Elevator System Master Car Switching

The present application is related to the following concurrently filed U.S. patent application Ser. Nos. 07/09,639, by J. W. Blain, et al. and entitled "Elevator System Graceful Degradation of Bank Service" (W. E. Case 53,785); 07/109,640, by J. W. Blain et al. and entitled "Elevator System Adaptive Time-Based Block Operation" (W. E. Case 53,782); and to concurrently filed on June 19, 1987, 07/064,915, by D. D. Shah et al. and entitled "Elevator System Monitoring Cold Oil" (W. E. Case 53,783); and Ser. No. 07/064,913, by J. W. Blain et al. and entitled "Elevator System Leveling Safeguard Control and Method" (W. E. Case 53,784), all of which are assigned to the same as the present assignee and the disclosures of which are incorporated herein by reference.

1. Field of the Invention

This invention relates in general to traction and hydraulic elevator systems with distributed control circuits, and more particularly, to a method and control system for protecting against control signal and communication failures with diminished elevator service because of the loss of a vital element in the system.

2. Description of the Prior Art

Computers have heretofore been pre-programmed to perform various functions in the operational control or management of car and hall call response strategies in an elevator system. Various arrangements for elevator bank configurations have been known to benefit from these state-of-the-art solid-state controllers, but assuming that dynamically defined tasks involve uniquely reconfigured failure mode arrangements; these have yet to emerge. Disturbingly present is the likelihood that the failure of components assigned for dedicated control functions, such as in a fixed dispatcher controller used with the present day elevator control apparatus, will eventually interrupt or discontinue to communicate with other controllers in the system. These systems may have a back-up mode of operation with some form of service being retained, but it is of significantly inferior quality to the normal service.

With the introduction of microprocessor based elevator controllers, and the distribution of electronic circuits located with each car and proximate to the respective floors, communication with the remote controllers is of fundamental concern since the integrity of hall call signals and the control strategy in assigning cars to answer these calls is critical to operational efficiency and to the satisfied customer and prospective passengers.

One of the principal problems with a distributed control system for controlling a plurality of elevator cars is that normally the remote controller which has been selected for implementing the control strategy is also responsible for checking the integrity of the communication with the other controllers in the system. In a failure mode the other controllers are not immediately informed and they don't assume the self-selection necessary to begin implementing a master control strategy remaining available to them such as if there were good signal integrity between this controller and the hallway serial link of corridor communication.

Another problem is in the situation where there is a failure of the master controller and all of the remaining controllers simultaneously begin to assume the task of dispatcher for the bank of cars because there is no priority of command for controllers and there is insufficient communication to alert each controller as to the redundancy of controllers in the system. Asserting the authority of master controller by each would result in the potential for multiple car assignments to the same floor and inexcusably not the best car efficiency for the bank of cars which still has the potential for providing efficient service and to minimize waiting time.

The present invention is a new and improved elevator system and method of protecting against control signal failures and loss of elevator car service essentially of the type which uses a distributed control system implemented with electronic circuits located with each car of a two-car-pair and at each floor for corridor call information and having input and output signals which are communicated serially for each car over a travelling cable connected to an associated per car remote controller. Each remote controller includes a microprocessor based computer circuit, which is also serially connected over a communication link to the distributed electronic circuits proximate to each floor and serves to implement a two-car-pair floor control (FC) master strategy for responding to hall calls. The remote controllers function individually to respond to the car associated car calls and each non FC master remains on stand-by to assume implementing the floor control master strategy for answering hall calls if the selected floor controller for this responsibility falls or there is a communication failure with it.

The microprocessor for each car repeatedly implements a program to select which remote controller should assume and retain this role of directing the floor control master strategy for the two-car-pair by becoming the FC master controller and it signals this status to the other remote controller. The FC master controller then controls a set of floor control circuits over a serial communication riser for processing the hall calls and sending back corridor signals of an audible and visual type in order to provide information to a waiting passenger.

Further in accordance with the invention, when used with an elevator bank consisting of a plurality of two-car-pairs, the microprocessor for each car repeatedly implements an additional program to select which remote controller should assume and retain the additional role of bank control (BC) master which serves as a dispatcher. This BC master functions to supervise all of the cars of the elevator bank in order to process all of the hall calls and assigns the best car for each hall call. The best car to respond is based on the relative car travel position in order to minimize waiting times for service and provide passenger convenience. The BC master signals its status to all of the other controllers through a third or multi-car communications link with the other remote controllers and controls the set of floor control circuits through the FC masters over a serial communications riser for each two-car-pair. Through its implementation of the FC master first program, the BC master can select itself to serve the dual function as FC master controller for its two-car-pair of the bank, and signal notification thereof is sent to the other controllers over the serial communications link.

