Methods and apparatus for controlling power supplied to a remote device through a network cable
First Claim
1. A method of terminating power supplied to a remote device through a network cable, the method comprising:
- monitoring a hardware-level signal received from the remote device over the network cable;
detecting that the remote device has been disconnected from the network cable by failing to sense voltage transitions in the hardware-level signal received from the remote device; and
in response to detecting that the remote device has been disconnected from the network cable, terminating power supplied through the network cable,wherein;
the monitoring comprises continually monitoring the network cable for the presence of a data communications signal sent by the remote device when attached to the network cable, the communications signal being present on the network cable even when the remote device is not actively transmitting data on the network cable;
and further comprising;
detecting, after terminating power supplied to the remote device through the network cable, that the remote device has been re-connected to the network cable by detecting the presence of the data communications signal sent by the remote device; and
in response to detecting that the remote device has been re-connected to the network cable, supplying power to the remote device through the network cable,and wherein the data communications signal is encoded according to a code such that a detectable voltage transition of the coded data communications signal is guaranteed to occur over no more than a small number of signaling intervals even when the remote device is not transmitting data.
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Accused Products
Abstract
A detection circuit monitors a hardware-level signal received from a remote device for voltage transitions indicating that the remote device is connected to a network cable. If the detection circuit does not sense voltage transitions in the hardware-level signal, it is presumed that the remote device has been unplugged from the network cable and the detection circuit generates an immediate or delayed control signal to terminate supplying power through the network cable. In one application, the network cable supports communications based on a layered network protocol such as Ethernet and the detection circuit is employed at physical layer associated with the layered network protocol. Based on this topology, power supplied through the network cable can be terminated on the order of milliseconds instead of 1.5 seconds according to conventional methods.
31 Citations
21 Claims
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1. A method of terminating power supplied to a remote device through a network cable, the method comprising:
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monitoring a hardware-level signal received from the remote device over the network cable; detecting that the remote device has been disconnected from the network cable by failing to sense voltage transitions in the hardware-level signal received from the remote device; and in response to detecting that the remote device has been disconnected from the network cable, terminating power supplied through the network cable, wherein; the monitoring comprises continually monitoring the network cable for the presence of a data communications signal sent by the remote device when attached to the network cable, the communications signal being present on the network cable even when the remote device is not actively transmitting data on the network cable; and further comprising; detecting, after terminating power supplied to the remote device through the network cable, that the remote device has been re-connected to the network cable by detecting the presence of the data communications signal sent by the remote device; and in response to detecting that the remote device has been re-connected to the network cable, supplying power to the remote device through the network cable, and wherein the data communications signal is encoded according to a code such that a detectable voltage transition of the coded data communications signal is guaranteed to occur over no more than a small number of signaling intervals even when the remote device is not transmitting data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system for terminating power supplied through a network cable, the system comprising:
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a power source that conditionally provides power to a remote device through the network cable; a detection circuit to monitor a hardware-level signal received from the remote device over the network cable, the detection circuit generating a control signal identifying when the remote device is disconnected from the network cable based on a lack of voltage transitions in the hardware-level signal received from the remote device; and a control circuit associated with the power source that receives the control signal and, in response to receiving the control signal indicating that the remote device has been disconnected from the network cable, terminates power supplied by the power source through the network cable, wherein; the detection circuit continually monitors the network cable for the presence of a data communications signal sent by the remote device when attached to the network cable, the communications signal being present on the network cable even when the remote device is not actively transmitting data on the network cable; after the control circuit has terminated power supplied through the network cable, the detection circuit detects that the remote device has been re-connected to the network cable by detecting the presence of the data communications signal sent by the remote device; and the control circuit responds to the detection of the re-connection of the remote device to the network cable by supplying power to the remote device through the network cable, wherein the data communications signal is encoded according to a code such that a detectable voltage transition of the coded data communications signal is guaranteed to occur over no more than a small number of signaling intervals even when the remote device is not transmitting data. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification