14
DSU 5600 User Manual
61200.078L1-1
Chapter 3. Test Modes
NEAR END TEST
The local DSU 5600 is capable of performing the following near
end tests:
• DTE Only
• DTE with Test Pattern
• DTE and Loop (LL)
• Loop Only (RT)
DTE Only Test
The DTE Only test provides a method for testing both the DTE
interface of the local DSU 5600 plus its loop transmitter and
receiver. For this test, the loop transmit data is connected to the
loop receive data at a point close to the physical network inter-
face. A block diagram illustrating the loopback point and the
signal paths for this test is shown in Figure 3-1.
To initiate the DTE Only test, perform the following steps:
1. Press
Select
once to turn
On
the DTE test indicator.
2. Press
Test
while the test indicator is
On
.
To terminate this test, press
Test
.
Test data from the terminal or test equipment is routed through
the DTE section of the DSU 5600 and then to the output of the
loop transmitter section where the signal is encoded for trans-
mission. The output of the loop transmitter is coupled back to
the loop receiver input. This receive test signal is then decoded
and returned to the terminal or test equipment where it is
checked for bit errors.
