X.21 DCE Cable
The X.21 DCE cable has a DB15 (female) connector at the network end. Figure 12
illustrates the X.21 DCE cable.
Figure 12
X.21 DCE Cable
Table 17 lists the X.21 DCE cable pinouts.
Warning:
To prevent damage to the router and ports, do not connect or
disconnect the interface cable to the 4-port synchronous/asynchronous serial
module with X.21 while the router is powered on.
Before connecting the 4-port synchronous/asynchronous serial module with X.21,
confirm the mode of the equipment that is connected to it (the synchronous/
asynchronous mode, DTE/DCE mode of the peer, and so on), the signaling
criterion required by the access equipment, baud rate, and synchronous clock.
To connect cables to the 4-port synchronous/asynchronous serial module with
X21:
1
Power off the router.
2
Verify the interface type of the peer device and choose the synchronous/
asynchronous serial interface cable of correct type.
Table 17
X.21 DCE Cable Pinouts
DB28
Signal
Signal direction
DB15 (female) Signal
6
GND
<-->
8
Circuit GND
9
MODE2
21
GND
<-->
1
Shield GND
13
RTS+
->
5
Ind
14
RTS-
->
12
Indication -
23
CTS+
<-
3
24
CTS -
<-
10
Control -
19
RXD+
<-
2
T
20
RXD-
<-
9
Tr
1
TXD+
->
4
R
2
TXD -
->
11
Receiver -
15
TXCE+
->
6
16
TXCE -
->
13
Timing -
Shielding shell
Core-shielding
layer
<-->
Core-shielding
layer
Shielding shell
3Com Router Release Notes for V1.20
26
