20
DSU 5600 User Manual
61200.078L1-1
Chapter 3. Test Modes
Loop Only Test
The Loop Only test allows the loop interface and a major portion
of the DTE interface of the local DSU 5600 to be tested from a
remote site over the actual digital data circuit.
During the Loop Only test, the network receive data is looped to
the network transmit data inside the DTE interface section of the
DSU 5600. The physical DTE interface is ignored for this test. A
block diagram illustrating the loopback point and the signal
paths for this test is shown in Figure 3-4.
To initiate the Loop Only test, perform the following steps:
1. Press
Select
four times to turn
On
the loop test indicator.
2. Press
Test
while this test indicator is
On
. The Loop LED
Flashes
during initialization of the test and turns
On
solid
once the test is in progress.
To terminate this test, press
Test
.
DTE
TRANSMIT
INTERFACE
LOOP
TRANSMIT
INTERFACE
DTE
RECEIVE
INTERFACE
LOOP
RECEIVE
INTERFACE
LOOP
ONLY
TD
RD
LOOP RX
LOOP TX
DTE OR
TEST
EQUIPMENT
INTERFACE
NETWORK
INTERFACE
Figure 3-4
Loop Only Test Diagram
