JPH0833306B2 - Vehicle diagnostic device and analog display method for vehicle diagnostic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an electronic control device mounted on a vehicle,
A vehicle diagnostic device for reading and displaying data values by bidirectional communication of input and output data in the electronic control device,
More specifically, the present invention relates to a vehicle diagnostic device for displaying positive and negative signed digital data in a two's complement representation format output from the electronic control device as analog data, and an analog display method for the vehicle diagnostic device.

Recently, most electronic devices process internal data as digital data, and when displaying and reading out these digital data, if the digital data changes at high speed, the data is difficult to read, and changes at such high speed. When displaying data via a holding circuit such as a latch in order to read digital data, it may be difficult to understand the content of the data because there is a time delay with respect to changes in the data, and it may be easier to understand it as an analog value. There were many.

Such an analog display device is also required for a vehicle diagnostic device that reads digital data output from an electronic control device mounted on a vehicle and performs a failure diagnosis.

The one that displays the digital data of the electronic control unit mounted on the vehicle as analog data is the actual development of Sho 58-12.
This is disclosed in Japanese Patent No. 4626, which displays a self-diagnosis result of an automobile engine control device mounted on a vehicle using an analog meter.

However, there are two types of digital data in the internal representation of this kind of electronic control device, an unsigned binary number representation and a signed two's complement representation. Normally, an analog meter is represented by a binary number representation. It is designed to swing. In this case, for example, for 8-bit data, 00H to FFH
Corresponds to full scale from the zero point of the analog meter.

On the other hand, when the signed 2's complement data is displayed on this analog meter, for example, the data of -1,0, + 1 is FFH, 00H, 01H. The pointer bounces because it returns to zero and then becomes +1 and it is very difficult to read because there is a delay in the pointer, etc. In particular, when the fluctuation of data at +-around 0 is large, the pointer always bounces greatly, It was difficult to read the value from the analog meter.

Therefore, as shown in FIG.
The applicant of the present invention has devised a technique for converting the data of the complementary expression of ## EQU1 ## and displaying it by allocating it to the left and right with the center of the analog meter 100 as the zero point (Japanese Patent Application No. 63-109742).

[Problems to be Solved] However, since most of the data represented by the two's complement changes in the vicinity of zero, if it is displayed as it is, as shown in FIG.
00a shows only a slight swing angle near the zero point. Therefore,
There is a problem that the pointer only shakes only in a part of the display range of the analog meter, that is, only near the zero point, making it difficult to read the data and increasing the reading error.

In view of the above circumstances, the present invention divides positive and negative digital data in a two's complement representation format output from an electronic control unit mounted on a vehicle into positive and negative values from a zero point and easily displays them in an analog form for analysis by a diagnostic operator. An object of the present invention is to provide a vehicle diagnostic device capable of improving workability and an analog display method for the vehicle diagnostic device.

[Means for Solving the Problems] In order to achieve the above object, the invention according to claim 1 is connected to an electronic control device mounted on a vehicle, and input / output data in the electronic control device is read by bidirectional communication. In the vehicle diagnostic device for displaying the data value by, the digital / analog conversion means for analog-converting the digital data of the two's complement expression format output from the electronic control device and the analog value after the analog conversion are compared with the set value. Then, the comparison means for judging whether the digital data is a positive value or a negative value and the normal display and the enlarged display are selectively switched. When the normal display is at the front end, the analog after analog conversion by the digital / analog conversion means is performed. When the enlarged display is selected, the value is output as it is, and the analog value obtained by multiplying the analog value after analog conversion by the digital / analog conversion means by a predetermined value When it is determined by the expansion switching means that outputs a zoom value and the comparison means to be a positive value, a preset offset value for determining the zero point is added to the analog value output from the expansion switching means. The value after the addition is displayed on the analog display means as a deviation from the zero point, and when it is determined to be a negative value, the offset value is subtracted from the analog value output from the enlargement switching means and the subtraction is performed. Display conversion means for displaying the subsequent value on the analog display means as a deviation from the zero point.

