
LOOPBACK TESTING
Initiate loopback testing from the HiGain HDSL2 Monitor screen or use the MODE and
SEL buttons. The inband codes below can also be sent by a test set.
For more information about the maintenance screens, refer to the H2TU-C-388 List 3E
technical practice, document number LTPH-TP-1001-xx. Contact Customer Service to
obtain a copy of the practice.
106
105
104
103
102
101
100
DSX-1RCV(out)
DSX-1XMT(in)
205
204
203
202
201
200
119
118
117
116
115
114
113
112
111
110
Ground Ground
Frameground
Fusealarm*
Ring1
Tip1
Management bus
Ring
Tip
Factoryuseonly
-48Vdc
219
218
217
216
215
214
213
212
211
210
209
208
207
206
109
108
107
* Fuse alarm is normally floating (0 to 80 V maximum)
and at -48 Vdc (10 mA maximum) when activated.
RS-232 Craft port
The Bantam 210 jack provides bidirectional communication
between the H2TU-C and a maintenance terminal
for access to maintenance, provisioning, and
performance screens.Use jack adapter 120-1035-01
to connect a standard 9-pin terminal cable between the
serial port on a PC and the H2TU-C craft port.
Four-character display
Displays status, provisioning, and
alarm messages. See tables below
for a list of message descriptions.
Status LED
Configuration number label
Use MODE and SEL to manually modify user options,
initiate loopbacks, and display DSX-1 line parameters.
MODE and SEL pushbuttons (for manual setting of
system parameters)
1
2
3
4
Press the MODE button for 1 second and release.
The front panel alternately displays the first
system parameter and its current setting.
Press SEL to step through all possible system
settings for the displayed parameter.
Press MODE to update the parameter and advance
to the next parameter.
After scrolling through all the parameters, press SEL
to confirm changes when prompted with a CONF NO
message, or press MODE to cancel all changes.
9600 baud
8 data bits
No parity
1 stop bit
Hardware flow control: OFF
Terminal emulation software: VT100
MaintenanceTerminal Modem Settings Front Panel Card-Edge Connector
Customer Remote Loopback (CREM)
or Network Local Loopback (NLOC)
is in effect.
Green LED Normal operation.
Flashing Red LED HDSL2 acquisition or system alarm.
Red LED Fuse alarm.
Yellow LED
FlashingYellow LED System is in Armed (ARM) mode.
Off Line power is off.
HDSL2 span
Ring
Tip
HiGain
HDSL2
SETUP
H
2
T
U
•
C
3
8
8
L
R
S
2
3
2
DCE
M
O
D
E
S
E
L
List number
Extraction handle
CLEI/ECI bar code label
3E
STATUS
LED Functions
GNLB Loopback Commands
Loopback Inband Code Description
NLOC 1111000 DSX-1 signal is looped back to the network at the H2TU-C.
NREM 1110000 DSX-1 signal is looped back to the network at the H2TU-R.
SMJK 11000 DSX-1 signal is looped back to the network at the H2TU-R
SmartJack module.
CREM 1111110 DS1 signal from customer is looped back to the customer
at the H2TU-C.
CLOC 1111100 DS1 signal from customer is looped back to the customer
at the H2TU-R.
Loopdown 11100 Deactivates any of the above loopbacks.
Front-Panel Alarm Messages (a)
Message Description
PWR FEED SHRT (b) A short between the Tip and Ring of the HDSL2 pair.
PWR FEED GND (b) The HDSL2 loop is grounded.
PWR FEED OPEN (b) A line-power open condition.
SPNn-LOSW The HDSL2 loop has lost synchronization. The span closest to the network has
highest priority.
LLOS No signal is detected at the DSX-1 input to the H2TU-C-388.
RLOS No signal is detected at the DS1 input to the H2TU-R.
LAIS Local Alarm Indication Signal.
RAIS Remote Alarm Indication Signal.
TRCI An RAI alarm (yellow LED) from the CPE with an error-free signal from the line unit
or network.
RRAI An RAI alarm (yellow LED) from the Customer Premises Equipment (CPE) with errors
from the line unit or network.
xxx-DBER A system DS1 Bit Error Rate (BER) alarm. (xxx denotes either TUC or TUR.)
PRMF H2TU-R Performance Report Messaging BER threshold exceeded at far end.
PRMN H2TU-R Performance Report Messaging BER threshold exceeded at near end.
xxx-HBER A system HDSL2 Block Error Rate (BER) alarm. (xxx denotes either TUC or TUR.)
xxx-MAL The margin on the HDSL2 loop has dropped below the threshold setting. (xxx
denotes either TUC or TUR.)
xxx-LA The attenuation on the HDSL2 loop has exceeded the maximum threshold value. (xxx
denotes either TUC or TUR.)
(a) Front-panel alarm messages are listed in order of priority. ALRM displays prior to any alarm message.
Pressing the SEL button initiates an Alarm Cutoff (ACO) message.
(b) Message displays repeatedly as long as the alarm condition exists and is not included in the priority order.
To comply with the interbuilding wiring requirements of
GR-1089 CORE, Section 4.5.9, the shields of the ABAM-type
cables that connect the H2TU-C-388 List 3E DSX-1 output ports
to the cross-connect panel must be grounded at both ends.
