CA1055135A

CA1055135A - Train monitoring and reporting system

Info

Publication number: CA1055135A
Application number: CA266,644A
Authority: CA
Inventors: Truman L. Allison; Francis L. Slane
Original assignee: Industrial Solid State Controls Inc
Current assignee: Industrial Solid State Controls Inc
Priority date: 1976-01-16
Filing date: 1976-11-26
Publication date: 1979-05-22
Also published as: US4041470A

Abstract

ABSTRACT OF THE DISCLOSURE
A train monitoring and reporting system in which each car of a multi-car train is provided with senesors to monitor brake, door, motor and other functions. A controller in each car sequentially and repetively reviews the condition of each sensed function and evaluates the conditions to determine whether a fault condition exists. The evaluation result is stored and the review is con-tinued and repeated. The lead car of the train repetitively and sequentially interrogates the storage units in each car for each type of fault condition, stores the responses to the interroga-tion and displays to the motorman any faults reported. The cars communicate through a multiplex data link system which connects the cars in series in a multiplex current loop. The number of times each fault occurs is counted, the count being then available for readout by maintenance personnel.

Description

1055~3S

SPEC~FIC~TION

This invention relates to a communication system and, more particularly, to a system for surveillance and monitoring of selected functions in a multi-car vehicle such as a railroad train.

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BACKGROUN~ OF THE INV~NTION

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In recent years, various systems have been devised for monitor~ng functions and controlling functions on the various cars assembled into a railroad train of the intercity as well as intracity variety. These systems have been desi~ned to perform various special functions, generally including, for example, interrelated control of multiple locomotives, moni-toring of various critical operating parameters on the various cars of a train, and communication between various cars to permit some degree of monitoring, in the lead or drive vehicle of the train, the critical functions which can affect train operation or which involve safe operation of the train.
~ umerous patents have issued to systems of these qeneral types, including systems in which multiplex communication between cars is employed, and examples of these include the following patents:
3,336,577 3,601,806 ` 3,4g2,089 3,622,994 3,516,063 3,828,313 3,575,604 3,882,465 While this is by no means an exhaustive list of the art in this field, these patents represent and constitute examples of the development which has occurred.

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; . . :. , . ; . , BRIEF S[~IMARY OF TI~E INVE:I~TION
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It is an object of the present invention to provide a function monitoring system usable on the cars of a multiple-car vehicle, which system provides a significant improvement in flexibility of application and standardization of e~uipment for trains of varying types.
A further ob`ject is to provide a train monitoring and control system which is capable of providing continuous moni-torin9 of functions in each càr and substantially continuous monitoring and display functions of interest in all cars at a selected location.
Another object is to provide a system which is capable of producing and maintaining a record of failures in selected train functions to improve maintenance and repair operations.
Briefly described, the invention comprises a monitoring and reporting system for use on a vehicle having a plurality of interconnected cars including a lead car and at least one other car, comprising sensor means in each of the cars for monitoring a plurality of physlcàl conditions in the cars and for altering circuit conditions to represent the state of the physical conditions, means in each of the cars connected to the sensor means in the same car for repetitively and sequen-tially detecting each of the circuit conditions and for producing a digital signal having a value representative of the state of each physical condition, means for evaluating the digital signals in accordance with predetermined criteria -to produce and repetitively update a set of second digltal 8ignals having values representative of the existence or , --3-- .

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~ . ,: , , : : , lOSSS~35 nonexistence of fault conditions, memory means for storing the set of second digital signals, circuit means interconnect-ing the cars for transmission of digital signals, logic means in the lead car for repetitively and se~uentially sending interrotation signals individually to the memory means in each o the cars, including the lead car, to determine the existence of faults, means in each o~ the cars responsive to the interrogation signals for transmitting status signals respresentative of the second digital signals to the lead car ~o provide fault information to the lead car, and display means in the lead car for receiving and storing the status signals and for providing a visual display of fault conditions reported in those signals.
In order that the manner in which the foregoing and other objects are attained in accordance with the invention can be understood in detail, particularly advantageous embodi-ments thereof will be described with reference to the accompAny-ing drawings, which form a part of this specification, and wherein:
Fig. 1 is a schematic diagram of a multi-car train incorporating a system according to the present in~ention;
Fig. 2 is a block diagram of the apparatus on one car of a system according to Fig. l;
Fig. 3 is an illustration of a display panel usable -in the apparatus of Figs. 1 and 2;
Fig. 4, appearing on the same sheet as Fig. 1, is a schematic diagram of an input monitor circuit usable in t~e apparatus of Fig. 2;
Fig. S is a typical ladder diagram used with the present invention in fault detection;