The invention may be better understood, and further advantages and uses thereof more readily apparent, when considered in view of the following detail description of exemplary embodiments taken with the accompanying drawings in which:

FIG. 1 is a block diagram of a plural car elevator system, shown driven in the alternative with either traction or hydraulic drives and including remote controllers which may be implemented in two-car-pair sets and operated according to the teachings of the invention;

FIG. 2 is a block diagram of a pair of microcomputer circuits each of which are associated with a car and in the elevator system of FIG. 1;

FIG. 3 is a flow chart of an abbreviated program module of the type which may be programmed into the EPROM within each microcomputer circuit of FIG. 2 and run in a repeating sequence in order to switch a dispatcher or bank controller (BC) master strategy for plural two-car-pair sets;

FIG. 4 is a flow chart of a program module FCMHSL with its associated sequencing routine which is programmed into the respective EPROMs of the microcomputer circuits of FIG. 2 and run in a repeating sequence in order to implement the floor control (FC) master strategy for servicing hall calls along with car calls; and

FIG. 5 is a flow chart of a program module for dispatcher switching with its associated sequencing routine also programmed into the respective EPROMs of the microcomputer circuits and run in a repeating sequence in order to implement the dispatcher or BC master strategy which is concurrent with the FC master strategy of FIG. 4 for the two-car-pair sets .

The invention is a new and improved elevator system and a method of operating an elevator system of the type which uses a distributed control system disposed partly in a plurality of elevator cars and partly in an associated plurality of remote controllers disposed therefrom while communicating over a travelling cable serving as a local area network (LAN) using token passing strategies for bi-directional communication. Each car associated remote controller is grouped into a two-car-pair which is serially connected over a communication link to a plurality of distributed electronic circuits proximate to each floor in order to implement a two-car-pair strategy for responding to hall calls, while the remote controllers function individually to respond to their car associated car calls. The remote controllers communicate with each other over a third serial network link so that each remains on standby with respect to the other to assume implementing the floor control strategy should there be a communication failure or failure in the previously established remote controller priority of operation.

The new and improved system and method are described by illustrating only those parts of an elevator system pertinent to the understanding of the invention, and supplemental portions of the elevator system have been incorporated by reference to an allowed U.S. patent assigned to the same assignee as the present application. Accordingly, allowed U.S. patent application Ser. No. 06/829,744 filed Feb. 14, 1986, entitled "Elevator Communication Controller" (W. E. 53,109), describes an addressable elevator communication controller for controlling full duplex serial communication between various remotely located corridor fixtures and car functions in a controller which controls a central bank of elevator cars. Each communication controller may be placed on a single IC custom chip which may be used redundantly in the elevator system in order to control the various corridor fixtures including hall call pushbuttons and associated indicator lamps, up and down hall call lanterns located at each floor, digital or horizontal car position indicators and status panels located at selected floors. It is used as well for elevator car located functions such as the door controller, car position indicator, direction arrows, and the car call pushbuttons and associated indicator lamps.

More specifically, FIG. 1 now shows an elevator system 10 which may incorporate this controller which may be utilized according to the teachings of the present invention. The elevator system 10 includes one or more elevator cars, or cabs, such as elevator car 12a, the movement of which is alternatively driven either as shown above the car from a penthouse 19 in a building structure (not shown), as in a traction elevator system, or as shown from below the car in a machine room 26, as when the implementation is in a hydraulic elevator system. When the invention is used in a traction elevator system, the car 12a is mounted in a hatchway of the building structure, such as shown for car "B", which forms with car "A" a two-car-pair which occupies the space to the left of center in the drawing of FIG. 1. The building structure has a plurality of landings such as the ZERO, 1ST, 6TH, 7TH floors or landings which are shown in order to simplify the drawing.

The car 12a is supported by a plurality of wire ropes 18a which are reeved over a traction sheave 20a mounted on the shaft of a drive machine 22a regarded as the #0 drive machine and a counterweight (CTWT now shown) is connected to the other ends of the ropes 18a. A similar arrangement is shown for car "B" which is supported by the wire ropes 18b over the sheave 20b and driven by the #1 drive machine 22b. The drive machine 22a, 22b may be AC systems having an AC drive motor, or a DC system having a DC drive motor such as used in the Ward-Leonard drive system or it may use a solid-state drive system.

A traction elevator system incorporates a car movement detection scheme to provide a signal for each standard increment of travel of the car such as 0.25 inch of car travel. This may be developed in several ways with one such way using a sensor located on car 12a cooperating with indicia disposed in the hatchway. Distance pulses are then developed for a car controller 24a which includes a floor selector and speed pattern generator for the elevator system. A further discussion of a car controller and a traction elevator system of the type in which a pulse count is maintained to enable a car to be leveled in the correct travel direction is described U.S. Pat. No. 4,463,833 which is assigned to the assignee of the present application, and the present invention may be used to enhance the functioning thereof.

Normally the car controller 24a through its floor selector keeps track of the position and the calls for service for the car 12a, and it also provides the starting and stopping signals for the car to serve calls, while providing signals for controlling auxiliary devices such as the door control for the elevator car doors 13a. Likewise, the car controller 24b for car "B" provides the same functions as the car controller 24a does for its respective car "A". In the two-car-pair traction elevator system of the present invention, each of the respective car controllers 22a and 22b controls hall lanterns such as hall lantern pair of up-floor lanterns 112L associated with the pushbutton 116L at FLOOR O, and each of the controllers also controls the resetting of the car call and hall call controls when a car or hall call has been serviced. Car 12b is shown located at the landing 15b with its doors 13b shown in a closed position.

