Apparatus and method for communicating between nodes in a network

Claim 2

A communications network apparatus, comprising: a master node and a plurality of subject nodes; a plurality of connections running between nodes, each said connection comprising a single serial data signal carrier connected a pair of nodes, wherein one of said pair of nodes is a parent node with respect to the other of said pair of nodes, and the other of said pair of nodes is a child node with respect to said parent node, wherein said plurality of connections connect said master node and said plurality of subject nodes in a tree configuration, said tree having said master node at its root, wherein each of said plurality of subject nodes is connected to one or more nodes, one and only one of which is its parent; means in said master node and in each of said plurality of subject nodes for transmitting and receiving messages comprising serial data on said connections; end of message detection means in said master node and in each of said plurality of subject nodes for determining that a message being received has ended, wherein said end of message detection means determines that a message has ended when no more serial data is received on said connection for a predefined timeout period; and collision avoidance means in said master node and in each of said plurality of subject nodes for determining when said node is entitled to initiate transmission of a message on said connections, wherein said means permits a child node to initiate transmission of a message to its parent only during a predefined interval following the occurrence of a predefined event, and said means prevents a parent node from transmitting a message to said child during said predefined interval.

Claim 3

The communications network apparatus of claim 1, wherein said collision avoidance means determines that the child node is entitled to initiate transmission of a message during a predetermined interval following the receipt of a message from another node.

Claim 4

The communications network apparatus of claim 1, further comprising transmission timeout means in said master node and in each of said plurality of subject nodes for aborting transmission of a message, said message comprising a plurality of predefined units of data transmitted serially, if a predefined timeout period has elapsed since transmission of the previous unit of data of said message.

Claim 5

The communications network apparatus of claim 1, wherein at least one of said subject nodes is connected, by one of said plurality of connections, to a child node of said subject node.

Claim 6

The communications network apparatus of claim 4, wherein: said master node comprises means for initiating a broadcast message to be transmitted to every subject node in said network; and each subject node in said network being connected by at least one of said connections to a child node comprises means for re-transmitting said broadcast message to each node which is a child node of said subject node.

Claim 7

The communications network apparatus of claim 4, further comprising transmission timeout means in said master node and in each of said plurality of subject nodes for aborting transmission of a message, said message comprising a plurality of predefined units of data transmitted serially, if a predefined timeout period has elapsed since transmission of the previous unit of data of said message.

Claim 8

The communications network apparatus of claim 1, wherein said subject nodes comprise means for monitoring the status of one or more devices and reporting said status to said master node.

Claim 9

The communications network apparatus of claim 1, wherein said serial data signal carrier is a pair of wires running between said pair of nodes.

Claim 10

A subject node in a communication network, wherein said network comprises a master node, a plurality of subject nodes and a plurality of connections running between nodes, each said connection comprising a single serial data signal carrier connecting a pair of nodes, wherein one of said pair of nodes is a parent node with respect to the other of said pair of nodes, and the other of said pair of nodes is a child node with respect to said parent node, wherein said plurality of connections connect said master node and said plurality of subject nodes in a tree configuration, said tree having said master node at its root, wherein each of said plurality of subject nodes is connected to one or more nodes, one and only one of which is its parent, said subject node comprising: means for coupling at least one of said plurality of connections to said subject node; means for transmitting and receiving messages comprising serial data on said connection coupled to said subject node; end of message detection means for determining that a message being received has ended, wherein said end of message detection means determines that a message has ended when no more serial data is received on said connection for a predetermined timeout period; collision avoidance means for determining which node of the pair of nodes connected by said connection is entitled to initiate transmission of a message on said connection, wherein said means permits said child node to initiate transmission of a message to its parent only during a predefined interval following the occurrence of a predefined event, and said means prevent said parent node from transmitting a message to said child during said predefined interval.

Claim 11

A subject node in a communication network, wherein said network comprises a master node, a plurality of subject nodes and a plurality of connections running between nodes, each said connection comprising a single serial data signal carrier connecting a pair of nodes, wherein one of said pair of nodes is a parent node with respect to the other of said pair of nodes, and the other of said pair of nodes is a child node with respect to said parent node, wherein said plurality of connections connect said master node and said plurality of subject nodes in a tree configuration, said tree having said master node at its root, wherein each of said plurality of subject nodes is connected to one or more nodes, one and only one of which is its parent, said subject node comprising: means for coupling at least one of said plurality of connections to said subject node; means for transmitting and receiving messages comprising serial data on said connection coupled to said subject node; end of message detection means for determining that a message being received has ended, wherein said end of message detection means determines that a message has ended when no more serial data is received on said connection for a predetermined timeout period; collision avoidance means for determining which node of the pair of nodes connected by said connection is entitled to initiate transmission of a message on said connection, wherein said means permits said child node to initiate transmission of a message to its parent only during a predefined interval following the occurrence of a predefined event, and said means prevent said parent node from transmitting a message to said child during said predefined interval.

Claim 12

The subject node in a communications network of claim 9, further comprising transmission timeout means for aborting transmission of a message, said message comprising a plurality of predefined units of data transmitted serially, if a predefined timeout period has elapsed since transmission of the previous predefined unit of data in said message.

Claim 13

The subject node in a communications network of claim 9, wherein said serial data signal carrier is a pair of wires running between said pair of nodes.

Claim 14

The subject node in a communications network of claim 9, wherein said collision avoidance means permits said subject node to initiate transmission of a message to its parent only during a predefined interval following the receipt of a message from said parent.

Claim 15

The subject node in a communications network of claim 12, further comprising transmission timeout means for aborting transmission of a message, said message comprising a plurality of predefined units of data transmitted serially, if a predefined timeout period has elapsed since transmission of the previous predefined unit of data in said message.

Claim 16

The subject node in a communications network of claim 13, further comprising means for monitoring power availability status of a device in a computer system.

Claim 17

The subject node in a communications network of claim 13, further comprising means for receiving a program for executing in said subject node from said network.

Claim 18

The subject node in a communications network of claim 9, further comprising means for transmitting and receiving messages comprising serial data on at least two of said plurality of connections, wherein at least one of said plurality of connections runs to a child node of said subject node.

Claim 19

The subject node in a communications network of claim 16, further comprising transmission timeout means for aborting transmission of a message, said message comprising a plurality of predefined units of data transmitted serially, if a predefined timeout period has elapsed since transmission of the previous predefined unit of data in said message.

Claim 20

The subject node in a communications network of claim 16, wherein: said master node comprises means for initiating a broadcast message to be transmitted to every node in said network other than said master node; and said subject node comprises means for re-transmitting said broadcast message to each node which is a child node of said subject node.

Claim 21

The subject node in a communications network of claim 18, further comprising: means for broadcasting a message to a plurality of child nodes attached to said subject node simultaneously; and means for ignoring responsive messages received from said child nodes when said responsive messages are received in response to a message which is broadcast to a plurality of child nodes simultaneously.

Claim 22

The subject node in a communications network of claim 18, further comprising means for receiving a program for executing in said subject node from said network.

Claim 23

The subject node in a communications network of claim 18, further comprising means for monitoring power availability status of a rack used for housing devices in a computer system.

Claim 26

The method of claim 22, wherein said step of transmitting a responsive message comprises the steps of: resetting a transmit timer whenever a predefined unit of data is transmitted to said parent node; and aborting transmission of said message if said transmit timer times out before said message has been transmitted in its entirety.