DS3112
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7.5 T1/E1 Loopback Control Register Description
Register Name:
T1E1LLB1
Register Description:
T1/E1 Line Loopback Control Register 1
Register Address:
50h
Bit
# 7 6 5 4 3 2 1 0
Name
LLB8 LLB7 LLB6 LLB5 LLB4 LLB3 LLB2 LLB1
Default
0 0 0 0 0 0 0 0
Bit
# 15 14 13 12 11 10 9 8
Name
LLB16 LLB15 LLB14 LLB13 LLB12 LLB11 LLB10 LLB9
Default
0 0 0 0 0 0 0 0
Note: Bits that are underlined are read-only; all other bits are read-write.
Bits 0 to 15: T1/E1 Line Loopback Enable for Ports 1 to 16 (LLB1 to LLB16).
These bits enable or disable the
T1/E1 Line Loopback (LLB). See the Block Diagrams in Section
1
for a visual description of this loopback. LLB1
corresponds to T1/E1 Port 1, LLB2 corresponds to T1/E1 Port 2, and so on. Since ports 4, 8, 12, 16, 20, 24, and 28
are not active in the G.747 mode, the LLB4, LLB8, LLB12, and LLB16 bits have no effect in the G.747 mode.
0 = disable loopback
1 = enable loopback
Register Name:
T1E1LLB2
Register Description:
T1/E1 Line Loopback Control Register 2
Register Address:
52h
Bit
# 7 6 5 4 3 2 1 0
Name
LLB24 LLB23 LLB22 LLB21 LLB20 LLB19 LLB18 LLB17
Default
0 0 0 0 0 0 0 0
Bit
# 15 14 13 12 11 10 9 8
Name — — — —
LLB28
LLB27
LLB26
LLB25
Default — — — — 0 0 0 0
Note: Bits that are underlined are read-only; all other bits are read-write.
Bits 0 to 11: T1 Line Loopback Enable for Ports 17 to 28 (LLB17 to LLB28).
These bits enable or disable the
T1 Line Loopback (LLB). See the block diagrams in Section
1
for a visual description of this loopback. LLB1
corresponds to T17 Port 17, LLB18 corresponds to T1 Port 18, and so on. Since ports 17 to 28 are not active in the
E3 mode, these bits have no effect in the E3 mode. Since ports 4, 8, 12, 16, 20, 24, and 28 are not active in the
G.747 mode, the LLB20, LLB24, and LLB28 bits have no effect in the G.747 mode.
0 = disable loopback
1 = enable loopback