AT&T MERLIN LEGEND System Reference Manual page 467

System Applications
a serial port assigned to COM1 or C0M2. The serial port can use either a
DB-9 or DB-25 connector. If a DB-9 connector is used, a 9-pin to 25-pin
adapter is also required. The 9-pin side must be female.
a monochrome or color monitor
D8W modular cord and 355AF modular adapter if PC is less than 50 feet
from the control unit. Distances of greater than 50 feet require back-to
back ADUs.
The connection of SPM to the control unit depends on whether or not the
distance between the control unit and the PC is less than 50 feet and whether or
not the control unit and the PC are plugged into the same AC power branch
circuit. Figure 3-9 shows the connection when the distance is less than 50 feet
and the control unit and the PC are plugged into the same circuit. Figure 3-10
illustrates the connection when the distance is 50 feet or more and the control
unit and the PC are plugged into different circuits.
System Programming and Maintenance 3-35