
3 -PWR Negative terminal for battery power supply (fused)
4 +PWR Positive power supply terminal

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10.7.1 Mains Connector (Minirack LTU only)

Contains the 230/115Vrms selector and two IEC127 fuses. The values for the fuses are
2xT500mA for 115V, and for 230V they are 2xT250mA.
The connector Type is an IEC 320 C14.

10.7.2 2048kHz Input (Minirack LTU only)

External Clock Input
Type: BNC 75Ω
The input is transformer-coupled.

10.7.3 TMN Alarms (Minirack LTU only)

This is the connector for alarm relay contacts and for the RS485 interface.
Type: SubD15, female

Pin Signal Description

1 GND Protective Ground (connected to pin 8)
2 RX_485+ RS485-Input, (positive)
3 NC Not connected
4 TX_485+ RS485-Output, (positive)
5 NC Not connected
6 NAL_NO Non-Urgent Alarm: Contact Normally Open
7 DAL_NO Urgent Alarm: Contact Normally Open
8 SGND_485 RS485 Signal Ground (connected to pin 1)
9 RX_485- RS485-Input, (negative)
10 NC Not connected
11 TX_485- RS485-Output, (negative)
12 NC Not connected
13 NAL_NC Non-Urgent Alarm: Contact Normally Closed
14 DAL_NC Urgent Alarm: Contact Normally Closed
15 AL_COM Common for Urgent and Non-Urgent Alarms (Alarm
relays)

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11 Technical Specifications

11.1 Interfaces

11.1.1 DSL Line Interface

Norm referred: ETSI TS 101 135
Number of Pairs: 2
Line Rate per Pair: 1168kbit/s ± 32ppm (ETSI-Clock-Mode)
Line Code: 2B1Q
Nominal Line Impedance: 135Ω
Transmit Power: 13.5dBm @ 135Ω
Signal Bandwidth: 0 .. 287kHz (-3dB)
Overvoltage Protection: LTU: ITU-T Rec. K.20
NTU: ITU-T Rec. K.21
Connector Type: RJ-45, 8 pin

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11.1.2 User Interface

E1:
Norm referred: ITU-T Rec. G.703 / G.704
Bit Rate: 2048kbit/s ± 50ppm
Line Code: HDB3
Framing: ITU-T G.704 / transparent
Input Impedance: 120Ω
75Ω
Signal Amplitude: ± 3.00V @ 120Ω
± 2.37V @ 75Ω
Jitter Performance: According to ITU-T Rec. G.823
ESD - Protection: 8kV (Air discharge)
Connector Type: LTU: SubD9 male 120Ω or BNC 75Ω
NTU: SubD25 female 120Ω or BNC 75Ω
PRA:
Norm referred: ETS 300 233, ETS 300 011, ETS 300 046
n x 64kbit/s:
V.35 V.36 X.21
Bit Rate: nx64 kbit/s (n=1..32)
Signal Levels:
Data Lines: ITU-T V.35 ITU-T V.11 ITU-T V.11
Clock Lines: ITU-T V.35 ITU-T V.11 ITU-T V.11
Control Lines: ITU-T V.28 ITU-T V.11/V.10 ITU-T V.11
ESD-Protection: 8kV (Air discharge)
Connector Type HDSL: SubD25 (ISO SubD25 (RS 530), SubD25 female
2110), female female
Connector Type Cable: 34 pin (ISO 37 pin (ISO 4902) 15 pin (ISO
2593) 4903)

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11.1.3 Monitor Interface

Signal Level: RS-232
Data Rate: 9600 Baud, Asynchronous
Protocol: 8 Bit, No Parity, 1 Stop Bit
No Linefeed with Carriage Return
XON/XOFF enabled
Connector Type: SubD9 female

11.1.4 TMN and Alarm Interface (Minirack LTU Only)

Connector Type: SubD15, female
TMN:
Signal Level: TIA/EIA-485 == RS-485
Data Rate: max 9600 Baud, Asynchronous
Protocol: SZ Proprietary
Alarm Relays:
Max. Switching power 30W
Max. Switching current 1A
Max. Switching voltage 110V DC, 125Vrms
Electrical isolation contact- 100Vrms for 1min
coil

Note: As the RS485 bus requires a 120Ω termination impedance, hence a cable connector
attached to the last minirack-LTU in a chain has to provide the bus termination.