The simplification and abbreviation of the elevator system 10 thus far described in FIG. 1 presumes that a traveling cable 84a for car "A" and a traveling cable 84b for car "B" provide, respectively, bi-directional communication paths to the respective control electronics for each car. Microprocessing control electronics may be located in the penthouse 19 proximate to the car controllers 24a and 24b or as shown remote therefrom as in FIG. 1 with correspondingly numbered micro-computers #0 and #1 which are located in a machine room 26. In this instance, the #0 micro-computer 80a is connected on a car control communication link 28a to the car controller 24a, and likewise #1 micro-computer 80b is connected on a car control communication link 28b to the car controller 24b in order to provide a complete bi-directional communication path for the cars over the respective traveling cables and car control links.

The traveling cable 84a is a composite cable in the sense that a control cable is present therein in order to control certain relay logic functions for the car door operator of car 12a, and there is also present a CAR DATALINK 86a which is shown emerging from the bottom of car "A" or from a car position terminal 83a shown functionally located on the side of the car 12a. A similar arrangement for car "B" is intended for the traveling cable 84b which is shown for purposes of this description in the same respective alignment with respect to car "B". This provides the proper complement of relay control functions as well as the bi-directional communication paths for the #1 micro-computer 80b connected thereto. The conductors in the CAR DATALINK 86a are constituted in an arrangement of three pairs of two conductor wires that are twisted and shielded from extraneous noise which might be otherwise inductively coupled to the traveling cable. This cabling is used in order to preserve data quality of the transmission signals and to ensure the credibility of the information received at the circuits in the car as it relates to the control of the car operation through various control circuit boards (not shown herein). Floor circuit boards of the type which may be used in the present invention are disclosed in FIG. 1 of the aforementioned U.S. allowed application Ser. No. 06/829,744, filed Feb. 14, 1986, which is incorporated by reference in the teachings of the present invention.

The description has thus far proceeded on the basis for FIG. 1 that cars "A" and "B" are in a two-car-pair for a traction elevator system with the respective micro-computers 80a and 80b located remote from the car controllers 24a and 24b which are shown in the location of the penthouse 19. Also shown in FIG. 1 is the provision for bi-directional communication paths from the micro-computers 80a and 80b to the various corridor fixtures via a HOISTWAY DATALINK 82a and 82b which are collectively designated 82L (Left side designation). These may be constituted by three pair of two conductor wires 106a/b which are twisted and shielded from extraneous noise and ensure the highest quality of data transmission. Located in the hatchway 16b at some appropriate position with respect to the floor 0 and 1ST is shown FC01, a hall fixture circuit board 108a/b which interfaces between a pair of upward-pointing floor lanterns 112L for Floor 0 which are associated with an UP pushbutton 116L located therebetween at the same floor location. The hall fixture circuit board 108a/b is further connected to communicate with a pair of upward- and downward-pointing floor lanterns 114L for the 1ST floor and also the UP and DOWN pushbutton set 118L positioned therebetween. The corridor location of the leftmost floor lanterns 112L and 114L may be associated with the hoistway location served by car "A", and the floor lanterns to the immediate right side of pushbuttons 116L and 118L are then associated with the corridor location proximate to the hoistway 16b served by car "B". The pushbuttons 116L and 118L are displaced on a vertical center line from floor to floor which may be used to serve this two-car-pair of adjoining or spaced hoistways which are not so far physically removed from one another. It is intended that when the invention is used for a two-car-pair the hall fixture circuit board 108a/b bi-directionally communicates with all of the associated hallway fixtures in the two-car-pair. With the special arrangement of the present invention, there is a measure of redundancy in the fact that micro-computer 80a can provide the complete control over the HOISTWAY DATALINK 82a as can micro-computer 80b on the hoistway riser 82L.

Another hall fixture circuit board 110a/b is also located between the same pair of floors as hall fixture circuit board 108a/b, but it is intended for the purpose of serving one or both of these floors, 0 and 1ST, at a rear entrance door or doors of elevator cars 12a and 12b. Elevator systems with this arrangement are in frequent demand for passenger and rear door freight movement between the floors of many building structures. The rear hall fixture circuit 110a/b provides for the same complement of hall fixture signalling and lighted directional indications of pushbuttons and of upward and downward directional arrows as does the hall fixture circuit board 108a/b.

Near the top of the hoistway 16b is another identical hall fixture circuit board 120a/b located at an appropriate position to serve the 6TH and 7TH floors by interfacing the shielded pair conductors 106a/b of the hoistway riser 82L, with an upward- and downward-pointing directional pair of floor lanterns 130L and UP and DOWN pushbuttons 132L for the 6TH floor in communication with the hall fixture circuit board 120a/b. This is on the same communication circuit as the downward-pointing pair of hall lanterns 126L associated with the DOWN pushbutton 128L of the 7TH floor. The manner of serving the hoistway location of car "A" is with the leftmost directional pair of floor lanterns 130L and 126L and likewise the floor lanterns to the immediate right of pushbuttons 132L and 128L is for car "B" similar to that as for the lower floors previously described. And the same is true for the horizontal position indicator 122L for car "A" on the left and horizontal position indicator 124L on the right for car "B" in order to provide a reading of the location of the respective elevator cars 12a and 12b during the movement of same so that potential passengers who are waiting at the terminal landings of the building structure are given a fair amount of notice of when to prepare to enter the car when it reaches their respective floor.

