ADTRAN DSU 56/64, User Manual

Page: 33 / 44

Chapter 3. Test Modes
61200062L1-1 DSU 56/64 User Manual 3-5
56/64 from the remote site over the actual communications circuit.
Testing from the remote end of the circuit is performed with test
data generated by the remote DSU or terminal type test equipment.
The
DTE
AND
L
OOP
test splits the DSU 56/64 into separate DTE and
Loop interface sections and then loops the transmit data of each
interface back to its respective receive data. Figure 3-3 illustrates
the loopback points and the signal paths for this test. The
DTE
AND
L
OOP
LEDs flash during initialization of the test and turn on solid
once the test is in progress.
Figure 3-3. DTE and Loop Test Diagram
To initiate the
DTE
AND
L
OOP
test, perform the following steps:
1. Press S
ELECT
three times to turn on both the DTE
AND
L
OOP
test indicators.
2. Press T
EST
while these test indicators are on.
3. To terminate this test, press T
EST
.
56/64 DSU
DTE
Receive
Interface
DTE
Transmit
Interface
Loop
Transmit
Interface
Loop
Receive
Interface
DTE
and
Loop
TD
DTE or Test
Equipment
Interface
Network
Interface
RD
Loop TX
Loop RX