4 7511-A2-GN10-10
January 1999
Table 1. Configuration Options (2 of 5)Switch Options and Usage Default in Bold
TX Timing Source
S1-2 & S1-3 (DSU A)
S3-2 & S3-3 (DSU B)
S1 S2
S3 S4
DSU A
DSU B
ON ON
ON ON
The timing source for the DSU.
Off Off DDS
For DDS, both switches must be Off.
For LADS:
Off ON Receive
Receive means timing is derived from the line receive signal.
ON Off Internal
Internal means timing is provided by the unit’s internal clock.
ON ON External
External means timing is provided by the DTE.
Ten-Minute Test
Abort Timer
S1-4 (DSU A)
S3-4 (DSU B)
S1 S2
S3 S4
DSU A
DSU B
ON ON
ON ON
Determines whether user-initiated tests automatically terminate after
10 minutes.
Off Enable
Tests terminate automatically after 10 minutes.
ON Disable
Tests run indefinitely.
Network-Initiated
DSU Loopback
S1-5 (DSU A)
S3-5 (DSU B)
S1 S2
S3 S4
DSU A
DSU B
ON ON
ON ON
Determines whether the DSU responds to DSU latching loopback start
and stop sequences sent by the network. This option is applicable only
if the DDS line rate is 64 kbps clear channel.
Off Enable
The DSU responds to loopback sequences.
ON Disable
The DSU ignores loopback sequences.