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1. means for selecting the numeric readout mode control means for receiving said identification code and selectively illuminating one or more of said plurality of gauge and symbol means in response to said identifi cation code and the instrument panel being in the normal display mode or the numeric readout mode a plurality of warning lights each of said warning lights being associated with one of the switch type inputs means for selecting the status mode display means for selectively indicating a pin code for each switch type input having a fault condition means for flashing each of said warning lights having an associated switch type input in the fault condition in response to the instrument panel being in the status mode means for selecting the service mode means for indicating a pin code in response to each of the diagnostic inputs having a present or a previous fault condition in response to the instrument panel being in the service mode a digital display means for selecting one of said plurality of diagnostic sensor signals corresponding to the one or more of said plurality of gauge and symbol means illuminated in response to said identification code and means for displaying the selected sensor signal in digital form on said digital display in response to the instru ment panel being in the numeric readout mode 2 A method for indicating levels of sensed parameters related to machine operation warning conditions
2. 2 digits normally used to display the three fourths of full scale units for the speedo tacho gauge 13 Regardless of whether the currently displayed fault con dition has changed status the instrument 10 determines whether any other diagnosable sensor inputs have changed status in a similar manner by comparing the current status of each diagnosable sensor input to the status stored in memory for that input If one or more of the inputs have changed status then the new input status of each of the changed inputs is stored in memory in place of the earlier status and the instrument 10 produces a control signal causing the pin number for each input that has changed status to be dis played on the 2 digits normally used to display the three fourths of full scale units for the speedo tacho gauge 13 If there is more than one input that has changed status the 5 453 939 21 instrument 10 causes the pin numbers to scroll by alterna tively producing commands to display each of the pin numbers If the instrument 10 is in the status mode the instrument 10 stores the status i e grounded or open voltage condition in memory for each of the switch type inputs In response to one of the switch type inputs being in an open voltage condition the instrument 10 produces a command causing the 2 digits normally used to display the full scale units for the speedo tacho gauge 13 to indicate the pin number associated with that switch type input If more t
3. 25 30 35 40 45 50 55 60 65 20 to be displayed on each gauge the status report level for each input the signal filtering debounce scaling or aver aging characteristics associated with each input and the switch type input associated with each indicator light 14 The instrument 10 reads all of the inputs being used in connection with the machine to which it is connected and performs the system diagnostics on those inputs as described above If the instrument 10 is in the service mode the instrument 10 produces a plurality of control signals causing a plurality of fault codes to be displayed with respect to one of the stored fault conditions which may or may not be currently present The MID associated with the fault condition is displayed on the middle scaling digits at the top center of the speedo tacho gauge 13 Similarly the instrument 10 pro duces control signals to cause the CID associated with the fault condition to be displayed as 3 digits on the digital display 28 the FMI associated with the fault condition to appear as a 1 or 2 digit number on the gear display 30 and is followed by the letter F and the SERV CODE indicator 33 to be illuminated if the fault condition is currently present The instrument 10 also produces a control signal to indicate the pin number of the sensor signal for which the fault codes are displayed Preferably the pin number is displayed on the 2 digits normally used to display t
4. 694 408 9 1987 Zaleski 364 551 ate et al isses 4 748 843 6 1988 Schafer et al sse 731173 5 034 889 7 1991 Abe 364 424 04 4 809 177 2 1989 Windle et 364 424 0 5 041 980 8 1991 Maddock et al 364 431 03 4 811 240 3 1989 Ballou et al 364 424 01 X 5 050 080 9 1991 364 424 04 4 812 744 3 1989 Havel 324 115 5 091 858 2 1992 364 431 12 4 815 824 3 1989 Sharples 350 336 5 150 609 9 1992 Ebner et al 7317 3 4 845 557 6 1989 Ka et al 364 431 77 5 157 610 10 1992 Asano 364 424 03 4 862 395 8 1989 Bey et al 364 561 SORS 3541424 03 4 896 276 1 1990 Saglimbeni et al 364 550 21 4 926 331 5 1990 Windle et al 364 424 04 5 257 190 10 1993 364 424 03 4 939 652 7 1990 Steiner 364 424 04 5 313 388 5 1994 364 424 04 4 967 143 10 1990 Raviglione et 324 73 1 5 327 344 7 1994 Hoffman et al 364 424 03 5 453 939 Sheet 1 of 17 Sep 26 1995 U S Patent 8c 55 el 090 J 809888 og 070 009 sy K E 88 D 10108 VI ge meer 96 ve 8L Oc gz 0 6 29 m MAN GIS o LT U S Pat
5. SPD IN METRIC UNITS TURN ON THE KMH ISO SYMBOL IUIS LL BLINK THE GAUGE OUTLINE TURN ON THE RPM ISO SYMBOL TURN ON THE ISO SYMBOL 5 453 939 1 COMPUTERIZED DIAGNOSTIC AND MONITORING SYSTEM TECHNICAL FIELD The invention relates generally to a computerized moni toring and diagnostic system and more particularly to a monitoring and diagnostic system having a plurality of operating modes BACKGROUND ART In a variety of engine powered vehicles monitoring and diagnostic devices are employed to detect the presence of various undesirable operating conditions such as overheat ing of the engine low oil pressure low fuel and the like and indicators are provided to warn the operator of such condi tions These instruments are typically connected to various sensors and switches for monitoring or controlling condi tions on the vehicle via a wire harness and or a communi cation link In many applications these instruments are also connected to electronic control systems for example elec tronic engine controls electronic transmission controls and the like Most prior art systems have included dedicated instru ments in which the functions and conditions of the vehicle to be monitored or diagnosed as well as the particular sensors provided on the vehicle are identified in advance Therefore the instruments are specifically designed for and hence dedicated to the monitoring or diagnosing of tho
6. U S Patent Sep 26 1995 Sheet 10 of 17 5 453 939 cL IS BRIGHTNESS CONTROL PHOTOCELL ONLY CONTROL BRIGHTNESS IN RESPONSE TO PHOTOCELL OUTPUT IS BRIGHTNESS CONTROL SPST EXECUTE LOGIC FOR SPST BRIGHTNESS CONTROL SWITCH EXECUTE LOGIC FOR SPDT BRIGHTNESS CONTROL SWITCH U S Patent Sep 26 1995 Sheet 11 of 17 5 453 939 SUE IE IS THIS A LOW WARNING STYLE GAUGE TURN ON UPPER GAUGE OUTLINE ENABLE UPPER WARNING SEGMENTS READ GAUGE DATA MAP GAUGE DATA TO SEGMENT DATA READ SINGLE FILL INPUT BUILD AND TRANSMIT SENSOR DATA MESSAGE TURN ON LOWER GAUGE OUTLINE ENABLE LOWER WARNING SEGMENTS U S Patent 26 1995 Sheet 12 of 17 5 453 939 O 50 TURN ON THE APPROPRIATE SYMBOL 52 IS THE GAUGE IN SINGIE COE ENT IS THE GAUGE N LOW WARNING STYLE GAUGE IN A LOW WARNING CONDITION FLASH THE ILLUMINATE LOW WARNING INDICATING SEGMENTS SEGMENTS IS THIS A HIGH WARNING STYLE GAUGE IS THE GAUGE IN A HIGH WARNING CONDITION FLASH THE HIGH WARNING AND ALL T INDICATING SEGMENTS ILLUMINATE INDICATING SEGMENTS U S Patent Sep 26 1995 Sheet 13 of 17 5 453 939 ees IS THE GAUGE IN A LOW WARNING CONDITION IS THIS A LOW WARNING STYLE GAUGE IS THIS A IS THE GAUGE HIGH WARNING HI WAR
7. and fault conditions on any of a plurality of machines having an instrument panel and a plurality of switch type inputs and diagnostic inputs the instrument panel including a plurality of indicating lights and a plurality of gauges and symbols comprising the steps of producing an identification code each of the plurality of machines having a unique identification code for iden tifying the machine to which the apparatus is con nected selecting one of a normal display mode a status mode a service mode or a numeric display mode sensing parameters and responsively producing sensor signals indicating one of a fault condition and a normal condition receiving the identification code assigning one of the sensor signals to each of the illuminated gauges in response to the identification code and the selection of either the normal display mode or the numeric display mode and selectively illuminating one or more of a plurality of gauges and symbols each symbol identi fying the sensed parameter indicated on the illuminated gauges indicating a level of the sensed parameters on the illumi nated gauges selectively indicating a pin code for each switch type input having a warning condition in response to selec tion of the status mode flashing each indicator light having an associated switch type input in a fault condition in response to selection of the status mode indicating a pin code in response to each of the diagnosti
8. filter 15 shown in FIG 2 must be provided to reduce the amount of ambient light reaching the VF display segments Advantageously the optical filter 15 is mounted in a bezel for mounting on the front of the instrument 10 over the VF display segments so that any ambient light must pass through the optical filter 15 before reaching the display segments and any light produced by illuminating the display segments must also pass through the optical filter 15 The optical filter 15 also advantageously includes anti glare characteristics to improve readability for the operator Since ambient light is filtered as it enters the instrument 10 and any reflected light is also filtered contrast is greatly improved In the preferred embodiment only the display segments that are illuminated by the instrument 10 are substantially visible to the operator The VF display segments are available in various different colors for example blue green blue green yellow and red However each of the colors are not of the same brightness when illuminated by the instrument 10 It is therefore advantageous to select the optical filter 15 such that each of the colors appear to be of approximately the same brightness to the operator or alternatively for the warning colors to be somewhat brighter than the other segments For example since the blue green display segments are typically brighter than the red and yellow display segments the optical filter 15 preferably a
9. inputs the sensed parameters having normal operating ranges The method includes the steps of indicat ing a level of the sensed parameters on a plurality of gauges identifying the sensed parameter being indicated on each of the gauges receiving an identification code and selectively illuminating one or more of the plurality of gauges in response to the identification code selectively indicating a pin code for each switch type input having a warning condition flashing each indicator light having an associated switch type input in a fault condition sensing parameters and responsively producing sensor signals indicating one of 20 25 30 35 45 55 60 65 4 a fault condition and a normal condition and indicating a pin code in response to each of the diagnosable inputs having a present or a previous fault condition The invention also includes other features and advantages which will become apparent from a more detailed study of the drawings specification and appended claims BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention ref erence may be made to the accompanying drawings in which FIG 1 illustrates a computerized monitoring and diag nostic system FIG 2 is an illustration of a bezel and optical filter FIG 3 illustration of a computerized diagnostic and monitoring system functioning in the normal display mode and having a plurality of inputs and the bezel and opti
