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4-2
Diagnostics
GDC 048R154-000
The local diagnostic functions work on a "first come, first served"
basis: only one of the three means of control can be in effect at a time,
and a test that has begun cannot be overridden by either of the other
two types of control. While the terminal interface Diagnostic screens
are open the DSU ignores the front panel switches and the DTE
interface test leads.
Inband loop codes received from the remote site DSU take precedence
over local diagnostic functions. If a locally initiated test is running
when a loop code is received, the DeskTop T1 DSU terminates the test
and performs the remote loopback.
Test:
Can be commanded by –
Network QRSS Self Test
Terminal Interface, Front Panel Switch ST (T1 indi-
cator, controlled by T1 switch, must be On)
Network Payload Loopback
Terminal Interface
Network Line Loopback
Terminal Interface, Front Panel Switch LL (T1 indi-
cator, controlled by T1 switch, must be On)
Network Local Test
Terminal Interface
Network Local Test with QRSS
Self Test
Terminal Interface
Network Remote Test
Terminal Interface, Front Panel Switch RL (T1 indi-
cator, controlled by T1 switch, must be On)
Network Remote Test with QRSS
Self Test
Terminal Interface, Front Panel Switches RL and ST
(T1 indicator, controlled by T1 switch, must be On)
DTE Self Test
Terminal Interface, Front Panel Switch ST
DTE Local Loopback
Terminal Interface, Front Panel Switch LL, DTE In-
terface pin L
DTE Digital Loopback
Terminal Interface
DTE Remote Digital
Loopback
Terminal Interface, Front Panel Switch RL, DTE In-
terface pin BB
DTE Remote Digital
Loopback with Self Test
Terminal Interface, Front Panel Switches RL and ST