XRT7245
DS3 UNI FOR ATM
á
PRELIMINARY
REV. 1.03
116
Bit 2—TxLev (Transmit Output Line Build-Out
Select Output)
This “Read/Write” bit-field allows the user to control
the state of the “TxLev” output pin of the UNI device.
This output pin is intended to be connected to the
Tx-Lev input pin of the XRT7300 DS3/E3 LIU IC. If
the user commands this signal to toggle “high”, then
the XRT7300 DS3/E3 LIU IC will disable the “Transmit
Line Build-Out” circuitry, and will transmit unshaped
(square-wave) pulses onto the line. If the user com-
mands this signal to toggle “l(fā)ow”, then the XRT7300
DS3/E3 LIU IC will enable the “Transmit Line Build-
Out” circuitry, and will transmit shaped pulses onto
the line.
In order to insure that the transmit output pulses of
the XRT7300 device meet the “DSX-3 Isolated Pulse
Template Requirements (per Bellcore GR-499-CORE),
the user is advised to set this bit-field to “0”, if the
length of cable (between the XRT7300 transmit out-
put and the Cross Connect) is greater than 225 feet.
Conversely, the user is advised to set this bit-field to
“1”, if the length of cable (between the XRT7300
transmit output and the Cross Connect) is less than
225 feet.
Note:
If the customer is not using the XRT7300 DS3/E3
LIU IC, then he/she can use this bit-field and the TxLev out-
put pin for other purposes.
Bit 1—RLOOP (Remote Loop-back)
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 LIU IC.
In the XRT7300 DS3/E3 LIU IC, the state of the
“RLOOP” and the “LLOOP” pins are used to dictate
which loop-back mode the XRT7300 device will
operate in. The following table presents the relationship
between the state of these two input pins (or bit-fields)
and the resulting loop-back modes.
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 DS3/E3 LIU’s
operation, during each of these above-mentioned
loop-back modes, please consult 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
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 LIU IC.
In the XRT7300 DS3/E3 LIU IC, the state of the
“RLOOP” and the “LLOOP” pins are used to dictate
which loop-back mode the XRT7300 device will
operate in. The following table presents the relation-
ship between the state of these two input pins (or
bit-fields) and the resulting loop-back modes.
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”.
RLOOP
LLOOP
R
ESULTING
L
OOP
-B
ACK
M
ODE
OF
THE
XRT7300 D
EVICE
0
0
Normal Operation (No loop-back Mode)
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
-
BACK
M
ODE
OF
THE
XRT7300 D
EVICE
0
0
Normal Operation (No loop-back Mode)
0
1
Analog Local Loop-back Mode
1
0
Remote Loop-back Mode
1
1
Digital Local Loop-back Mode