10. it is desirable to indicate a warning when the parameter exceeds a certain level The level of the sensed parameter is within the normal operating range The indication of a parameter for which it is desirable to indicate a low warning condition in the single bar mode would look similar to the gauge shown in FIG 4e except the low outline segment 24 would 10 20 25 35 45 50 55 60 65 10 be illuminated instead of the high outline segment 22 For each parameter level being displayed on the gauge 12 a high or a low warning value is established as described below The behavior of the gauge 12 in the fill the graph mode when the sensed parameter is above or below the high or low warning value respectively is best described in connection with FIGS 4b and 4d For parameters having a high warning value once the level of the sensed parameter exceeds the high warning value all of the indicating segments 16 the central and high outline segments 22 23 the symbol 26 and one of the high warning segments 18 are caused to flash As the level of the sensed parameter increases even farther the second of the high warning segments 18 is also caused to flash As shown in FIG 4b the sensed parameter has increased to a level at which all of the indicating segments 16 the symbol 26 the central and high outline segments 22 23 and both of the high warning segments 18 are all caused to flash With respect to a parameter having a
11. low warning value once the level of the sensed parameter decreases below the low warning value the central and low outline segments 23 24 the symbol 26 and one of the low warning segments 20 are caused to flash As the level of the sensed parameter decreases even farther the second of the low warning segments 20 is also caused to flash As shown in FIG 4d the sensed parameter has decreased to a level at which the central and low outline segments 23 24 the symbol 26 and both of the low warning segments 20 are all caused to flash The display of a sensed parameter in the single bar mode when the level of the sensed parameter is above the high warning value includes the flashing of the central and high outline segments 22 23 the symbol 26 and one of the high indicating segments 18 Similarly the display of a sensed parameter being below the low warning value in the single bar mode includes the flashing of the central and low outline segments 23 24 the symbol 26 and one of the low indicat ing segments 20 Which of the two high or low indicating segments 18 20 to be flashed is determined in response to the degree to which the level of the sensed parameter is above or below the high or low warning values respectively In addition to the above warning indications the warning horn 17 or the alarm lamp may be activated when the level of the sensed parameter exceeds the high or low warning value A gear display 30 is advantageously dispo
12. neither of the low indicating segments 20 is illuminated Thus if the number 7 is retrieved as the number of segments to indicate in the fill the graph mode then segments 2 through 7 are illuminated as shown in FIG 4a If the number 12 is retrieved as the number of segments to indicate in the fill the graph mode and the gauge is a high warning style gauge then segments 2 through 12 are caused to flash as shown in FIG 4b If the number 4 is retrieved as the number of segments to indicate in the fill the graph mode and the gauge is a low style warning gauge then segments 2 through 4 are illuminated as shown in FIG 4c If the number 0 is retrieved as the number of segments to indicate in the fill the graph mode and the gauge is a low style warning gauge then segments 0 and 1 are caused to flash as shown in FIG 4d If the gauge is in the single bar mode then the segment corresponding to the retrieved number is the only one of the warning and indicating segments 16 18 20 that is illuminated or caused to flash If the number 0 or 1 is retrieved the parameter is considered to be below the low warning value and if the number 11 or 12 the parameter is considered to be above the high warning value In keeping with the above example suppose that the scaled sensor data received from the instrument and asso ciated with the oil pressure in an engine is 179 and that the oil pressure is to be displayed in the low warning format The instrument wou
13. segments 22 23 24 and symbols 26 are not visible when not being used to indicate a parameter level The instrument 10 is programmed so that a normal operating level for each gauge on a given vehicle is close to the center of the gauge For this reason the scaling for each 10 15 20 25 30 35 40 45 50 55 60 65 24 gauge is both parameter and vehicle dependent and is established by the instrument in response to the identifica tion code On some vehicles where turn signals are unnecessary or the function is performed by devices outside the instrument 10 the turn signal indicators 32 are disabled Similarly the high beam indicator 34 and retarder indicator 36 are dis abled if unnecessary for use in connection with a given vehicle As is the case with the gauges the turn signal indicators 32 retarder indicator 36 and high beam indicator 34 are not substantially visible unless illuminated In addition the appearance of the gauges 12 may be changed by changing the status of the display mode select means 41 In the fill the graph mode the parameter level is reflected by the number of gauge segments that are turned on In this mode the gauge appears like a bar graph In the single bar mode the gauge appears more like a mechanical gauge with only one segment at a time being turned on While in the service mode the pin numbers correspond ing to the diagnosable sensor signals having a present or previous f
14. voltage conditions or electrical signals could be defined as corresponding to the fault condition without deviating from the invention Thus the programming switch type inputs are referred to as being in the fault condition when in the open voltage condition even though it may in fact be desirable for that programming input to be at the open voltage condition Similarly when a switch typc sensor produces an open voltage condition on one of the switch type inputs in response to the sensed parameter being outside a normal operating range the switch type input is also referred to as being in a fault condition The indicator light 14 function while in the status mode is advantageously defined such that an indicator light 14 is flashed when the associated input is in an open voltage condition and is turned off when the associated input is at ground potential In the preferred embodiment there are more switch type inputs to be indicated in the status mode than the number of available indicator lights 14 To indicate all of the desired inputs the clear input 52 is used to toggle between two sets of inputs Thus when the clear input 52 is grounded one set of inputs is displayed on the indicator 5 453 939 13 lights 14 and when the clear input 52 is open the other set of inputs is displayed Pin number s of monitored conditions presently in the fault condition are shown scrolled on the 2 digits normally used to show the full scale units for t
15. warning horn 17 sounds briefly each time the SERV CODE indicator 33 changes state FIG 5 illustrates the instrument 10 operating in the service mode The pin numbers are shown for the locked condition and for the change of state condition As noted above pin numbers are shown only when locked on a particular code When leaving a locked code state that is advancing to another fault condition or leaving the service mode all pin number information is erased from memory and is no longer displayed Referring now primarily to FIG 6 the status mode is preferably used to identify fault or warning conditions in switch type inputs that are not easily diagnosed and are generally used in connection with the indicator lights 14 The switch type inputs advantageously include switch inputs vehicle identification codes and various other inputs having a limited number of possible states and indicate one of a normal state and a fault condition Advantageously the fault condition corresponds to an open or floating voltage condition Some of the inputs are used to program the instrument 10 to perform certain functions and may be either at ground potential or an open or floating voltage condition and are thus treated as switch type inputs in the status mode For the purposes of discussion the term fault condition with respect to the switch type inputs is used generically to refer to an open voltage condition However it should be appreciated that other
16. when the parameter exceeds a certain level for example engine temperature the high warning segments 18 are enabled To indicate the level of a parameter for which it is advantageous to indicate a warning when the parameter is below a certain level for example fuel level the low warning segments 20 are enabled In some cases it is advantageous to indicate both high and low warning con ditions Advantageously the gauges 12 also inciude a high outline segment 22 central outline segments 23 and a low outline segment 24 all of which being located around the periphery of each gauge and being illuminable The high outline segment 22 is located adjacent the high warning segments 18 and the low outline segment 24 is located adjacent the low warning segments 20 The central outline segments 23 are located between the high and low outline segments 22 24 The central outline segments 23 are illuminated in response to the gauge 12 being used to indicate the level of a sensed parameter In response to a parameter having a high warning value being indicated the high outline segment 22 is illuminated and in response to a parameter having a low warning value being indicated the low outline segment 24 is illuminated Thus the appearance of the gauge 12 indi cates that the displayed parameter has either high or warning level and better informs the operator that the level of the sensed parameter is approaching a warning level In the preferre
17. 26 If the parameter number corresponds to engine speed the RPM symbol is displayed to the right of the digital display 28 If the currently displayed parameter number corresponds to vehicle speed the instrument reads an English metric programming input not shown to determine whether the MPH or km h symbol is to be illuminated to the right of the digital display 28 Advantageously the instrument 10 illu minates the MPH symbol in response to the English metric input being in an open or floating voltage condition and illuminates the km h symbol in response to the English metric input being grounded Industrial Applicability The operation of an embodiment of the present invention is best described in relation to its use in displaying a plurality of parameter levels and operating conditions on a vehicle The instrument 10 is operable in a number of modes including the normal display mode the service mode the status mode the tattletale mode and the numeric readout mode The instrument 10 automatically enters the normal display mode of operation when power is applied To access other display modes the service and clear inputs 50 52 are grounded simultaneously When both inputs 50 52 are grounded a mode number corresponding to the current operating mode appears on the digital display 28 Preferably the five operating modes are numbered from 0 through 4 If the service and clear inputs 50 52 both remain grounded for advantageously 2 second
18. 38 and a brightness switch 40 The brightness switch may be either a single pole double throw switch or a single pole single throw switch If the photocell 38 is to be used in tandem with a single pole double throw momentary switch the operator adjusts the brightness level either up or down from the value selected by the photocell 38 depending on which way the brightness switch 40 is activated The single pole double throw switch controls a brightness down input and a bright ness up input in the instrument 10 When the brightness down input is grounded the display brightness decreases in steps until the minimum brightness level is reached When the brightness up input is grounded the display brightness increases in steps until the maximum brightness level is reached In connection with still other machines the brightness level is determined in response to both the photocell and a single pole single throw switch When the brightness switch input is grounded the display brightness cycles first the brightness decreases in steps to the minimum level and then increases in steps to the maximum level When used in connection with some machine types the instrument 10 may also be connected to one or more electronic controls 46 via a communication link 48 In the preferred embodiment the communication link 48 is a two way serial communication link on which the instrument 10 can both transmit and receive information In the pre ferred embo
