3Com Router 3000 Series Manual page 30

Internal DIP Switches
3Com Router Release Notes for V1.20
Table 20 E1 Cable Pinouts (continued)
DB15
15 Rx Ring
7 Rx Shield
Table 21 lists 4E1 conversion cable pinouts.
4E1 Conversion Cable Pinouts
Table 21
DB25
Pinout Signal
2 TxR4
16 RxSD4
14 RxT4
1 TxT4
3 TxSD4
15 RxR4
0 TxR3
19 RxSD3
17 RxT3
4 TxT3
6 TxSD3
18 RxR3
0 TxR2
22 RxSD2
20 RxT2
8 TxT2
10 TxSD2
21 RxR2
12 TxR1
25 RxSD1
23 RxT1
11 TxT1
13 TxSD1
24 RxR1
The 4-port E1/CE1/PRI module provides internal DIP switches, and the setting of
DIP switches decides the interface impedance and grounding mode. On the 4-port
E1/CE1/PRI module, DIP switch S4 sets the impedance and grounding mode for
interface 2.
By default, all the DIP switches for the 4-port E1/CE1/PRI module are switched on
so the impedance of the E1 interface is 75-ohm. If you connect a 75-ohm cable,
switch BIT1-8 to ON. If you connect a 120-ohm cable, switch BIT1-8 to OFF.
Personnel who haven't received training should not change the position of DIP
switch.
30
BNC (75-ohm coaxial
cable) RJ-45 (120-ohm twisted pair)
Rx Ring 5
- 6
DB15
Pinout Signal
2 TxRing
7 RxShield
8 RxTip
9 TxTip
10 TxShield
15 RxRing
2 TxRing
7 RxShield
8 RxTip
9 TxTip
10 TxShield
15 RxRing
2 TxRing
7 RxShield
8 RxTip
9 TxTip
10 TxShield
15 RxRing
2 TxRing
7 RxShield
8 RxTip
9 TxTip
10 TxShield
15 RxRing
Rx Ring
Rx Shield
Serial number
4
3
2
1