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Advance Data Sheet
May 1998
T7633 Dual T1/E1 3.3 V Short-Haul Terminator
99
Lucent Technologies Inc.
Alarms and Performance Monitoring
(continued)
Loopback and Transmission Modes
Primary Loopback Modes
Framer primary loopback mode is controlled by register FRM_PR24. There are seven primary loopback and trans-
mission test modes supported:
1.
Line loopback (LLB).
2.
Board loopback (BLB).
3.
Single time-slot system loopback (STSSLB).
4.
Single time-slot line loopback (STSLLB).
5.
CEPT nailed-up broadcast transmission (CNUBT).
6.
Payload loopback (PLLB).
7.
CEPT nailed-up connect loopback (CNUCLB).
The loopback and transmission modes are described in detail below:
1.
The LLB mode loops the receive line data and clock back to the transmit line. The received data is processed
by the receive framer and transmitted to the system interface. This mode can be selected by setting register
FRM_PR24 to 001xxxxx (binary).
2.
The BLB mode loops the receive system data back to the system after:
A. The transmit framer processes the data, and
B. The receive framer processes the data.
In the BLB mode, AIS is always transmitted to the line interface. This mode can be selected by setting register
FRM_PR24 to 010xxxxx (binary).
3.
The STSSLB mode loops one and only one received system time slot back to the transmit system interface.
The selected looped back time-slot data is not processed by either the transmit framer or the receive framer.
The selected time slot does not pass through the receive elastic store buffer and therefore will not be affected
by system-AIS, RLFA conditions, or controlled slips events. Once selected, the desired time-slot position has
the programmable idle code in register FRM_PR22 transmitted to the line interface one frame before imple-
menting the loopback and for the duration of the loopback. This mode can be selected by setting register
FRM_PR24 to 011A
4
A
3
A
2
A
1
A
0
, where A
4
A
3
A
2
A
1
A
0
is the binary address of the selected time slot.
The STSLLB mode loops one and only one received line time slot back to the transmit line. The selected time-
slot data is looped to the line after being processed by the receive framer, and it passes through the receive
elastic store. The selected time slot has the programmable idle code in register FRM_PR22 transmitted to the
system interface one frame before implementing the loopback and for the duration of the loopback. In CEPT,
selecting time slot 0 has the effect of deactivating the current loopback mode while no other action will be taken
(time slot 0 will not be looped back to the line and should not be chosen). This mode can be selected by setting
register FRM_PR24 to 100A
4
A
3
A
2
A
1
A
0
, where A
4
A
3
A
2
A
1
A
0
is the binary address of the selected time slot.
4.
5.
The CNUBT mode transmits received-line time slot X to the system in time slots X and time slot 0 (of the next
frame). Any time slot can be broadcast. This mode can be selected by setting register FRM_PR24 to
101A
4
A
3
A
2
A
1
A
0
where A
4
A
3
A
2
A
1
A
0
is the binary address of the selected time slot.