ELECTRONIC SEQUENTIAL FAULT FINDING SYSTEM

Abstract: An electronic sequential fault-finding system which may be applied to monitoring railway wagons for faults in brakes and doors, or for shipping containers to monitor refrigeration and security. In one broad form the present invention comprises a controller station (1) and a plurality of serially connected sub-stations (2), wherein said controller station (1) sequentially monitors said substations (2) to determine the presence of faults. When said faults are detected, the fault and its location are indicated back to said controller station (1).

Description: ELECTRONIC SEQUENTIAL FAULT FINDING SYSTEM The present invention relates to an electronic sequential fault finding system which continuously monitors a plurality of serially-connected sub-stations for faults, and indicates said faults and their location back to a controller station. The electronic sequential fault finding system of the present invention may be applied to many industries, for instance, for monitoring railway wagons for faults in brakes and doors, for shipping containers to check on refrigeration and security, and for machinery in factory assembly lines to monitor breakdowns. Other uses for the present invention include its use in hospitals for monitoring a plurality of beds simultaneously by one centralised nursing staff or, in vital areas such as intensive care, to monitor a number of vital functions. The device of the present invention can also be used in the mining industry to monitor any required number of underground points for safety reasons. Various systems of monitoring have been known for many years, however they have the disadvantages that their use is limited to monitoring physically stationary objects, and, that they are extremely costly. One of these prior art systems is the multiplex system, which is used in industries such as security, safety and general machinery monitoring. However this system is only good if the monitored object is physically stationery in its place, therefore, when the objects to be monitored are parts of railway wagon such as doors or brakes, or containers on a cargo ship, the multiplex system is not suitable and direct connection to the required position is required, which in many cases involves hundreds of wires and a very complex wiring system. Another prior art monitoring system, is the system used typically in security system, which consists of a modem and microprocessor at both the operator end and the monitoring end of the link, thus making the monitoring system extremely costly. The present invention seeks to overcome these problem providing a relatively inexpensive electronic sequential fault finding system which may be applied to monitor both stationary and mobile systems. The present invention also seeks to provide a monitoring system, in which the monitoring sub-station positions may be placed as far as 1km apart from the controller station without having interference effects, and is capable of monitoring sequentially and separately at least one fault at each sub-station, and indicates the type of fault and its location back to the controller station. The present invention in one embodiment seeks to provide a portable system which consumes a relatively small amount of power and preferably can run on a 12 volt power supply or battery. It also is capable of monitoring a plurality of sub-stations with minimal wire connections - the monitors being connected to the controller unit in series. The present invention also seeks to provide a monitoring system which will give a visual or audible warning whenever a fault occurs and has a response time of 1/1000 second. The present invention will be more clearly understood from the following detailed description with reference to the accompanying drawings, in which: Fig. 1 is a generalised block diagram of the monitoring system; Fig. 2 is a diagram of an embodiment of a controller statitoring system. Fig. 4 is a detailed block diagram of the sequential fault location system of the present invention; Fig. 5 is a circuit diagram of one embodiment of a controller station of the monitoring system; Fig. 6 is a circuit diagram of one embodiment of a sensor station of the monitoring system; Fig. 7 is a detailed block diagram of a preferred embodiment of the present invention; Fig. 8 is a detailed circuit diagram of the controller station of Fig 7; Fig. 9 is a detailed circuit diagram of the sub-station of Fig 7; and Fig. 10 is a detailed circuit diagram of the serial interface of Fig 7. The electronic sequential fault location system shown in Fig. 1 comprises a controller station 1, a plurality of sub-stations 2, a power supply unit 3 which supplies a regulated DC voltage to the controller station 1, a clock unit 4 which provides the system timing, a display * 5 which indicates the location of any faults, should they occur, and an alarm system 6 which visually or audibly alerts an operator should any erroneous situation occur. The controller station 1 is used to simultaneously monitor a plurality of sub-stations 2, and to display the location of faults to an operator. Any suitable display means may be utilised to indicate the fault locations for example, a plurality of LED lights - one corresponding to each sub-station 2, or, if a large number of sub-stations 2 are to be monitored, the display would more preferably consist of one or more 7-segment LCD displays. A suitable display unit, particularly adapted to the latter system, is shown in Fig 2. The display unit 5 is preferably constructed of strong metal or plastics material, and is shown provided with two switches 7 and 8, three 7-segment LCD displays 11 and two indicator lights 9 and 10. Such a display unit is capable of displaying two faults in up to 999 sub-stations. Switch 7 is switched to display fault No. 1 and is indicated by activating indicator light 9, and similarly, by switching switch 8, fault No. 2 may be displayed on the display 11, indicated by activating indicator