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PRELIMINARY
DS3 UNI FOR ATM
XRT7245
REV. 1.03
141
In order to comply with the “Isolated DSX-3 Pulse
Template” Requirements (per Bellcore GR-499-CORE),
the user is advised to set this bit-field to “0” if the
cable length (between the transmit output of the
XRT7300 device and the Digital Cross Connect
System) is less than 225 feet. Conversely, the user is
advised to set this bit-field to “1” if the cable length
(between the transmit output of the XRT7300 device
and the Digital Cross Connect System) is greater
than 225 feet.
Note:
If the customer is not using the XRT7300 DS3/E3/
STS-1 IC, then he/she can use this bit-field and the TxLev
output pin for other purposes.
Bit 1—RLOOP (Remote Loop-back Select)
This “Read/Write” bit-field allows the user to control
the state of the “RLOOP” output pin of the UNI device.
This output pin is intended to be connected to the
“RLOOP” input pin of the XRT7300 DS3/E3/STS-1
LIU IC.
The state of this bit-field (or pin) along with “LLOOP”
are used to configure the XRT7300 device into one of
four (4) loop-back modes. The relationship of the values
of “RLOOP”, “LLOOP” and the resulting loop-back
mode (within the XRT7300 device) is tabulated below .
Writing a “1” into this bit-field commands the UNI to
toggle the “RLOOP” output signal “high”. Writing a
“0” into this bit-field commands the UNI to toggle this
output signal “l(fā)ow”.
For a detailed description of the XRT7300 LIU’s oper-
ation during each of these loop-back modes, please
see the “XRT7300 DS3/E3/STS-1 LIU IC” Data Sheet.
Note:
If the customer is not using the XRT7300 DS3/E3/
STS-1 LIU IC, then he/she can use this bit-field and the
“RLOOP” output pin for other purposes.
Bit 0—LLOOP (Local Loop-back Select)
This “Read/Write” bit-field allows the user to control
the state of the “LLOOP” output pin of the UNI device.
This output pin is intended to be connected to the
“LLOOP” input pin of the XRT7300 DS3/E3/STS-1
LIU IC.
The state of this bit-field (or pin) along with “RLOOP”
are used to configure the XRT7300 device into one of
four (4) loop-back modes. The relationship of the values
of “RLOOP”, “LLOOP” and the resulting loop-back
mode (within the XRT7300 device) is tabulated below.
Writing a “1” into this bit-field commands the UNI to
toggle the “LLOOP” output signal “high”. Writing a “0”
into this bit-field commands the UNI to toggle this
output signal “l(fā)ow”.
For a detailed description of the XRT7300 LIU’s oper-
ation during each of these loop-back modes, please
see the “XRT7300 DS3/E3/STS-1 LIU IC” Data Sheet.
Note:
If the customer is not using the XRT7300 DS3/E3/
STS-1 LIU IC, then he/she can use this bit-field and the
“LLOOP” output pin for other purposes.
RLOOP
LLOOP
R
ESULTING
L
OOP
-
BACK
M
ODE
(
WITHIN
THE
XRT7300 D
EVICE
)
0
0
Normal Mode (No Loop-back)
0
1
Analog Local Loop-Back Mode
1
0
Remote Loop-Back Mode
1
1
Digital Local Loop-Back Mode
RLOOP
LLOOP
R
ESULTING
L
OOP
-B
ACK
M
ODE
(
WITHIN
THE
XRT7300 D
EVICE
)
0
0
Normal Mode (No Loop-back)
0
1
Analog Local Loop-Back Mode
1
0
Remote Loop-Back Mode
1
1
Digital Local Loop-Back Mode