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150-402-111-02 Initializing the Maintenance Terminal Screens
HRU-402 List 1A December 8, 1998 45
When the HRU is in its AIS/DIS SmartJack Loopback state, its T1 input LOS,
Code and Frame monitoring circuits are connected to the network signal
which is being looped back to these circuits through the loopback relay.
The CPE input signal is no longer being monitored since its input circuit has
been opened and terminated. The FRM and LOC LOS LEDs indicate the
status of this signal from the network. The Code LEDs also indicate the code
(AMI or B8ZS) of this signal if the Code option is set to AUTO. It indicates
AMI or B8ZS if the Code option is set to either AMI or B8ZS respectively.
The TLOS, SMJK, and NREM loopbacks are identical. They differ only in
how they are initiated. The SMJK identifying label indicates that the
loopback was initiated by the 2-in-5 in band or by the ESF-DL command.
NREM is used to indicate that the loopback was initiated by other than the
2-in-5 or ESF-DL command (3-in-7, 16-bit, addressable, repeater commands,
front panel push-button, or Craft port). TLOS is used to indicate that the
loopback was initiated by a LOS of T1 input at the HRU from the customer.
The HRU-402 front panel loopback button is used to initiate NREM and
terminate an NREM loopback. To initiate an NREM loopback at the HRU,
press the loopback button for five seconds. Pressing this button terminates all
HiGain loopbacks that may be present (except SMJK) before executing an
NREM loopback in the HRU. If another HiGain loopback is active, the user
will have to press the loopback button for up to 10 seconds (five seconds to
loop down and five more seconds to loop up NREM.
Loopback Test Procedures
Testing the HiGain system allows you to verify the integrity of the HDSL
channels to the HLU as well as the DS-1 channels to the customer and the
HLU DSX-1 interface. While the HRU-402 displays system condition
messages at the Remote Terminal and by color-coded LED displays on the
front panel, the HLU indicates system conditions by a four-character LED
message display and by a tri-color status LED. To facilitate test messaging
with central office test personnel, front-panel messages for the HLU-231
List 8x are provided in
Table 5 on page 12 . The four character messages also
apply to the HLU-319 List 5x and the HLU-388 List 5x.
If you encounter trouble at the T1 interface, verify that the unit
is making a positive connection with the mounting assembly
connector.