Abstract: A node configuration system with identical nodes includes a master 10 connected to a plurality of identical servant nodes 12-18 through a shared communication link (or bus) 20 and an unshared communication link (daisy-chain) (28,34,38,44,48). The master 16 assigns a unique identifier to each of the servant nodes 12-18, sequentially and individually, in a clockwise (CW) direction by sending configuration messages on the shared bus and configuration enable signals on the unshared link. The process begins with the master setting its configuration enable signal (CW-Cout port 24) to one and broadcasting a configuration message on the bus 20, which configures the servant node 12. As each servant node is configured, it sets its CW-Cout port to one which enables the next node in the chain to be configured. This process continues until all the servants 12-18 have been configured. In the event of a fault, the master 10 attempts to configure the remaining servant nodes in the counter-clockwise (CCW) direction.

Abstract: A hierarchial elevator control system (FIG. 2) utilizes standard Control Area Network (CAN) hardware and message protocols. A broadcast message format includes priority bits and source address bits in subfields within the standard CAN message identifier field, to separate priority levels from message type information, while maintaining collision avoidance by means of the source addresses. In a unicast message format, message response by individual receiving nodes is accomplished with simple standard CAN hardware filtering by providing, within the standard CAN message identifier field, a multi-bit destination address field to identify a unique receiving node to which the message is directed. In the unicast format, remote transmission requests are identified by a control bit in the standard CAN data field, and responded to utilizing a message-type field that is also in the data field portion of the message.

Abstract: If a transceiver has a message to send during an idle medium condition, it transmits a jam pattern onto the medium for a predetermined time (based on maximum network propagation delay). If a transceiver detects a jamming pattern, it inhibits its own transmissions and waits for the next slot progression. If multiple transceivers begin jamming within a propagation delay of each other (within the network vulnerable time), their jamming transmissions will not destructively interfere with each other. When jamming ceases, all transceivers begin a slot progression. Thus, the end of the jamming period when all transceivers have finished jamming serves as a network-wide synchronization for the start of an implicit token slot progression.

Abstract: Primary implicit token slots (that is, token slots following a message or jam used to restart network activity) are assigned to multiple transceivers. When a transceiver assigned to a shared slot has data to transmit, it emits a jamming signal instead of a message in its token slot. This jamming signal serves as a synchronization for a second implicit token slot progression in which only transceivers sharing the primary level implicit token slot participate.

Abstract: A multiplexer receives a message from a first bus and a message from a second bus, wherein a preamble is received at the head of each message, compares the preamble from each bus against an ideal preamble and, prior to receiving the next bit in either message, provides to a transceiver the message which is least noisy as indicated by the comparison; if the preamble in the message on the bus presently selected for reception by the transceiver does not compare favorably with the ideal preamble, the message from the other bus is selected.

Abstract: A LAN elevator network includes (a) a pair of redundant car buses for exchanging signals with car control system elements, (b) a pair of redundant group buses for exchanging signals with the redundant car buses by means of a car-group bridge, and (c) with a pair of redundant building buses, which exchange messages with a building controller, by means of a group-building bridge. Communication among all nodes on the car bus, group bus, and building bus occurs by means of a single protocol. Each communications element on a bus communicates with the bus by means of a communications coprocessor including a transmitter and a receiver.