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Detection of Connection Status for Devices in a Daisy Chain Disclosure Number: IPCOM000013232D
Original Publication Date: 2001-May-06
Included in the Prior Art Database: 2003-Jun-18

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The mechanism being disclosed provides an automated means to determine if devices are, or not, connected in a daisy chain. If so: detect where it is connected in the chain (start, end or within the chain) detect a change of connection in the chain Presently, when there are several computer systems installed in a rack, the connections to the KVM (Keyboard, Video display and Mouse) console devices is usually performed by means of a KVM switch/multiplexer such as made by Apex*, Cybex* and others. This requires a cabling approach that is expensive, bulky, and cumbersome. This is due to the fact that fairly long cables must connect each system's KVM connectors to the appropriate port connectors in the switch/multiplexer. This is further complicated when the quantity of systems to be multiplexed is greater than the number of ports supported by a single switch/multiplexer (usually four or eight). In such a case, the KVM switches must be connected in a tiered or cascade scheme thereby requiring greater amounts of cabling. An alternate solution consists of connecting the systems to the KVM devices in a daisy chain fashion by including in each system a circuit that performs the KVM switch/multiplexer function. The systems would have a connector for attaching the "chain IN" and one for attaching the "chain OUT" connection for each system in the chain. Therefore, the chain starts with a cable from the "OUT" connector of a system to the KVM devices, it's "IN" connector is connected to the "OUT" connector of the system downstream in the daisy chain, and so on, until the last system in the chain (which does not have any system connected to its "IN" connector). This would replace the bulky, cumbersome and lengthy cabling and the switch/multiplexers (and the need for supplying power for them) with chaining cables . The chaining cables, therefore, consist of only one "breakout" cable that provides the means of connecting the KVM devices to the OUT connector and short "point to point" cables to interconnect the systems.