Another information display part of the elevator system 10 which is present in a two-car-pair resides in the status panel 134 which is typically provided in a central location of the building structure which may be in the building manager's office or at the concierge's desk in the lobby of the building. The status panel 134 communicates with the micro-computer 80a or 80b via the conductors 106a/b assembled in the hoistway riser DATALINK 82L. This provides a display of position indicators such as LEDs for each elevator car in the two-car-pair 12a and 12b, along with some status indicators for indicating car position on the floor being served by each elevator car and the direction in which it is proceeding.

The status panel 134 is shown at floor 0, and it is also central to its position for a bank of elevator cars which are formed by a dual two-car-pair with cars "C" and "D" constituting the second two-car-pair. With certain exceptions it should be noted that the two-car-pair to the right of center in FIG. 1 is essentially a mirror image of the various corridor fixtures such as floor lanterns 112R and UP pushbutton 116R (R designating right side) which are controlled by a hall fixture circuit board 108c/d which interfaces therebetween. This is at about the same vertical height in the building structure in hoistway 16c rather than hoistway 16b which provides the location for the hall fixture circuit board 108a/b. It is essential to the invention when used in a dual two-car-pair that a second HOISTWAY DATALINK 82c and 82d, consolidated into the hoistway riser 82R, be used to provide the bi-directional communication over a set of three conductor twisted shielded pair 106c/d for the second two-car-pair of cars "C" and "D". This serves the various hall fixtures in the mirror image portion and supplies the status panel 134 with information concerning this two-car-pair. An alternative would be to use a status panel of similar construction but separately located or used, despite the provision of related service with a four car bank of cars being involved.

The present invention described thus far with respect to the showing in FIG. 1 has not made specific reference to the alternative showing of a hydraulic elevator system 10 with the #0 micro-computer 80a teamed with a #0 pump unit of a hydraulic power supply 32a. The communications described is portable to this type of system with minor changes accordingly. With the hydraulic elevator system 10, equipment in the penthouse 19 such as the drive machine 22a and car controller 24a, along with the wire ropes 18a, sheave 20a and CTWT, are likewise absent or removed. Likewise, the car communication link 28a between the micro-computer 80a and the car controller 24a is no longer necessary since the elevator car 12a is driven by the hydraulic system from the pump unit 32a through supply pipe sections 60a to drive a hydraulic jack 40a (shown in phantom since considered in the alternative). As shown in phantom for the car "A" the hydraulic system can use multistages 42a with 43a being the intermediate section thereof. A single action piston or plunger 42a fixed to the underside of the car 12a is also sufficient in order to move the car according to the movement of the plunger 42a. The base of the jack 40a is to be firmly anchored to the base of the building structure or ground. Similarly, hydraulic power supplies 32c and 32d are respectively designated #2 and #3 pump units all located in the machine room 26 and each is controlled by correspondingly designated micro-computers 80c and 80d. The hydraulic jacks 40c and 40d complete the hydraulic drive systems through the supply pipe sections which are appropriately routed and designated 60c and 60d, respectively.

Although the description does not show that the #1 micro-computer 80b in any but a traction elevator configuration, it is not to be regarded as unassailable for the mode of movement by hydraulic means in order to provide a uniform bank of hydraulically driven elevator cars consisting of a dual two-car-pair bank in the preferred embodiment. The versatility of the present invention, however, makes it readily applicable to any two-car or plural two-car-pair which may include matched or unmatched car pairs be they traction elevator or hydraulic elevator car-pairs or otherwise. It is fundamental to the invention, however, that the two-car-pair of cars "A" and "B" are provided with a third bi-directional communication link 133a/b connected between their respective micro-computers 80a and 80b so that they may communicate with each other. One of these two micro-computers can then tell the other that it is the floor control (FC) master of the hallway serial link, meaning bi-directional communication via the hoistway riser 82L, and that the other micro-computer such as 80b should remain on standby for the job of FC master of the hallway serial link in case there should be a failure of communication of the micro-computer 80a. This is done in order to implement the floor control master strategy for answering hall calls should 80a fail or if there is a communication failure such that micro-computer 80a cannot communicate with micro-computer 80b over the third communication link 33a/b.

The invention also provides that if there are two FC masters currently operating redundantly, as micro-computer 80a and 80b, then the micro-computer having the lower car station address (#0 smaller than #1) micro-computer 80a will continue to be the FC master with the micro-computer 80b being cleared of this responsibility. A similar third bi-directional communication link is present between the #2 and #3 micro-computers 80c and 80d with a similar purpose for the operation of the two-car-pair including cars "C" and "D". Still another third bi-directional communication link 33b/c connects the #1 and #2 micro-computers 80b and 80c in order to provide that each of the micro-computers can talk over this third bi-directional communication link, especially those that are the floor control masters for the respective hallway serial links 82L and 82R in a dual two-car-pair elevator bank. One of the FC master controllers or micro-computers 80a and 80b will further assume the additional role as dispatcher or bank control (BC) master which serves as a dispatcher for all of the car associated micro-computer controllers in the elevator bank. This BC master functions to supervise all of the cars and process all of the hall calls in order to select for each hall call the best car to assign to it based on the relative car travel position and in order to minimize waiting times for service and provide passenger convenience that is enhanced.

