Electrical computers and digital processing systems: support – Computer power control
Reexamination Certificate
2000-06-19
2004-03-02
Lee, Thomas (Department: 2185)
Electrical computers and digital processing systems: support
Computer power control
C713S300000, C713S310000, C713S340000, C700S022000, C700S286000
Reexamination Certificate
active
06701443
ABSTRACT:
BACKGROUND OF THE INVENTION
There is a wide variety of data communications networks suitable for carrying data between devices. For example, Ethernet is a widely used architecture for local-area networks (LANs). The architecture for such a computer network, along with variants defined in the IEEE 802.3 standard, is the result of work performed at a variety of companies.
Initially, the purpose of an 802.3 network was to carry data communications exclusively. All of the devices attached to such a computer network included their own power supplies and derived power from these power supplies. Accordingly, each device operated as a standalone system with unlimited local power.
Today, there exists a wide range of devices for which remote powerability is highly desirable. For example, it would be convenient if certain devices, which can attach to an 802.3 network, could draw power from the 802.3 network in order to operate properly. Examples of such devices include Internet telephones (IP phones) and security/surveillance devices.
SUMMARY OF THE INVENTION
Unfortunately, if a power source (e.g., a power supply) simply applies power to an 802.3 computer network in order to power a remotely powerable device on that network, there is a high risk of damaging any non-remotely powerable device on the network, i.e., a device which does not require and draw remote power. A conventional non-remotely powerable device typically includes circuitry (e.g., a network termination circuit) that is unable to handle power provided over a computer network. In the event of remote power application, such circuitry can overheat or burn out resulting in permanent damage to the non-remotely powerable device.
Furthermore, applying power to a computer network that does not require such power runs the risk of creating adverse conditions within the computer network itself. For example, applying power to an 802.3 network runs the risk of generating broadcast firestorms within the 802.3 network.
In contrast, the invention is directed to techniques for discovering a powerability condition of a computer network such as the existence of a remotely powerable device attached to a connecting medium of the computer network. Such detection can then control whether a remote power source (e.g., a data communications device such as a switch, or a mid-span device such as a patch panel) provides remote power to the computer network (e.g., phantom power from a VDC power source connected to digital communication lines of the network, direct power, etc.).
One arrangement of the invention is directed to an apparatus for discovering a powerability condition of a computer network. The apparatus includes a signal generator, a detector, and a controller which is coupled to the signal generator and the detector. The controller configures the signal generator to provide a test signal to a connecting medium of the computer network, and configures the detector to measure a response signal from the connecting medium of the computer network. The controller then indicates whether a remotely powerable device connects to the connecting medium of the computer network based on the response signal. Accordingly, if the apparatus discovers a remotely powerable device attached to the computer network (i.e., a powerability condition of the network), the apparatus can provide power to the device remotely (e.g., through the connecting medium). However, if the apparatus does not discover a remotely powerable device attached to the computer network (e.g., another powerability condition of the network), the apparatus can avoid providing power remotely and thus avoid possibly damaging any non-remotely powerable devices on the computer network.
In one arrangement, the computer network supports connection of a remotely powerable device that receives, during normal operation, an operating voltage having a first voltage magnitude. Here, the controller configures the signal generator to supply, as the test signal, a test voltage having a second voltage magnitude that is substantially less than the first voltage magnitude. Accordingly, if there is no remotely powerable device connecting to the computer network but there is a non-remotely powerable device that connects to the computer network, the current resulting from the application of the second (lower magnitude) test voltage is less likely to cause damage to the non-remotely powerable device compared to the current that would result from the application of the first (higher magnitude) test voltage.
In one arrangement, the controller configures the signal generator to supply, to the connecting medium, (i) a first voltage during a first time period, and (ii) a second voltage that is substantially different than the first voltage during a second time period. Preferably, the controller configures the signal generator to apply one of a positive and negative test voltage to the connecting medium as the first voltage (e.g., −5 volts), and the other of the positive and negative test voltage to the connecting medium as the second voltage (e.g., +5 volts). This arrangement enables the controller to determine whether a remote device, which allows current to flow when in only one direction (e.g., a remotely powerable device), connects to the computer network and, if so, whether that device is properly connected (or reverse-wired).
In one arrangement, the connecting medium includes (i) a first connecting link having a local end that terminates at a first transformer and a remote end, and (ii) a second connecting link having a local end that terminates at a second transformer and a remote end. In this arrangement, the controller preferably configures the signal generator to apply the test signal to the connecting medium through a centertap of the first transformer and a centertap of the second transformer. This arrangement is particularly advantageous in 802.3 networks since such networks typically use centertapped transformers thus enabling the invention to utilize existing network-related components.
In one arrangement, the connecting medium includes a local end and a remote end. Preferably, the controller selectively identifies, through the local end of the connecting medium, one of (i) a backwards wired device condition at the remote end, (ii) an open condition at the remote end, (iii) a remotely powerable device condition at the remote end, and (iv) a shorted
on-powerable device condition at the remote end. Accordingly, the controller can distinguish between a variety of computer network conditions (i.e., powerability conditions).
One arrangement of the invention is directed to a data communications device (e.g., a switch, a hub, a router, a bridge, etc.) or other device (e.g., a patch panel) that includes normal operating circuitry which communicates with a remote device over a computer network during normal operation, and power circuitry coupled to the normal operating circuitry. In this arrangement, the power circuitry, which is capable of discovering whether the remote device is remotely powerable over the computer network, is built into the data communications device itself.
Another arrangement of the invention is directed to a remotely powerable device having normal operating circuitry which couples to a connecting medium of a computer network, and a powerability indicator which couples to the normal operating circuitry. The powerability indicator is capable of receiving a test signal from the connecting medium of the computer network, and providing a response signal to the connecting medium of the computer network to enable discovery of the remotely powerable device based on the response signal.
Another arrangement of the invention is directed to a computer program product that includes a computer readable medium having instructions stored thereon for discovering a powerability condition of a computer network. The instructions, when carried out by a processor, cause the processor to perform the steps of: (i) providing a test signal to a connecting medium of the computer network; (ii) measuring a re
Chapin & Huang , L.L.C.
Cisco Technology Inc.
Huang, Esq. David E.
Lee Thomas
Patel Nitin C.
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