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APPENDIX D: QUICK-REFERENCE SUMMARIES
DEFINITY Communications System
7400B Data Module
Page D-8
User’s Guide
Pin
Circuit
Direction
Function
1
—
—
not used
2
BA (SD)
to 7400B
transmit data
3
BB (RD)
from 7400B
receive data
4
CA (RTS)
to 7400B
request to send
5
CB (CTS)
from 7400B
clear to send
6
CC (DSR)
from 7400B
data set ready
7
AB (SG)
common
signal ground
8
CF (RLSD)
from 7400B
receive line signal detector
9
—
—
not used
10
—
—
not used
11
—
—
not used
12* CI
from 7400B
data signal rate select
13
—
—
not used
14
—
—
not used
15
—
—
not used
16
—
—
not used
17
—
—
not used
18
—
—
not used
19
—
—
not used
20
CD (DTR)
to 7400B
data terminal equipment ready
21
—
—
not used
22
CE (RI)
from 7400B
ring indicator
23*
CI
from 7400B
data signal rate select
24
—
—
not used
25
—
—
not used
*CI on pin 12 is Bell 212A, on pin 23 is EIA-232-D
TABLE D-5 EIA-232-D PIN ASSIGNMENTS