Lantech IES-3208C, User Manual

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6.7 Power over Ethernet (IPES series)
This segment shows the PoE(Power over Ethernet) function complying with IEEE
802.3af/at standards, for the IPES-3208C/3307C switch, they only support PoE mode
A, so there will display only Power of Ethernet in Web GUI, but for the IPES-
3208CB/3307CB switch, they support both the PoE Mode A and Mode B, so there
will display Mode A and Mode B in Web GUI.
Most passive applications use the pinout of 802.3af mode B - with DC plus on pins 4
and 5 and DC minus on 7 and 8 (see chart below). Data is then on 1-2 and 3-6. This
limits operation to 100Mbit/s. Gigabit passive injectors use a transformer on the data
pins to allow power and data to share the cable and is typically compatible with
802.3af Mode A. In the common "passive" PoE system, the injector does not
communicate with the powered device to negotiate its wattage requirements, but
merely supplies power at all times. Passive midspan injectors up to 12 ports simplify
installations. Devices needing 5 Volts cannot use PoE at 5 V on Ethernet cable
beyond about 15 feet (4.6 m) due to IR loss, so a 24 V or 48 V to 5 V DC-DC
converter is required at the remote end. Passive DC-to-DC injectors also exist which
convert a 9 V to 36 V DC input power source to a stabilized 24 V 1 A or 48 V 0.5 A
PoE feed with '+' on pins 4 & 5 and '−' on pins 7 & 8. These DC-to-DC PoE injectors
are used in various telecom applications.