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. 'J~ 1055135 ~ ig. 6 is a transducer circuit usable in the system of Figs. 1 and 2; and Fig. 7, appearing on the same sheet as Fig. 2, is a block diagram of a data link unit usable in the apparatus of Fig. 2.
Fig. 1 shows a multiple-car train, in very simplified form, with an indication of the nature of the e~uipment installed on each car in accordance with a system of the present invention.
In Fig. 1 there is shown a lead car 10 and additional cars 11 and 12 which will, for purposes o the present explanation, be regarded as car Nos. 2 and 3 of a three-car train. It will be recognized, of course, that a smaller or somewhat larger number of cars can be used in a system incorporating the present invention and that the general nature of the system will not deviate from the equipment existing in this example. Indeed, it is a particular advantage of the system disclosed herein that no equipment modification is required in order to add cars. Furthermore, cars 10, 11 and 12 can easily be cars of different types without any fundamental modification to the equipment.
In each car, there is a main processing unit indicated generally at 15 which includes a data link portion 16, a processor portion 17, and an input-output section 18, abbre-viated ~I/0". In addition, there is a digital readout and display console 19 and a group of condition sensors indicated schematically by box 20. It will be recognized in connect~on with these sensors that they do not andprobably never would constitute a single unit as depicted in ~ig. 1, but would constitute a plurality of physical condition sensing devices ., ; , ''.

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distributed about the car in the most logical physical relation-ship ~o the conditions which are being monitored. They are ~hown, for simplicity, as a single unit in ~ig. 1, this unit being connected by a conductor cable 21 to the I/O section 18 of car unit 15. The display console is similarly connected by a cable 22 to the I/O section. A two-wire ~ultiplex line (~SUX) 24 is connected to the data link and, through conventional coupling connectors at the couplings interconnecting the various cars, to other cars o the train. The basic multiplexing tech-ni~ue using a two-wire interconnection system to minimize the number of wires running through the couplings is generally conventional in concept and does not, in itself, constitute a fundamentally novel aspect of the invention.
It will be observed from Fig. 1 that the cars have sub-stantially identical equipment including a display console, processing equipment and condition sensors. Some deviations from this pattern should be mentioned. First, if the cars are of different types~ the number and type of condition sensors -~
will usually also be different. ~or example, in the brake-sensing equipment, brakes manufactured by one organization for the transit system of a particular metropolis for train cars of a particular type generally do not exhibit the same kinds of faults and therefore do not require the same kinds of condition sensors as the brakes manufactured by a different co~pany. Thus, different kinds of sensors would be employed.
~owever, the sensors in themselves are conventional in nature and do not per se form a part of the present inventions.
The other major difference which can occur depends upon the different kinds o cars employed by a specific transit , --6-- .

~055135 system. For example, some transit system employ cars of a type which permits any of them to be used as "lead cars" in an assembled train. Each such car has a motorman's compartment, sometimes at each end of the car, and when a train is assembled, one such motorman's compartment at one end of the train is activated and upon such activation that car becomes the lead car o the train. Other transit systems, howevel-, employ cars of this type às well as cars which do not have lead car capacity, i.e., they do not have a motorman's compartment at all. Those which can function as a lead car arè commonly referred to as A-type cars and those which cannot so function are commonly designated B-type cars. It is contemplated, in the present invention, that all A-type cars would be provided with equip-ment as illustrated in Fig. 1, whereas B-type cars would have the same equipment except that they would not have the digital readout and display console.
The apparatus to be provided in each car, with the above noted exceptions, is shown in block diagram form in Fig. 2.
As shown therein, and as to be described hereinafter, the processing equipment and I/O units contemplated for use in -this invention can be industrial programmable controller equipment manufactured and sold by Industrial Solid State Controls, Inc., 435 West Philadelphia Street, York, Pennsyl-vania, under the designation IPC-300, or similar equipment.
Programmable controllers manufactured by other companies can, however, be employed with suitable modification. The descrip-tion herein will be in terms of the IPC-300 as being a particularly advantageous system for this purpose.

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~OS5135 The data link, display and sens~r units 16, 19 and 20, respectively, are interconnected through I/O unit 18 to the processing equipment 17, as previously indic~ted. I/O unit 18 includes two solid state random access memories 26 and 27, memory 26 being re~erred to as the input status table and memory 27 being identified as the output status table. Each of these status tables typically is provided with a capacity of 256 bits of information, each bit location havinq a specific address identifiable and correlated with a wire connection at its interface with the display, data link and sensor units.
Considering first the input status table, each memory location in a designated portion of that table is dedicated to a specific kind of input function, whether a sensor or an input from the processor of another car. ~or example, the first 100 bit locations of table 26 can be dedicated to transducer input, specifically ones of those locations being further identified with and dedicated to specific kinds of sensors. Thus, the door sensors can be connected with locations 001-016 in table 26 and, in every car in which this equipment is installed, the door sensors would always be connected with those specific locations in the input status table. Similarly, the lighting system of a specific car, if it is to be monitored, might always be connected to inputs 024-030 in the input status table. ~f the lighting system is not to be monitored, those locations simply would not be used.
In similar fashion, the data link connections to other cars would be connected with locations 101-156, each of those locations being further identified and associated with a :