FIG. 2 shows the micro-computer circuit 80a located within block 246 on the left side of the page and micro-computer 80b within block 246' which is substantially the mirror image of block 246 in order to represent that there is a substantially identical special purpose microprocessor based controller designed to control the overall operation of each car "A" and "B". A substantially similar showing of the micro-computer 80a within block 246 has been shown in FIG. 7 of the related U.S. patent application No. 07/064,913 filed June 19, 1987 and entitled "Elevator System Leveling Safeguard Control and Method" (W. E. 53,784) which has been incorporated by reference into the present application. The last mentioned U.S. patent application describes a car controller which implements program control functions which incorporate elevator safety codes to insure safe operations.

Another slightly modified showing of the micro-computer circuit 80a within block 246 was presented in a hydraulic elevator system incorporated by reference into the present application by the showing of FIG. 3 in U.S. patent application Ser. No. 07/064,915 also filed on June 19, 1987 and entitled "Elevator System Monitoring Cold Oil" (W. E. 53,783). Both of these applications are assigned to the same assignee as the present application. This latter referenced U.S. application utilizes the microprocessor within block 246 to implement a program to inactivate an in-service elevator car during which time a hydraulic drive pump is activated to pass oil through a route which bypasses the hydraulic jack in order to bring the hydraulic oil up to an operating temperature to provide smooth starts and prevent damage to the motor and associated equipment.

The present FIG. 2 is substantially similar to the figures mentioned for the incorporated U.S. applications, and the reference to features and the numerals used within blocks 246 and 246' are identical for the most part, with the exception of modified portions which concern the present invention, as will become apparent from the following description. The micro-computer 80a controls the overall operation of a car 12a such as in the alternative hydraulic elevator system 10 shown in FIG. 1 via the bi-directional communication path in the traveling cable 84a and similarly for traveling cable 84b and the micro-computer 80b. A similar bi-directional communication path for the corridor fixture signalling functions is seen for the HOISTWAY DATALINK 82a joined in common with 82b which may communicate with either of the identically numbered CPUs 286. These are the respective central processing units either or both of which can receive information through a respectively numbered serial input/output controller 296 through an ADDRESS bus 300, DATA bus 302, and CONTROL 304.

The CPUs 286 are both highly-integrated 8-bit units that are designed to operate at 6-MHz operating speed and are of the type available from INTEL with a Model No. 80188. Also in the circuit 246 is the random access memory RAM 294 which can provide 8K bytes of data storage, a portion of which can retain approximately 2K bytes of data in extended long-term storage in the absence of any operating supply voltage except for a long-term shelf life storage battery. An EPROM memory 292a is present in circuit block 246 and a similar EPROM 292b is present in circuit block 246' with each of these memory devices being split into two sections which can both either be 32K or 16K bytes of the same type of programmable "read only" memory which is available for storage of the main processing functions. The EPROM programs are sequentially stepped through by the respective CPUs 286 as a chain of continuous subroutines for operating the hydraulic elevator system under consideration and its various car signalling, control, and strategy functions as well as for corridor signalling processing functions.

A visual diagnostic module 295 is provided to indicate the status of the micro-computer circuit 246, and along with the respective EPROMs 292a and 292b and RAM 294, communicate with the respective CPUs 286 over the buses 300 and 302 with control from 304 which is likewise used for an input and output of information to devices which communicate with the external portions of the system. Communications networking and higher voltage interfacing is available on relay buffer I/O 298 for the respective input and output channels of cars "A" and "B". A more detailed explanation for these channels is presented in the incorporated U.S. application No. 07/064,913, filed on June 19, 1987, as previously referenced above.

A serial input/output I/O communication controller 296 in each micro-computer circuit block 246 also communicates on the address bus 300, data bus 302 and control line 304 with its serial interfacing functions being present on the outputs for the respective CAR DATALINKS 86a and 86b being present in the respective travelling cables 84a and 84b. Two interdependent floor controller links utilize the respective serial controllers 296 for the HOISTWAY DATALINK with the merger of 82a and 82b for the HOISTWAY riser 82L. This serves the bi-directional communication path with the appropriately selected floor control (FC) master of the hallway serial link which provides all of the corridor fixture signalling functions such as pushbutton hall calls, visual lanterns, and audible car position signalling. The selection process for the FC master controller will be seen more clearly with respect to the description of the program module FCMHSL with its associated sequencing routine, as shown in FIG. 4, which is programmed into the respective EPROMs 292a and 292b. This is shown herein for a two-car-pair elevator system, whether it be driven by a traction drive or implemented with hydraulic power drives. A further description of this pairing of elevator controllers of the same micro-computer construction is not further shown for the car "C" and "D" since it would merely be redundant, with the understanding that the same program modules including FCMHSL are to be resident in the respective EPROMs therein. These programs depend for effectiveness on their taking communication control for the purpose of FC master switching or dominance by one of the micro-computer circuits of each two-car-pair. This is based on the FC master controller with the lower car station address taking priority, unless there is some communication failure on the corridor serial link in which event the associated car may put on block operation as will be further seen with respect to FIG. 4.

