X.21
C–31
Table C–19. DTE X.21 Pin Assignments
MCS
Network
26-Pin
Description
Function
15-Pin
3
Transmit A
T
2
12
Transmit B
T
9
8
Control A
C
3
17
Control B
C
10
2
Receive A
R
4
11
Receive B
R
11
4
Indication A
I
5
13
Indication B
I
12
7
Common return
G
8
23
25
Signal element timing A
S
6
24
26
Signal element timing B
S
13
The remaining pins are not used.