) ~pecific kind o~ faul~ to be reported by another car to the processin~ equipm~nt sl)own in Fig. 2 if that equipment is in the lead car.
In similar fashion, the output status table is associàted with certain connections in the data link unit and certain bit locations are associated with certain connections in the display unit. The actual` identification of these locations is, of course, o~ no relevance except to a specific installation.
The input and ou~put status tables are connected through multiple conductor cables 28 and 29 to address selection logic 30, logic unit 30 being connected to provide information to, and receive information from, a central processor logic unit 31 through multiconductor cables 32 and 33.
A main memory unit 35 provides instruction information through a decoder 36 to processor 31 and provides address selection instructions through a decoder 37 to logic unit 30.
The main memory, in this system, contains instruction infor-mation to evaluate the various bits of information received from the car sensors and transducers to solve logic equations and to determine whether or not a fault condition in a given car exists. In addition, the main me~ory unit can include a program portion 38 which contains instructions to permit the -processor to interro~ate other cars in the train if the car in which the equipment is installed is to function as a lead car. The lead car functions are activated only when that car ls designated as a lead car and only when a lead car key switch i8 operated. Clearly, only one unit in any train assembly can ;;. .
function as the lead car. While each unit in ea~h car can be .
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~0 ... .

~(~SS135 provided with a memory having the lead car function instructions, they simply are not employed unless the lead car key switch is operat~d.
A typical display panel usable as display panel 19 is shown in Fig. 3, the panel havin~ a digital indicator and a plurality of lights which can be illuminated to indicate to the operator that a speciic kind of ault exists and on which car. The di~i~al indicator 40 is illuminated to shown the car number ànd a self-test light 41 is illuminated, or can be made to be illuminated continuously, so long as the apparatus is operating.
If no faults exist, the remaining lights remain not illuminated.
If a fault does exist, an appropriate one of lamps 42 is illum-inated to indicate that a fault of a specific type exists in the car identified. The display apparatus can be caused to remain with no indication portrayed unless a fault exists, at which time a car number appears in display 40 and one of lamps 42 is illuminated. After the fault has been recognized by the operator, he can actuate a "continue" switch 43, acknowledging recognition of the fault and causing the system to proceed with its continual monitoring function. Alternatively, depend-ing upon the nature of the fault, the operator can take steps to remove the defective car from the train or to alert main-tenance personnel to the fact that the fault exists and that it is of such a nature as to jeopardize the safety of the train should it continue. ~he precise steps to be taken are a func-tion of the operating policies of the transit system. A "Data Link Pault" lamp 44 can also be provided.
~ he fault-sensing devices to be incorporated in a train ~enerally consitute two diferent types, one being a relatively .

` ` 1055135 simple on-of condition, such as a door switch which is either open or closed. Thc other type of sensor involves a variable voltage condition, the amplitude of which indicates whether or not the specific piece of equipment is operating properly.
For example, a motor temperature sensor can produce a variable voltage proportional to temperature, which voltage becomes an indica~ion of an undesirable condition when it exceeds a pre-determined threshold. A typical input monitor circuit usable in a transducer of this second type is shown in Fig. 4, cir-cuits of this type being includable in the IjO box foe connection to the appropriate sensors. The input circuit receives a typical transducer-type input signal which is in the form of a voltage or current level and then translates that eYternal signal into a logic level which can be used by the digital processing equipment of Fig. 2. Because of the high noise level imposed by a train environment on electronic systems, due both to conducted noise on power lines and input signals` and also due to radiated noise from the inductive~ -components such as the motor pro~ulsion system, air conditioners, and the like, extreme care must be taken to eliminate the noise effect on the processing system. The input monitor circuit therefore advantageously includes a metal oxide varistor 45 `connècted in parallel between the input 46 and train ground to clamp high speed transients to tolerably low levels. The input signal, absent the transients, is then supplied to a threshold detector 47, the output of which is connected to an `
optical isolator 48 including a liqht-emitting diode 49, the emitted light from which is optically conducted to a photo-responsive diode or transistor 50. A h~gh frequency filter ~ . .

lOS5135 .
51 is further employed to remove specific undesirable high frequency componcnts. The output of transistor 50 is con-nected to ~ threshold detector 51, the output of which is cla~ped to a logic level acce~table and recognizable by the processing equipment. A low pass filter 52 connected to the input of circuit 51 provides integration to eliminate high spèed transients to prevent their being interpreted as true sisnals. Suitable grounding and shielding should also be provided.
The fault detection process in the system of the present invention occurs as follows. Pirst, each car, independent of each other car, detects various signal conditions through the I/O unit from the car sensors and transducers for its own car.
These various conditions do not, in themselves, necessarily indicate the existence of a fault condition in the car, but rather simply indicate the existence of certain physical-conditions. The processing equipment takes the information provided by the various monitors and solves logic equations, ~n accordance with predetermined criteria, to ~e~ermine whether or not a fault exists. When it is determined that a fault does exist, this fact is stored. More accurately, the result of the logic equation solution is stored, whether or not it indicates the existence of a fault. That result is store~
in the output status table in preselected locations. The equipment in the lead car, which can be regarded as a master controller, then serves as an interrogator by following the se~uences stored in portion 38 of the ~ain memory to interro-gate each car through the data link and multiplex lines to ~ask~ each processor in turn if it has a particular kind of fault.

