What are the difference between Mode A and Mode B of Ethernet- Type
In mode A ,Pin 1 and 2 from one side of the 48VDC , And Pin3 and 6 form the other side. These are the same two pairs used for data transmission in 10 BASE-T and 100BASE-TX , allowing the provision of both power and data over onl two pairs in the such networks.
The free polarity allows POE to accommodated for crossover cables,patch cables and auto-MDIX.
In mode B , Pin4 -5 form one side of the DC supply and pin 7-8 provide the return. These are the 'spare' paris in 10BASE-T and 100BASE-TX. Mode B , therefore , requires 1 4-pair cable.
Mode A and Mode B ::
The free polarity allows POE to accommodated for crossover cables,patch cables and auto-MDIX.
In mode B , Pin4 -5 form one side of the DC supply and pin 7-8 provide the return. These are the 'spare' paris in 10BASE-T and 100BASE-TX. Mode B , therefore , requires 1 4-pair cable.
Mode A and Mode B ::
Pin Assignment Ethernet-Type | ||||
Pins on switch | Mode A | Mode B | ||
Ethernet | POE (DC) | Ethernet | POE (DC) | |
Pin1 | TX | + | TX | |
Pin2 | TX | + | TX | |
Pin3 | RX | _ | RX | |
Pin4 | NONE | NONE | + | |
Pin5 | NONE | NONE | + | |
Pin6 | RX | _ | RX | |
Pin7 | NONE | NONE | _ | |
Pin8 | NONE | NONE | _ |