11.1.5 The 230/115Vrms and 48VDC Supply of the Minirack

The minirack containing the LTU can be powered either from the 230/115Vrms mains or
from a 48VDC supply or from both.
The 230/115Vrms power entry module can be selected between 230 or 115Vrms . Changing
the mains option must be complemented by replacing both mains fuses. The 230/115Vrms
supply module contains the mains transformer, which galvanically separates the minirack
circuitry from the mains.
The 48VDC supply input is inverse-polarity proof and is also protected with a 1A slow-
blow fuse. The 48VDC voltage delivered to the LTU or NTU is buffered with a 1500µF
capacitor. In the case of a power-fail, the stored energy assures that the power-fail alarm
is asserted before the power shut-down by at least 60ms.

11.1.6 External Clock

The LTU-Minirack equipped with an external 2048 kHz clock input option contains a
module designed to receive and supervise the external clock. The external clock input is a
75Ω BNC type and is coupled to the module via a transformer, providing a physical
isolation barrier of up to 1500Vrms .

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The clock input is converted to TTL levels and is delivered to the LTU. This allows for
the LTU's E1 interface to be synchronized to a central master clock, if needed.
The clock input accepts a 2048kHz signal with a peak voltage range from 375mVp-p to
3Vp-p, without disruption to the clock delivery. This allows for a connection between a
clock source and the clock input, having an insertion loss of max. 6dB (according to ITU-
T G.703, Sec.10, the minimum clock peak voltage must be not less than 1.5Vp-p).
Below the 375mVp-p the Loss of External Clock (LOXCK) alarm is asserted. The
LOXCK signal switches on-off threshold has a hysteresis of about 25mV.

11.2 Power Supply

11.2.1 LTU
Local Powering: -40.5VDC .. -72VDC
Power Consumption:
remote power off remote power on
total local
SZ.363.V510 4.4W 14.8W 7.1W
SZ.363.V530 @2*2.4km REG+NTU
SZ.363.V511 5.6W 27.5W 8.4W
SZ.363.V533 @2* 2km REG+REG

11.2.2 NTU
Power Consumption:
local power remote power
Supply voltage -40.5VDC .. -72VDC -120VDC .. -65VDC at NTU DSL-
Connector
SZ.364.V510 2.9W 2.5 W
SZ.364.V530
SZ.364.V580 3W 2.75W

11.2.3 REG
Power Consumption:
local power remote power
Supply voltage - -120VDC .. -65VDC at DSL-Connector
SZ.372.V2 _ 3.4W (25°C)
3.8 W (-25°C)

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11.3 Environment

11.3.1 Climatic Conditions

Storage: ETS 300 019-1-1 Class 1.2 -25°C … +55°C
Transportation: ETS 300 019-1-2 Class 2.3 -40°C … +70°C
Operation: ETS 300 019-1-3 Class 3.2 -5°C … +45°C
ETS 300 019-1-3 Class 3.3 -25°C ... +55°C only for REG

11.3.2 Safety
According to EN 60950

11.3.3 EMC
According to EN 300386-2

11.4 Physical Dimensions

11.4.1 LTU
19” Plug-in unit: height: 259mm (6 HE), width: 30mm
Minirack LTU: height: 43.5mm, width: 483mm, depth: 230mm
PCB dimensions: height: 233.35mm, length: 220mm

11.4.2 NTU
Tabletop unit: width 220mm, depth 195mm, height 43mm
Minirack NTU: height: 43.5mm, width: 483mm, depth: 230mm

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12 Diagnostics and Troubleshooting

12.1 Test Loops

Standard Test Loops

The test loops can be activated via the monitor interface for both the master and the slave
side. However, only one test loop can be activated at any one time. Activation of a further
test loop will deactivate the previous loop. A system reset will deactivate any pending test
loop.
Slave Master
TX RX
HDSL
User User
Interface Interface

RX Loop 1 Loop 2 Loop 1 TX

Figure 12-20: Standard Test Loops

Notes:
• On the slave side, Loop 1 can only be activated locally, while Loop 2 can only be
activated remotely by the master.
Both the “Status Local” LED on the slave and the “Status Remote” LED on the master
will be lit amber when a loopback is active.
• On the master side, Loop 1 can only be activated locally. Activating Loop 2 turns on
Loop 2 at the slave station. The “Status Local” LED will be lit amber when Loop 1 is
active.

Analog Loopback
To test the DSL equipment itself, the Analog Loopback can be used. To perform this test,
the DSL - cable has to be disconnected from the unit, which must be configured as
master. The test can then be activated with the appropriate monitor command (see
chapter “Monitor”).
During the Analog Loopback Test, the DSL transceiver receives the signal of its own
transmitter due to the impedance mismatch in the DSL line transformer.

