3
61220010L2-5, Issue 3
61220010L2-5C
C A U T I O N !
SUBJECT TO ELECTROSTATIC DAMAGE
OR DECREASE IN RELIABILITY.
HANDLING PRECAUTIONS REQUIRED.
Quality Monitor (QM)
When QM (SW1-2) is ON, the IDSL OCU-R
monitors the customer interface for errors. If
excessive errors are detected the unit blocks customer
data transmission and sends Abnormal Station Code to
the network. Customer data transmission is
automatically restored when the trouble condition is
cleared.
Error Correction (EC)
When EC (SW1-3) is ON, the unit enables the
appropriate technique to ensure data integrity across
the digital network.
Latching Loopback Enabled (LLEN)
When LLEN (SW1-4) is ON, the IDSL OCU-R will
respond to latching loopback sequences.
False Loopback Immunity
ADTRAN’s Protected Loopback family of channel
units include an algorithm compatible with SARTS,
Hekimian, TPI, and other test systems that virtually
eliminates false latching loopback occurrences. This
algorithm is always enabled at 64 kbps. In addition,
ADTRAN’s Protected Loopback family features a
Protected Loopback mode for further false latching
loopback protection.
Latching Loopback
During operation up to 56 kbps, with LLEN enabled
(SW1-4 ON), the IDSL OCU-R will respond to the
legacy OCU latching loopback sequences and
translates CSU latching loopback sequences to the
DSU/CSU per TR62310 and ANSI T1.417. With
LLEN OFF, the IDSL OCU-R will not respond to
latching loopback.
At 64 kbps the function of the LLEN switch is altered.
At 64 kbps, placing LLEN ON will permit the IDSL
OCU-R to respond to the legacy latching loopback
sequence per TR62310 and ANSI T1.417. At 64
kbps, with LLEN OFF, the IDSL OCU-R enables
ADTRAN’s Protected Loopback.
Protected Loopback
ADTRAN’s Protected Loopback supports the new
proposed DDS latching loopback standard in T1E1.2/
99-007R1. When enabled, the IDSL OCU-R will
respond to latching loopback when the idle code
preamble is sent prior to the latching loopback
sequence specified in TR62310 and ANSI T1.417.
See
Table 2
for the latching loopback sequence
requirement when Protected Loopback is enabled.
3. INSTALLATION
After unpacking the unit, inspect it for damage. If
damage is noted, file a claim with the carrier, then
contact ADTRAN. See
Warranty and Customer
Service
.
WARNING
•
Never install telephone wiring during a
lightning storm.
•
Never install telephone jacks in wet
locations unless the jack is specifically
designed for wet locations.
•
Never touch uninsulated telephone wires
or terminals unless the telephone line has
been disconnected at the network interface.
Table 2. Protected Loopback Mode
Requirement T1E1.2/99-007R1 (Latching
Loopback)
Sequence
Function
# of Received
Bytes
Byte Code
Exit data
protocol
Clear existing
loopbacks
Identify device
to be looped
Prepare to loop;
send MAP code
after 30 bytes
Activate
loopback
Minimum of 35 TIP bytes required to disable
established latching loopback.
X = Don't care bit
Idle - 11111110
Transition in
progress (TIP)
X0111010
Loopback select
code (LSC)
X0000101 - DS0
X1010101 - OCU
X0110001 - CSU
Loopback
enabled (LBE)
X1010110
Far-End voice
(FEV)
X1011010
Minimum of
35 Idle bytes
Minimum of
35 TIP bytes
Minimum of
35 LSC bytes
Minimum of
100 LBE bytes
Minimum of
32 FEV bytes
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