1055~3S

In respon~e to these interrogation signals; each logic processor responds to the master controller via the multiplex lines with an answer as to whèther or not a fault exists. If a fault does exist, the master controller receives this signal and illuminates the appropriate light on panel 19 to indicate to the motorman that the fault does exist.
Thcre are various ways in which the master controller can be programmed to ask each car about its faults. In one form, the master controller can transmit an interrogation signal which will cause each car, in turn, to respond with siqnals reporting any faults located up to that time in that car. In another form, the master controller can individually ask for responses aboùt each fault in one car, going through an interrogation sequence about fault type 1, then type 2, etc., alternatively, the master controller can be progra~med ` to repetitively and sequentially interrogate one car at a .,~ .
time as to its fault condition. In this form, it starts with car No. 1 (the lead car itself), interrogating its own processor about the existence of a specific fault and then proceeds throu~h each car asking about that particular fault. It then ~oes on to another type of fault condition and queries each as to its state. The system would then be designed to contin-ually cycle through each type of fault condition on a looping basis. - - ;
The manner in which the above is accomplished can be more `~
clearly understood by specific example. Consider first the process of monitoring the door condition. Door condition is particularly important in an urban transit system in which the doors are opened and closed very frequently. Door command .

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wircs in a typical kind of train car are refcrred to as the ~open wlre" and the "unlock wire", signals on these driving the door-operating mechanisms. When'these two wires are not energized, the doors sho~ld be closed. Each door-operating mechanism actuates a normally open limit switch when the door is closed. These limit switches are connected in series cir-cuit relationship to a wire re~erred to as the "S wire" which ls connected to a solenoid. When all of the doors are closed, the solenoid is energized closing a contact which provides an illuminated motorman's indication, apart from the present system, in the lead car to indicate that all of the doors aré closed.
~ here are two specific'types of door problems which are important to detect and which can be detected easily by the present system. The first one of these is when the doors are commanded closed but one or more remain open or partially opened. The second problem is when the doors are actually ciosed but the motorman's indication does not come on because the solenoid contact failed to close. These two types of problems can be monitored by observing the voltages at five specific points, these bein`g the open wire voltage, the unlock wire voltage, the S wire voltage, a voltage VA on the wire leading to the motorman's "closed door" indication, and a voltage VB on the other side of the solenoid contact from ~oltage VA. The first type of fault des-cribed above can be detected by noting that when the "open wire" is not energized, the unlock wire is not energized and a door is still open, the S wire will not be energized. A Bo'olean equation represent-ing this fault can therefore be written as follows:
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PAULT 1 ~ (S)(OP~N)(UNLOC~) Eq. 1 ~05513S
However, since a delay occurs from the time the doors are commandcd closed until they actually close, an appropriate time delay should be incorporated. The equation then becomes:

FAULT 1 = ~S~(OP~N)tUNLOCK)tON delay ~1) Eq. 2 The equation for the second kind of fault can be ~ritten by noting that when the "S wire" is energized, the solenoid contact should be closed and thus voltages VA and VB should be egual. If these voltages are not equal, a fault exists.
Again, there is a delay involved from the time a relay is energized until its contact closes. Accounting for this delay, ;
the second type of fault can be represented as follows:

FAULT 2 = (S)tVA VB + VA VB)tON dela~ ~2) Eg. 3 The results of these two equations can then be subjected to a logical OR operation to produce a resulting indication of whether or not a fault exists, i.e., there is a door fault if either kind of fault exists, and this should be indicated.
The overall door fault relationship is therefore represented as follows:
DOOR FAl)LT = FAULT 1 ~ FAULT 2 (S)(OPEN)(U~LOCK)(ON delay ~
(S)(VA VB + VA VB) (ON delay t2) Eq. 4 .
It will be noted that, in standard logic equation terminology, the expression (A) ~B) is read "A AND B", and A+B means "A OR B~, the ~AND" and "OR" being logic gate operations.
The previously mentioned IPC-300 controller employs relay ladder logic, permitting these equations to be implemented in 8uch logic as shown in Fig. 5. It wili be seen in this figure that the above eguations are simply implemented in a form using normally opcn and normally closed contacts, each of equations 1055~35

2 and 3 being solved individually to arrive at an output sub-function represented by the circular symbols identified as fault 1 and fault 2. These output functions can be regarded as relay windings, contacts of which are closed if a fault exists. These contacts, identified as fault 1 and faul~ 2, are then connected in a ~urther ladder to determine whether or not a door fault exists.
In actuality, relays are no~ employed. Instead, a portion of the output status tablè 27 is 'devoted to storage of sub-function results such as the fault 1 and fault 2 results shown in Fig. 5. The program then looks at these to see whether a positive indication of a fault is present, i.e., a logic "1".
If so, this is interpreted as be'ing a closed contact and is fed back into the ladder diagram to result in a door fault indication which is then stored in the output status table as a true fault indication.
` The door fault output tben ropresents tbe aggregate fault for the faulted car and is reported to the No. 1 or lead car for display via the data link. It will be observed that either of the individual faults could be reported, but this approach tends to overly complicate the display panel.
As will be indicated hereinafter, the existence of these faults can be counted for subsequent analysis, this technique being particularly helpful when the faults are of a transitory nature.
As a second example of fault analysis, the problem of a 8tuck brake will be consi'dered. In a typical train car, there is provided a subsystem to control brake pressure, a block diagram of a system of this type being shown in Fig. 6. AS

