3Com S7906E Getting Started Manual page 9

Figure 1-2 Rear panel of the S7902E
(1) COM port for monitoring PoE (RS485)
(3) Grounding screws
(4) RTN terminal (+) of external PoE power supply
(5) Negative terminal (–) of external PoE power supply (–46 V to –55 V)
There are two DC power input (PoE power supply input) terminals and two COM ports (monitor ports)
on the rear panel of the chassis.
The S7900E series are Power over Ethernet (PoE) capable, that is, they can supply power to
devices such as IP phones, wireless access points, and network cameras connected to their
Ethernet ports through twisted pair cables.
For the S7902E and S7903E-S, the external PoE power supply is connected to the PoE power
supply input terminals on the rear panel, while for the other models of the S7900E series, the
external PoE power supply is connected to a power module. For details, refer to section
"PSR1400-D" on page
S7903E-S
Figure 1-3 shows the front panel of the S7903E-S.
1-14 and section "PSR2800-ACV" on page 1-15.
1-3
(2) COM port for monitoring PoE (RS232)