Csu Loop; Dsu Loop - Black Box MT160A Manual

CHAPTER 6: DDS Testing
6.4.1 CSU L
OOP
The CSU Loop is activated when the central office reverses the DC sealing current
that flows between the TX pair and the RX pair. In this case, the MicroCSU/DSU
recognizes this and loops signals on the RX pair back to the central office on the
TX pair. While the CSU Loop is activated by the central office, the TM light is
illuminated.
DSU CSU
DIGITAL
NETWORK
6.4.2 DSU L
OOP
The DSU Loop is activated when the central office sends a DSU loop signal over
the twisted-pair wire. The MicroCSU/DSU senses this signal and loops the digital
data back to the central office. While the DSU Loop is activated, the TM light is
illuminated.
DSU CSU
DIGITAL
NETWORK
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