DESCRIPTION OF PARTS
11
2. 7 X.21 DTE Port
The X.21 DTE port is equipped with a 15-way female D-type connector in accordance with
ISO 4903. The connections are shown below.
Note:
The X.21 port is regarded as a SELV port within the scope of EN 41003.
Figure 2.13 X.21 DTE port connector layout
Pin No
Function
Definition
CCT No.
1
Chassis
Shield
101
2
Tx(A)
Transmit (A)
103
3
C(A)
Control (A)
107
4
Rx(A)
Receive (A)
104
5
I(A)
Indication (A)
109
6
S(A)
Signal timing (A)
115
7
X(A)
DTE Signal timing (A)
113
8
Ground
Ground
102
9
Tx(B)
Transmit (B)
103
10
C(B)
Control (B)
107
11
Rx(B)
Receive (B)
104
12
I(B)
Indication (B)
109
13
S(B)
Signal timing (B)
115
14
X(B)
DTE Signal timing (B)
113
15
Not connected
