Power forwarding via a powered device
The present invention relates to a powered device ( 331 a , 331 b , 531 a ) with two interfacing connections. The powered device ( 331 a , 331 b , 531 a ) comprises power switching units ( 350 a , 350 b , 550 a 1 , 550 a 2 ) for forwarding the data signal as well the power received on the input to the output. Forwarding may be based on a detection of the powering state of the PD. In another embodiment, the Power-over-Ethernet input/output ports function bi-directionally, thereby allowing the user to daisy-chain devices in any direction. As power switching units, relays or solid-state power switches may be used.
1. A powered device for use in a Power-over-Ethernet network where power is supplied through network connections, said powered device comprising:
a first port;
a second port; and
a power switching unit configured to enable power forwarding via said second port in a first mode, and to disable power forwarding via said second port in a second mode;
characterized in that said powered device is configured to detect whether the first port receives power directly from a power sourcing equipment of said Power-over-Ethernet network or alternatively via a second powered device based on whether said first port receives power without prior negotiation.
2. The powered device as defined in claim 1 , wherein said power switching unit is configured to enable power forwarding only after said powered device is powered.
3. The powered device as defined in claim 1 , wherein said powered device is configured to increase its power consumption with a slew rate that is lower than or equal to a predefined maximal slew rate if said powered device detects that the first port receives power from the second powered device.
4. The powered device as defined in claim 1 , wherein said first port is configured to receive power from the power sourcing equipment, wherein said second port is configured to forward power to a subsequent powered device for use in said Power-over-Ethernet network.
5. The powered device as defined in claim 1 , wherein said first port is configured to receive power via four pairs of a cable from a group comprising category 5 cables and category 6 cables.
6. The powered device as defined in claim 1 , wherein said powered device comprises first and second power bypass units, wherein said first power bypass unit is passive, and wherein said second power bypass unit comprises said power switching unit.
7. The powered device as defined in claim 1 , wherein said first port is configured to receive power via two pairs of a cable from a group comprising category 5 cables and category 6 cables, and wherein said second port is configured to receive power via two pairs of an Ethernet cable.
8. The powered device as defined in claim 1 , wherein said powered device comprises first and second power bypass units, wherein said first power bypass unit comprises said power switching unit, and wherein said second power bypass unit comprises a second power switching unit.
9. The powered device as defined in claim 1 , wherein said power switching unit comprises a Single Pole Single Throw relay unit and/or a Double Pole Single Throw relay unit, and/or
wherein said power switching unit comprises a solid state switch, and/or
wherein said solid state switch comprises a MOSFET.
10. A Power-over-Ethernet network system, where power is supplied through network connections, said Power-over-Ethernet network system comprising:
a power sourcing equipment;
first and second powered devices, wherein said first and second power devices are powered devices according to claim 1 ,
wherein an output of said power sourcing equipment is coupled to said first port of said first powered device, and wherein said second port of said first powered device is coupled to said first port of said second powered device.
11. The Power-over-Ethernet network system as defined in claim 10 , wherein said Power-over-Ethernet network system comprises a detector for detecting a powering state of said first powered device.
12. The Power-over-Ethernet network system as defined in claim 11 , wherein said first powered device is configured to forward power to said second powered device based on said powering state.
13. A method of power forwarding via a powered device in a Power-over-Ethernet network where power is supplied through network connections, said method comprising:
receiving power via a first port of said powered device,
detecting whether the first port receives power directly from a Power Sourcing Equipment of said Power-over-Ethernet network or alternatively via a further powered device based on whether said first port receives power without prior negotiation,
in a first mode, enabling power forwarding via a second port of said powered device; and
in a second mode, disabling power forwarding via said second port of said powered device.
14. A non-transitory computer program product comprising code means for producing the steps of claim 13 when run on a computer device.