The communication between micro-computers 80a and 80b also includes a third bi-directional communication link 133a/b which connects between a remaining capacity for handling multiple communication links by the respective serial I/O controllers 296. Each microprocessor circuit 246 is able to handle multiple communication links of, for example, up to five (5), with certain links being capable of enabling and disabling the drivers so that loading of a single line is avoided. As described with respect to FIG. 1, a similar bi-directional communication link 133c/d was said to exist in the manner of communicating between the micro-computers 80c and 80d. This was also described for the communication linkage 133b/c which exists in the dual two-car-pair so that communication between selected remote FC master controllers, such as the O and 2 micro-computers 80a and 80c, can take place during conditions of the normal selection process with unimpaired communications. These are the remote controllers with the respective lower car station addresses relative to the other car station addresses of the two-car-pair sets of remote controllers as previously defined. The provision of the third bi-directional communication links 133a/b, 133b/c, and 133c/d also provides the proper communication serial path so that the FC master controller can transmit information to its associated remote controller as well as to the FC master of any other two-car-pair of remote controllers, such as over the third bi-directional communication link 133b/c.

This communications link also make possible the sharing of one of the selected remote controllers to act as a dispatcher or bank control (BC) master for the switching strategy. This provides that all of the remote controllers can token pass so that each remote controller is given an opportunity to transmit while all the other controllers receive, in a sequential or orderly manner, until the token is given to the next remote controller. This is done in order to communicate such information as the car travel position, the direction of travel up and down, when the car is stopped, and whether the doors of the car are open or in the closed position. This is an RS-485 type of communication protocol which allows the remote controllers to communicate with the corridor fixtures through the respective clocking of serial input data .+-.SID in order to provide the serial output data .+-.SOD so that the remote controllers can recognize that there is a hall call entered at any of the pushbutton locations such as 118R at FLOOR 1. This will be entered into a Table of Calls, and this information will be communicated to the FC master or #2 micro-computer 80c which will communicate this information on the third bi-directional communication links 133b/c and 133a/b.

The other normally chosen FC master #0 micro-computer 80a will also recognize that there is a hall call, and car "A" or "B" controllers will then output a serial message on the HOISTWAY DATALINK 82L so that there will be synchronization between the corridor fixtures 118L and 118R such as lightning and extinguishing the pushbuttons. The same is true with respect to the floor lanterns 114L and 114R during the servicing of the floor 1 since all calls signalled by the dispatcher or BC master direction is a function inherently directable to any one of the micro-computer remote floor controllers. Since each of these remote controllers operate under the same program control, with the exception of priority. The assumption in the floor control strategy is based on the setting of timers for each remote controller in proportion to the car station address so that priority proceeds from the lowest car number to the highest if there is a failure in elevator service.

Referring now to the flow chart of FIG. 3 which is an abbreviated program module of the type which may be programmed into the EPROM within each micro-computer circuit of FIG. 2, the CPU 286 begins the serial sequencing at the label 310 and proceeds to make a pass through various decision steps which are contained within a hexagon-like containers such as at 312 and 316 and rectangular-type containers for the action blocks such as 314 and 318 in a traverse of the flow diagram in order to reach a label 321 designated as EXIT. The CPU 286 will proceed to serially step through any relevant program routines which are designated to be sequenced during the time that this module is being run, and the discussion of other modules of this type would present a chain of continuous subroutines for operating the elevator system and its various car signalling, control, and corridor signal processing functions. This extension would unreasonably inflate the description of the present invention beyond the necessity to do so.

The first decision step 312 shown in FIG. 3 checks to see if the power to the elevator system has just been turned on, and since the power has just been turned on at 310, the answer is yes "Y" so the action block 314 sets the DISP timer in RAM 294. This is done in order to provide a program type counter or software counter which may be set at a different value for each remote controller corresponding to the length of time that the timer is to be active before timing out. For example, the minimum timer FO may be set to 00000111 binary which corresponds to 7 hexadecimal (HEX), also corresponding to DECIMAL 7. A counter may be set to count at 0.5 second intervals, so for counting down from 7, the time it would take would be 3.5 seconds. The #1 remote controller timer F1 may be set for 00001001 binary, corresponding to 9 hexadecimal, also corresponding to DECIMAL 9 and therefore 4.5 seconds for counting down from 9. Likewise in order of increasing magnitude timer F2 represents a count of 5.5 seconds and timer F3 may be set for 6.5 seconds in order to provide a staggered relationship of the type described or otherwise. The DISP timer will each count down from a different value in order to allow the time out of counting from the lowest numbered car to the highest unless there is the disablement of timers which should occur immediately after a dispatchers signal is detected on the #3 link. This corresponds to the multi-car communication link which corresponds to the third bi-directional communication link 133a/b in FIG. 2.

After the respective timers have been set, the next decision step 316 checks to see if there is a dispatcher signal on the #3 link. If the answer is affirmative the action block 318 disables the dispatcher timer of this car which has been presumed to be enabled and in the process of counting out since the power was just turned on. This will indicate that a DISP timer which has become disabled is not the minimum timer FO which would have counted out after seconds according to the example. It would be still counting after seconds corresponding to the DISP timer's F1, F2, or F3 which correspond to 4.5, 5.5 and 6.5 seconds respectively. Considering that the minimum timer FO would not be disabled, because of the decision step 316 finding that a negative would be the answer to checking if there is a dispatcher signal on #3 link, the DISP timer for the #0 micro-computer 80a would proceed to count out through the decision step 322 checking if the respective timer is timed out. The answer is no "N" so proceed to loop back through decision step 316 until the timer FO is actually found to be timed out by decision step 322 after seconds.