19. NING IN A HIGH WARNING CONDITION U S Patent Sep 26 1995 Sheet 14 of 17 5 453 939 lt JEDE READ THE HARNESS IDENTIFICATION CODE READ ALL INPUTS PERFORM SYSTEM DIAGNOSTICS IS THE SYSTEM IN SERVICE MODE Y DISPLAY FAULT CODES AND STATUS DISPLAY NEXT FAULT CODE AND IS SERVICE INPUT GROUNDED STATUS N FAULT CURRENTLY Y ALARM FOR DISPLAYED CHANGED 0 5 SECONDS DISPLAY INPUT PIN NUMBER U S Patent Sep 26 1995 Sheet 15 of 17 5 453 939 es ae HAVE ANY Y DISPLAY THE INPUT OTHER DIAGNOSABL PIN FOR ALL CHANGED FAULTS CHANGED TATUS FAULT CONDITIONS IS THE SYSTEM iN STATUS MODE FLASH ALL INDICATOR LIGHTS CORRESPONDING TO INPUTS THAT ARE NOT GROUNDED DISPLAY PIN FOR ALL SWITCH INPUTS THAT ARE NOT GROUNDED STEADILY ILLUMINATE INDICATOR LIGHT CORRESPONDING TO DISPLAYED PIN Y SOUND HORN FOR 0 5 SECOND DISPLAY INPUT FOR SWITCH INPUTS THAT CHANGED STATUS U S Patent Sep 26 1995 Sheet 16 of 17 5 453 939 IN NUMERIC N RESET READOUT EADO TIMER Y SET PARAMETER N NUMBER TO ZERO SCROLL ACTIVE TIMER EXPIRED INCREMENT PARAMETER TIMER N DISPLAY CURRENT PARAMETER DISPLAY CURRENT PARAMETER DATA U S Patent Sep 26 1995 Sheet 17 of 17 5 453 939 IS THIS A GAUGE PARAMETER IS THE PARAMETER ENGINE SPD IS THE PARAMETER VEHICLE SPD IS THE
20. United States Patent 19 Hoffman et al IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII US005453939A 5 453 939 Sep 26 1995 Patent Number 4 Date of Patent 54 COMPUTERIZED DIAGNOSTIC AND MONITORING SYSTEM 75 Inventors John P Hoffman Peoria Ricky D Vance Washington Dennis A Barney Morton Joseph G Kozlevcar Peoria all of Ill 73 Assignee Caterpillar Inc Peoria Ill 21 Appl No 945 451 22 Filed Sep 16 1992 51 In amp Ola uuu agua G06F 11 00 B60Q 1 00 52 US CL sasa 364 551 01 364 424 03 73 117 2 340 438 340 439 340 461 58 Field of Search 364 551 01 424 01 364 424 03 424 04 73 116 117 2 117 3 340 438 439 461 945 959 56 References Cited U S PATENT DOCUMENTS 3 509 529 4 1970 Utter 340 52 3 516 063 6 1970 Arkin et al 340 163 3 866 166 2 1975 Kerscher III et al 340 52 3 893 108 7 1975 McBride Jr et al 340 420 3 906 437 9 1975 Brandwein et al 340 27 4 053 868 10 1977 340 52 4 072 925 2 1978 Yashima et al 340 52 4 128 005 12 1978 Arnston et al 73 173 4 197 650 4 1980 Bailey et al 33 143 4 223 302 9 1980 Hocking 340 525 4 271 402 6 1981 Kastura et 340 52 4 287 504 9 1981 Simon
21. al or a floating terminal While the preferred embodiment of the invention is described in connection with a ground input potential and a floating condition it should be appreciated that the particular states of the binary signals could be modified without deviating from the spirit of the invention In general the machine dependent functions and displays are determined in response to the identification code although other inputs may be used to determine such things as whether speed will be displayed in MPH or km h Typically the instrument 10 retrieves a number of identifiers from a memory device not shown within the instrument 10 in response to receiving the identification code The instru ment 10 then uses the identifiers to determine which func tions and displays are to be used in connection with machines having the received identification code In the preferred embodiment the instrument 10 includes a plurality of operating modes for use in normal operation and as a diagnostic tool The operating modes preferably include a normal display mode a service mode a status mode a tattletale mode and a numeric display mode The instrument 10 preferably includes terminals for receiving signals from a clear input 52 and a service input 50 A service tool is advantageously included having two single pole single throw SPST switches corresponding to the clear input 52 and service input 50 The technician actuates the switches to selectively
22. ated symbol 26 corresponding to the parameter being indicated by that gauge Alternatively the symbol 26 may also be flashed either independent from or in conjunction with the flashing outline segments when the associated parameter number is selected When engine speed or ground speed is selected the correct units label i e RPM MPH or km h is illuminated to the right of the digital display 28 In the cases of ambient light level and system voltage the parameter number dis played on the gear display 30 is the only means for identi fying the parameter therefore the technician must refer to a table to correlate the parameter number to the indicated parameter For example the instrument 10 functioning in the numeric readout mode is shown in FIG 7 The speedo tacho gauge 13 is displaying speedometer information in MPH The engine coolant temperature is displayed by the digital display 28 as 98 degrees Celsius the gear display 30 is indicating gauge 2 and the central and high outline seg ments 22 23 for the top center gauge ie gauge 2 are flashed Advantageously the gauge outline segments of the selected gauge are flashed at a 1 Hz rate Upon entering the numeric readout mode the gear display 30 indicates parameter 0 which preferably corresponds to ambient light level When the service input 50 is grounded the gear display 30 begins scrolling through the parameters By ungrounding the service input 50 the instrument 10 is lock
23. ault condition are scrolled on the full scale units for the speedo tacho gauge 13 Fault codes are also scrolled on the one half of full scale units for the speedo tacho gauge the gear display and the digital display One of the sensor signals having a present or previous fault condition is locked on through activation of the service input 50 The SERV CODE indicator 33 is illuminated when the locked on input is presently in a fault condition When the instru ment 10 is locked on a particular diagnostic code thc technician views the SERV CODE indicator 33 while manipulating the wire harness or disturbing a connector or plugging unplugging a sensor to help determine the location or cause of an intermittent problem Each of the pin numbers associated with a changed state on one of the instrument 10 terminals is also displayed To aid troubleshooting by one technician the warning horn 17 supplements the SERV CODE indicator 33 by producing an audible signal each time the SERV CODE indicator 33 changes state When in the status mode the indicator lights 14 are used diagnostically to indicate the status of various inputs In response to being assigned to a group of switch type inputs through activation of the clear input 52 each indicator light 14 assigned to a switch type input being in a fault i e open voltage condition is flashed The pin number of each Switch type input in a fault condition is individually dis played by the instr
24. c inputs having a present or a previous fault condition in 5 453 939 27 28 response to selection of the service mode displaying the level of the selected sensor signal in digital form on a digital display in response to selecting the j ne of said sensor signals assigned to the i selecting o sor signas 8 Bauges numeric readout mode being illuminated in response to the identification code and 5 k k 20 25 30 35 40 45 50 55 60 65
25. cal filter shown in FIG 2 FIG 4a and 4b illustrate gauges indicating the level of parameters having a high warning value in the fill the graph mode FIG 4c and 4d illustrate gauges indicating the level of parameters having a low warning level in the fill the graph FIG 4e illustrates a gauge indicating the level of a parameter having a high warning level in the single bar mode FIG 5 illustrates the computerized monitoring and diag nostic system functioning in a service mode FIG 6 illustrates the computerized monitoring and diag nostic system functioning in a status mode FIG 7 illustrates the computerized monitoring and diag nostic system functioning in a numeric readout mode FIGS 8a through 8fillustrate a flow chart of an algorithm used in connection with a preferred embodiment of the invention functioning primarily in the normal display mode FIGS 9a and 9b illustrate a flow chart of an algorithm diagraming operation of the instrument while in the serviced and status modes and FIGS 10a land 106 illustrate a flow chart of an algorithm used in connection with a preferred embodiment of the invention functioning primarily in the numeric readout mode BEST MODE FOR CARRYING OUT THE INVENTION An instrument for displaying parameter values is shown generally by the reference numeral 10 in FIG 1 In the preferred embodiment the instrument 10 is a computerized diagnostic and monitoring system for monitoring and dis pla
26. d embodiment the high and low warning segments 18 20 are colored differently than the indicating segments 16 and the high and low outline segments 22 24 are colored differently from the central outline segments 23 and similarly to the high and low warning segments 18 20 Advantageously the high and low warning segments 18 20 and high and low outline segments 22 24 are red and the indicating segments 16 and central outline segments 23 arc blue green However the low warning segments 20 and low outline segment 24 for the gauge 12 indicating fuel level are preferably yellow One or more of the gauges include a plurality of illumin able symbols 26 to identify the parameter being indicated The symbols 26 are advantageously of VF design bluc green in color and selected from the symbols approved by ISO for indicating the parameters of interest One of the symbols 26 is illuminated in connection with each gauge 12 so the operator can identify the indicated parameter Thus the gauge 12 is capable of indicating the level of one of two or more different parameters by illuminating one of the 5 453 939 9 symbols 26 The parameter and hence symbol 26 selected for each gauge 12 depends on the vehicle to which the instrument 10 is connected and choices made by the vehicle and system designers The digital display 28 indicates either speedometer or tachometer information in digital form In the preferred embodiment one of the speedo tacho gaug
27. de either from the instrument 10 or from other system modules a SERV CODE indicator 33 located adjacent the digital display 28 is illu minated The SERV CODE indicator 33 is advantageously illuminated to report a detected condition regardless of the present status of the inputs i e whether or not any input is 10 20 30 40 45 50 55 60 65 8 presently in a fault condition In this way the operator and or technician are informed that a fault condition has existed on the machine in the past even though none are currently present The instrument 10 operating in the normal display mode is sufficiently flexible to be used in connection with a number of different machines and to indicate a number of different parameters For example each gauge except the central gauge indicating speedo tacho information is capable of indicating either a high warning condition or a low warning condition Each of the gauges 12 other than the speedo tacho gauge 13 includes a plurality of indicating segments 16 high warning segments 18 and low warning segments 20 How ever a single high or low warning segment 18 20 may be used The high warning segments 18 are advantageously located in the most clockwise position on the gauge 12 and the low warning segments are located in the most counter clockwise position on the gauge 12 When it is desirable to indicate the level of a parameter for which it is advantageous to indicate a warning
28. diment the instrument 10 builds a serial data message which may include a module identifier correspond ing to the electronic control 46 to receive the data an identifier for each scaled parameter to be transmitted over the communication link the scaled data representing the level of the parameter associated with each identifier and the status of each switch type input Once the message is built the instrument 10 transmits the message over the commu nication link 48 Since the communication link 48 is typically used for other purposes it is advantageous to reduce the amount of communications traffic on the communication link 48 This is possible because each machine does not include all of the possible electronic controls 46 and each of the electronic controls 46 does not require all of the sensor data that is available Each of the electronic controls 46 may also require updates at different rates The communication rate for each machine and electronic control is therefore also established in response to the identification code As described above the instrument 10 retrieves identifiers to 20 25 30 35 40 45 50 55 60 65 16 determine what information is to be sent to which electronic control 46 and at what rate in response to the identification code In the preferred embodiment the instrument 10 executes the algorithm illustrated by the flow chart in FIGS 8a f while operating in the normal display mode Th