The invention according to claim 2 is an analog display method of a vehicle diagnostic device, which is connected to an electronic control device mounted on a vehicle, reads input / output data in the electronic control device by bidirectional communication, and displays the data value in analog. The digital data in the two's complement representation format output from the electronic control unit is input, and the presence / absence of a data enlargement display request is determined, and the digital data is a positive value based on the value of the most significant bit in the digital data. If the digital data is a positive value when an enlarged display request is made, the data value of the digital data is multiplied by a predetermined value and then a preset offset value is added to determine the zero point. Display data, and when the digital data is a negative value, the data of the digital data from the preset full scale value After the difference calculated by subtracting is multiplied by a predetermined value, the value multiplied by the predetermined value is subtracted from the offset value to obtain display data. At the time of normal display request, when the digital data is a positive value, The offset value is added to the data value to form display data. When the digital data value is a negative value, the offset value is subtracted from the data value of the digital data to form display data, and the display data is converted to analog. After that, the deviation from the zero point is displayed in analog.

[Operation] In the invention described in claim 1, when input / output data in the electronic control unit mounted on the vehicle is read into the vehicle diagnostic device by bidirectional communication and displayed in analog, a two's complement representation format output from the electronic control unit. The analog value obtained by analog-converting the digital data of (1) by the digital / analog converting means is compared with the set value by the comparing means to determine whether the digital data value is a positive value or a negative value. When the normal display is selected by the enlargement switching means,
The analog value after the analog conversion by the digital / analog conversion means is output from the enlargement switching means to the display conversion means as it is, and when the enlarged display is selected, the analog value is multiplied by a predetermined value and output to the display conversion means. . In the display conversion means, when the digital data is a positive value, a preset offset value for determining the zero point is added to the analog value output from the enlargement switching means, and the added analog value is When the digital data has a negative value, the offset value is subtracted from the analog value output from the enlargement switching means, and the analog value after the subtraction is the above-mentioned value. The deviation from the zero point is displayed on the analog display means.

According to the second aspect of the present invention, when the input / output data of the electronic control unit mounted on the vehicle is read into the vehicle diagnostic device by bidirectional communication and displayed in analog, the digital data of the two's complement representation format output from the electronic control unit. It is determined whether the data value of the digital data is a positive value or a negative value based on the value of the most significant bit in. Then, at the time of requesting enlarged display, when the data value is a positive value, after multiplying the data value by a predetermined value, a preset offset value for determining the zero point is added to obtain display data, and the display data is When the data is a negative value, the difference calculated by subtracting the data value from the preset full scale value is calculated. After being multiplied by a predetermined value, this value is subtracted from the offset value to obtain display data, and the display data is analog-converted to be displayed in an analog state with a large deviation from the zero point. On the other hand, normally, at the time of a display request, when the data value is a positive value, a read / set offset value that determines a zero point is added to the data value to obtain display data, and the display data is converted into an analog signal from the zero point. Is displayed in an analog state in the normal state, and when the data value is a negative value, the offset value is subtracted from the data value to obtain display data, and the display data is converted into an analog signal to convert it from the zero point. Analog display with normal deviation.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment of the present invention, FIG. 1 (a) is an external view of a vehicle equipped with an electronic control unit, and FIG. 1 (b) is a vehicle diagnosis having an analog display means. FIG. 2 is an external view of the device, FIG. 2 is a block diagram of an electronic control device and a vehicle diagnostic device mounted on a vehicle, and FIG. 3 is a display diagram of an analog meter.

(Structure) In FIG. 1, reference numeral 100 is a vehicle such as an automobile, 1 is an example of an electronic device, and is an electronic control unit (ECU) mounted on the vehicle 100 for performing air-fuel ratio control and the like. As shown in FIG. 2, a central processing unit (CPU) 2, a read / write memory (RAM) 3, and a read-only memory (ROM) of the ECU 1
4, an input interface 5, and an output interface 6
And are connected via a bus line 7.

Output signals from various sensors such as a cooling water temperature sensor, a 02 sensor, a suction pipe negative pressure sensor, a throttle opening sensor, and an engine speed sensor are input to the input interface 5.

In the ECU 1, the various signals are subjected to data processing according to a program stored in the ROM 4, and once stored in the RAM 3, the CPU 2 performs various arithmetic processing based on the stored data. Based on the calculated data, the actuators such as a fuel pump solenoid, a canister purge solenoid, an EGR actuator, an idle control actuator, an ignition coil, and an injector via the output interface 6 and the drive circuit 8 are used. Outputs control signal.

