Pin Assignment - AT&T Bell System Plant Series Identification And Operation

(
(
(
spring relays are used in automatic-answer
and control circuits. The control circuit
also uses three dry reed relays which are
mounted in combination with the data out-
ISS 5, SECTION 594-011-100
put relays. Fig. 3 shows arrangement of
components in the cabinet
3. 04 Fig. 4 shows a simplified block dia-
gram of data set 401B. Interface
leads and pin assignments are shown in
Table B.
TABLE B
INTERFACE PIN ASSIGNMENT
Data Set
Data Set
Interface
401B 401D
Lead
Early
Current Early
Current
Model
Model Model Model
Al A 3
A 3
A2
B 4
B 4
A3
C 5
C 5
A4 D 6
D
6
A Common K 7
K 7
Bl
E
9
E
9
BZ F
10 F
10
B3
H
11 H
11
B4
J 12
J 12
B Common
z
13
z
13
Cl
V 14
CZ
w
15
C3
X
16
C4
y
17
C Common
a 18
Start-Ans Back
T 19 T
19
Check or Aud
p
20
p
20
Answer Back
Squelch L 21
L 21
Line Control
s
22
s
22
Line Status
R 23 R 23
Line Status
u
24
u
24
Frame Ground N 1 N
1
Ground M
M
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