Transferring mastership in a multi-master communications channel of a system having a plurality of intercommunicating stations is accomplished by a method which includes the grouping into a logical loop of high traffic stations those stations which must be serviced frequently, and the grouping into at least one other logical loop of low traffic stations those requiring less frequent service. The token signifying mastership is passed from station to station in the high traffic loop at a maximum speed compatible with the work to be done by each station until a predetermined time period has lapsed since the mastership was passed through the low traffic group. Upon expiration of that time period, mastership is passed sequentially through the low traffic loop stations. Mastership is then returned to a previously determined high traffic loop station.
A transmission line fault detecting method and system use fault detectors capable of sending and receiving a fault locating frame of an arbitrary length for reliably detecting the location in the transmission line where the fault occurred. A number of such fault detectors are incorporated in a ring transmission system, wherein each detector sends and receives a fault locating frame including a first frame bounded by a starting delimiter and an ending delimiter, and a second frame following the first frame and containing other data bounded by an ending delimiter. The fault locating frame has a large frame length, preferably on the order of 4000 bytes. The first frame is formatted according to the communication protocol inherent to the transmission system. The present invention advantageously enables even a fault of less significance to be detected with high reliability.
A network system comprises a plurality of network elements connected to one another and a monitoring device for monitoring the network elements. Each of the network elements produces first through N-th fault signals when first through N-th faults occur in each of the network elements, where N represents a positive integer which is greater than one. In each of the network elements, a classifying circuit classifies the first through the N-th fault signals in accordance with a predetermined fault level to produce at least one classified signal. A selecting circuit is supplied with the first through the N-th fault signals as a fault message signal and the classified signal and selects one of the fault message signal and the classified signal to produce a selected signal. The selected signal is delivered as a monitoring signal to the monitoring device.
A self-healing drop/insert (D/I) communication method and network are provided. The network comprises two end stations and a chain of intermediate D/I multiplexer stations to which the two end stations are connected by two lines, so as to provide communication in both directions, East and West, for multiple data and/or voice channels between any of the stations. According to the invention, the end stations are collocated or located near one another and in the event of a break or failure in the network, they are interconnected to form one D/I multiplexer station, whereas the stations on each side of the break or failure become new end stations. The communication transmitted by the multiple data and/or voice channels is then redirected away from the point of break or failure, when it occurs, thereby allowing the network to self-heal and remain operational after the break or failure.
An activity monitor for monitoring activity on a bus connecting a plurality of processors, monitors the bus to determine the bus master and other bus activities. In response thereto, predetermined memory locations are enabled to count events on the bus or calculate time spans for various bus activities.
Each car controller (10) in a multicar elevator system provides two serial asynchronous full duplex I/O channels to communicate with the next and previous car controllers. These two channels allow the transmission of a message in two opposite directions (32,34) on a communications ring. A single interruption of the ring, by an interrupted transmission line or a disturbed car controller for example, guarantees the transmission of messages to each car controller in at least one of the two directions. Each car controller contains three remote serial link interfaces. The first remote serial link interfaces to the car fixtures; car buttons, car tell tale lights, etc. The second remote serial link interfaces to car related hall fixtures; hall position indicator hall lantern, etc. The third remote serial link interfaces to the group related hall fixtures; hall buttons, hall tell tale lights, etc. To ensure the operation of the group related hall fixtures if a car controller fails or is switched off, a switchover module (28,36) is used. The purpose of the switchover module is to connect the group related hall fixtures to one of two car controllers. In the event that a car controller fails or is switched off, the switchover module connects the group related hall fixtures to the other car controller.
