Diagnostics
4-19
GDC 048R154-000
Figure 4-16
DTE End-to-End Self Test, Front Panel Control
DTE Local Loopback
The data path for the DTE Local Loopback is illustrated in Figure 4-
17. The DSU loops the transmit signal back to the receive path just
beyond the DTE interface, which remains active so that a test signal
can be generated and checked by an external device.
DTE Local Loopback checks the DTE interface and the DTE-to-DSU
connection. Error detection and reporting is entirely the responsibility
of the external device that supplies the test signal.
To initiate the loopback from the Diagnostics Selection screen, select
[B] Start DTE Local Loopback
.
Figure 4-18 shows the switches and indicators that are involved when
you command a DTE Local Loopback from the front panel. You can
also command the test by means of DTE interface pin L when the DTE
Test Leads configuration option is enabled (switch S10-2 On).
2. Press ST switch to start DTE End-to-
End Self Test. Press switch again to
end test.
1. T1 indicator must be Off; press T1
switch if indicator is On.
3. TM and ST indicators are On
during the test.
TM flashes to indicate detect-
ed errors.
General Data-
Comm
DeskTop
T1
ON
SD RD
OOF LOS BPV ALM
TM
T1
ST
LL
RL
