4.0 - APPENDIX
4.1 X.21 INTERFACE CHART
ITU X.21 INTERFACE CHART (DB-15 CONNECTOR)
NOT USED
15
X
BYTE TIMING (B-)
14
X
SIGNAL TIMING (B-)
13
X
INDICATE (B-)
12
X
RECEIVE (B-)
11
X
CONTROL (B-)
10
X
TRANSMIT (B-)
9
-
-
GROUND
8
X
BYTE TIMING (A+)
7
X
SIGNAL TIMING (A+)
6
X
INDICATE (A+)
5
X
RECEIVE (A+)
4
X
CONTROL (A+)
3
X
TRANSMIT(A+)
2
-
-
SHIELD
1
FROM DTE
FROM DCE
PIN NAME
PIN NUMBER
East Coast Datacom, Inc. DMM-X21 OPERATIONS MANUAL
Page 9
1
8
1 5
9
DB-15 FEMALE
