Link Interfaces Reference
V.11 & X.21 Link Pinouts
The connector shown here and pinouts described here correspond to
the connector labeled “V.11/X.21” on the back of the
8
1
15 
9
DB15 Female DTE
| X.21 |
| Direction | |
Contact | Circuits | Circuit | To | From |
Number | Reference | Name | DCE | DCE |
1 |
| Protective Ground | NA | |
2 | T (A) | Transmitted Data (A) | X |
|
3 | C (A) | Control (A) | X |
|
4 | R (A) | Received Data (A) |
| X |
5 | I (A) | Indication (A) |
| X |
6 | S (A) | Signal Element Timing (A) |
| X |
7 |
|
|
| |
8 | Ground | Signal Ground | NA | |
9 | T (B) | Transmitted Data (B) | X |
|
10 | C (B) | Control (B) | X |
|
11 | R (B) | Received Data (B) |
| X |
12 | I (B) | Indication (B) |
| X |
13 | S (B) | Signal Element Timing (B) |
| X |
14 |
|
|
| |
15 |
|
|
| |
Figure 3 – 8 V.11 Link Pinouts
The connecting cable must be a shielded cable.
Circuits which are paired (contain an (A) and (B) reference) should be connected to twisted pairs within the connecting cable.
NOTE For U.K. Approval:
The connecting cable should be manufactured from Belden Cable, or a cable with equivalent specifications. Each end must be terminated in a male 15 pin X.21 connector as defined in
3.6—
