B-20
Cisco MWR 1941-DC Mobile Wireless Edge Router Hardware Installation Guide
78-15827-06B0
Appendix B Cable Specifications
Serial Connection Signals and Pinouts
X.21 Interface
This section contains the following topics:
•
X.21 Connections
•
X.21 Serial Cable Assembly
X.21 Connections
The X.21 interface uses a 15-pin connection for balanced circuits and is commonly used in the United
Kingdom to connect public data networks. X.21 relocates some of the logic functions to the DTE and
DCE interfaces and, as a result, requires fewer circuits and a smaller connector than EIA/TIA-232.
The network end of the X.21 adapter cable is a standard DB-15 connector. (See
Figure B-13
.)
X.21 cables are available as either DTE (DB-15 plug) or DCE (DB-15 receptacle).
Figure B-13 X.21 Adapter Cable Connectors, Network End
X.21 Serial Cable Assembly
Figure B-14
shows the X.21 serial cable assembly.
Table B-14
lists the DTE pinout and
Table B-15
lists
the DCE pinout.
Arrows indicate signal direction: —> means DTE to DCE and <— means DCE to DTE.
Figure B-14 X.21 Serial Cable Assembly
1
8
15
9
DCE
DTE
H1346a
H1974
60-pin connector (J1)
34-pin connector (J2)
Connectors are not to scale.
J2-8
J2-15
J2-9
J2-1
J1-46
J1-45
J1-16
J1-15
J1-1
J1-30
J1-31
J1-60