363-206-305
Circuit Pack Descriptions
7-80
Issue 3 June 2000
The 26G2-U OLIU interfaces via VT-G signals with circuit packs in the low-speed
slots and via STS-1 signals with the circuit packs in the main and function unit
slots. It selects the signals from the service or protection slot of each pair as
directed by the SYSCTL.
Fault Detection Circuitry
7
The 26G2-U OLIU circuit pack has in-service and out-of-service built-in test
capability. In-service testing is continuous, and errors are reported when they
occur to the SYSCTL via the intrashelf control bus. An out-of-service test is
performed whenever the OLIU circuit pack is inserted or recovers from a transient
failure.
The 26G2-U OLIU has STS-1 and VT1.5 signal degrade protection switching and
STS signal degrade protection switching capabilities.
Performance Monitoring
7
The 26G2-U OLIU provides PM circuitry for the following performance
parameters:
■
STS-1 section severely errored frame seconds (B1 SEFS) count
■
Line coding violation counts (B2 parity)
■
Line errored seconds
■
STS-1 path coding violation counts (B3 parity)
■
STS-1 path errored seconds
■
VT path coding violation counts (V5 parity)
■
VT path errored seconds.
Power Circuitry
7
Power for the 26G2-U OLIU circuit pack is provided by two DC-to-DC converters
located on the 26G2-U OLIU circuit pack. The converters supply +5 volts. Both A
and B
−
48 volt backplane busses supply power to the converters through diode
ORed circuit pack-mounted power select circuits and a circuit pack-mounted fuse.
The 26G2-U provides +5V power to the low-speed slots. Failure of the fuse or
converters causes the red FAULT LED to light.
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