Adapters; T1 L1 Channel Service Unit Connections - AT&T MERLIN LEGEND System Reference Manual

Hardware

Adapters

System Adapters
Channel Service Unit
For more on B8ZS line coding, see
Chapter 4 "Functional Description."
Figure 5-10 551 T1 L1 Channel Service Unit Connections
Adapters connect adjuncts to the system and stations. They provide access for
both voice and data signals.
Two adapters connect directly to the control unit: the channel service unit (CSU)
and the Universal Paging Access Module (UPAM).
The CSU
is the interface
provided by the telephone company. This facility contains 24 channels on one
4-pair wire that connects to the back of the CSU. The CSU then connects to the
modular jack on the 100D module.
There are an ESF T1 CSU and a 551 T1 L1 CSU. The ESF T1 CSU (extended
superframe) is recommended for this system because it allows the unit to be
maintained without interrupting service and provides diagnostic and testing
capabilities, and it is the only CSU that provides bipolar 8 zero code substitution
(B8ZS) line coding. The lower-cost 551 T1 L1 CSU performs most of the
functions of the ESF T1 CSU but does not provide the B8ZS line coding required
for 64-kbps data and for maintenance features. The 551 T1 L1 CSU also does
not provide diagnostic and testing capabilities.
Figures 5-10 and 5-11 detail the CSU connections.
between the 100D module and the DS1 facility
Adapters 5-19