light 10. The logic flow of the sequential fault locating system is shown in Fig. 3. The logic flow is detailed for a plurality of sub-stations or slave units 2, each sub-station being checked for the presence of two fault operations. The logic flow illustrates that after initial reset of the system, no change is noticed until a fault occurs in one of the sub-stations or slave units 2 when a fault is found to does occur in a sub-station 2, the controller station 1 initiates a search procedure to systematically examine each sub-station 2 until all faults are displayed. In Fig 4, is shown a detailed block diagram of an embodiment of the present invention, detailing the logical operation of the fault locations system. The system comprises the controller station, generally designated by the numeral 13, and a plurality of sub-stations, designated 12. The controller station is shown comprising of a number of smaller blocks, which will be herein described with reference to the system operation. When the system power is switched on, the power-on reset circuit 17 forces the reset lines 25 to a logic 'I' state, to reset each of the sub-stations 12, the counter latch display driver 14, the bit '1000' store 22, and to set the bit '000' store 23. A logic '1 * state is then impressed on the data line 26, and the test line 27 has a logic * 0' state. The counter (part of block 14) then starts counting, however no display of the count is given. A pulse is continually generated by the controller station and moved through the sub-stations in succession. The control station carries this task out in about 1/1000 second for all sub-stations, and simultaneously, the controller station counts the number of sub-stations which are connected together in series. When the process reaches the last sub-station, the controller starts the process again. When a fault occurs at one of the sub-stations 12, the fault line 28 is pulled to logic 'O * state. The 100m sec initialise timer 20 is then triggered, the reset (clear) line 25 is forced to a logic '1 * state, the reset functions are performed again and the bit '000' store 23 is set. The sub-stations 12 then operate as a shift register, clocking a test enable bit along the clock line 110 starting from bit '000', through each sub-station until the fault is discovered, and the test line 27 goes to a logic '1 * state. A short time (about 30% clock high - 5 - time) later, the clock line ringing compensator 21 triggers the 2-second timer 18 and the 1msec line ringing compensator 19. The clock 16 is then stopped and the test enable bit remains at the faulty sub-station 12. At this stage, the count is displayed on the 7-segment display (part of block 14) for a period of 2 sec, after which time the test enable bit is clocked through the remaining sub-stations 12, operating as a shift register. The display (in block 14) retains the location of the last fault until the next fault is found, at which time the process repeats itself. When the test enable bit reaches the last sub-station 12, it is returned to the control station 13 to initiate a reset load bit in the bit '000 * store 23, etc. The process continually repeats itself. For example, if there are faults in sub-stations Nos. 2, 9 and 900, the display would repeat *000', '002', '009' '900' until these faults were removed or others added. Each display is maintained for a minimum of . 2 sec to allow time to read the display. If it takes longer to • find' the next fault, then the display shows the previous sub-station number until the next fault is found. The timing, however, may be adjusted for specific requirements. If, for instance, line ringing is a problem, then the master clock can be slowed down and the line ringing compensator times can be increased. The converse may also be desirable when using short lengths of cable. A 'find size' button may also be optionally provided on the controller such as to display the number of sub-stations 12 connected to the control system 13. This is useful for situations where self-sizing of road trains, shipping containers, etc., is designed. For permanent installations of fixed length systems, it is not necessary and should be deleted both for cost and power consumption minimisation. To provide this facility, a link- should be fitted on the last sub-station unit to return the 'end of scan' bit to the controller station. Any number of faults may be detected in any one sub-station unit, by providing the appropriate number of test lines. In the case as hereinbelow described, two faults may be detected, the provided test lines being test 1, fault 1, test 2 and fault 2. Thus, 2 extra lines are required to extend the system to detect 1 extra fault in each of the sub-stations. In the present embodiment each of the said sub-stations has a 12-wire plug so as to interconnect either with said controller station directly or in parallel with a similar sub-station. Said sub-stations have the capacity to independently detect two faults, in the format connected in the attached figures in the form of an open or closed circuit switching mechanism. Furthermore, each of these said two fault sensors can be multiplied so as the system is capable of measuring many points of the same type of fault in any machinery, railway wagon, or the like. Each independent fault locator in each sub-station, may for example, be in the form of two wires, such as a switch. In Fig 5, a circuit diagram of the control system as outlined in Fig 4 is detailed. The circuit shows one of a variety of possible implementations to achieve the operation of the functional block diagram. Each part of the circuit is labelled corresponding to like parts of Fig 4. In Fig. 6, a circuit diagram of the sub-station, as outlined in Fig 4, is detailed. When a fault is located the Q (non inventing) output of the Flip Flop in the sub-station changes to logic '0' thus making all of the inputs of the 4001 nor gates at logic '0', so the test open collector " driver is biased on. In Fig 7, is shown a