The affirmative answer to decision step 322 then proceeds through action block 324 to provide a signal on the #3 link as car dispatcher, and the exit from block 324 is through label 325. This would provide a signal to all of the remote controllers to stop counting out the respective DISP timers at decision step 316 which is being sequenced by each of the remaining micro-computers 80b, 80c and 80d which receive the signal on the multi-car communication #3 link and thus proceed with a yes "Y" to the right action block 318 to disable the respective car dispatcher timer before the exit at label 321.

In this manner the remote controller with the #0 micro-computer 80a has priority to become the dispatcher or bank control (BC) master of the bank of cars and assigns the car to answer the corridor calls after it calculates which of the cars can get there in the most expedient manner. The dispatcher knows where every one of the elevator cars is located because it communicates with every other microprocessor for the bank of cars in the system, and the invention proceeds in a manner to automatically transfer dispatcher control in a plural two-car-pair elevator system. This occurs upon a continuous communications failure between the remote controller selected to be the dispatcher, originally, and the other cars in the bank. Likewise there is a switching of the dispatcher function upon shutdown of the remote controller that was selected to be the dispatcher. This occurs in an orderly sequence which will be described further.

The description for implementing the floor control (FC) master strategy for servicing hall calls proceeds, according to a similar priority. This priority is based on similar but separate timers utilizing RAM 294 in order to provide a second set of program type counters or software counters which may be set at different values or four different time intervals FC0, FC1, FC2, and FC3, simply by the program insertion of a number of counts corresponding to the length of time that the timer is to be active. The same relative magnitude for the minimum timer FC0 of 3 seconds is chosen as it may be represented in various numbering systems with the counter rate at 0.5 second intervals thereby counting down from DECIMAL 6. The proportional scale in seconds for FC1, FC2, FC3 is likewise chosen to differ by one second from each other and one count respectively from timers used for the DISP timers thereby 4, 5 and 6 seconds, respectively.

The flow chart of FIG. 4 is for a program module FCMHSL with its associated sequencing routine which is programmed into the respective EPROMs 292a and 292b of a two-car-pair of micro-computer circuits 80a and 80b and run in a repeating sequence in order to implement the floor control (FC) master strategy for servicing hall calls. It will also determine and select the FC master strategy for each two-car-pair if used in each pair of remote controllers as programmed into their respective EPROMs. Each of the CPUs 286 begins the serial sequencing of the program module FCMHSL at label 410 which is an acronym designation for "Floor Control Master of the Hallway Serial Link". It is assumed that the timers have all been set to their initial staggered count as mentioned above for the FC timers with the minimum time out of 3 seconds for the remote controller of car "A". The decision step 412 checks if this car is currently FC master of HSL and the answer is no "N" since it is assumed that the power was just turned on. The programs will sequence once in order to determine that the appropriate implementation of car "A" will emerge as the FC master over car "B" since its timer will be the earlier to time out after 3 seconds rather than at 4 seconds. The decision step 422 checks to see if this car can communicate with the FC master which has not yet been selected, so that answer is no "N". The next decision step 424 checks if the hallway link has been checked, and the decision is negative since the FC master has not yet been selected, as it will after the expiration of the respective timer has occurred after decision step 430 has been traversed in the affirmative. The next decision step 426 checks if the timer is enabled which does not occur until the next action block 428 to enable the timer of this car. The next decision step 430 checks if the timer has expired which is answered no in the path to the right which loops back to the decision step 422 which checks again if this car can communicate with the FC master.

In the present situation for the car "A" remote controller, it will become the FC master after 3 seconds since it will time out earlier than the 4 seconds of the remote controller time out for car "B". The same conclusion is reached for car "C" remote controller which will time out after 5 seconds which is earlier than the remote controller for car "D" which times out after 6 seconds. It should be recognized that 3 seconds and 5 seconds should also be appropriate for the timers in both two-car-pair sets which gives the FC priority to cars "A" and "C", which is the same result reached with the more staggered distribution of timer settings used in the current example.

After decisioin step 430 has checked to see if timer FC0 has expired in the affirmative, decision step 432 checks if there is signal activity on the hallway link which would correspond to HOISTWAY DATALINK 82L. If signal activity is determined in the affirmative, this implies that the communications link to the #0 micro-computer 80a is not operating properly. This remote controller with the expired timer goes to the action block 438 which puts this car on block operation, which means there is a failure in the hallway serial link which adversely affects the integrity of this remote controller which normally has the priority of FC master. In this event it would not be reliable as such, so it does not become effective to control the hallway serial link 82L if decision step 432 has answered affirmatively.

In this eventuality it would still be possible for car "B" to become the FC master after the 4 second timeout in the counting out of its FC timer, and if it were to determine at decision step 432 that there was no signal activity on the hallway link this permits the action block 436 to activate this car "B" as FC master of HSL with an EXIT at label 421. The possibility exists that decision step 432 would individually find signal activity on the hallway link for both cars "A" and "B" which would indicate that the communications link to both of the cars mentioned is not operating appropriately. So it is possible for both cars to be put on block operation 438 respectively in which event neither car would be the FC master, and this two-car-pair would continue to operate after first bringing each car down to the main floor. Without the benefit of an FC master strategy for responding to hall calls on the DATALINK 82L, each controller could continue to respond to car calls registered in the individual cars and could continue to respond to call assignments directed by a dispatcher or BC master which would likely be car "C" along the lines of its timer counting out with priority. Car "C" could become the FC master for its two-car-pair as well as dispatcher for the bank of elevator cars as long as the multi-car communication link 133b/c is still able to communicate with the micro-computers 80a and 80b.

