GB2248942A

GB2248942A - Acquisition of diagnostic data from motor vehicles

Info

Publication number: GB2248942A
Application number: GB9118402A
Authority: GB
Inventors: Thomas Forchert; Ulrich Visel
Original assignee: Daimler Benz AG; Mercedes Benz AG
Current assignee: Daimler Benz AG
Priority date: 1990-08-31
Filing date: 1991-08-28
Publication date: 1992-04-22
Anticipated expiration: 2011-08-28
Also published as: ITRM910638A0; GB2248942B; FR2666418B1; DE4027626A1; JPH0711471B2; ITRM910638A1; GB9118402D0; JPH05240741A; IT1250765B; DE4027626C2; FR2666418A1

Description

1 22+8942 System for the acquisition of diagnostic data from electronic

units in a motor vehicle The invention relates to a system for the acquisition of diagnostic data from electronic units in a motor vehicle which comprises a diagnostic device with keyboard for the input of diagnosis instructions and a display for the indication of diagnosis results, the electronic units being connected for the purpose of emitting diagnostic data via one line each to a junction box in the form of a plug-in connection part fixed to the vehicle, which has at least a number of individual contacts corresponding to the maximum number of electronic units to be tested, by means of which contacts the system for the acquisition of diagnostic data can be connected to the units.

DE-Al-37 31 836 discloses a fault diagnosis system for electronic units of a motor vehicle, which is designed for recording fault signals from electronic units with selfdiagnosis function and indicating them. In this case, a vehicle contains at least one, preferably more, electronic units which have self-diagnosis functions and for this purpose are in each case equipped with a microcomputer, a memory etc. Diagnostic signals of the individual electronic units are passed to a connector, to which a diagnostic tester with keys and a display can be connected. The display is provided in order to indicate data which are sent by an electronic unit selected in each case - by means of the keyboard - at the same time a code being indicated which designates the selected electronic unit. The data transmission from the connector to the display takes place in parallel. In order to carry out the diagnosis, keys are actuated in a predetermined sequence on the diagnostic tester connected beforehand to the electronic units, so that each one of the electronic units can be successively selected. This takes place by entering a code which designates the corresponding electronic unit, so that then records of data can be read out manually one after the other from the electronic units and displayed on the display of the tester.

2 The present invention seeks to develop further a system for the acquisition of diagnostic data from electronic units in a motor vehicle in such a way that it permits not only the capture of such data but also an efficient and very reliable diagnostic communication between the system and a multiplicity of electronic units in a motor vehicle, to be precise excluding fault-induced reactions of different electronic units on one another.

According to the present invention there is provided a system for the acquisition:of diagnostic data from a plurality of electronic units in a motor vehicle, which comprises a diagnostic device with keyboard for the input of diagnosis instructions and a display for the indication of diagnosis results, the electronic units being connected for the purpose of emitting diagnostic data via one line each to a junction box in the form of a plug-in connection part fixed to the vehicle, which has at least a number of individual contacts corresponding to the maximum number of electronic units to be tested, by means of which contacts the system for the acquisition of diagnostic data can be connected to the units, wherein a signal path control system is present and spatially separate from the diagnostic device and connected to the latter via a connection cable in a multi-pole plug-in connection module, and wherein the signal path control system comprises an actuating circuit and a cut-in system, actuatable by the latter and remote-controllable, via said connection cable on the basis of a test program executable in the diagnostic device, in such a way that in each case a certain one of the diagnosis lines leaving from electronic units is able to be switched through in the plug- in connection module to the diagnostic device, and a bidirectional data exchange is possible between the diagnostic device and the respectively selected electronic unit.

This system offers the advantage that, apart from the communicating electronic units, no further additional devices are required as equipment permanently installed in the vehicle which have to constantly withstand the ambient conditions in the vehicle, and that only one line with only one - possibly double - signal core for data is required from a signal path 3 control device to the diagnostic device for data signals, providing high reliability. At least one microcomputer, which operates in the diagnostic device and cuts in the signal control system under remote control via just two lines for control signals thus permits an efficient bidirectional data communication between electronic units permanently installed in the vehicle and the diagnostic device.

Accordingly, the system can be used both for on-board diagnosis and for off-board diagnosis of electronic units in motor vehicles. An on-board diagnostic device can thus use the same signal paths as an off-board diagnostic device, to be connected temporarily, which for its part can, if need be, be in connection with a larger diagnostic computer, in order to permit for example in the workshop a more accurate diagnosis and/or a diagnosis taking in further test criteria.

