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DS3/E3 FRAMER IC
XRT7250
REV. 1.1.1
111
Transmit Line Build-Out circuitry, and will transmit un-
shaped (square-wave) pulses onto the line. If the us-
er commands this signal to toggle "Low", then the
XRT7300 DS3/E3 LIU IC will enable the Transmit
Line Build-Out circuitry, and will transmit shaped puls-
es 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
output and the DSX-3 Cross Connect System) 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 DSX-3 Cross Connect sys-
tem) is less than 225 feet.
Writing a "1" to this bit-field commands the Framer to
toggle the TxLev output "High". Writing a "0" to this
bit-field commands the Framer to toggle this output
signal "Low".
NOTES:
1. The TxLEV function is only applicable to DS3 appli-
cations. E3 LIUs do not support this kind of Line
Build out feature.
2. If the customer is not using the XRT7300 or the
(XRT7296 DS3 Line Transmitter) IC, then this bit-
field and the TxLev output pin can be used for other
purposes.
Bit 1 - RLOOP - (Remote Loopback)
This Read/Write bit-field allows the user to control the
state of the RLOOP output pin of the Framer 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 oper-
ate 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 Framer
IC to toggle the RLOOP output signal "High". Writing
a "0" into this bit-field commands the Framer IC to
toggle this output signal "Low".
For a detailed description of the XRT7300 DS3/E3
LIU's operation, during each of these above-men-
tioned 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 this bit-field and the RLOOP output pin
can be used for other purposes.
Bit 0 - LLOOP - (Local Loop-back)
This Read/Write bit-field allows the user to control the
state of the LLOOP output pin of the Framer 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 oper-
ate 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 LLOOP output signal "High". Writing a "0"
into this bit-field commands the Framer to toggle this
output signal "Low".
RLOOP
LLOOP
RESULTING LOOP-BACK MODE OF THE XRT7300 DEVICE
0
Normal Operation (No Loop-back Mode)
0
1
Analog Local Loop-back Mode
1
0
Remote Loop-back Mode
1
Digital Local Loop-back Mode
RLOOP
LLOOP
RESULTING LOOP-BACK MODE OF THE XRT7300 DEVICE
0
Normal Operation (No Loop-back Mode)
0
1
Analog Local Loop-back Mode
1
0
Remote Loop-back Mode
1
Digital Local Loop-back Mode