Black Box MT136A, User Manual, Page: 79 / 116

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CSU/DSU MS DBU
Table 12-4. DTE With Test Pattern Commands
Front Panel AT Command Description
1=2047 PATTERN _T0&T8 Standard 2047 random data pattern.
2=511 PATTERN _T1&T8 Standard 511 random data pattern.
3=STRESS PTRN #1 _T2&T8 Stress pattern with alternating high and
low ones densities. Repeated pattern of
100 octets: 1111 1111, followed by
100 octets: 0000 0000.
4=STRESS PTRN #2 _T3&T8 Stress pattern with alternating medium
and low ones densities. Repeated pattern
of 100 octets: 0111 1110, followed by
100 octets: 0000 0000.
5=STRESS PTRN #3 _T4&T8 Stress pattern with medium ones density.
Continuous series of octets: 0011 0010.
6=STRESS PTRN #4 _T5&T8 Stress pattern with low ones density.
Continuous series of octets: 0100 0000.
12.3.1 DTE & L
OOP
(LL)
The DTE & Loop test splits the CSU/DSU MS DBU into two separate DTE and
loop interface sections and then loops the receive data of each interface back to its
respective transmit data. The DTE & Loop test provides a bidirectional loopback at
the DSU/CSU. Figure 12-5 illustrates the loopback points and the signal paths for
this test.
Figure 12-5. DTE & Loop Test.
LOCAL
DSU/CSU
DTE
Rx
Tx
TELCO
NET Rx
NET Tx
DTE Rx
DTE Tx