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~ 055135 ~ho~n therein, a P wire is connected in series with the various brakes of a car to transrnit to the brakes a control signal to alter the brake pressure. This control signal, which is sup-plied by standard equipment in the car, is supplied to a current-to-voltaqe converting amplifier 45, the output Vl of which is applied to one input of a differential ampli-fier 4G. A dynamic brake effect also occurs in the motors of an electrically driven train car and the motor current is therèfore monitored and supplied to a current-to-voltage converting amplifier 47, the output of which is connected through a summing resistor 48 to the other input of differential amplifier 46. The brake pressure is monitored by a pressure transducer 49 which supplies a feedback signal through a summinq resistor 50 to be summed with the signal through resistor -48 and applied to the second input of amplifier 46 as a voltage VS. The output of amplifier 46 is applied to the brake pressure applying device 51 which actuates the brakes. Thus, the dynamic brake signal and the feedback signal are summed and the resultant is compared with the "p wire" signal. When the P wire signal calls for a change in brake application, the comparison of Vl and the sum voltage VS will be unbalanced, causing the output of differential amplifier 46 to change the brake pressure until the two voltages are again equal. By monitoring Vl and VS, one can determine` if a brake is stuck. The voltage Yl is threshold detected, as by the circuit shown in Fiq.
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~, to determine when it calls for full brake release. The voltage VS is also threshold detected to determine if any brake pressure greater than "snow" brake pressure is applied.
If Vl calls for full release while the VS still shows greater than snow brake pressure, then a stuck brake fault is present.

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Thus, with respons~ time taken into account, thc equation for a stuck brake fault is as follows:

STUCK BR~KE FA~LT = (FULL RELE~SE)(B~E PRESSURE)(ON del~y) = tVl release threshold)(VS Snow brake threshold)(ON delay) Eq. S

^ It is also possible to monitor the s~pply voltages to the circuit shown in Fig. 6 and to indicate a fault if these voltages drift beyond a predetermined tolerance. The circuit normally requires +15 volt supplies and a tolerance of ~0.S volts can easily be detected. Thus, the total bràke fault condition which would be reported is represented by the following logical rela-tionship:

.BRAKE ~AULT = STUCK BRAKE ~ SUPPLY VOLTAGE OUT OF TOLERANCE
Eq. 6 ; ', ' `' '`' ' - .
Again, either or both of these individual faults could be progr~mmed to be reported to the operator dispiay, if desired.
ilso, either one or both of these faults can be counted and storea in the individual car monitoring unit for display for preventative or corrective maintenance. ' In this connection, a plurality of counting means 39 are coupled to the fault storage portion of status table 27, one counter per fault type, to enter a count each time a fault is found. The counter means can be storage locations in the main memory in which binary representations of the counts are stored, or they can be separate read or other counting deYices. For ~implicity they will be referred to as counters herein. These counters do not reset themselves, but simply continue to count up faults until they are manually reset. In addition, it is desirable to connect the counters so that they,count not only ,~:
~18-~, those faults which are reported to the motorman (e.g., "BR~KE
FAULT") but also the interim fault solutions (e.g., "STUCIt BRAKE" and "SUPPLY VOLTAGl~ OUT OF TOLERANCE" ) .
This permits greatly improved and eficient maintenance procedures. When a car is delivered to à maintenance yard, the maintenance pers~nnel can connect a counter reader to the counters and obtain a readout of the number of times each fault has occurred since the last maintenance proc~dure, and of the specific area in which the fault has occurred. This is parti-cularly helpful in locating and correcting problems which are transitory in nature, i.e. those which occur from time to time but which are not in evidence when the car is taken to the maintenance facility.
A unit which is commercially available and which is parti-cularly suitable for this purpose is a Program Monitoring Uni.
manufactured by Industrial Solid State Controls, Inc., of York, Pennsylvania. This unit is provided with a paper tape printer and addressing means for addressing any counter or timer value in memory. The operator thus can address each relevant memory point and obtain a permanent printed record of the storage location for each fault type and the number of times the faul~
has happened, which information can then be used to guide maintenance procedures and to build a permanent record of fault history for redesign and other purposes.
Another example of a fault which can be monitored by the 8ystem is a dead motor fault which involves the monitoring of -~
four wires to determine whether the motors of a car should be active. A relay is normally provided to sense the loss of the ~third rail" supply which is usually 600 volts. The motors can draw current only during the ~ime this relay is closed indicating that the 600 volts is present. The r~lay is, in some systems, referrcd to as the PTR relay. ~orward movement is called for ~hen three other wires, referred to as the No. 1, No. 6 and GS
wires, are energized. Reverse movement is called for when the No. 2, No. 6 and GS wires are energized. During the time that movement is called for and the PTR relay is closed, if there is no motor current, it can be concluded that a dead motor fault has been detected. Incorporating a factor to allow for the PTR and motor current response times, the logical equation to detect a dead motor fault can be written as follows:

