3Com Router 3000 Series, Manual, Page: 25 / 37

X.21 DTE Cable
The X.21 DTE cable has a DB15 (male) connector at the network end. Figure 11
illustrates the X.21 DTE cable.
Figure 11 X.21 DTE Cable
Table 16 lists X.21 DTE cable pinouts.
15 TXCE+ -> V SCR+
16 TXCE- -> X SCR-
3 TXC+ -> Y SCT+
4 TXC- -> AA SCT-
17 RXC+ <- U SCTE+
18 RXC- ? W SCTE-
11 DCD+ -> F RLSD
22 LL <- J LL
Shielding shell Core-shielding
layer <--> Core-shielding
layer Shielding shell
Table 16 X.21 DTE Cable Pinouts
DB28 Signal Signal direction DB15 (male) Signal
6 GND <--> 8 Circuit GND
10 MODE_DCE
9 MODE2
21 GND <--> 1 Shield GND
13 RTS+ -> 3
14 RTS- -> 10 Control -
23 CTS+ <- 5 Ind
24 CTS - <- 12 Indication -
19 RXD+ <- 4 R
20 RXD- <- 11 R
1 TXD+ -> 2 T
2 TXD - -> 9 Transmit-
17 RXC+ ? 6
18 RXC - <- 13 Timing -
Shielding shell Core-shieldin
g layer <--> Core-shielding
layer Shielding shell
Table 15
V.35 DCE Cable Pinouts (continued)
DB28 Signal Signal direction 34PIN (female) Signal
3Com Router Release Notes for V1.20
25