Embodiments of the invention are explained below by way of example with reference to the drawing, in which:

Figure 1 shows a diagrammatic illustration of the component parts of the system; Figure 2a shows a diagrammatic view of the system, implemented as an on- board testing system; Figure 2b shows a diagrammatic view of the system, implemented as an off- board testing system; Figure 3 shows a diagrammatic illustration of the function blocks in the plug-in connection module.

According to Figure 1, the system comprises a diagnostic device 1, which is preferably equipped with input means 1.1, for example a keyboard 1.1, and at least one indicating means 1.2, for example a display. The diagnostic device 1 is connected to a signal path control system 4A, 4B in a plug-in connection module 4 via a connection cable 2 which comprises a plurality of cores. On the input side, the plug-in connection module 4 has n electric contacts 4.1 to 4.n, to which are assigned to this extent n individual channels for the bidirectional transmission of data and commands. In addition, the plug-in connection module 4 may also have further contact means 4.m, via which the diagnostic device 1 and the signal path control system 4A, 4B can in addition also be fed operating power from the vehicle. The 4 plug-in connection module 4 is implemented to fit into a plugin connection part or a junction box 5 which has corresponding counter- contacts 5.1 to 5.n and 5.m.

The contacts 5.1 to 5.n are connected via lines 7.1 to 7.n to various electronic units 6.1 to 6.n in the motor vehicle; thus, at the plug-in connection part or the junction box 5 on the vehicle side there are to this extent n data channels. The contact means 5.m lead via-lines 7.m for instance to the terminal 87 (on-board voltage connected by ignition lock switch), terminal 30 (on-board voltage) and terminal 31 (earth) in the motor vehicle. The corresponding contact means 4.m in the plug-in connection module 4 are connected to corresponding cores 2.3 of the cable 2 in the diagnostic device 1. In the plug-in connection module 4 there is provided as a component part of the signal path control system 4A, 4B a cut-in systpm 4A, which can be activated by an actuating system 4B, to be precise on the basis of signals which are received by the diagnostic device via selection lines 2.2 of the cable 2. The cut-in system 4A correspondingly switches the input of the - possibly double - signal core 2.1 to individual contact elements 4.1 to 4.n, so that a bidirectional data exchange is possible between the diagnostic device 1 and one of the electronic units 6.1 to 6.n via the cable 2.

It may be provided that, after establishing a proper connection of the plug-in connection module 4 to the plug-in connection part or the junction box 5 on the vehicle side, once the diagnostic device I is switched on initially the cutin system 4A is con-trolled to a predetermined channel, via which data and/or program parts which are vehicle-dependent or specify the electronic equipment of the vehicle are transmitted at the beginning of a diagnosis from the electronic unit concerned in the vehicle to the diagnostic device.

If, for example as in a practical case, 35 individual electronic units are to be diagnosed, the signal path control system 4A, 4B does not just provide a considerable saving of lines to the diagnostic device. A corresponding cable 2, which apart from the - possibly double - signal line 2.1 only comprises a few further lines 2.2 and 2.-3, can to this extent be made relatively thin, is flexible, therefore has less of a tendency for the cores to rupture and is consequently suitable for rough operation. This also rules out signal crosstalk along the cable between various diagnostic channels or reactions of individual electronic units on one another, for instance due to a faulty short-circuit between individual cores of a line correspondingly made with four channels.

Figure 2a illustrates a permanent installation in a vehicle of the system according to the invention by the example of an omnibus 3. In the engine compartment at the rear, a plug-in connection module 4 containing the signal path control system is accommodated, for example on a junction box 5, to which said data lines 7.1 to 7.n (not shown here), coming from electronic units, are led. The signal path control system with the function described above is to this extent plugged into the junction box 5. The line 2 runs in the vehicle forwards to the diagnostic device 1, where the latter is fitted for example in the driver's field of view and/or area of access. Thus, in this case the diagnostic device is a permanent component part of the vehicle equipment.

Figure 2b illustrates the system according to the invention used as an off-board system. Here too, the plug-in connection part or the junction box 5 on the vehicle side is accommodated in the engine compartment of a motor vehicle. The plug-in connection module 4 containing the signal path control system is plugged into it in the case of servicing, i.e. in the workshop. Workshop personnel can then check from the diagnostic device 1, via the connection cable 2, either all the electronic units according to a fixed stored program or select only individual units by manual input. This takes place by corresponding actuation of the cut-in system 4A by means of the actuating system 4B, which consequently selects under remote control the test channel respectively of interest, via said cores 2.2.