block diagram of a alternative embodiment of the electronic sequential fault location system of the present invention. The control station, designated generally by the numeral 28 is shown comprising a microprocessor 30, two LED Drivers 31 and 32 each connected to 8 LED's 43, and a line interface logic block 33 which connects the control station 28 to the sub-stations 29. Additional LED drivers 34 and 35 and LED's may be connected to the microprocessor 30 if the system is to be expanded to monitor 32 inputs instead of the shown 16 inputs. Fig 7 also shows how a serial interface generally desigrated by the numberal 36, may be connected to the microprocessor 30. Connection of an RS232 serial interface card allows the fault location system to be interrogated by other equipment. The serial interface 36 consists of the parallel to serial interface block (UART) 37, the address set-up block 38 and the RS232 Driver and Receiver circuits 39 and 40. The shown embodiment of the fault location ' system allows monitoring of up to 16 inputs or , with the additional LED drivers 34 and 35, up to 32 inputs. The system uses a 4-wire interconnection system to serially interrogate and power each of the sub-stations 29. Each of the shown sub-stations 29 can monitor either one or two faults 41 and 42 respectively. The fault location system is optionally supplied by with either a mains power supply or an external DC source. In Fig 8, a circuit diagram of the control system 28 of Fig 7 is detailed, like parts being represented by the same numerals. A single chip microprocessor 30 is used as the control station, and is programmed to interrogate the sub-station 29 and to display faults by means of LED's 43. The alarm LED's 43 are driven by the octal latches 31, 32, 34 and 35 via the current limiting resistors 44. Ports B4 to B7 of the microprocessor 30, latch the data from the data bus ports A0 to A7, into the octal latches 31, 32, 34 and 35. The reset switch SW1 allows a master reset on the microprocessor 30 and clears all current alarms. Alarms are latched when received and remain activated until reset. Ports CO to C3 are provided with switches SW2 to SW5 which allow the number of alarm inputs to be set. The microprocessor 30 looks for an alarm to be present on the input subsequent to the switch setting number to validate the data system. If this is not found, a system fault will be brought up. If a 32 input option is connected, port Bl on the microprocessor 30 is pulled low to signal that the number of alarm input switches is now 17 to 32. Port B3 of the microprocessor 30 is connected to an octal latch 45 to drive the system fault LED 46, the alarm sonalert 47, and the alarm output relay 48 via the transistor 49. The data bit to be serialized through the slave units 29 is output via transistor 50. The operating LED 51 is connected across this output and winks as the pulse is output. Transistor 52 drives transistors 53 and 54 to provide the 10 volt rail to operate the sub-stations. aThe 10 volt rail is also pulsed, providing the clock information to serialize the alarm information back on the alarm input. The alarm information is read by the microprocessor 30 on port B2. In Fig. 9, a circuit diagram of sub-station 29 of Fig. 7 is detailed. The power input 95 to the sub-station 29 is coupled by diode 55 into the storage capacitor 56. This holds power to the sub-station circuitry when the line is clocked low. While the line 95 is high, the output of gate 57 is low, the output of gate 58 is low, and the output of gate 59 is low. Capacitor 60 discharges via resistor 61 and gate 62 goes high and resets the flip-flop 63. When the clock line 95 goes low, gates 57 and 58 go high and latch the data on the data in line 96 into the flip-flop 63. Gate 59 goes high thus charging capacitor 60 and removing the reset. The time constant of resistor 61 and capacitor 60 is longer than the normal time between clock pulses, keeping the flip-flop 63 from resetting during operation. The chip 63 is a dual flip-flop, the output from the first stage going into the second stage, to allow the unit to clock two alarm inputs onto the alarm line 97. The two alarm inputs go via gates 66 and 67 which, by cutting a link, enable the inputs to be either active high or active low. The two alarm inputs go via gates 64 and 65, and at the appropriate time turn on transistor 68 to activate the alarm line 97 to the microprocessor 30. If only one alarm line 41 is to be used (to detect only one fault), the data out to the next slave is taken form the first data output line 69 of the flip-flop 63, but if both alarm lines 41 and 42 are to be used, the second data output line 70 is used. The fourth line provided is the common line 98. In Fig 10, a circuit diagram of the serial interface 36 of Fig 7 is detailed. The serial communications interface 37 contains a UART and a baud rate generator. Baud rates are set up internally by dividing the 1.8432 MHz crystal 71. The serial communications interface 37 is connected across the same data bus 99 on the microprocessor 30 as drives the indicator leds 43, etc. Ports CO to C3 of the microprocessor 30 now control the interface 37 instead of reading the switches SW2 to SW5 which are now removed. The UART output is buffered by driver 39 to provide the line drive output 100 required by the RS232 port. The receive 40 provides the interface from the RS232 inputs 101 to the UART. The Op-Amp 72 is wired as an oscillator, the frequency being determined by the resistor 73 and capacitor 74. The output rail is full-wave rectified by diodes 75 and 76 to provide .a negative rail for the RS232 driver 39. The unit address circuit 77 enables the unit address switch bank 81 onto the data bus 99 to be read by the microprocessor 30, and the circuit 78 enables the alarm and data rate switches to be set. The unit address circuit 77 enables the system to have a unique address on the serial data bus 99 and only respond to its own calls. The circuit 78 allows the operator to set the baud