Here, the ECU 1 is connected to the vehicle diagnosis device 60 via the connector 60a, and various kinds of failure diagnosis are performed. The vehicle diagnostic device 60 is provided in a dealer service factory or the like, and includes a control unit 10, a comparison means 20a that is built in the vehicle diagnostic device 60 or is replaceably connected, a display conversion means 20b,
It is composed of an analog meter 35 as an analog display means, an enlargement switching means 40 and the like.

The control unit 10 has a CPU 12 and a RAM 1 via a bus line 11.
3, ROM1, input / output I / O) interface 15, and D / A converter 16 as digital / analog conversion means are connected to each other, and diagnostic target data is stored in the ECU 1 according to the diagnostic program stored in ROM 14. Command the output request of
The output signal from the ECU 1 is read via the I / O interface 15.

The switch SW0 is normally 2 when connected to the contact A.
This is a selection switch for displaying digital data in binary notation in analog form and, when it is connected to the contact B, distributes positive and negative signed digital data (data in two's complement form) into positive and negative and analog display.

In the comparison means 20a, the inverting input terminal of the comparator 21 is connected to the output terminal of the D / A converter 16, while the non-inverting input terminal of the comparator 21 has both ends between a positive power supply and ground. The sliding terminal of the connected variable resistor 27 is connected. In the display conversion means 20b, the output terminal of the comparator 21 is connected to the input terminal of the inverter 22 and the control terminal of the analog switch 23, and the input terminal of the analog switch 23 has a positive power supply and a ground at both ends. It is connected to the sliding terminal of the variable resistor 28 connected in between. Further, the output terminal of the analog switch 23 is connected to the inverting input terminal of the operational amplifier 25 via the resistor 30.

The output terminal of the inverter 22 is connected to a control terminal of an analog switch 24, and the input terminal of the analog switch 24 is connected to a sliding terminal of a variable resistor 29 having both ends connected between a positive power supply and the ground. It is connected. Further, the output terminal of the analog switch 24 is connected to the inverting input terminal of the operational amplifier 25 via the resistor 30.

The operational amplifier 25 is configured as an adder, and its inverting input terminal is connected to the output terminal of the D / A converter 16 via the resistor 31 and the expansion switching means 40 in addition to the above. . On the other hand, the non-inverting input terminal of the operational amplifier 25 is grounded, and the output terminal and the inverting input terminal are connected via the feedback resistor 32. Further, the output terminal of the operational amplifier 25 is connected to the inverting input terminal of the operational amplifier 26. The operational amplifier 26 is configured as an inverter, a non-inverting input terminal is grounded, and an output terminal and an inverting input terminal are connected via a feedback resistor 33. Further, the output terminal of the operational amplifier 26 is connected to the contact B of the switch SW0. The contact SW of the switch SW0 is connected to the output terminal of the D / A converter 16.

The expansion switching means 40 includes an operational amplifier 41 forming an inverting amplifier, an operational amplifier 42 forming an inverter, operational amplifiers 43 and 44 forming a differential amplifier, analog switches 45 and
46, a switch SW1 and the like, which amplifies the analog output converted by the D / A converter 16 to enlarge the data, and outputs it to the display conversion means 20b.

The output of the D / A converter 16 is the operational amplifiers 41 and 43.
Of the switch SW1 and the inverting input terminal of the switch SW1 via resistors 47 and 50, respectively.

The inverting input terminal of the operational amplifier 41 is connected to the output terminal via the feedback resistor 48, and this output terminal is further connected to the inverting input terminal of the operational amplifier 42. On the other hand, the non-inverting input terminal of the operational amplifier 41 is grounded. In the operational amplifier 42, the non-inverting input terminal is grounded, the inverting input terminal is connected to the output terminal via the feedback resistor 49, and the output terminal is connected to the input terminal of the analog switch 45.

On the other hand, the inverting input terminal of the operational amplifier 43 is a feedback resistor 51
Is connected to the output terminal via the resistor 54, and this output terminal is connected to the inverting input terminal of the operational amplifier 44 via the resistor 54. The output terminal of the operational amplifier 44 is connected to the input terminal of the analog switch 46. The non-inverting input terminals of the operational amplifiers 43 and 44 are respectively connected to the sliding terminals of the variable resistors 52 and 56 whose both ends are connected between the positive power source and the ground, and further to the non-inverting input terminal. Are connected to resistors 53 and 57 whose one end is grounded.