29. e 13 and digital display 28 indicates speedometer information while the other indicates tachometer information however either speedometer or tachometer information may be indicated on both if so desired Advantageously the digital display 28 is also adapted to indicate the level of other parameters when the instrument 10 is operating in a numeric readout mode or diagnostic information when the instrument 10 is operating in the service mode The gauges 12 are capable of displaying the parameter values in a plurality of display modes including a single bar mode and a fill the graph mode In the single bar mode only one of the indicating segments 16 is illuminated when the level of the sensed parameter is within the normal operating range Thus the appearance of the gauge 12 simulates the appearance of a mechanical gauge In the fill the graph mode the level of the sensed parameter is indicated by illuminating a plurality of indicating segments 16 such that the appearance of the gauge 12 simulates a bar graph The instrument 10 selects a group of gauges and a display format for each parameter to be indicated on the machine type of interest in response to the identification code The instrument 10 is shown in FIG 3 with the optical filter 15 placed over the face of the instrument 10 including the VF display segments so that only the segments being illumi nated by the instrument 10 are substantially visible to the operator Referring now t
30. e and the gauge reading One of the symbols 26 is illuminated for each gauge 12 in response to the identifica tion code Likewise the switch type input associated with 10 25 35 40 45 50 55 60 65 6 each indicator light 14 is defined for each machine type on which the instrument 10 is used in response to the identifi cation code An identification means 42 produces the identification code and a display mode select means 41 produces a display mode identifier In the preferred embodiment the identifi cation means 42 and display mode select means 41 are connected to the instrument 10 via one or more identification lines 44 forming part of the wire harness and carrying the identification code and the display mode identifier In the preferred embodiment the identification code and display mode identifier are in the form of binary signals that are produced by connecting each of the identification lines 44 to a ground input potential or allowing the voltage of the identification line to float in response to any voltage to which the identification line 44 is connected In the preferred embodiment the identification means 42 and display mode select means 41 directly connect the identification lines 44 to a terminal having one of the above described voltage characteristics however it should be appreciated that the identification lines 44 could be connected to a switch type device for connection to a ground input potenti
31. e instrument 10 reads the identification code from the identification means 42 and determines whether the turn signal indicators 32 are to be enabled by retrieving a turn signal identifier from a memory device not shown within the instrument 10 in response to the identification code If the turn signal indicators 32 are enabled the instrument 10 reads the turn signal switch type inputs and determines whether each of the left or right turn signal indicator 32 is to be activated The instrument 10 responsively causes the left or right turn signal indicator 32 to flash if either the left or right turn signal is activated respectively The instrument 10 determines whether the high beam indicator 34 is to be enabled in response to an identifier retrieved from memory not shown in response to the identification code If the high beam indicator 34 is enabled the instrument 10 reads the high beam switch type input and determines whether the high beam indicator should be illuminated The instrument 10 responsively illuminates the high beam indicator 34 if the high beam input is at a state being defined to indicate that the high beam lights arc activated The instrument 10 determines whether the retarder indi cator 36 is to be enabled in response to an identifier retrieved from memory not shown in response to receiving thc identification code If the retarder indicator 36 is enabled the instrument 10 reads the retarder switch type input not sh
32. e scrolled The place where the pin number s for change of state conditions are shown is the 2 digits normally used to display the three fourths of full scale units for the speedo tacho gauge 13 As stated earlier in the service mode the SERV CODE indicator 33 is illuminated for present faults and turned off otherwise When the instrument 10 is locked on a particular 20 25 40 45 50 55 60 65 12 fault condition the SERV CODE indicator 33 is aided by the warning horn 17 The warning horn 17 sounds briefly each time the SERV CODE indicator 33 changes state Note that the warning horn 17 sounds only for changes in the locked condition while in the service mode If tbere is a change of state of any of the other diagnosed conditions within service mode the warning horn 17 does not sound When for instance the instrument is locked on a particular diagnostic code service personnel may watch the SERV CODE indicator 33 while manipulating the wire harness or disturbing a connector or plugging unplugging a sensor to help determine the location or cause of an inter mittent problem In this example typically two people are needed to make the procedure efficient since the wire harness and connectors to be manipulated are often located remotely from the instrument 10 To help one person be an effective troubleshooter the warning horn 17 is used as a special audible version of the SERV CODE indicator 33 since the
33. ed onto a given parameter The numeric readout mode is exited by simultaneously grounding both the service input 50 and the clear input 52 for advantageously 2 seconds In the preferred embodiment the parameter levels being displayed in graphical form on the gauges 12 while in the 5 453 939 15 normal display mode are also displayed in graphical form in the numeric readout mode The indicating segments to be illuminated and the warning levels are established as described above in connection with the normal display mode Thus the technician is able to view all of the param eters in graphical form in addition to being able to view each of the parameters in digital form by scrolling and or lock ing onto each of the parameters individually Any param eter that is not used by the machine or for which a sensor signal is not being received is displayed as a zero on the digital display 28 when the corresponding parameter number is being displayed on the gear display 30 The brightness of the VF display segments may be determined in a number of different ways depending on the machine to which the instrument is connected In connection with some machines the brightness level is determined solely in response to a photocell 38 that produces an electrical signal in response to the level of ambient light in a manner well known in the art In connection with other machines the brightness level is determined in response to both the photocell
34. ensors that actually are producing accurate signals which tends to increase the time required and thus the cost for repairs It is therefore advantageous to determine whether the sensor is producing an accurate signal without replacing the sensor Since gauges included in the standard operator display do not provide a sufficiently precise readout of the sensed parameter for this purpose one method of determin ing the output would be to display the parameter level being reported by the sensor on a digital display and comparing the displayed level to a measurement reported by a test sensor For example if the technician is interested in checking the engine coolant temperature sensor the technician obtains a reference to which to compare the sensor by measuring coolant temperature with a service tool By comparing the temperatures reported by the vehicle mounted sensor and the service tool the technician can determine whether the vehicle mounted sensor has failed without spending time replacing the sensor The present invention is directed to overcoming one or more of the problems set forth above DISCLOSURE OF THE INVENTION The subject invention avoids the disadvantages of known diagnostic and monitoring systems and provides a flexible system capable of operating in a plurality of operating modes for displaying the level of sensed parameters and indicating warning conditions and fault conditions The instrument is sufficiently flexible
35. ent Sep 26 1995 Sheet 2 of 17 5 453 939 i E 5 453 939 Sheet 3 of 17 Sep 26 1995 U S Patent Lv 71041409 910419373 lt 9V 0900 089 o Dw a e AS 48 AES ES HOLIMS 1 1 4 NOILVOIHILN3GI Av dsig 55 aygo 30 35 3i S U S Patent Sep 26 1995 Sheet 4 of 17 5 453 939 a m Za m M e Fos 25 44 TER p e w to m T lt P als e T Tra E U S Patent Sep 26 1995 Sheet 5 of 17 5 453 939 U S Patent Sep 26 1995 Sheet 6 of 17 5 453 939 5 453 939 Sheet 7 of 17 Sep 26 1995 U S Patent Del JL N 3 9 zu 0 28 HD 169 99 5 uas N CS Vas Vas NEIS u U S Patent Sep 26 1995 Sheet 8 of 17 5 453 939 READ THE IDENTIFICATION CODE ARE TURN SIGNALS USED ON THIS VEHICLE READ THE TURN SIGNAL INPUTS Y IS THE RIGHT RN ON THE RIGHT TURN SIGNAL ON TURN ON IHE RIG IS THE LEFT M TURN ON THE LEFT TURN SIGNAL ON n TURN INDICATOR U S Patent Sep 26 1995 Sheet 9 of 17 5 453 939 Qv IEEE THE HIGH BEAM INDICATOR ON THIS IS THE HIGH BEAM ON TURN ON THE HIGH BEAM INDICATOR IS THE RETARDER INDICATOR USED NEN IS THE RETARDER ON Y TURN ON THE RETARDER INDICATOR
36. etal 340 52 4 376 298 3 1983 Sokol et al 364 551 4 442 424 4 1984 Shirasaki et al 340 52 4 497 057 1 1985 Kato et al 371 29 4 521 885 6 1985 Melocik et al 371 29 4 551 801 11 1985 Sokol 364 424 4 583 176 4 1986 Yamato et 364 431 11 List continued on next page FOREIGN PATENT DOCUMENTS 3837592A1 5 1990 Germany 60 107109 of 1985 Japan WOS89 12279 12 1989 WIPO W092 04693 3 1992 WIPO OTHER PUBLICATIONS Caterpillar Service Manual Computerized Monitoring System With LCD Bargraph Gauges published in 1991 Journal Article Microelectronics takes to the road in a big way a special report pp 113 122 in the Nov 20 1980 edition of Electronics Journal Article Expert systems applied to earth moving vehicle transmission troubleshooting pp 38 40 published in the Dec 1990 edition of Automotive Engineer Publication entitled Introducing the Vital Signs Monitor plus Load Weighing System by Marathon LeTrouneau published on or about 1988 Journal Article all on board with O amp K belived to have been published on or about Jan 1990 and sales literature attached thereto Article from Ropec Industries Inc re Micrologue tm Model SW100 which is a Vehicle Management System Primary Examiner Emanuel T Voeltz Assistant Exa
37. ge 13 the instrument causes that indicator light 14 to be steadily illuminated rather than flashed The instrument 10 also determines whether any of the switch type inputs have changed status by comparing the current status of each of the switch type inputs to the status stored in memory for that input If any of the switch type inputs have changed status the instrument 10 stores the new status in memory produces a control signal causing the warning horn 17 to produce an audible signal for advanta geously 0 5 seconds and produces a command causing the 2 digits normally used to display the three fourths of full scale units for the speedo tacho gauge 13 to indicate the pin number associated with the changed input If more than one switch type input has changed status the instrument 10 causes the pin numbers to scroll by alternatively producing commands to display each of the pin numbers Within each of the service and status mode the function of determining whether each of the inputs have changed status is repeated at predefined intervals Advantageously the interval is selected to be sufficiently short that substan tially any intermittent change of status caused by manipu lations of the wire harness or connectors by the technician is detected In the preferred embodiment the instrument 10 executes the algorithm illustrated in FIGS 10 and 10b while oper ating in the numeric readout mode The instrument 10 reads the service and clea