rate at which the system operates, with switches 80. The number of alarms are set by the operator with switches 79, replacing switches SW2 to SW5 on the microprocessor card. An ideal application for the fault-finding system of the present invention is on trains, for example, immediately finding if any door is opened and locating its exact location, such as carriage number and door number. The system.may be conveniently located in the train driver's instrument panel.One or more fault detectors are placed at the desired monitoring points in each railway wagon, the controller and monitors being connected together with one cable in a series form of connection. When the driver starts the instruments, the display 5 of Fig 2, will either automatically give the number of points in the case of more than one sensor per wagon, or simply the number of wagons in the case of placing one sensor per wagon. When the doors are opened, the display will give the number of each opened door in sequence starting form the locomotive or drivers' side, and each display will remain for 2 seconds which of course can be ignored while the train is stationary. The warning alarm will work only when the train is in motion which is more critical: for example, if a door suddenly opens, an immediate warning sound is given to the driver and the display on the control station immediately gives the number of the point or wagon. In the case of using the full capacity of said device, said sensors could utilise both fault detections by monitoring the doors as described above and also monitoring the emergency stop handles, a few of which are found in each wagon or carrier. Another very important use for said inventions to monitor the overheating of axles, brake assemblies, and brake pressure using exactly the same method as described above. Even in the case of overheating which is very common in large trains travelling for long distances, one fault inlet is coupled to a heat sensor so as to trigger at about 700°C and warn the driver of heating problems, while the other fault inlet is connected to a much higher temperature sensor for example 1100°C to give the driver a final and a stronger warning such that the train can be stopped before any severe damage occurs. Once again, said warning which the driver is receiving, can be a sound warning and a display, giving him the wagon number and indicating which type of fault, such as axle overheating or brake overheating, has occured. As most railway wagons have only 2 wheel assemblies or "bogies" a sensor could be installed at each bogy where the troubles may occur. Another major use of the present invention is in the marine cargo industry where container position are always changed between trips. Said invention could be used in such industry in the following manner. Firstly, for the security of the containers. This is carried out by knowing the location of each container in relation to its sequence number and in relation to the sensor' then one sensor is placed at the door of each container and all sensors are wired by the 12-wire cable to said controller which is then located with the ship's instrument panel. If a door of a container is opened without the knowledge of the ship's security, an alarm will sound at the ship's control room giving the exact location of the container which is being tampered with. A second application is for temperature in control of the refrigerated containers: It is common that many refrigerated containers do reach a much lower temperature due to power failure, crossing very hot areas such as the Equator, and resulting in very expensive damage to meat, fruit and vegetables or may other frozen cargo. Said sensors may be installed at any position within the container and one of its faults inlet in connected to a temperature sensor of the desired maximum temperature, said temperature sensors could be of either normally opened or normally closed type. It is very important to notice that a single sensor can be used in detecting both the above functions 1 & 2 which adds to the power of this invention. It will be appreciated that the present invention which provides a sequential fault finding system is not limited to the particular above mentioned applications. It will be recognised by person skilled in the art, that numerous variations and modifications may be made to the hardware and applications of the invention as described herein without departing from the overall spirit and ' scope of the invention.

Claims: THE CLAIMS : 1. An electronic sequential fault-finding system comprising, a controller station and a plurality of serially-connected sub- stations, wherein, said ' controller station sequentially monitors to determine the presence of faults at said sub-stations, indicating said faults and the location of said faults back to said controller station. 2. An electronic sequential fault-finding system according to claim 1 where said controller station is adapted to send a test signal to the serially connected sub-station, if a fault is detected in any sub-station, a fault signal is generated and transmitted to the controller station, a fault location signal is then generated by the controller and fed to the serially connected sub-stations to determine the location of the fault or faults, the locations of which are displayed. 3. An electronic sequential fault-finding system according to claim 2 wherein each sub-station acts as a shift register to the fault location signal. 4. An electronic sequential fault-finding system according to any one of claims 1 to 3 wherein the sub-stations include switch means which are opened or closed depending whether or not a fault is present. 5. An electronic sequential fault-finding system substantially as hereinbefore described with reference to the accompanying drawings.

Inventors: KILGOUR NEIL, MICHAEL SHAWKY SHAFEEK, KILGOUR, NEIL, MICHAEL, SHAWKY, SHAFEEK
Applicants: MONITRONIX LTD, MONITRONIX LIMITED
Application year: 1986
Main classification: G08B26
IPC codes: G08B26