The analog switches 45 and 46 are connected to their respective control terminals, the output terminal of the comparator 21 of the comparison means 20a and the output terminal of the inverter 22 of the display conversion means 20b.
Both output terminals of 46 are connected to the contact D of the switch SW1.

Here, when an instruction to transmit data from the control unit 10 to the ECU 1 is given by operating the vehicle diagnostic device 60, the EC
Digital data is transmitted from U1, converted into analog data by the D / A converter 16, and output to the analog meter 35. Furthermore, if the digital data is positive / negative signed data, the analog data is the switch SW.
By connecting 0 to contact B, the analog meter 3
The display conversion means 20b can be used to display the analog data 35 with a deviation from the zero point so that the zero point of the pointer 35a of 5 is substantially centered with respect to positive and negative data. In this case, when the switch SW1 is switched from the contact C to the contact D, the display on the analog meter 35 is enlarged.

(Operation) Next, the operation of the embodiment having the above configuration will be described.

If the data from the above ECU1 is 8-bit data, 0000
A digital signal is output as 0000 to 11111111 and is input to the D / A converter 16 via the I / O interface 15.
If this is expressed in decimal, the data changes in the range of 0-255. In the D / A converter 16, the digital signal as the 8-bit data is converted into an analog signal, and the voltage corresponding to the digital data 0 to 255 (hexadecimal notation 00H to FFH, the following numerical values are explained in decimal) Is output.

Here, there are two types of digital data representations: an unsigned binary representation and a signed two's complement representation.
The switch SW0 is operated according to any of the above.

(Unsigned Digital Data) In the case of ordinary unsigned binary-expression digital data, the switch SW0 is connected to the contact A.

If the digital data from the ECU1 is 8-bit data, the digital data input to the D / A converter 16 is 0 to 2
Converted to an analog voltage corresponding to the 55 range. Therefore, by associating the digital data from 0 to 255 from zero to full scale of the analog meter 35 as in the past,
The analog data converted by the D / A converter 16 can be displayed on the analog data 35.

(Signed Digital Data) When the 8-bit data from the ECU 1 is signed 2's complement representation data, the switch SW0 is connected to the contact B.

Then, since the analog output voltage converted by the D / A converter 16 remains uncertain as to whether it is positive or negative, it is input to the inverting input terminal of the comparator 21 and the positive or negative of the data is compared and judged.

Here, as is well known, in order to express the sign of 8-bit data, the sign is expressed by the most significant bit (MSB), and the numerical value is expressed by the remaining 7 bits. When the MSB is 0, it is a positive number, and when the MSB is 1, it is a negative number. And to express negative numbers, we use two's complement notation. The positive number that can be represented is +12 when all 7 bits are 1, ie, up to 01111111.
The negative number that can be represented is 7 when all 7 bits are 0, that is, up to 10000000, which is 128 in the usual unsigned binary representation, but the two's complement representation inverts all bits. (1's complement) Since 1 is added,-
Represents 128. That is, +12 in the range of 8-bit 0 to 255
Represents 7 to -128.

Therefore, in order to determine whether the analog output voltage converted by the D / A converter 16 corresponds to a positive number or a negative number, the analog output voltage is set to 12 as a set value.
It is sufficient to compare whether the voltage corresponding to 7 is larger or smaller.

(Positive data) First, the case where the switch SW1 of the enlargement switching means 40 is connected to the contact C, that is, the case where enlarged display is not performed will be described.

A variable resistor is connected to the non-inverting input terminal of the comparator 21.
When adjusted by 27, a reference voltage corresponding to 127 is applied, and the input voltage from the D / A converter 16 to the inverting input terminal of the comparator 21 is equal to or lower than the voltage corresponding to 127 (that is, In case of positive data), the comparator 21 outputs a high level signal and the analog switch 23
Input to the control terminal of. Further, the output of the comparator 21 is input to the inverter 22, inverted, and output as a low level signal from the inverter 22 and input to the control terminal of the other analog switch 24.

The analog switches 23 and 24 are turned on when a signal input to the control terminal is at a high level, and outputs a signal applied to the input terminal. Therefore, the analog switch 23 is turned on, and one of the analog switches is turned on.
24 is off.