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All data of the user interface is looped back according to the interface settings. No other
test loop can be activated during Analog Loopback, which in turn can only be deactivated
by means of a system reset or power-up. If activated, the Analog Loopback sets off a non-
urgent alarm.
Regenerator Loopback:
When using a regenerator, the master can activate an additional loopback in the
regenerator:
Slave Regenerator Master
TX RX
HDSL HDSL
User
User
Interface
Interface
Loop 1 Loop 2 Loop REG Loop 1 TX
RX

Figure 12-21: Regenerator Loopback

During Regenerator Loopback operations, DSL frames coming from the LTU are looped
back to the LTU while the return path from the NTU is open. When a Regenerator
Loopback is activated, the following two restrictions must be considered:
• NTU (Slave) is not available by means of EOC related management functions.
• No startups are performed on the second REG-NTU section. However, if the REG-
NTU section was running prior to the activation of the Regenerator Loopback, the
second section will remain active.
Regenerator

RX TX

HDSL HDSL
to Slave Framer from Master

TX RX

only one pair shown; other pair similar

Figure 12-22: Regenerator in Loopback Mode

If activated, the Regenerator Loopback causes the following alarms:

• LOOPREG, indicating that Regenerator Loopback command was entered (LTU-R
only).
• REG-A and REG-B, indicating that regenerator has executed the loopback command.

12.2 Hints for Troubleshooting

Problem To do:
No response from the • Please check your physical serial connection.
modem • Does the PC/cable combination work on other

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modems?
• Is it the correct cable (see manual section "Cables")?
• Is the cable grounding correctly connected (floating
ground)? Check cable.
• Please check your baud rate, COM1, COM2, etc
configuration on the PC (see chapter "Monitor").
• Try typing <Control-Q> which is XON and <ECHO>, (to
re-enable communication to LTUs occasionally left in
XOFF state)
• Try selecting the modem using <%n>, n being modem
address. (See chapter "Monitor").

Strange signs are received • Check baud rate of PC

in response from the • Try typing <Control-Q> which is X-on and <ECHO>
modem.

Problems with E1 clock • Check configuration: Do not configure the E1 interfaces

(frequency, drift, slips): at both ends to use the receive clock as transmit clock
except if one DSL equipment is an LTU using the
“External Clock” option. Otherwise there will be no
defined clock.

No startup • If both system units are configured as master or as

slave, no start-up will occur. To identify the master unit,
check if both LED’s are lit ‚ON‘ The slave has only the
local LED turned on.
• Check that you use twisted pair cables till to the end of
DSL RJ-45 connector. Do not use other cable types as
twisted pairs.

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13 Appendix

13.1 Abbreviations
2B1Q 2 Binary - 1 Quaternary
ACO Alarm Cut Off
ACU Alarm Control Unit
AIS Alarm Indication Signal
AIS-R Alarm Indication Signal (Alarm bit in DSL frame)
AIS-S Alarm Indication Signal Subscriber
BER-H Block Error Rate High (≥ 30 % according G.826)
BER-L Block Error Rate Low (> 15 % & < 30% according G.826)
BER-S Excessive Block Error Rate (CRC-4 Errors > 805) on Subscriber
CAP Carrierless Amplitude Phase Modulation
CCITT International Telegraph and Telephone Consultative Committee
CCS Common Channel Signaling
CMU Control and Management Unit
CRC Cyclic Redundancy Check
DSL Digital Subscriber Loop
E1 ITU-T G.703 User Interface at 2048 kbit/s
ET Exchange Termination
EOC Embedded Operations Channel
ESR Errored Second Ratio (G.826)
FAS Frame Alignment Signal
FC Failure Condition
FEBE Far End Block Error
frE1 Fractional E1
HDSL High Bit Rate Digital Subscriber Loop
HRP HDSL Regenerator Present

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ISDN Integrated Services Digital Network

ITU-T International Telecommunication Union
LFA Loss of Frame Alignment
LFA-L Loss of Frame Alignment DSL
LFA-S Loss of Frame Alignment Subscriber
LOS-L Loss of Signal
LOS-S Loss of Signal Subscriber side
LT Line Termination
LTU Line Termination Unit
MSDSL Multi-rate Symmetrical DSL
NC Not Connected
NEXT Near End Cross Talk
NM Noise Margin
NT Network Termination
NTU Network Termination Unit
PDH Plesiochronous Digital Hierarchy
PRA Primary Rate Access
RCBE Regenerator Central Block Error
RRBE Regenerator Remote Block Error
Rx Receive
SDH Synchronous Digital Hierarchy
SESR Severely Errored Second Ratio (G.826)
SMF Sub-Multiframe
SNMP Simple Network Management Protocol
SQ Signal Quality
TE Terminal Equipment
TMN Telecommunication Management Network
Tx Transmit
UIF User Interface
UTP Unshielded Twisted Pair
XVR Transceiver

