Control Port Operation; Appendix A. Hdsl2 Loopbacks; Figure 3. Hdsl2 Loopbacks; Figure 4. Rs-232 (Db-9) Pin Assignment - ADTRAN T200 H2TU-R Installation And Maintenance Manual

H2TU-C Network-Side Loopback
DSX-1
H2TU-C
H2TU-R Network-Side Loopback or
H2TU-R NIU Loopback
DSX-1
H2TU-C
H2TU-R Customer-Side Loopback
X
DSX-1
AIS
H2TU-C
H2TU-C Customer-Side Loopback
X
DSX-1
AIS
H2TU-C
H2TU-R Bidirectional Loopback
DSX-1
H2TU-C
X = Signal Inactive

Figure 3. HDSL2 Loopbacks

Second, the H2TU-R will respond to the industry
defacto HDSL2 loopback codes as designated in the
ANSI document T1E1.4/92. A synopsis of the
method described by ANSI is presented in Appendix A.
Third, the H2TU-R will respond to manual loopback
activation by pressing the LOC LBK button on the
faceplate. This will activate a bidirectional loopback
at the H2TU-R.
Finally, the H2TU-R responds to T1 Network
Interface Unit (NIU) loopback codes as described in
Bellcore TR-TSY-000312 if the H2TU-R is optioned
for NIU loopbacks. The NIU loopback codes are as
follows:
In-band Codes: Loop up ...........11000
Loop down.......11100
ESF Codes: Loop up ...........0001 0010 1111 1111
Loop down.......0010 0100 1111 1111
Receiving the in-band codes for more than five
seconds or the ESF codes for four consecutive
repetitions will cause the appropriate loopback action.
61222024L6-5A
AIS
LOCAL
DS1
LOOP
X
H2TU-R
AIS
LOCAL
DS1
LOOP
X
H2TU-R
LOCAL
DS1
LOOP
H2TU-R
LOCAL
DS1
LOOP
H2TU-R
LOCAL
DS1
LOOP
H2TU-R
61222024L6-5, Issue 1
The H2TU-R will respond to the loop up codes by
activating the NIU loopback from either the disarmed
or armed state. The loop down codes will return the
H2TU-R to the normal state from the armed or loop
up state.
Refer to Appendix A for more details on loopbacks
and loopback arming sequences.
Figure 3 illustrates all of the possible loopback
locations of the ADTRAN HDSL2 equipment.
Customer Loopbacks
In addition to the loopbacks in the direction of the
network, the H2TU-R may also be looped back in the
direction of the customer using the terminal control
port of the H2TU-C or the LOC LBK switch on the
front panel of the H2TU-R. The LOC LBK switch
enables a bidirectional loopback. The H2TU-C can be
looped to the customer using the REM LBK switch on
the front panel of the H2TU-R. The H2TU-C and
H2TU-R Customer Side Loopbacks are illustrated in
Figure 3.
NOTE
Network and customer loopbacks are governed
by the loopback time out option configured on
the H2TU-C.

5. CONTROL PORT OPERATION

The H2TU-R provides a faceplate-mounted DB-9
connector that supplies an RS-232 interface for
connection to a controlling terminal. The pinout of
the DB-9 is illustrated in Figure 4.
1
6
2
7
3
8
4
9
5
Figure 4. RS-232 (DB-9) Pin Assignments
The terminal interface operates at data rates from
1.2 kbps to 19.2 kbps. The asynchronous data format
is fixed at 8 data bits, no parity, and 1 stop bit. The
supported terminal type is dumb terminal, VT100 or
compatible.
TXD (Transmit Data)
RXD (Receive Data)
SGN (Signal Ground)
5