IBM 5170 Technical Reference page 370

The following is an illustration of data terminal equipment
connected to an external modem using connections defined by the
RS-232C interface standard:
Data
Terminal
Equipment
Communications
line
-----:?'.o<:- _ _ __
/ /
/
",,,,,
..........
,
"
/ ' Adapter , ' / Cable Conforming ............ "
//
/ "
To RS-232C Standards
..........................
"
" / , ' , ,
/
,
""
/ ' ,EIA/CCITT Telephone Co.
line Number Lead Number
' r - - - - - '...
Protective Ground
0-
AAI 1 01
Signal Ground @-AB/102
Transmitted Data
®--
BAI 103
Received Data
0--
BB/1 04
Request to Send
CV-CA/105
Clear to Send
@-CB/106
Data Set Ready
®-CC/107
Data
Terminal
Modem
Data Terminal Ready @--CD/108.2
Equip­
Connect Data Set to line
--@--"/108.1
ment
Received Line Signal Detector CF/109
Speed Select
CH/111
Transmit Signal Element Timing
~
DB/114
Receive Signal Element Timing
~
DD/115
Select Standby
@--"/116
Ring Indicator @--DE/125
Test
~"I'"
I
External Modem Cable Connector
13121110 9 8 7 6 5 4 3 2 1
\oooooooooooool
\ooooooooooooj
252423222120191817161514
. +(MOdem)DCE
Dat~
Terminal . _ _ _ Data Communications----l
~---
EqUIpment E q u i p m e n t - I
Pin Number
"Not used when business machine clocking is used.
""Not standardized by EIA (Electronics Industry Association).
"'Not standardized by CCITT
8-4 Communications