38. ge is a high or low warning style gauge in response to the gauge style identifier described above If the gauge is a low warning style gauge the gauge either illuminates or flashes the appropriate portions of the gauge in response to the retrieved segment number determined as described above Similarly if the gauge is a high warning style gauge the instrument 10 either illuminates or flashes the appropriate portions of the gauge in response to the retrieved segment number determined as described above In response to the switch type inputs the electronic control 10 determines whether and which indicator lights 14 should be flashed in a manner well known in the art For example if the data message associated with a particular switch type input indicates that the switch type sensor has been activated in response to a fault condition the indicator light 14 associated with that switch type sensor is illumi nated Referring now to FIGS 9a and 9b a flow chart of an algorithm illustrating operation of the instrument 10 while in the service and status modes is shown The instrument 10 reads the identification code and responsively retrieves a number of identifiers from a memory device not shown within the instrument 10 The identifiers are defined such that the microprocessor not shown within the instrument 10 determines for that particular machine the parameter monitored at each input from the wire harness the parameter 10 15 20
39. ground the clear input 52 and service input 50 The service and clear inputs 50 52 are advantageously used by the technician to select the mode of operation for the instrument 10 and to provide commands to the instrument 10 when operating in one or more of the modes of operation It should be understood however that many other devices may be used to select a desired operating mode The instrument 10 automatically enters the normal display mode of operation when power is applied To access other display modes the service and clear inputs 50 52 are grounded simultaneously When both inputs 50 52 are grounded a mode number corresponding to the current operating mode appears on a digital display 28 Preferably the five operating modes are numbered from 0 through 4 If the service and clear inputs 50 52 both remain grounded for advantageously 2 seconds the instrument 10 begins scroll ing through the modes When the desired mode is reached 5 453 939 7 i e the mode number corresponding to the desired operating mode is displayed on the digital display 28 the technician locks on to that mode by disconnecting the service and clear inputs 50 52 from ground While in the normal display mode the instrument 10 displays sensed parameter levels and indicates warning conditions in response to sensed parameters being outside a given range Vital vehicle functions are monitored and reported on the gauges and displays The gauges 12 prefer ably i
40. han one switch type input is in an open voltage condition the instrument 10 causes the pin numbers to scroll by alterna tively producing commands to display each of the pin numbers Advantageously the inputs are divided into a group including predominantly switch type sensors and a group including predominantly programming inputs Each of the switch type inputs including both the switch type sensors and the programming inputs is assigned a pin number corresponding to the connector contact number on which the signal is received In addition each of the switch type inputs being selected by the clear input 52 is assigned to one of the indicator lights 14 As set forth above when there are more switch type inputs than indicator lights 14 only a select group of inputs are assigned to the indicator lights 14 in response to the state of the clear input 52 Advantageously a table is also provided for reference by the technician to aid in identification of the switch type input corresponding to each of the pin numbers and indicator lights 14 The instrument 10 also reads the clear input 52 and responsively produces a command to flash each of the indicator lights 14 assigned to one of the switch type inputs having an open circuit condition Each time a pin number corresponding to one of the indicator lights 14 assigned to one of the switch type inputs being in an open circuit condition is displayed on the full scale units of the speedo tacho gau
41. he full scale units for the speedo tacho gauge 13 If the service input 50 is grounded the instrument 10 causes the fault codes and associated pin number for each of the stored fault conditions to be scrolled on the available displays such that each is displayed for a predefined period of time before being replaced by the fault code and associ ated pin number of another stored fault condition and so forth Once all of the stored fault conditions have been displayed the sequence is repeated If the technician disconnects the service input 50 from ground potential the fault codes and associated pin number are locked onto and the instrument 10 responsively stores the present status of each of the diagnosable sensor inputs in memory That is the memory device not shown includes an identifier for each of the diagnosable sensor signals indicating whether it is in a fault condition or a normal state at the time the service input 50 is removed from ground potential The instrument 10 compares the current status of the locked input to the status stored in memory for that input If the currently displayed fault condition has changed status then the instrument 10 stores the new status of that input in place of the previous status and produces a control signal causing the warning horn 17 to produce an audible signal for advantageously 0 5 seconds The instrument also produces a command to cause the pin number of that input to be displayed on the
42. he speedo tacho gauge 13 It should be noted that all pin numbers corresponding to inputs presently in a fault condition are displayed regardless of the state of the clear input 52 When the pin number is shown for a parameter presently displayed by an indicator light 14 that indicator light is steadily illuminated rather than flashed If the condition changes i e the parameter goes to a non fault condition the indicator light 14 turns off and the pin number is no longer displayed as being in a fault condition As described above the indicator lights 14 are only flashed or steadily illuminated in response to the state or pin number display respectively of inputs to which they are assigned in response to the state of the clear input 52 Pin number s are also displayed for a status change of any of the parameters monitored in the status mode e g a change from open to ground or ground to open In the case of multiple changes the pin numbers are scrolled These pin numbers are displayed on the 2 digits normally used to display the three fourths of full scale units for the speedo tacho gauge 13 The pin number information relating to inputs having changed status is erased from memory in response to leaving the status mode by simultaneously grounding the service and clear inputs 50 52 The warning horn 17 is used in the status mode to augment the usefulness of the indicator lights The warning horn 17 sounds briefly each time one of the swi
43. ighway work vehicle However not all machines will use all func tional indicators Thus the instrument 10 controllably enables each of the functional indicators 32 34 36 that are needed by the machine to which the instrument 10 is connected As is the case with the display segments associ ated with the gauges the functional indicators are also of VF design and are substantially visible to the operator only when illuminated by the instrument The instrument 10 monitors itself and the I O circuits for status for intermittent fault conditions and for current present fault conditions while in the normal display mode The instrument 10 monitors both diagnosable inputs i e those inputs that can be detected as being outside a valid range and switch type non diagnosable inputs The instru ment 10 also retains fault information relating to fault conditions on diagnosable inputs in non volatile memory not shown within the instrument 10 Thus the memory device not shown includes indications of each fault con dition relating to a diagnosable input that has existed on the machine whether or not the fault condition is currently present However fault conditions on switch type inputs are only indicated when present Advantageously the service and clear inputs 50 52 may be used to clear the stored fault information in one or more of the diagnostic modes If any fault conditions are sensed on the diagnosable inputs while in the normal display mo
44. instrument 10 produces a command to display the current parameter number on the gear display 30 Since the memory device includes identifiers assigning one of the sensed parameters to each of the gauges 12 used on each machine to which the instrument 10 may be con nected the instrument 10 determines which parameter is assigned to each gauge 12 by retrieving the identifiers for that machine from memory in response to the identification code Also in response to the identification code the inputs are defined for the parameters to be displayed in the numeric readout mode but which are not assigned to one of the gauges 12 Similarly a symbol 26 is also illuminated for each of the used gauges 12 in response to the symbol identifier retrieved from memory in response to the identi fication code as set forth above in connection with the normal display mode The instrument 10 reads all of the sensor inputs and graphically displays each of the parameters assigned to the gauges 12 The segments illuminated on each gauge is determined by scaling the sensor signal retrieving a param eter value in engineering units from memory in response to the scaled sensor signal and retrieving a segment number from memory in response to the parameter value which is representative of the number of gauge segments to be illuminated as described above in connection with the normal display mode The level of the parameter corresponding to the currently displayed para
45. ld retrieve for example the number 6 from the look up table and segments 2 through 6 would be illuminated if in the fill the graph mode The instrument 10 reads the display mode identifier from the identification line connected to the display mode select means 41 and builds and transmits a serial data message over the communication link To build the message the instru ment 10 retrieves a communication identifier from memory in response to the identification code The instrument 10 responsively determines which sensor data is to be trans mitted to which electronic controls 46 The communication identifier advantageously includes a group of commands of 5 453 939 19 a type well known in the art instructing the instrument 10 to build and transmit a serial data message The communication identifier preferably also includes a command establishing the period of time between data transmissions so the sensor data being sent to each of the electronic controls 46 is updated at the appropriate rate The instrument 10 responsively builds and transmits the serial data message over the communication link 48 at the desired rate If the gauge includes a plurality of symbols 26 the instrument 10 produces a control signal to illuminate one of the symbols 26 in response to a symbol identifier that is retrieved from the memory device not shown In the preferred embodiment the gauge includes two symbols and the symbol identifier indicates which of the t
46. llows more energy in the yellow or red portion of the electromagnetic spectrum to pass through the filter than energy in the blue green portion of the electro magnetic spectrum In the preferred embodiment the optical filter passes approximately 5 of the energy in the blue green portion of the electromagnetic spectrum approxi mately 7 5 of the energy in the yellow portion of the electromagnetic spectrum and approximately 16 percent of the energy in the red portion of the electromagnetic spec trum It should be understood however that the invention is in no way limited to these particular values and other transmissivity levels may be used in connection with the invention Advantageously each machine type has an identification code to be delivered to the instrament 10 which responsively reconfigures itself in response to the layout chosen by the designer for that machine In response to the identification code the instrument determines the parameter monitored at each input from the wire harness the functional indicators to be illuminated the type of display brightness control to be used the parameter that is displayed on each gauge the status report level for each input the gauges to be used the data to be transmitted over the communication link to another electronic control the signal filtering debounce scaling or averaging characteristics associated with each input and the functional relationship between each param eter valu
