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Issue 6
5 - 50
4.10.5
Alarm Conditions
A brief description of each alarm condition referred to
under the SW2, position 0 alarm Indications is given
below.
Layer 1 Status
LED is on red when layer 1 is active. The LED is off
when layer 1 is inactive.
Controlled Slip indication (SLIP)
When the difference between the timing of a
synchronous receiving terminal and the received
signal
synchronous terminal, the LED is on red.
Remote Alarm Indication (RAI) Detection
When RAI is received, the LED is on red.
Loss of Frame (LOF) Condition Detection
When two of the four or five framing data bits
received are in error, the LED is on red.
Alarm Indication Signal (AIS) Detection
When the system is receiving an Alarm Indication
Signal from a PRT trunk, the LED is on red.
Cyclic Redundancy Check (CRC) Error Event
Detection
When a CRC Error occurs, the LED is on red.
Active Call
LED is on red to indicate an active call.
4.10.6
Connectors
The PRT(1)-U( ) ETU has two connectors:
CN1
CN3
exceeds
the
buffering
Connects to the backboard
9-pin
RS-232C
connector
maintenance
Installing Electronic Telephone Units
Electra Elite
ability
of
the
used
for
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