Here, the analog switch 23 has its input terminal adjusted by the variable resistor 28 to apply the voltage corresponding to 128, and therefore outputs the voltage corresponding to 128.

Here, the voltage corresponding to 128 is the full scale value 255 of the analog meter 35 in a normal unsigned binary number.
Corresponding to a value obtained by subtracting the maximum value 127 that can be represented by 7 bits, and the zero point of the positive data displayed by the analog meter 35 is set in the approximate center of the display of the analog meter 35 in advance. Offset value.

Next, the output voltage of the D / A converter 16 and the output voltage of the analog switch 23 are input to the inverting input terminal of the operational amplifier 25 via the resistor 31 and the resistor 30, respectively. The operational amplifier 25 operates as an adder for inverting the output via the feedback resistor 32, and the output voltage of the D / A converter 16 and the output voltage of the analog switch 23 are added and inverted and output. Further, the added and inverted voltage is input to the inverting input terminal of the operational amplifier 26, the polarity is returned to the original by the inverter composed of the operational amplifier 26 and the feedback resistor 33, and the analog meter is connected through the contact B of the cylinder SW1. 3
The pointer 35a of 5 is shaken.

That is, the voltage input to the analog meter 35 is a voltage obtained by adding the voltage corresponding to 128 as an offset to the output voltage of the D / A converter 16, and thus the pointer 35
In the case of a, the zero point is added and shifted by the voltage corresponding to the above 128 and is swayed to indicate positive data. Therefore, the above ECU1
If the digital data from is positive data, the positive data is analog-displayed with the center of the analog meter 35 as the zero point.

(Enlarged display of positive data) Here, when the change of the positive / negative signed digital data from the ECU1 is small and the pointer 35a of the analog meter 35 shows only a slight swing angle near the zero point, the switch
Connect SW1 to contact D.

Then, the output of the D / A converter 16 is the operational amplifier 41,
For example, the amplified output is inverted and amplified at a magnification of 5 times, the amplified output is inverted by the operational amplifier 42, the polarity is returned to the original value, and the analog switch 45 is input. As described above, in the case of positive data, since the analog switch 45 is on and the other analog switch 46 is off, the output of the D / A converter 16 is amplified and the display conversion means is 20b
It is input to the operational amplifier 25, that is, the adder. Therefore,
In this case, the original output of the D / A converter 16 is, for example, 5
Since the amplified output voltage is amplified twice and the voltage corresponding to the zero point of the analog switch 23 is added, even if the data slightly changes near the zero point, as shown in FIG. , The data is expanded and the above analog data
Appears on 35. Therefore, the digital data with positive and negative signs that slightly changes near the zero point can be easily identified, and the content can be reliably determined.

(Negative data) On the other hand, when the input voltage from the D / A converter 16 to the inverting input terminal of the comparator 21 is larger than the voltage corresponding to 127 (that is, in the case of negative data), the comparator 21 Outputs a low level signal and turns off the analog switch 23 as described above, while the analog switch 24 turns on by the high level signal inverted by the inverter 22.

Here, the voltage corresponding to −128 adjusted by the variable resistor 29 is applied to the input terminal of the analog switch 24, so that the voltage corresponding to −128 is output.

Then, in the adder including the operational amplifier 25 and the feedback resistor 32, similarly, the output voltage of the D / A converter 16 and the output voltage corresponding to −128 of the analog switch 24 are added (subtracted) and inverted, and output. To be done. Furthermore, this addition (subtraction)
The inverted voltage is returned to the original polarity by the inverter composed of the operational amplifier 26 and the feedback resistor 33, and
Swing the pointer 35a of the analog meter 35 through the contact B of SW0.

That is, the voltage input to the analog meter 35 is a voltage obtained by subtracting the voltage corresponding to 128 as an offset (adding the voltage corresponding to −128) from the output voltage of the D / A converter 16. Similarly, the pointer 35a of the analog meter 35 is shifted with the zero point subtracted and shifted by the voltage corresponding to 128, and indicates negative data. Therefore, when the digital data from the ECU 1 is negative data, the negative data is displayed in analog in the opposite direction to the case of the positive data described above, with the approximate center of the analog meter 35 as the zero point.

(Enlarged Display of Negative Data) Here, similarly, when the switch SW1 is connected to the contact D, the display of the analog meter 35 is enlarged and displayed.