47. mal display mode The Module Identifier indicates which module diagnosed the fault condition The MID appears on the middle digits at the top center of the speedo tacho gauge 13 The Component Identifier indicates the component which has failed The CID is advantageously displayed as 3 digits on the digital display 28 The Failure Mode Identifier indicates the nature of the fault condition The FMI advantageously appears as a 1 2 digit number on the gear display 30 and is followed by the letter F If there are no fault codes available the CID and FMI appear as and F respectively While in the service mode system fault codes are viewed and or cleared individually Upon entering the service mode the fault codes identifying the first available fault condition are displayed To view the fault codes identifying the remaining fault conditions the service input 50 is grounded With the service input 50 grounded the instrument scrolls through all available fault conditions Any fault condition that is currently present is identified by the SERV CODE indicator 33 being illuminated When the fault is not present the SERV CODE indicator 33 is not illuminated When the service input 50 is disconnected from ground the instrument 10 locks onto the fault condition associated with the currently displayed fault codes To clear a particular fault condition once it has been locked the clear input 52 is grounded When a fa
48. meter number is displayed digitally on the digital display 28 In one embodiment the parameter value in engineering units that was retrieved from memory in response to the scaled sensor data is displayed whereas in another embodiment the scaled sensor signal is divided by a full scale value The instrument 10 then causes the digital display 28 to indicate the value of this ratio and thus indicate the percent of full scale being indicated by the sensor For example suppose the scaled sensor data described in connection with the operation of the numeric display mode is 128 The instrument 10 responsively retrieves 100 kPa from memory as the stored parameter value for oil pressure and produces commands causing the digital display 18 to indicate the number 100 to represent 100 kPa Alternatively the sensor signal is displayed as a percent of the full scale reading of the parameter sensor 11 For example if the scaled sensor data is 128 and the range of possible values is 0 255 then the instrument 10 produces commands to cause 5 453 939 23 the digital display 18 to indicate the number 50 to represent that the sensor signal is substantially at 50 percent of full scale If the currently displayed parameter number corresponds to one of gauges 1 through 6 the instrument 10 produces a signal to flash the outline segments of the selected gauge at preferably 1 Hz Alternatively the instrument 10 may also produce a command to flash the symbol
49. miner M Kemper Attorney Agent or Firm Thomas J Bluth Steven R Janda 57 ABSTRACT Systems for monitoring sensed parameters and diagnosing fault conditions are useful in many applications Advanta geously such systems are capable of operating in a plurality of operating modes and in connection with each of a plurality of machines In the subject invention a plurality of gauges are included for indicating the levels of the sensed parameters A plurality of symbols are included for identi fying sensed parameters A control receives an identification code and selectively illuminates one or more of a plurality of gauges and symbols in response to the identification code A plurality of warning lights are each associated with a switch type input A display selectively indicates a pin code for each switch type input having a fault condition The indicator lights having an associated switch type input in the fault condition are flashed A device selectively indicates a pin code in response to each diagnosable input having a present or a previous fault condition 2 Claims 17 Drawing Sheets DISPLAY MODE SELECT si a 48 46 ELECTRONIC CONTROL 5 453 939 Page 2 U S PATENT DOCUMENTS 4 975 848 12 1990 Abe et al 364 424 03 4 667 176 5 1987 Matsuda 340 52 a oe P 4
50. ndicate the level of a plurality of sensed parameters for example ground speed engine RPM oil temperature fuel level transmission oil temperature and the like and may be used in connection with any of a plurality of different machine types In the preferred embodiment one of the gauges 12 is a speedo tacho gauge 13 that displays either the speed of the vehicle or the RPM of the engine or transmis sion and includes scaling digits for displaying the magnitude of the sensed parameter at various points along the speedo tacho gauge 13 Since the desired scaling digits may be different for each machine the instrument 10 modifies the scaling digits in response to choices made by the designers of the machine to which the instrument 10 is connected Fault and warning conditions are brought to an operator s attention by the indicator lights 14 a flashing gauge a flashing alarm lamp and or a warning horn 17 Advanta geously the indicator lights 14 are lit in response to switch type inputs being in a fault condition In the preferred embodiment one or more of the indicator lights 14 are associated with fault conditions for parameters indicated by the gauges 12 When used in connection with some machines it is also desirable for the instrument 10 to include turn signal indi cators 32 a hi beam light indicator 34 and a retarder _ indicator 36 for informing the operator that a transmission retarder is engaged on for example a large off h
51. nt of the full scale reading of the parameter sensor 11 Once the numeric readout mode is entered the parameters are scrolled by grounding the service input 50 until the desired parameter number is displayed by the gear display 30 The technician disconnects the service input 50 from ground potential to lock onto the displayed parameter number The level of the selected parameter is displayed in digital form on the digital display 28 either in engineering units or as a percentage of the full scale sensor reading If the selected parameter corresponds to one of the parameters displayed on gauges 1 through 6 the outline segment for that gauge is flashed Each of the symbols 26 identifying the parameters being displayed on the gauges 12 is also illumi nated If either engine speed or vehicle speed is selected the appropriate unit identifier is illuminated to the right of the digital display 28 By using the numeric readout mode the technician can precisely determine the parameter level and or effectively troubleshoot sensors suspected of producing erroneous sig nals If for example it is desired to know the engine oil pressure at a specific engine speed it can be displayed directly in kPa by way of the numeric readout mode As another example assume that there is a suspicion about the accuracy of the transmission temperature sensor In the numeric readout mode the temperature can be displayed in degrees Celsius for comparison with a cer
52. o FIGS 4a 4e the operation of the gauges 12 is described As shown in FIGS 4a and 4b when it is desirable to indicate the level of a parameter for which it is advantageous to indicate a warning when the parameter exceeds a certain level for example hydraulic oil tempera ture on one of the gauges 12 in the fill the graph mode the high warning segments 20 are enabled the high outline segment 22 is illuminated and the indicating segments 16 are progressively illuminated in the clockwise direction as the sensed parameter increases from a low level to a maxi mum warning level FIG 4a illustrates a parameter for which it is desirable to indicate a high warning condition and being within the normal operating range As shown in FIGS 4c and 4d a parameter for which it is advantageous to indicate a warning when the parameter is below a certain level for example fuel level is indicated in the fill the graph mode by enabling the low warning seg ments 18 and illuminating the low outline segment 24 The indicating segments 16 are illuminated to indicate the sensed parameter being at a high level and progressively turned off in the counter clockwise direction as the level of the sensed parameter decreases FIG 4c illustrates a parameter for which it is desirable to indicate a low warning condition and being within the normal operating range FIG 4e illustrates a gauge 12 in the single bar mode indicating the level of a sensed parameter for which
53. own and determines whether the retarder indicator 36 should be illuminated The instrument 10 responsively illu minates the retarder indicator 36 if the retarder input is at a state being defined to indicate that the retarder is engaged In response to the identification code of the machine thc instrument 10 retrieves a display brightness identifier from memory not shown The display brightness identifier informs the instrument 10 whether the display brightness level is to be controlled in response to a photocell 38 only a photocell 38 and a single pole single throw switch 40 or a photocell 38 and a single pole double throw switch 40 The display brightness identifier thus has one of three states being defined within the instrument 10 to control the display brightness level in one of tbe three manners If the display brightness identifier indicates that the brightness level is to be controlled in response to the photocell 38 only the instrument 10 reads a control signal from the photocell input only The signal from the photocell 38 is dependent upon the level of ambient light Thus the instrument 10 is able to adjust the drivers of the VF display segments to control the display brightness level in response to the level of ambient light If the display brightness identifier indicates that thc brightness level is to be controlled in response to the photocell 38 and a single pole single throw switch SPST the instrument 10 reads control
54. r inputs 50 52 and in response to receiving a grounded signal on both of the service and clear inputs 50 52 the instrument 10 individually produces com mands to display the mode numbers on the digital display 28 20 25 30 35 40 45 50 55 60 65 22 for a predefined length of time When the service and clear inputs 50 52 are removed from ground potential while the instrument is producing the command to display the mode number corresponding to the numeric readout mode the instrument 10 begins operating in the numeric readout mode If the instrument 10 is not in the numeric readout mode a timer is reset to zero and the parameter number is set to zero in the memory device within the instrument 10 If the instrument 10 is operating in the numeric readout mode the instrument 10 determines whether the parameter numbers should be scrolled by reading the service input 50 If the service input 50 is not grounded the timer is reset to zero and the instrument 10 produces a command to display the current parameter number on the gear display 30 If the service input 50 is grounded the timer is checked to determine whether it has exceeded a predefined maximum If the timer has exceeded the predefined maximum the parameter number is increased by one the timer is reset to zero and the instrument 10 causes the current parameter number to be displayed on the gear display 30 If the predefined maximum has not been exceeded the
55. s the fault condition is defined as the open voltage condition thus whenever the wire between the sensor and the display is severed or disconnected a fault condition is indicated Similarly if the switch type input is connected to a switch type sensor the switch type sensor disconnects the sensor output from ground potential when the sensed parameter exceeds a warning level Some prior art systems have illuminated a warning light for each switch type sensor that is in a fault condition Each warning light is associated with one of the switch type sensors and is illuminated when the display input associated with that switch type sensor is indicating a fault condition While adequate for many purposes in other cases it is advantageous to also indicate the pin number of the input associated with the switch type sensor Optimally the tech nician should be able to determine the pin number of each of the warning lights indicating a fault condition even though there are more than one of such warning lights This would allow technicians to more readily identify the fault condition and associate the sensor having the fault condition to the relevant connector pin While troubleshooting some diagnosable sensor prob lems it is sometimes difficult to determine whether a sensor is producing a signal that is truly representative of the actual level of the sensed parameter This often results in techni 5 453 939 3 cians spending time replacing s