Figure 3 illustrates in function block repre-sentation the implementation of the cut-in system 4A in the plug-in connection module 4. The signal lines 2.1 are decoupled by driver circuits 8a and 8b and brought together on the cut-in 6 system side. The driver circuits 8a, 8b are used for interface conversion. The actuating system 4B is fed on the input side via buffer amplifiers 9a and 9b, from, here for example, two selector control lines 2.2.

It does not depart from the scope of the inven-tion if, for example, in a corresponding diagnostic device 1 a rechargeable battery (not shown here) is provided, which is recharged in each case via at least two of the lines 2.3 when the system is put into operation and allows the execution of an initial program routine'.and a fault indication even if the vehicle battery is defective or there is some other fault in the on-board electrical system of the vehicle, which does not allow operating power for the diagnostic device 1 to be drawn from the vehicle.

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Claims

Claims

System for the acquisition of diagnostic data from a plurality of electronic units in a motor vehicle, which comprises a diagnostic device with keyboard for the input of diagnosis instructions and a display for the indication of diagnosis results, the electronic units being connected for the purpose of emitting diagnostic data via one line each to a junction box in the form of a plug-in connection part fixed to the vehicle, which has at least a number of individual contacts corresponding to the maximum number of electronic units to be tested, by means of which contacts the system for the acquisition of diagnostic data can be connected to the units, wherein a signal path control system is present and spatially separate from the diagnostic device and connected to the latter via a connection cable in a multi-pole plug-in connection module, and wherein the signal path control system comprises an actuating circuit and a cut-in system, actuatable by the latter and remote-controllable, via said connection cable on the basis of a test program executable in the diagnostic device, in such a way that in each case a certain one of the diagnosis lines leaving from electronic units is able to be switched through in the plug-in connection module to the diagnostic device, and a bidirectional data exchange is possible between the diagnostic device and the respectively selected electronic unit.
2. System according to Claim 1, wherein the data exchange between the signal path control system and the diagnostic device is possible via a single data line as a component part of said connection cable.
3. System according to Claim 1, wherein the data exchange between the signal path control system and the diagnostic device is possible via two data.lines as a component part of said connection cable, namely via a forward line and a return line.

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4. System according to Claim 1, wherein, for the selection of electronic units to be connected to the system, only two control lines are provided as a component part of said connection cable.
5. System according to Claim 1, wherein the diagnostic device is adapted to be fed operating power from the vehicle to be diagnosed, via at least two additional plug-in ' contacts of the plug-in connection part or the junction box on the vehicle side and of the plug-in connection module and via at least two lines of the cohnection cable.
6. System according to Claim 1, wherein the diagnostic device is adapted to be fed the on-board voltage, which can be turned off in the vehicle to be diagnosed by the ignition lock switch, via at least one further plugin contact of the plugin connection part or the junction box on the vehicle side and of the plug-in connection module and via at least one further line of the connection cable.
7. System according to Claim 1, wherein the diagnostic device includes a rechargeable battery, rechargeable or kept charged when the system is connected to the corresponding interface of a vehicle and is able to deliver the operating energy for the diagnostic device.
8. System according to Claim 1, wherein the signal path control system in the plug-in connection module also comprises driver circuits for amplification or inter-face conversion, inserted into (the) data line(s) and into the control lines.
9. System according to Claim 1, wherein, after putting into operation the system connected to the plug-in connection part or the junction box on the vehicle side, the cut-in system is actuatable for connection to an in each case quite specific electronic unit in the vehicle, and at least data for the test program to be executed by the diagnostic device can be loaded from the corresponding electronic unit into the diagnostic device.

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10. System according to Claim 1, wherein, in addition, vehicle-specific parts of the test program to be executed in the diagnostic device loadable from the corresponding electronic unit into the diagnostic device.
11. System according to Claim 1, adapted for permanent installation in the vehicle and wherein the keyboard and display are protected by a normally closed cover.
12. System according to Claim 1, adapted to be implemented as a service device for operation outside the vehicle, and the diagnostic device is implemented as a hand-held device.
13. System for the acquisition of diagnostic data from a plurality of electronic units in a motor vehicle, substantially as described herein, with reference to, and as illustrated in, the accompanying drawings.