In this case, the analog switch 45 is off,
On the other hand, since the other analog switch 46 is on,
The output of the operational amplifier 44 is input to the operational amplifier 25 of the display conversion means 20b, that is, the adder.

The output of the D / A converter 16 is input to the inverting input terminal of the operational amplifier 43 via the resistor 50, while a reference voltage corresponding to 256 is applied to the non-inverting input terminal by the sliding resistor 52. The difference between the reference voltage corresponding to 256 and the output of the D / A converter 16 is amplified five times, for example.

As described above, in the case of negative data, it is 128 to 255, so if this is D (-), the analog meter 35
The data displayed at is represented as the difference Δ = D (−) − 128 minus 128 corresponding to the voltage indicating the zero point. Therefore, if the difference Δ is subtracted from 128 indicating the zero point and amplification is performed, it is possible to expand while maintaining a linear relationship between the amplification ratio and the expansion ratio. Therefore, the operational amplifier 43 amplifies the difference between 256 and the negative data.

By the differential amplifier composed of the operational amplifier 43,
For example, the output amplified by 5 times is
It is input to the differential amplifier composed of 44. The differential amplifier constituted by the operational amplifier 44 is set to have an amplification factor of 1, and the non-inverting input terminal has a sliding resistor 56
To 256, the reference voltage corresponding to
To the analog switch 46. The difference between the reference voltage corresponding to and the amplified output of the operational amplifier 43 is output. The output from the analog switch 46 is added with the offset corresponding to −128 described above by the operational amplifier 25 of the display conversion means 20a, and similarly, as shown in FIG. Displayed at 35.

For simplicity, the operational amplifier 2 of the display conversion means 20b is used.
It is also possible to provide another set of adders composed of 5 and adjust the feedback resistor 32 so that the addition output is multiplied by a constant coefficient to switch these adders. In that case, since there is no linear relationship with the enlargement ratio, fine adjustment may be somewhat difficult.

Second Example Next, a second example of the present invention will be described. 4 and 5 (a), (b), (c) show a second embodiment of the present invention, and FIG. 4 is a block diagram of an electronic control unit and a vehicle diagnostic device mounted on a vehicle, 5 (a), (b),
(C) is a flow chart showing an operation procedure of enlarged display on the analog display means.

The same members as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the second embodiment, the enlargement switching means 40 is composed of a resistor 58 and a switch SW2.
0 is connected to the input port P of the I / O interface 15. On the other hand, the output of the D / A converter 16 is connected to the analog meter 35.

That is, the terminal E of the switch SW2 is connected to the other terminal of the resistor 58 whose one end is connected to the power source and the input port P of the I / O interface 15, and when the switch SW2 is ON, A low level signal is input to the input port P of the I / O interface 15, and enlarged display is selected.

The operation of this enlarged display will be described with reference to the flowchart of FIG.

First, in step 70, the vehicle diagnostic device 60 requests the ECU 1 to transmit data, and in step 71, the vehicle diagnostic device is used.
When the 60 receives the signed digital data from the ECU 1 via the I / O interface 15, the process proceeds to step 72, and it is determined whether the enlarged display is performed.

That is, in step 72, the I / O interface 1
The state of the input port P of 5 is checked to see if the switch SW2 is ON. That is, if the input port P is at the low level, it is determined that the switch SW2 is ON and the process proceeds to step 73 to call the enlarged display subroutine SUB1. On the other hand, when the input port P is at the high level, it is determined that the switch SW2 is OFF and the routine proceeds to step 74 to call the subroutine SUB2 for normal display.

(Enlarged display subroutine SUB1) In the enlarged display subroutine SUB1, in step 80,
First, the most significant bit (MSB) of the data D (two's complement expression) from the ECU 1 is examined to determine whether the data represents positive or negative. When MSB is 0, that is, a positive number, step 81 is proceeded to, and when MSB is 1, that is, a negative number, step 83 is proceeded to.

If the data from the ECU 1 is a positive number (1-127), the data D (+) is multiplied by the magnification K in step 81 to calculate the enlarged data M (+). Next, in step 82, the display data A (+) in which the data corresponding to the zero point of the analog meter 35, that is, 128, is added to the data M (+) as an offset value is calculated, and the process returns to the main routine.