Network
Customer
Premises
H2TU-C H2TU-R
NLOC CREM CLOC
1111000 NREM
1110000 1111100
1111110
11000
SMJK
TLOS*
* When enabled, TLOS is an automatic loopback that
occurs with a LOS at the remote DS1 input.
DS1
DSX-1
Front-Panel Diagnostic Messages
Display Code Description (normal operating messages in bold)
A=xx The loop attenuation of the longest (maximum loss) span, measured in dB.
ACQ The multiplexers of the H2TU-C-388 and H2TU-R are trying to establish synchronization.
AnL The multiplexers of the two devices on Span nare trying to establish synchronization with
each other, where nis the number of the span.
ARM Armed to respond to Intelligent Repeater Loop (ILR) codes.
BAD RT? The H2TU-C is not receiving a response from the H2TU-R.
FERR A framing bit error occurred at H2TU-C DSX-1 input.
FLDL Flash download of firmware updates. (Contact Customer Service for update procedures.)
HES H2TU-C HDSL2 loop cyclical redundancy check (CRC) error.
LBPV A local bipolar violation has been received at the DSX-1 input to the H2TU-C.
M=xx Indicates the power of the received HDSL2 signal relative to noise (S/N with respect to
21.5 dB). Any value of 6 dB or greater is adequate for reliable system operation.
MNGD The H2TU-C is under control of the HMU-319 network management unit.
PWR FEED ON Indicates that the HDSL2 loop is not grounded or shorted.
PWR FEED OFF HDSL2 span power is turned off.
SIG The transceivers of the H2TU-C and H2TU-R are trying to establish contact with each
other on Span 1 of the HDSL2 loop.
SnL The transceivers of the two devices on Span nare trying to establish contact with each
other, where nis the number of the span.
Front-Panel Configuration Options Using MODE and SEL
Display Code Description (default values in bold)
EQL Sets the DSX-1 Equalizer to: 0 (0 to 132 ft.), 133 (133 to 265 ft.), 266 (266 to 398 ft.),
399 (399 to 532 ft.), 533 (533 to 655 ft.).
RLBO Sets the H2TU-R line buildout to 0 dB, -7.5 dB, or -15 dB.
LPBK Enables (ENA) or disables (DIS) SmartJack loopback commands.
FT1 Enables (ENA) or disables (DIS) system response to DDS latching loopback commands for
fractional T1 applications.
SPLB xxxx Configures the system for generic (GNLB) or special inband loopback commands (A2LB,
A3LB, A4LB).
PWRF OFF = disables HDSL2 powering. ON = HDSL2 line voltage is -185 Vdc maximum.
HBER 1E-6 or 1E-7 = alarm activates when the HDSL2 BER alarm threshold exceeds 10-6 or 10-7.
NONE = prevents generation of a system alarm due to BER.
DBER Enables (ENA) or disables (DIS) fixed 24-hour DSX-1 BER alarm threshold.
LBTO Loopback timeout = NONE, 20, 60, 120 minutes.
DS1 DSX-1 line code = B8ZS or AMI.
CONV H2TU-R frame format conversion = OFF (framing determined by the DS1 frame formatting
option), ACON (autodetection of framing and potential frame conversion at the H2TU-R),
or FCON (autodetection of framing and forced frame format conversion at the H2TU-R).
FRMG DS1 frame formatting = AUTO (auto framing mode) or UNFR (unframed mode).
ALMP Enables system to output an alarm pattern: AIS or LOS.
BPVT Enables (ENA) or disables (DIS) Bipolar Violation Transparency.
NLBP Enables the H2TU-R to transmit either AIS or LOS towards the CI for any network loopback.
TLOS Enables (ENA) or disables (DIS) a logic loopback at the H2TU-R when an LOS occurs at its
DS1 input.
RTPV Enables (ENA) or disables (DIS) remote provisioning.
PRM OFF = no enhanced Performance Report Messaging; SPRM = Supplemental PRM;
NPRM = Network PRM; S + N = SPRM + NPRM.
NAIS If ALMP is set to AIS, this option specifies which pattern is sent to the network when a
remote LOS or AIS occurs. CI = AIS-CI sent to the network; AIS = AIS sent to the network.
ROVR Enables (ENA) or disables (DIS) conversion of an ESF DS1 payload from the network with
an embedded RAI pattern to an SF-RAI pattern towards the CI at the H2TU-R. CONV option
must be set to FCON or ACON.
RACI Enables (ENA) or disables (DIS) conversion of a DS1 SF-RAI signal received by the H2TU-R
to an SF-RAI-CI signal towards the network.
Front-Panel System Information Messages (Scroll Mode) (a)
Code Description
CODE xxxx Line code setting (AMI or B8ZS).
FRM xxxx Frame pattern received from the DSX-1 (SF, ESF, UNFR).
LATT xx Loop attenuation threshold (0 to 40 dB). Default is 32.
LIST xx List number of the H2TU-C-388.
MARG xx Margin threshold (0 to 15 dB). Default is 5.
VER x.xx Software version number.
(a) To scroll through system information messages, press the MODE button for 3 or more seconds.