IBM 3270 Manual page 223

3274 Model 51C with a 1200-BPS Integrated Modem
Attached to a Switched Line with Auto-Answer
( U. S. and Canada Only)
0
Attach the communication cable's color-coded wires to the data coupler as shown
in the following table and diagram.
......
Coupler Wire
Terminal
Color
Telephone Company-Provided
CBS Data Coupler or
DR Black
FCC-Certified Equivalent
DT
White
RI
Violet
OH Blue
@
~
~DA
~OH ~OT
CCT
Brown
DA Yellow
~
~
~ ~ ~
SH
SG CCT
RI
DR
SG Gray
SH
Red
~ 7
3274 Model 51 C
Label-DATA COUPLER
F-14
\
u
-
~
_)
\
\~