DEAD ~OTOR = ~PTR) (#1 + t~ 6) (GS) (~IOTOR CURRENT) (ON delay) Eq. 6 The retraction or extension of the coupler heads can also be easily monitored. To determine if a coupler head is retracted, it is convenient to simply monitor a contact in each head which, when closed, indicates that the head is ful1y extended and locked.
Only the No. 1 end of the two end cars should have retracted heads.
All other heads should be extended and locked.
It ~ill be seen from the above that logic equations can be written for any fault condition to be detected, the fault con-ditions being by no means limited to those described above.
Baving written the logic equations, the solution of them can be solved eithér by a system based on Boolean algebra or by the ladder network approach, the latter being the system employed by the IPC-300. The logic processor of the IPC-300 contains the processing logic, a read/write memory, power supplies and interface circuitry to the input and output sections and the data link. The logic processor can be regarded as being simi-~ar in function to a special purpose microcomputer in that it .

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- J ) -lOSS135 can solve logic equations which are programmed intG its memory.
The logic processor sequences through its memory on-: word at a time. As each word is read, the instruction in that word is decoded by decoder 36 and, according to the decoded instruc-tion, an operation is performed by the processor. A typical ; operation might be to examine the status of a logic si~nal coming into the processor from an input monitor unit. Logic operations such as "AND", "OR", "ADD", "SUBTRACT", "STORE", ~COMP~RE", "TIME DELAY", and "DIGITAL COUNTERS" can be per-formed by the processor as programmed into the memory. Thus, the logic processor is general purpose in that it can be programmed according to the user's needs. The size of the pro~ram which can be run by the processor is limited only by memory capacity which can conveniently be 2,048, 4,096 or 8,192 eight-bit words, as required by the size and complexity of the train system.
Clearly, instructions can be altered by the user as required without deleting or adding hardware.
; As indicated, the memory can also be used to store and count the number of times a fault has occurred. When the ; logic processor solves an equation to determine if a fault condition has occurred, the master control is alerted, as previously described, but in addition that fault is stored in a memory location. Each time tbe fault occurs it is counted and the added result is stored in memory. The solid state - memory can be provided with its own battery system so that if train power is removed, the battery will power the memory 80 that its data is not lost.

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The sequence of operation of an apparatus according to the invention bcgins with the energization of the system which commences the sequ~ncing of the operational program storcd in the main memory 35. The first part of the operation is identical for each piece of equipment in each car, except for differences in the faults being reviewed, depending upon the type of car as previously describ~d. The operation commences with the operation program in the main memory which sends a command, decoded by decoder 37, to read all inputs. The inputs are then read into the input status table 26 which then temporarily stores all of the inputs in the form of a ser`ies of ones and zeros. This is done at the beginning of every memory scan. The processor logic then begins to execute the program in the main memory. The first ladder in the main memory is then exàmined, at which time the appropriate bits of information stored in the status table are chosen and the first ladder network equation is solved, the processor logic going through the various logic operations, i.e., AND or OR operations or the like. The processor presents an output, indicatinq a fault or no fault and records that output at an appropriate address in the output status table.
It is, of course, stored in binary form. This can be a final result or it can be an interim solution as in the case of the fault 1 and fault 2 conclusions discussed with reference to Fiq. 5. Having sQlved the first ladder equation, the program then sequences to the next ladder equation and examines that equation to determine the existence of a fault, presenting an output at the result of that operation. The processor proceeds in this fashion through each ladder stored in the ~a~n memory, until the logic equations for all faults for .... ...

the car have been reviewed and the results stored in the output status table. - ' ~ s mentioned, a portion of the output status table can be used for interim solutions and another portion thereof or the storage of fault indications of a type which are to be transmitted to the lead car for display to the motor-man. At this stage, if the apparatus is not in a lead car, the program begins over again, sequencing through each ladder in the ladder diagram and solving the logic equations, ~pdating the output status table at the conclusion of each one. The memory would, most likely, be provided with the "lead car" or master controller program, permitting that car to be selected as a lead car, but that portion of the program would simply not be activated.
If the apparatus is in a lead car and is therefore the master controller, at the conclusion of a review of the fault -ladders in the lead car itself, the remainder of the program would be activated, sequentially interrogating the output table of each car for each fault. The first step is for the program to provide an output signal to the output status table -with an address for a specific car, this output being coapled to the data link and transmitted to the data link unit of the next car, in series. Each car is interrogated, first, for'the first fault and, after each car has been so interrogated, each car is interrogated for the second fault. In each case, the address and message in a serial code is transmitted through the data link to the input portion of the next car I/O unit, causing the unit to respond with a message containing the fault data on fault No. 1. This fault data is then returned' .
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~ -23-105~i~35 -to thc input status table of the l~ad car controller and, if the messa~e contains information that a fault exists, a display is illuminated indicating to the motorman that a fault in a specific car exists. Absent a fault indication, the program continues, fault by fault and car by car, to sequentially and repetitively interrogate each controller. Upon conclusion of this portion of the program, the fault review is recommenced.
Wit~ the specific apparatus referred to herein, the message format used in the data link begins with a message identifier. This first character can take a large number of forms, but only three types of message identifiers are used in the systèm as presently described. A "load data" identifier tells the car receiving the message to load the following data characters into its data link memory. A "report data" identi-fier tells the car receiving the message to send back any faults detected in that car. A ~fault report" identifier tells the master controller that the addressed car is reporting fault data,-as requested.
The second character of the message is the car number character, identifying the car which is to receive the trans-mission. Nith a seven bit ASCII code word, a maximum of 128 cars can be addressed. In the car addressing scheme, the master controller sends a message to the cars identified in ~he number. The message is received by each car beginning with the master which is identified as car No. 1. A11 cars are numbered successively, increasing in number away from the master controller. Each car receives the message, the cars being connected in series, and according to the ~essage identifier will act on the address character by , .,'~ .