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13.2 Referenced Documents

[1] EN 55024: "Information technology equipment - Immunity characteristics - Limits and
methods of measurement (CISPR 24: 1997, modified)".
[2] EN 55022: "Information technology equipment - Radio disturbance characteristics -
Limits and methods of measurement (CISPR 22: 1997, modified)".
[3] EN 300 386-2: "Electromagnetic compatibility and radio spectrum matters (ERM);
Telecommunication network equipment; Electro-Magnetic Compatibility (EMC)
requirements; Part 2: Product family standard".
[4] EN 60950, “Safety of Information Technology Equipment Including Electrical Business
Equipment”
[5] ETS 300 011, “Integrated Services Digital Network (ISDN); Primary rate user-network
interface. Layer 1 specification and test principles”
[6] ETS 300 019, “Equipment Engineering; Environmental Conditions and Environmental
Tests for Telecommunications Equipment”
[7] ETS 300 046, “Integrated Services Digital Network (ISDN); Primary rate access - safety
and protection”
[8] ETS 300 233, “Integrated Services Digital Network (ISDN); Access digital section for
ISDN primary rate”
[9] ETSI TS 101 135 V1.5.1, “Transmission and Multiplexing (TM); High bit-rate Digital
Subscriber Line (HDSL) transmission system on metallic local lines; HDSL core
specification and applications for 2048 kbit/s based access digital sections”
[10] ITU-T G.703, “Physical/Electrical Characteristics of Hierarchical Digital Interfaces”
[11] ITU-T G.704, “Synchronous Frame Structures Used at Primary and Secondary
Hierarchical Levels”
[12] ITU-T G.821, “Error Performance of an International Digital Connection Forming Part of
an Integrated Services Digital Network”
[13] ITU-T G.823, “The Control of Jitter and Wander within Digital Networks Which Are
Based on the 2048 kbit/s Hierarchy”
[14] ITU-T G.826, “Error Performance Parameters and Objectives for International, Constant
Bit Rate Digital Paths at or above the Primary Rate”
[15] ITU-T G.962, “Access Digital Section for ISDN Primary Rate Access at 2048 kbit/s”
[16] ITU-T I.604, “Application of Maintenance Principles to ISDN Primary Rate Accesses”
[17] ITU-T K.20, “Resistibility of Telecommunication Switching Equipment to Overvoltages
and Overcurrents”
[18] ITU-T K.21, “Resistibility of Subscribers’ Terminals to Overvoltages and Overcurrents”
[19] ITU-T V.10, “Electrical Characteristics for Unbalanced Double-Current Interchange
Circuits Operating at Data Signaling Rates Nominally up to 100 kbit/s”
[20] ITU-T V.11, “Electrical Characteristics for Balanced Double-Current Interchange Circuits
Operating at Data Signaling Rates up to 10 Mbit/s”

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[21] ITU-T V.24, “List of Definitions for Interchange Circuits between Data Terminal
Equipment (DTE) and Data Circuit-Terminating Equipment (DCE)”
[22] ITU-T V.28, “Electrical Characteristics for Unbalanced Double-Current Interchange
Circuits”
[23] ITU-T V.35, “Data Transmission at 48 kbit/s Using 60-108 kHz Group Band Circuits”
[24] ITU-T V.36, “Modems for Synchronous Data Transmission Using 60-108 kHz Group
Band Circuits”
[25] ITU-T V.54, “Loop Test Devices for Modems”
[26] ITU-T X.21, “Interface between Data Terminal Equipment and Data Circuit-Terminating
Equipment for Synchronous Operation on Public Data Networks”
[27] ITU-T X.24, “List of Definitions for Interchange Circuits between Data Terminal
Equipment (DTE) and Data Circuit-Terminating Equipment (DCE) on Public Data
Networks”
[28] ISO 2593, “Connector pin allocations for use with high-speed data terminal equipment”,
1973.
[29] ISO 2110, “Data communication - 25-pin DTE/DCE interface connector and pin
assignments”, 1980.
[30] ISO 4902, “Data communication - 37-pin and 9-pin DTE/DCE interface connectors and
pin assignments”, 1980.
[31] ISO 4903, “Data communication - 15-pin DTE/DCE interface connector and pin
assignments”, 1980.

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