On the other hand, when the data from the ECU 1 is a negative number (128 to 255), in step 83, the difference Δ between the preset full scale value 256 and the negative data D (−) is calculated,
In step 84, the difference Δ described above is multiplied by the magnification K for enlargement to calculate the enlarged data M (−). Then, the process proceeds to step 85, the display data A (-) is calculated by subtracting the data M (-) from the offset data 128, and the process returns to the main routine.

(Normal display subroutine SUB2) If the data is not enlarged, in step 90, similarly, the data D (two's complement expression) from the ECU1 is the data D (+) representing positive or the data D (-representing negative. ) Is determined. If it is a positive number, the process proceeds to step 91, the offset data 128 is added to the data D (+) to calculate the display data A (+), and the process returns to the main routine.

On the other hand, when the data is negative data D (-), the step
At 92, the display data A (-) obtained by subtracting the offset data 128 from the data D (-) is calculated, and the process returns to the main routine.

(Main routine) When returning to the main routine, display data A is displayed in step 75.
(+) Or A (-) is output to the D / A converter 16, and the analog data D / A converted in step 76 is displayed on the analog meter 35.

Therefore, as in the first embodiment, the digital data with positive and negative signs that slightly change near the zero point is enlarged and displayed, so that the data can be easily identified and the contents can be reliably determined.

[Effects of the Invention] As described above, according to the first aspect of the invention, when the input / output data in the electronic control device mounted on the vehicle is read into the vehicle diagnostic device by bidirectional communication and displayed in analog, An analog value obtained by analog-converting the output digital data in the two's complement representation format by the digital / analog conversion means is compared with the set value by the comparison means to determine whether the digital data value is a positive value or a negative value. When the normal display is selected by the enlargement switching means, the analog value after the analog conversion by the digital / analog conversion means is directly output from the enlargement switching means to the display conversion means. The analog value is multiplied by a predetermined value and output to the display conversion means. Then, when the digital data is a positive value, the display conversion means adds a preset offset value for determining the zero point to the analog value output from the enlargement switching means, and the analog value after the addition is added. , Is displayed on the analog display means with a deviation from the zero point, and when the digital data is a negative value, the offset value is subtracted from the analog value output from the enlargement switching means, and the analog value after the subtraction is performed. Is displayed on the analog display means with the deviation from the zero point, positive and negative digital data in the form of 2's complement expression output from the electronic control unit mounted on the vehicle can be properly sorted from the zero point to the positive and negative values and easily identified. Can be displayed on the analog display means to improve the visibility by the diagnostic operator and analyze the digital data in the two's complement representation format of the electronic control unit. It is possible to improve the work of and diagnostic workability.

Even when the digital data with positive and negative signs in the two's complement representation format output from the electronic control unit mounted on the vehicle changes slightly near the zero point, by selecting the enlarged display, it is possible to reduce Since it is possible to appropriately display positive and negative changes from the zero point and display them on the analog display means in an enlarged manner, the diagnostic operator must surely judge a minute change in the digital data with positive and negative signs output from the electronic control unit. It is possible to improve the visibility, and
It is possible to further improve the workability of analysis and the workability of diagnosis for digital data in the form of the complementary expression.

According to the second aspect of the present invention, when the input / output data of the electronic control unit mounted on the vehicle is read into the vehicle diagnostic device by bidirectional communication and displayed in analog, the digital data of the two's complement representation format output from the electronic control unit. It is determined whether the data value of the digital data is a positive value or a negative value based on the value of the most significant bit in. Then, at the time of requesting enlarged display, when the data value is a positive value, after multiplying the data value by a predetermined value, a preset offset value for determining the zero point is added to obtain display data, and the display data is When the data is a negative value, the difference calculated by subtracting the data value from the preset full scale value is calculated. After being multiplied by a predetermined value, this value is subtracted from the offset value to obtain display data, and the display data is analog-converted to be displayed in an analog state with a large deviation from the zero point. On the other hand, when a normal display request is made, when the data value is a positive value, the offset value set in advance to determine the zero point is added to the data value to form display data, and the display data is converted into an analog value to the zero point. The deviation from is displayed in analog in the normal state,
Further, when the data value is a negative value, the offset value is subtracted from the data value to obtain display data, and the display data is converted into an analog form to be displayed in an analog state in a normal deviation from the zero point. Therefore, as in the first aspect of the invention, the positive and negative digital data of the two's complement expression format output from the electronic control unit mounted on the vehicle is properly sorted into positive and negative from the zero point, and the analog display means can be easily identified. It is possible to improve the visibility by the diagnostic operator and improve the analytical workability and the diagnostic workability for the digital data of the two's complement representation format of the electronic control unit.

