ADTRAN DSU 56/64, User Manual

Page: 34 / 44

Chapter 3. Test Modes
3-6 DSU 56/64 User Manual 61200062L1-1
LOOP ONLY TEST (RT)
The L
OOP
O
NLY
test or R
EMOTE
L
OOPBACK
test (RT) is used to test
the loop interface and a major portion of the DTE interface of the
local DSU 56/64 from the remote site over the actual digital data
circuit.
For the L
OOP
O
NLY
test, the network receive data is looped to the
network transmit data inside the DTE interface section of the DSU
56/64. The physical DTE interface is ignored for this test. The
L
OOP
LED flashes during initialization of the test and turns on solid once
the test is in progress. Figure 3-4 illustrates the loopback point and
the signal paths for this test.
Figure 3-4. Loop Only Test Diagram
To initiate the L
OOP
O
NLY
test , perform the following steps:
1. Press S
ELECT
four times to turn on the L
OOP
test indicator.
2. Press T
EST
while this test indicator is on.
3. To terminate this test, press T
EST
.
56/64 DSU
DTE
Receive
Interface
DTE
Transmit
Interface
Loop
Transmit
Interface
Loop
Receive
Interface
Loop
Only
TD
DTE or Test
Equipment
Interface
Network
Interface
RD
Loop TX
Loop RX