AT&T System 75 Wiring Diagram page 232

DS1 Tie Trunks Using 551-Type CSU
Figure 4-20 shows the connections required to connect a DS1 tie trunk
to a T1 CSU. The CSU is required to interface the DS1 tie trunks with the
1.544 Mbps digital facility. For information on installing the CSU, refer to
the information provided with the unit. The most frequently used CSUs
are the 551A, 551V, 551V EFS/R, and ESF T1. The 551V EFS/R (R
means retrofit) can be used to upgrade the 551V to the new Extended
Superframe (ESF) status.
The maximum allowable cabling distance between the DS1 tie trunk and
the CSU is:
CSU
551A
551V
551V EFS/R
EFS T1
DS1 TIE
TRUNK
CIRCUIT
PACK
TN722
SYSTEM
75 OR 75 XE
* FOR DISTANCES OVER 50 FEET USE
C6E CONNECTOR CABLE(S) BETWEEN
C6C CONNECTOR CABLE AND DS1 TIE
TRUNK CIRCUIT PACK.
Figure 4-20. Connections Between DS1 Tie Trunk and T1 CSU
Miscellaneous Wiring Installation
Max. Cabling Distance (feet)
>
C6C
CONNECTOR
CABLE *
85
85
655
655
T1
1.544 MBPS
CHANNEL
DIGITAL
SERVICE
SERVICE
UNIT
INTERFACE
TB1
T
1
R
2
J1
>
T 1
4
R 1
5
TO
T1
CARRIER
4-35