The sequence of steps shown in FIG. 4 which has been traversed to the right of decision step 412 was in response to a negative answer since it was assumed that the power had just been turned on and there was no current FC master. The later assumption was that car "A" which would normally have priority in this situation was incapable of becoming the FC master and that instead car "B" was able to assume the role of implementing the floor control strategy as FC master at least until the serial communication link with car "A" is repaired since its status would normally alert the need for repair service. Car "A" would normally be expected to be performing the roll of FC master, and the same would apply to car "C".

Upon the next sequencing of the program module FCMHSL by the remote controller of car "B", the decision step 412 would check if this car is currently the FC master of HSL in the affirmative to the left, and step 414 would check if more than one FC master is in the link of the two-car-pair with these cars. The answer would be no and then the exit is at label 421. If we next assume that the serial link communication with the car "A" is repaired and the car "A" again sequences through the program module FCMHSL, the negative response at decision step 412 followed by the positive response to decision step 422 would block 424 disable the checking of the hallway #3 link and disable the timer for car "A".

Assume at some point in time that car "A" is restored and yet finds that it cannot communicate with the FC master car "B" in checking step 422, and this time it passes the test of decision step 430 and the negative in step 432. Car "A" can then be restored to its priority as FC master in action block 436. The next sequencing through decision step 412 for both of cars "A" and "B" would be to the left, and the decision step 414 checking if more than one FC master is in the link would result in an affirmative passing to decision step 416 which would check if the car station address respectively for each FC master is greater than the car station address respectively of the other FC master. The result in this situation of two FC masters is cleared by the priority scheme of car station address for that of the lower numbered car. This would be the situation described for car "A" and likewise car "C" which correspond to #0 and #2 or lower number for each respective two-car-pair.

The remaining description is for FIG. 5 which is an expanded flowchart of a program module DISPATCHER SWITCHING with its associated sequencing routine which is also programmed into the respective EPROMs of each of the micro-computer circuits #0, 1, 2 and 3. It is run in a repeating sequence in each of them in order to implement the dispatcher or bank control (BC) master strategy which is concurrent with the FC master strategy of FIG. 4 for a plural two-car-pair elevator bank of cars. It has been previously discussed with respect to FIG. 3 that the DISP timers are set up in a staggered time relationship F0, F1, F2, and F3 in the abbreviated program. It would not serve as a benefit to repeat the setting of the DISP timers except to state that it is important that this be taken care of when the system is powered up in the program module for DISPATCHER SWITCHING, similar to FIG. 3 as previously discussed.

The program module is entered at label 510, and the decision step 512 checks if this car is the current dispatcher. Since it is presumed initially that there is no dispatcher in the elevator bank a negative "N" will apply, and the decision step 522 will check if any dispatcher in the system is communicating. This may likewise be presumed to be answered in the negative. Decision step 526 for each of the cars checks if the dispatcher and timer has been loaded with a proportional timer value and enabled, and if properly loaded action block 528 will enable the timer to begin timing followed by the decision step 530 checking if the DISP timer is expired. This 530 decision step response is in the negative, and it will loop back to the decision step 522 until decision step 530 is answered affirmatively when the timer is expired. The action block 532 will thereafter set the dispatcher for directing other cars and action step 534 will provide a signal on the #3 link as the car dispatcher before exiting at 521.

The operation of the program module for dispatcher switching under consideration serves to engage the #0 micro-computer as the dispatcher or BC master for the two-car-pair bank of cars. Once it does so and provides a signal on the #3 link, each of the other remote controllers which are sequencing through this respective program module will determine at decision step 522 that the car "A" is the dispatcher and it will then at action block 524 send a signal on the #3 link to disable the DISP timer and disable checking before respectively exiting at label 525.

If there is a problem with the dispatcher selected so that the other remote controllers are not able to determine at decision step 522 that there is a dispatcher in the system communicating, then the respective timers will continue to time out and provide more than one or a collection of dispatchers for the elevator bank at action block 532. Multiple signals would be sent on the #3 link as each car dispatcher does action block 534. In this eventuality, however, decision step 512 for each of the dispatcher cars such as for example "A" and "C", would each provide a positive answer to the decision step 512 in the respective program module for DISPATCHER SWITCHING. The next decision step 514 would check if any other car dispatcher is in the system and if affirmative would proceed to the decision step 516 which checks if this respective car station address of the current dispatcher or BC master is greater than the car station address of the other dispatcher or BC master. In this event the car having the lower or lowest car station address would remain as the dispatcher while the other dispatcher would be cleared.

The priority of the lowest micro-computer is such that car "A" would prevail as dispatcher for the plural or dual two-car-pair bank of elevator cars as presently described in the system. This same strategy, however, can be extended to a system where there is a greater number of two-car-pair of controllers communicating redundantly according to the concepts presented for the present system mode of signal operation which is a fairly representative extension of the concept from this description.