Section 150-619-100
Revision 01
Page 11
8.2 USING AN RS-232 TERMINAL
8.21 The following three user options must be set
with an RS-232 terminal:
♦
Circuit ID
♦
DS0 Blocking
♦
♦
Margin Alarm Threshold.
8.22 The Circuit ID option is set by choosing the
H option from the RS-232 terminal’s Main Menu
screen (see Figure 6). The message “ENTER
CIRCUIT ID#:” (24 characters max) follows the “H”
selection. Press the Enter key after entering the
chosen set of alpha-numeric ID characters; choose
C to confirm. Note that if more than 24 characters
are entered, a “Beep” is emitted, and only the first
24 characters are accepted. The ID appears in all
HLU-619 screens, as shown in Figures 6 through
12. The ID does not appear on the HRU-612
screens when the maintenance port is accessed at
the remote unit. Note that the Circuit ID can not be
set to its factory setting (all blanks) when the DFLT
setting option is utilized.
8.23 To set the DS0 Blocking option, from the
Main Menu screen, press C to select the System
Settings Menu. The menu shown in Figure 9
appears. Next, press B, as shown in parentheses of
the DS0 blocking selection. The DS0 channels are
blocked or unblocked by entering each channel
number. Multiple channels can be selected by
inserting a space between each entry. After all the
new settings have been made, press E (“Exit”) and
then C (“Confirm”). The new choices are now
installed. Also, all blocked channels are temporarily
“unblocked” for all HiGain-2 loopback tests. This
allows the standard full bandwidth T1 loopback tests
to be performed.
8.24 To set the Margin Alarm Threshold, select G
from the System Settings Main Menu screen. Enter
the desired minimum acceptable alarm threshold
from the 0 to 15 dB range. This causes a minor
alarm to occur if the margin on the VHDSL loop
drops
below the selected threshold value (see
Section B Paragraph 8.02). Since the margin can
never drop below 0, choosing 0 for the margin
threshold turns the margin alarm off.
8.25 The other RS-232 terminal system settings
are set in a similar manner. Simply enter the key
represented by the letter in parentheses of the
parameter to be changed. Each entry of this letter
scrolls the parameter to its next value. Hit the Enter
key after making each selection. After all selections
have been made, press E to “Exit” and then C to
“Confirm” the changes. This activates the new
choices and returns control to the Main Menu
screen.
8.26 The Self-test mode, which occurs when the
VHDSL loop is not in-sync, includes the input DS1
transceiver chip in the self-test procedure. This
process can cause the Alarm Indicating Signal (AIS)
pattern, which is normally transmitted from the HLU-
619 during these out-of-sync intervals, to exhibit
occasional BPVs.
8.27 The HAIS option provides two selections (ENA
and DIS) for the T1 transmit outputs at both the
HLU-619 and HRU-612 for VHDSL loss-of-sync
conditions. The “ENA” selection causes the AIS
pattern to be transmitted at both T1 outputs when
the VHDSL loop experiences a loss-of-sync (LOSW)
condition or when a margin alarm occurs. This
choice causes all 24 channels to be lost from the
margin alarm, as they are replaced by the AIS
pattern. However, it allows both down and upstream
equipment to be made aware of the loss of the
VHDSL loop or a loop with low margin. The ENA
selection is the preferred setting to be able to start
an AIS state with just one conductor open in the
VHDSL pair. Short loops, below about 16 dB of loss
at 392 kHz, can remain in-sync with one conductor
open. Since the loop is still in-sync, no LOSW
condition occurs. However, the margin on a one-
conductor loop drops from 5 to 10 dB. Thus, if the
margin alarm is set to 5 dB below the normal margin
at turn-up, when one conductor opens, a minor
alarm occurs and causes the AIS condition. This
alerts the maintenance personnel of the problem.
The “DIS” choice requires the VHDSL loop to be
out-of-sync (LOSW) before the AIS signal is
transmitted. This choice preserves the integrity of
the 24 channels when a margin alarm occurs.