56. s the instrument 10 begins scroll ing through the modes When the desired mode is reached i e the mode number corresponding to the desired operating mode is displayed on the digital display 28 the technician locks on to that mode by disconnecting the service and clear inputs 50 52 from ground While operating in the normal display mode the instru ment 10 assigns each of the sensed parameters to a gauge 12 in response to the identification code The gauges 12 each include indicating segments forming the middle portion of the gauge with two warning segments at both the top and bottom of the gauge For each gauge the high warning segments are enabled if the instrument 10 assigns a param eter to that gauge 12 for which it is desirable to indicate a warning condition when the parameter exceeds a certain level whereas the low warning segments are enabled if the instrument 10 assigns a parameter for which it is desirable to indicate a warning condition when the parameter is below a certain level When a gauge 12 is to be used to indicate a parameter level the central outline segments 23 one of the high or low outline segments 22 24 and the appropriate ISO symbol 26 are illuminated If a gauge is not being used on a particular machine the symbol 26 and outline segments 22 23 24 are not illuminated Since the optical filter only allows the VF displays to be substantially visible when the segments are illuminated by the instrument 10 the gauge
57. s has been manually adjusted the photocell 38 continues to control the display brightness level as described above in response to the ambient light level For each of the gauges other than the speedo tacho gauge 13 the instrument 10 determines whether the gauge is a high or low warning style gauge Advantageously this is deter mined by retrieving a gauge style identifier from memory within the instrument 12 for each gauge to be used The gauge style identifier is retrieved from the memory device in response to the identification code Each of the gauge style identifiers are selected in response to choices made by the vehicle designers regarding which parameters are to be displayed and the preferred display format for each param eter If the gauge is a low warning style gauge the low outline segment 24 is illuminated and the low warning segments 20 are enabled If the gauge is a high warning style gauge the high outline segment 22 is illuminated and the high warning segments 18 are enabled The instrument 10 reads the sensor signals from the wire harness Since the sensor signals may be in the form of pulse width modulated signals frequency signals or switch type binary signals the instrument 10 converts and scales the inputs to a microprocessor readable form in manners 20 30 40 45 50 55 60 65 18 well known in the art For example if the output from one of the pulse width modulated sensors is sensing oil pre
58. se particular vehicle functions and conditions in response to signals from pre identified sensors Accordingly such dedi cated instruments generally cannot be readily modified to accommodate different machines different sensors and or different conditions and functions Rather such instruments are generally limited to use with a particular vehicle type or model for which the instrument has been designed However it is advantageous for these instruments to be usable in connection with many different machines Lower costs are achieved and less warehousing space is required if a single instrument can be manufactured which can be used in many different applications Similarly service time is reduced if software changes are avoided when an instrument is moved from one machine to another Some prior art systems have provided for standardized monitoring systems that are usable in connection with a variety of machines for example the system shown in U S Pat No 4 551 801 issued to Sokol on Nov 5 1985 While being an improvement over dedicated systems this moni toring system is still relatively inflexible and requires the addition or subtraction of monitoring modules and the use of decals to indicate the parameters being shown by each display module One area of desired flexibility is for each gauge in the instrument to be capable of indicating parameters having a high warning level for example engine temperature and also parameters ha
59. sed adjacent the digital display 28 The gear display 30 indicates the number and direction i e forward neutral or reverse of a vehicle transmission While in the service mode the instrument 10 identifies and diagnoses fault conditions in diagnosable inputs i e those inputs that can be detected as being outside a valid range In the preferred embodiment the sensors 11 diag nosed in the service mode are frequency based sensors or pulse width modulated sensors having a duty cycle being indicative of the level of the sensed parameter Predefined maximum and minimum frequencies or duty cycles define the valid range If the sensor signal is outside the valid range the instrument 10 recognizes the condition as a fault The service mode also is used advantageously to determine whether certain circuits are shorted to ground for example a warning horn circuit If an input is unused on the machine to which the instrument 10 is connected the instrument 10 ignores the unused input and does not indicate a fault condition The instrument 10 displays information relating to fault 5 453 939 1 conditions stored in memory Fault conditions are preferably identified by fault codes including a Module Identifier MID a Failure Mode Identifier FMI and a Component Identifier CID Advantageously the MID FMI and CID are displayed on the instrument 10 by illuminable displays also used in connection with the instrument 10 operating in the nor
60. signals from both the pho tocell input and the brightness switch input The signal from the photocell 38 is dependent upon the level of ambient light and the signal from the brightness switch 40 is dependent upon operator action The control signals from the photocell 38 and SPST switch 40 work in tandem to cause the instrument 10 to control display brightness The photocell 38 controls the brightness level as described above however the operator can manually adjust the brightness level by actuating the SPST switch 40 5 453 939 17 When the brightness switch input is grounded the instru ment 10 responsively cycles the display brightness level First the instrument 10 decreases the brightness level in steps to the minimum level and then increases the bright ness level in steps to the maximum level The magnitude of the steps are selected in response to the desired degree of control and the desired number of actuations required in one cycle of brightness levels After the display brightness has been manually adjusted the photocell continues to control display brightness as described above in response to changes in the ambient light level If the display brightness identifier indicates that the brightness level is to be controlled in response to the photocell 38 and a single pole double throw SPDT momentary switch 40 the instrument 10 reads control signals from the photocell input and the two brightness switch inputs from the SPDT s
61. ssure and has a duty cycle of 70 and the range of the scaled signal is from 0 255 the binary number 179 is assigned as the scaled sensor data for the oil pressure parameter In response to the scaled sensor data from the pulse width modulated and frequency sensors the instrument 10 deter mines which segments are to be illuminated on each gauge In the preferred embodiment the memory device not shown includes a plurality of stored parameter values corresponding to each possible magnitude of the scaled data for each sensed parameter The memory device not shown also includes a plurality of segment numbers included in a look up table of a type well known in the art to indicate the number of segments to be illuminated in response to each of the stored parameter values The instrument 10 thus maps the parameter value to the number of segments to be illuminated on the associated gauge Alternatively an equa tion could be developed defining the relationship between the parameter values and the segment commands and could be solved in place of the use of the look up table Similarly the scaled data could be mapped directly to the segment numbers In the preferred embodiment the high and low warning segments 18 20 and indicating segments 16 are numbered starting with the most counter clockwise positioned segment and progressing in the clockwise direction from 0 through 12 Provided that the sensed parameter is not below the low warning value
62. tch type inputs changes state The sounding of the warning horn 17 occurs for any of the parameters available in status mode The augmentation added by the warning horn 17 makes it possible for the technician to determine when a change of state has occurred even when working remotely from the instrument 10 which is advantageously fixedly located in the operator s station of a vehicle While in the tattletale mode all gauges and readouts are displayed in the most extreme readings since the previous time the tattletale mode was cleared Low warning style gauges display the minimum readings High warning style gauges display the maximum readings The speedo tacho gauge 13 displays the maximum reading Also any indicator light 14 that was activated since the previous time the tattletale mode was cleared is activated As an aid to the diagnosis of faulty sensors the numeric readout mode is included to digitally display the magnitude of sensed parameters n the preferred embodiment a num ber is displayed on the digital display 28 indicating the level of the sensed parameter in engineering units For example if the instrument 10 determines that the oil pressure is 100 kPa then the digital display 28 indicates the number 100 to represent 100 kPa In the preferred embodiment the number displayed for system voltage is equivalent to the sensed voltage multiplied by ten Thus if the sensed system voltage is 23 5 the digital display 18 indicates
63. technician manipulates the wire harnesses or wire connectors to deter mine the point at which the fault has occurred Prior art systems have indicated when fault conditions are present In connection with such systems the technician must view a visual display to determine whether the condi tion is present In troubleshooting intermittent problems when the fault condition is not currently present the tech nician must manipulate wire harnesses and connectors to recreate the fault and thus cause the fault indication to be displayed When the fault condition is present the techni cian must manipulate wire harnesses and connectors and observe whether the manipulations eliminate the fault and thus cause the fault indication to disappear In many cases however the machine is of sufficient size that the technician must leave the area of the diagnostic tool to recreate the fault condition Therefore any visual indi cator provided by the diagnostic tool is not visible to the technician To effectively troubleshoot the electrical system on such a large machine typically two or more technicians are required and repair expenses are thus greatly increased Similarly the vehicle may not be repairable immediately if only a single technician is available In addition these machines typically include switch type inputs that are either in an open voltage or grounded condition One of the voltage conditions is defined as a fault condition In most case