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lO5S~35 subtracting onc bit from the addr~ss code if the message identifier is eithcr "load da~a" or "report data". After one decimal value is subtracted from the address, a check for zero result is made.
If the result is ~ero, that car i5 the addressed car. ~f the result is not zero, the entire message is retransmitted to the next successive car until the zero checked car is reached. The addressed car will then receive the entire message and take appropriate action.
If the message identifier is "fault report", then each car will transmit the message to the succeeding car in a direction toward from the lead car. The master controller will ultimately receive the fault report identifier and recoqnize it as such by decoding the first character of the entire message block. The third character of the message is the address character for data storage, this character containing the starting address code for the data link memory locations within the receiving data link unit where the data is to be loaded into or from which it is to be reported. With the Memory capacity described, 256 memory address locations each containinq one data bit is the contemplated capacity of the system.
The next three characters of the message are data bytes 1, 2 and 3, which can exist in either the "load data" type of message or the "report fault" messa~e. In either case, these data bytes contain the data (either commands or fault reports) to be loaded in the addressed data link memory locations in accordance with the third messa~e character. In the report data message, the data bytes contain dummy information. Although three 7 bit characters are used for data transmission, where each bit corresponds to a reported fault condition, the number . lO5S~3S

of data charactcrs can be expanded accordinq to the number of fault reports required for a specific operating system.
The last portion of the transmitted message is the checksum which is simply a longitudinal parity or error detection word for checking the validity of the six previous characters. The checksum, in conjunc~ion with the parity bit in each word is used to check for transmiss~on errors in the message block.
q`he above description has been set forth on the basis of a seven bit code word for the message itself. In addition to this, a start bit is provided at the beginning of each portion and a parity bit and two stop bits are provided at the end, constituting a standard eleven bit word.
A functional block diagram of data link apparatus usable in the system of the prèsent invention is shown in Fig`. 7. A
direction gate 55 includes logic to channel signals in the appropriate direction from any unit toward one end of the train or the other, depending upon the nature of the message being handled. The direction gate is bidirectionally connected with two transmit-receive units 56 and 57, these being serially connected with the direction gate in a series current loop with the units in the other cars. The transmit-receive units contain logic to receive and send current loop signals at levels of, for example, 20 or 60, milliamperes and translate these current pulse signals to voltage type signals having sùitable voltage logic levels, e.g., at 5 volts. The transmit and receive units can include a commercially available device known as a univer-~al asynchronous receiver-transmitter ~ UART) and other lo~ic to effect the pulse form translation and handle the signals to and from the direction gate. Units 56 and 57 can also be employed ,. .
, , , 105~135 to accomplish a parity check on each charac~er sent, using the parity bit provided at the end of the character;
Direction gate 55 is conn~cted to transmit and receive signals to and from a message and address decoder 58 which includes a serial-to-parallel converter 59 which receives the digital signals in serial form from the direction gate and converts them to parallel form. An error detector 60 can be coupled to converter 59 to detect parity errors. Converted signals are supplied to a message decoder 61 which is capable of decoding and recognizing those signals on which the pro-cessor is to act. The decoder then provides decoded ~essage information to a random access memory 62 and a memory address ; register 63, register 63 being provided to recognize an address and properly direct it to the appropriate addressed location in memory 62. Memory 62 communicates bidirectionally with the I/O
equipment in the apparatus described with reference to Fig. 2 through multiple communication line 6~, and data to be stored in memory 62 after processing are appropriately addressed by signals to register 63 on a bus 65.
Data to be read out of memory 62 can be supplied to the parallel to serial converter 66 for coupling to the direction gate and transmission in the appropriate direction along the serial current loop. A parity generator 67 is coupled to converter 66 to supply the parity bits for outgoing messages.
An address recognition unit includeg a "subtract 1 from addressa unit 68 and a zero check register 69. As previously indicated, the message format is such that each message includes an address portion having a number in binary form representative of a decimal number corresponding to the number of the car. As .
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10551~S
cach unit reccives a messa~e, the address portion thereof is ~urpl~ed to unit 6~ which subtracts a binary number representa-tive of the decimal value 1 ~rom that address. The resulting binary number is then checked to see if it is equal to zero.
If so, the message is recognized as being intended for that car, and if not, the message is again put in serial f~`rm and retransmitted to the next succeedin~ car wherein the same substraction and examination process is accomplished. It will be recognized that the retransmitted address in the message represents a decimal value of one less than the message which was received by any specific unit.
Interconnection between units 59, 61, 62, 63, 66 and 68 is generally bidirectional or ~ultidirectional between various units and is indica~ed generally by a connection bus ?0.
A control timing and logic unit 71 is also provided, but this is also conventional in nature and will not be further discussed. The function thereof is to provide the clock and other timing pulses and control functions to assure correlative operation between the various units of the equipment. Micro-pro~ram control with read only memory function can be employed in unit 71.
Memory 62, while shown in Fig. 7 as being an independent memory in the data link can, alternatively, be part of the input or output status tables in the I/O unit of the processor.
The choice of whether to use part of the processor memory func-tions or to provide a separate data link memory depends upon memory capacity and the number of functions to be handled by the equipment.

