Bilevel node identifiers in control area network (CAN) protocol
First Claim
1. A method of communicating between various nodes of a multi-processor control system which has a plurality of class one nodes, each of which must communicate with other ones of said class one nodes and with nodes of said control system other than said class one nodes, and which has a plurality of class two nodes each of which needs to communicate with at least one of said class one nodes but none of which needs to communicate with other ones of said class two nodes, utilizing control area network (CAN) hardware which responds to a standard CAN message format in which the most significant bit is a start of frame bit, the next 31 most significant bits include a 29-bit identifier field, the next bit comprises a remote transmission request bit, the next six bits comprise a field of control bits, the next field of between 0 and 64 bits comprises a data field, the next 16 bits comprise a cyclic redundancy check field, the next 2 bits comprise an acknowledge field, and the least significant seven bits comprise an end of frame field, which method comprises:
- providing a message function-type portion consisting of a contiguous fraction of said CAN identifier field including the most significant bits of said identifier field, the content of which will identify other bits of said identifier field as a destination node identifier or a source node identifier, respectively;
providing a class one node identifier portion, consisting of a contiguous fraction of said CAN identifier field, the content of which comprises a class one node identifier which identifies one of a plurality of said class one nodes;
providing a selectable node identifier portion consisting of a contiguous fraction of said CAN identifier field other than said message function-type portion and said class one node identifier portion, the content of which comprises either, when communication is between one of said class one nodes and one of said class two nodes a class two node identifier which identifies one of said plurality of class two nodes.
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Abstract
The 29 bit identifier field of a standard CAN protocol message format is subdivided into a message function portion, a class one node identifier portion, to identify class one nodes which must be able to communicate with each other as well as with a large number of other nodes in the system, and a selectable node identifier portion, the vast majority of which is utilized for class two node identifiers, to identify class two nodes which never need to communicate with each other, but only need to communicate with class one nodes, and a small portion of which is utilized for class one node identifiers for cases where two class one nodes are communicating with each other. The least significant eight bits of the selectable portion represent class one identifiers when the most significant eight bits of the selectable portion are all zeros, but when any of the most significant eight bits of the selectable portion represents a one, then the lowest ordered eight bits are part of a class two identifier. Thus, the selectable portion can identify, for example, 256 class one nodes and 65,280 class two nodes.
21 Citations
8 Claims
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1. A method of communicating between various nodes of a multi-processor control system which has a plurality of class one nodes, each of which must communicate with other ones of said class one nodes and with nodes of said control system other than said class one nodes, and which has a plurality of class two nodes each of which needs to communicate with at least one of said class one nodes but none of which needs to communicate with other ones of said class two nodes, utilizing control area network (CAN) hardware which responds to a standard CAN message format in which the most significant bit is a start of frame bit, the next 31 most significant bits include a 29-bit identifier field, the next bit comprises a remote transmission request bit, the next six bits comprise a field of control bits, the next field of between 0 and 64 bits comprises a data field, the next 16 bits comprise a cyclic redundancy check field, the next 2 bits comprise an acknowledge field, and the least significant seven bits comprise an end of frame field, which method comprises:
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providing a message function-type portion consisting of a contiguous fraction of said CAN identifier field including the most significant bits of said identifier field, the content of which will identify other bits of said identifier field as a destination node identifier or a source node identifier, respectively;
providing a class one node identifier portion, consisting of a contiguous fraction of said CAN identifier field, the content of which comprises a class one node identifier which identifies one of a plurality of said class one nodes;
providing a selectable node identifier portion consisting of a contiguous fraction of said CAN identifier field other than said message function-type portion and said class one node identifier portion, the content of which comprises either, when communication is between one of said class one nodes and one of said class two nodes a class two node identifier which identifies one of said plurality of class two nodes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification
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- Resources
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Current AssigneeOtis Elevator Company (Otis Worldwide Corp.)
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Original AssigneeOtis Elevator Company (Otis Worldwide Corp.)
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InventorsHnida, Martin Georg Walter, Spielbauer, Hans-Kilian Josef
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Primary Examiner(s)YAO, KWANG BIN
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Application NumberUS09/267,960Time in Patent Office1,110 DaysField of Search370/389, 370/390, 370/392, 370/393, 370/465, 370/466, 370/470, 370/471, 370/472, 370/473, 370/474, 370/475, 370/410, 370/409US Class Current370/470CPC Class CodesH04L 12/4135 using bit-wise arbitrationH04L 2012/40215 Controller Area Network CANH04L 2101/604 Address structures or formatsH04L 61/00 Network arrangements, proto...
