AT&T System 75 Wiring Diagram page 328

CHAPTER 5. AUXILIARY EQUIPMENT INSTALLATION
Installing Processor lnterface/EIA Port
The processor interface circuit pack (TN765) provides a single EIA port
that allows access to one data link. Figures 5-31 and 5-32 show direct
connections and modem connections, respectively.
PI/EIA
TN765
CIRCUIT
PACK
SYSTEM 75
OR 75 XE
* THE MAXIMUM DISTANCE LIMITATION FOR TWO
SYSTEM 75/75 XE IS 50 FEET WHEN DIRECTLY
CONNECTED WITH 24 AWG WIRE. REDUCING THE
MAXIMUM DISTANCE MAY BE NECESSARY IF
HIGHER GAUGE WIRE IS USED OR IF THE
CAPACITIVE LOAD ON THE LINE IS INCREASED.
IN GENERAL, THE SYSTEM 75/75 XE SHOULD
BE DIRECTLY CONNECTED BY THE SHORTEST
POSSIBLE CABLE.
Figure 5-31. Direct Connections for Processor Interface/EIA Ports
Between Two System 75s or 75 XEs
MAXIMUM*
CABLING DISTANCE
50'
PI/EIA
TN765
CIRCUIT
PACK
SYSTEM 75
OR 75 XE
5-55