64. the number 235 Alternatively the sensor signal is displayed as a percent of the full scale reading of the parameter sensor 11 For example if the sensor is pulse width modulated and has a duty cycle of 50 percent then the digital display 28 indicates the number 50 to represent that the sensor signal is at 50 percent of full scale Each parameter is advantageously displayed in engineer ing units as follows 20 25 40 50 55 60 65 14 Temperatures degrees C Pressures kPa Speeds RPM Ground Speed MPH or km h Parameters are identified by their parameter number which is indicated on the gear display 30 for example as follows PARAMETER PARAMETER 0 Ambient Light Level 1 Gauge 1 2 Gauge 2 3 Gauge 3 4 Gauge 4 5 Gauge 5 6 Gauge 6 7 Engine Speed 8 Vehicle Speed 9 System Voltage where the gauges 12 other than the speedo tacho gauge 13 are numbered from left to right top to bottom starting with the upper left hand gauge such that the upper left hand gauge is known as gauge and the lower right hand gauge is known as gauge 6 In addition to the parameter number the parameters associated with the gauges 12 other than the speedo tacho gauge 13 are identified by flashing the central outline segments 23 and one of the high and low outline segments 22 24 for the gauge indicating that parameter value The parameter being displayed by the flashing outline segments is identified by referring to the illumin
65. tified temperature measurement Any specific values used in the above descriptions should be viewed as exemplary only and not as limitations Other aspects objects and advantages of this invention can be obtained from a study of the drawings the disclosure and the appended claims We claim 1 An apparatus for indicating levels of sensed parameters telated to machine operation warning conditions and fault conditions on any of a plurality of machines having an instrument panel and a plurality of switch type inputs and diagnostic inputs said instrument panel operating in one of a plurality of modes including a normal display mode a service mode a status mode and a numeric readout mode comprising means for producing an identification code each of the plurality of machines having a unique identification code for identifying the machine to which the apparatus is connected a plurality of diagnostic sensor means for sensing a plurality of parameter levels and responsively produc ing a plurality of diagnostic sensor signals a plurality of gauge means for indicating a level of the sensed parameters a plurality of symbol means for identifying the sensed parameter being indicated on each of said gauge means said plurality of gauge and symbol means being sub stantially visible to an operator only when illuminated 10 15 20 25 30 35 40 45 50 55 60 65 26 means for selecting the normal display mode
66. to be used in connection with each of a plurality of machine types In one aspect of the invention an apparatus is provided for indicating levels of sensed parameters warning condi tions and fault conditions on a machine having an instru ment panel The machine also includes a plurality of switch type inputs and diagnosable inputs which each indicate one of a normal state and fault condition A plurality of gauges are included for indicating the levels of the sensed param eters A plurality of symbols are included for identifying the sensed parameters A control receives an identification code and selectively illuminates one or more of the plurality of gauges and symbols in response to the identification code A plurality of warning lights are each associated with one of the switch type inputs A display selectively indicates a pin code for each switch type input having a fault condition The indicator lights having an associated switch type input in the fault condition are flashed A plurality of diagnosable sen sors produce a plurality of diagnosable sensor signals A device selectively indicates a pin code in response to each of the diagnosable inputs having a present or a previous fault condition In another aspect of the invention a method is provided for indicating levels of sensed parameters warning condi tions and fault conditions on a machine having an instru ment panel and a plurality of switch type inputs and diag nosable
67. ult condition has been cleared the fault codes associated with the next available fault condition appear as soon as the clear input 52 is disconnected from ground By grounding and ungrounding the clear input with the service input ungrounded all fault codes are cleared one at a time Fault codes are saved by grounding the service input and scrolling past fault codes without clearing them When all fault codes have been cleared the display remains blank for 3 seconds then the CID and appears as and F respectively A pin number is assigned to each of the inputs to the instrument 10 If the fault condition that has been locked upon represents a condition related to the instrument 10 the pin number associated with that condition is shown on the 2 digits normally used to display the full scale units for the speedo tacho gauge 13 Pin numbers are also shown for change of state condi tions ie a change from being within the valid range to being outside the valid range or vice versa The pin numbers monitored for this feature include all diagnosable condi tions not just the fault condition upon which the instrument 10 is locked Thus for example even though locked upon a transmission temperature diagnostic if while inspecting or disturbing the harness the transmission tem perature and the fuel level and the brake air pressure all changed state the connector pin numbers associated with each of these parameters ar
68. ument Each time a pin number corrc sponding to one of the flashing indicator lights 14 is dis played that indicator light 14 is steadily illuminated rather than flashed The pin number of each switch type input having changed states is also displayed The warning horn 17 augments the usefulness of the indicator lights 14 by sounding briefly each time any of the switch type inputs changes states The augmentation allows the technician to determine when a switch type input has changed state even when working remotely from the instrument 10 The pin numbers of switch type inputs having changed status are also displayed to provide the technician with a visual indication of which inputs have changed state While in the tattletale mode all gauges and readouts are displayed in the most extreme readings since the previous time the tattletale mode was cleared Low warning style gauges display the minimum readings High warning style gauges display the maximum readings The speedo tacho gauge 13 displays the maximum reading Also any indicator 5 453 939 25 light 14 that was activated since the previous time the tattletale mode was cleared is activated The numeric readout mode is included to digitally display the magnitude of sensed parameters In the preferred embodiment a number is displayed on the digital display 28 indicating the level of the sensed parameter in engineering units Alternatively the sensor signal is displayed as a perce
69. ving a low warning level for example brake fluid pressure Prior art systems required the use of decals to indicate that the gauge was indicating the level of a parameter having either a high or low warning level and or the use of a separate warning light to show that the param eter was outside the normal operating range To maximize system flexibility it is advantageous for the instrument to be capable of performing a number of diag nostic functions in addition to displaying parameter values and indicating warning conditions Today s machines and 20 25 40 45 50 55 60 65 2 particularly large off highway work vehicles are becoming increasingly complex in their design thus making it more and more difficult for service personnel to locate defects in machine sensors and systems This is particularly true of intermittent defects not resulting in a breakdown of a system or the vehicle but which interfere with its operation A major frustration when troubleshooting electrical prob lems on a large work vehicle is caused by intermittent problems Typically the operator reports some symptom to a technician and before the technician can get to the machine the problem is no longer present If the condition is not present it is helpful for the techni cian to re create the fault condition In many cases the fault condition is caused by a short to ground potential or an open circuit To recreate these fault conditions the
70. witch 40 known as the brightness up and brightness down inputs The signal from the photocell 38 is dependent upon the level of ambient light and the signal from the brightness switch 40 is dependent upon operator action The control signals from the photocell 38 and SPDT switch 40 work in tandem to cause the instrument 10 to control display brightness The photocell 38 controls the brightness level as described above however the operator can manually adjust the brightness level by actuating the SPDT switch 40 in each of the two directions The operator adjusts the brightness level either up or down from the value selected by the photocell 38 depending on which way the SPDT switch 40 is activated The SPDT switch 40 controls a brightness down input and a brightness up input The instrument 10 adjusts the drivers of the VF display segments to control the display brightness level in response to the photocell input and the brightness up and brightness down inputs When the brightness down input is grounded the instrument 10 decreases the display brightness level in incremental steps until the minimum brightness level is reached When the brightness up input is grounded the display brightness increases in steps until the maximum brightness level is reached The magnitude of the steps are selected in response to the desired degree of control and the desired number of actuations required in one cycle of brightness levels After the display brightnes
71. wo symbols 26 should be illuminated in response to the parameter assigned to that gauge Since the parameter assignment is made in response to the identification code the symbol identifier is also advantageously retrieved in response to the identifica tion code In response to the display mode identifier the instrument 10 determines whether the parameters should be displayed in the fill the graph mode or the single bar mode In the preferred embodiment the fill the graph mode is indicated when the display mode identifier is in an open or floating voltage condition and the single bar mode is indicated when the display mode identifier is at a ground potential If the display mode identifier is at an open or floating voltage condition and thus in the fill the graph mode the instrument determines whether the gauge is a high or low warning style gauge in response to the gauge style identifier described above If the gauge is a low warning style gauge the gauge either illuminates or flashes the appropriate por tions of the gauge in response to the retrieved segment number determined as described above Similarly if the gauge is a high warning style gauge the instrument 10 either illuminates or flashes the appropriate portions of the gauge in response to the retrieved segment number determined as described above If the display mode identifier is at a ground potential and thus in the single bar mode the instrument 10 determines whether the gau
72. ying parameters and informing an operator by visible and or audible indications when a warning condition exists The instrument 10 is advantageously microprocessor based and functions in response to internal software The instru ment 10 includes a plurality of indicator lights 14 preferably LEDs and a plurality of electronic gauges 12 having a plurality of illuminable segments preferably of the vacuum fluorescent VF type The instrument 10 is connected to each of a plurality of sensors 11 by a wire harness The instrument 10 preferably performs some processing of signals received from the sensors over the wire harness and scales the signals received from pulse width modulated type sensors and frequency based sensors in manners well known in the art Similarly 5 453 939 5 the instrument 10 receives signals from switch type inputs The signals associated with these inputs are received by the instrument 10 but generally no scaling is required VF displays provide a visually attractive appearance however ambient light often causes VF display segments to appear to be illuminated even though the control to which the display is connected is not producing an electrical signal to illuminate the display segments Thus the display is difficult to read since there is very little contrast between segments that are illuminated by the control and those segments that appear to be illuminated due to ambient light To improve contrast an optical

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