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, , 105~ 5 It will be rccognized from this description that control functions in individual cars can be accomplished using basic-ally the same equipment as that disclosed herein. For example, messages describcd herein as "LOAD DATA" command can contain control orders to one or more cars to energize or deenergize systems in a car such as liqhting, air conditioning or the like. Outputs to activate such systems can be taken from the output status table to operate suitable drive circuits to respond to the control orders.
While certain advantageous em~odiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various chanqes and modifications can be made therein without departing from the scope of the invention as defined in tbe appended claims.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A monitoring and reporting system for a plurality of interconnected cars including a lead car and at least one other car, comprising sensor means in each of said cars for monitoring a plurality of physical conditions in said cars and for alter-ing circuit conditions to represent the state of said physical conditions;
means in each of said cars connected to said sensor means in the same car for repetitively and sequentially detecting each of said circuit conditions and for producing a digital signal having a value representative of the state of each physical condition;
means in each car for evaluating said digital signals in accordance with predetermined criteria to produce and repetitively update a set of second digital signals having values representative of the existence or nonexistence of faults in said physical conditions;
first memory means in each car for storing said set of second digital signals;
circuit means interconnecting said cars for transmission of digital signals;
logic means in said lead car for repetitively and sequentially sending interrogation signals individually to said memory means in each of said cars, including said lead car, to determine the existence of faults;

means in each of said cars responsive to said interrogation signals for transmitting status signals representative of said second digital signals to said lead car to provide fault information to said lead car; and display means in said lead car for receiving and storing said status signals and for providing a visual display of fault conditions reported in said signals.

2. A system according to claim 1 wherein said means for detecting includes means for receiving signals representative of each of said circuit conditions and for converting each of said signals into digital form; and second memory means for storing said signals in digital form.

3. A system according to claim 2 wherein said means for evaluating includes third memory means for storing an instruction program to con-trol the reception of said signals by said means for receiving, and for storing said predetermined criteria; and data processing means for sequentially receiving said digital signals from said second memory means, for evaluating said signals in accordance with said criteria, and for providing said second digital signals to said first memory means.

4. A system according to claim 3 wherein said display means includes a display panel having a digital numerical display and a plurality of lamps, each of said lamps being visually identified as being related to a predetermined type of fault; and logic means for selectively changing thestate of illumination of an appropriate one of said lamps to indicate the existence of a fault of the type represented by that lamp and for simul-taneously displaying on said numerical display a number identifying the car in which said fault condition is reported to exist.

5. A system according to claim 3 wherein said circuit means includes multiplex circuit means in each of said cars for bidirectionally sending and receiving serial digital current signals; and means for serially interconnecting all of said multiplex circuit means.

6. A system according to claim 5 wherein said multiplex circuit means includes logic means for receiving said digital current signals and converting said signals into serial voltage level digital signals, and for converting voltage level digital signals into serial digital current signals for transmission to other cars.

7. A method of monitoring functions in a train system of the type having plural cars wherein each car is provided with a plurality of condition sensors capable of providing electrical outputs representative of specific physical conditions in the car, comprising sequentially and repetitively examining the output of each sensor in each car and digitally storing in each car values representative of the physical conditions sensed in that car;

evaluating selected ones of the stored values, single and in groups, in accordance with predetermined criteria to determine the existence of fault conditions in each car as defined by the criteria;

storing in each car digital signals representative of the fault conditions in that car;

sequentially and repetitively interrogating, from a selected one of the cars, the stored signals representating the fault conditions in each car, including the selected one of the cars;

storing, in the selected car, the responses to the interrogating;
and visually displaying in the selected car the existence of a fault and an identification of the car in which the fault exists.

8. A method according to claim 7 and further comprising the step of counting the number of times each type of fault is determined to have occurred in each car.