Further, similarly to the invention described in claim 1, even when the digital data with positive / negative sign in the form of 2's complement expression output from the electronic control unit mounted on the vehicle slightly changes near the zero point, the enlarged display By selecting, the slight change in the vicinity of the zero point can be appropriately divided into positive and negative from the zero point to be enlarged and displayed, so that the diagnostic operator can make a minute change in the digital data with positive and negative signs output from the electronic control unit. Can be reliably determined, the visibility can be further improved, and the analysis workability and the diagnosis workability of the digital data in the two's complement representation format of the electronic control device can be further improved.

Further, the digital data with positive and negative signs such as positive and negative distribution based on the zero point with respect to the digital data with positive and negative signs in the two's complement expression format output from the electronic control unit mounted on the vehicle and the expansion of the data when the enlarged display is selected. It is possible to handle the display conversion when displaying data in analog by software, and it is possible to easily realize it without major changes in hardware.

[Brief description of drawings]

1 to 3 show a first embodiment of the present invention, FIG. 1 is an external view showing a vehicle equipped with an electronic control device and a vehicle diagnostic device having an analog display means, and FIG. 2 is a vehicle. Block diagram of electronic control unit and vehicle diagnostic device installed in
FIG. 4 is a display diagram of an analog meter, FIGS. 4 and 5 show a second embodiment of the present invention, FIG. 4 is a block diagram of an electronic control device and a vehicle diagnostic device mounted on a vehicle, and FIG. FIG. 6 is a flow chart showing the operation procedure of enlarged display on the analog display means, and FIG. 6 is a display diagram of a conventional analog meter. 1 ... Electronic control device 16 ... D / A converter (digital / analog conversion means) 20a ... Comparison means 20b ... Display conversion means 35 ... Analog meter (analog display means) 40 ... Enlargement switching means 60 ... … Vehicle diagnostic device 100 …… Vehicle

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Claims (2)

[Claims] 1. An electronic control unit mounted on a vehicle,
In a vehicle diagnostic device for reading input / output data in the electronic control unit by bidirectional communication and displaying a data value, a digital / analog conversion means for converting the digital data in the two's complement representation format output from the electronic control unit into an analog form. And a comparison means for comparing the analog value after analog conversion with the set value to judge whether the digital data is a positive value or a negative value, and the normal display and the enlarged display are selectively switched to select the normal display. Occasionally, the analog value after the analog conversion by the digital / analog conversion means is output as it is, and when the enlarged display is selected, the expansion switching means for outputting the analog value obtained by multiplying the analog value after the analog conversion by the digital / analog conversion means by a predetermined value. When the above comparison means determines a positive value,
A preset offset value for determining the zero point is added to the analog value output from the enlargement switching means, and the value after the addition is displayed on the analog display means as a deviation from the zero point, and a negative value is displayed. When judged, the display conversion means is provided for subtracting the offset value from the analog value output from the enlargement switching means and displaying the subtracted value on the analog display means as a deviation from the zero point. A vehicle diagnostic device characterized in that 2. An electronic control unit mounted on a vehicle,
In the analog display method of a vehicle diagnostic device for reading input / output data in the electronic control unit by bidirectional communication and displaying the data value in an analog manner, the digital data in the two's complement representation format output from the electronic control unit is input. , Whether or not there is a request to enlarge the data, and whether the digital data is positive or negative based on the value of the most significant bit in the digital data is determined. When the value is, after multiplying the data value of the digital data by a predetermined value,
A preset offset value is added to determine the zero point and used as display data.When the digital data is a negative value, the difference calculated by subtracting the data value of the digital data from the preset full scale value. Is multiplied by a predetermined value, and the value multiplied by the predetermined value is subtracted from the offset value to obtain display data. When a normal display request is made and the digital data is a positive value, the offset value is added to the data value of the digital data. When the digital data value is a negative value, the offset value is subtracted from the data value of the digital data to obtain display data, and the display data is analog-converted and then deviated from the zero point. An analog display method for a vehicle diagnostic device, which is characterized by analog display as a position.