GB2036507A - Fault diagnosis for computer- controlled apparatus - Google Patents

Abstract

The individual sub-assemblies (Bl,...Bn) for instance of a coin-box telephone are checked for faults by entering predetermined test steps. Each test step is assigned to a sub- assembly, e.g. a coin-checking device (Bl) in the case of a coin box telephone. Such a test step is entered via the telephones push-button set (7), whereafter the assembly is put into operation by the maintenance man. The computer (5) checks the signals generated by the sub- assembly against what the signals should be as stored in a memory (3), and gives a fault indication which is displayed on a number/letter combination on the display (6) otherwise used as the credit display. <IMAGE>

Description

SPECIFICATION Fault diagnosis for computer-controlled apparatus This invention relates to fault diagnosis for computer-controlled apparatus, and particularly for computer-controlled coin box telephones with several sub-assemblies, such as push-button set, coin checking device and credit display.

Computer-controlled coin box telephones are complex, which makes them difficult to maintain.

The computer is intended to facilitate the work of the maintenance personnel by making it easier to check the coin telephone. German Offenlegungsschrift (DE-OS) 27 18 430 disposes a prepayment telephone containing a micro-computer via which the charges collected or the amount of credit remaining to the customer can be displayed. This telephone also has a readonly memory and a separate display unit for monitoring and diagnostic purposes. This memory holds an output programme for all registers of a processor included in the micro-computer, which programme is not described in detail. These means are to enable the maintenance personnel to check the operation of all registers via the additional display unit and to intervene in the event of a failure. Thus the registers can be tested semi-automatically.The other sub-assemblies, such as hookswitch, push-button set, display unit, coin-collecting device, etc., must be checked for faults in the conventional manner, i.e. by means of test equipment and measuring instruments. Since a thorough check by the maintenance personnel is not possible in situ, it is frequently necessary to demount the entire coin telephone and perform a thorough check and the repair in another, suitable place.

An object of the invention is to enable individual sub-assemblies of coin telephones to be tested largely automatically, with display of the faulty sub-assemblies and/or components.

According to the invention there is provided a method of fault diagnosis for computer-controlled apparatus, and particularly for computercontrolled coin telephones comprising several sub-assemblies, such as push-button set, coinchecking device, and credit display, wherein the sub-assemblies are tested successively, wherein during the testing of a sub-assembly, actual signals generated by said sub-assembly or by the component contained therein are compared with associated reference signals stored as fixed values in the computer-controlled apparatus, and wherein in the event of an inadmissible difference between an actual signal and an associated reference signal the identify of sub-assembly or the associated component associated with said signal is displayed in alphabetically and/or numerically coded form.Particularly advantageously, the credit display provided in coin telephones is also used to display the faulty subassemblies or components.

Since different sub-assemblies have to be tested, and different sequences of operations are involved, fault diagnosis is advantageously performed by first automatically prechecking static actual signals occurring in the coin telephone and then carrying out several test steps assigned to specific sections of operation. The individual test steps may be performed selectively on the initiative of the maintenance personnel. A number specifying the test step to be executed is entered through the push-button keyboard of the telephone. Individual fault indications may also be stored and then called up and displayed later.

Through the check on the actual signals generated by individual sub-assemblies or components, fault diagnosis is performed largely automatically. If a sub-assembly is indicated as faulty, it is replaced by an operational one, and repaired at a later time. The coin telephone need not be demounted, which results in more economic operation. Simple faults can be corrected in situ by taking simple action.

An embodiment of the invention will now be described with reference to the accompanying drawing.

The actual signals Sist, generated by different sub-assemblies BI to Bn, are fed to a selection circuit 1 via inputs a to z. The output of the selection circuit 1 is coupled to a comparator 2 having its second input connected to a read-only memory 3. The memory 3 provides reference signals Ssoll to the comparator 2, which compares these signals Ssoll with the actual signals Sist from the selection circuit 1. The comparator 2 provides a difference signal which is applied to a detector 4. If the actual signal Sist shows an inadmissible difference from the reference signal Ssoll, the detector 4 provides a corresponding signal to the processor 5. In the presence of a fault, the processor sends a "turn-on signal" to the display 6, so that the faulty sub assembly or component is indicated.

The processor 5 contains the information which specifies the sub-assembly or component being tested. Through an input device 7, the processor 5 is informed which of the sub-assemblies BI to Bn is to be tested. The processor 5 then causes a check to be done on the actual signals Sist of the selected sub-assembly - e.g. the sub-assembly BI -, by applying corresponding control signals to the selection circuit 1 the read-only memory 3, and a code translator 8. These control signals represent the addresses specifying a particular input - e.g. b - of the inputs a to z of the selection circuit 1, and, at the same time, the associated location in the memory 3.Such a control signal or address is simultaneously fed to the code translator 8, whose output is connected to the display 6, so that the corresponding sub assembly or component can be indicated. This requires, however, that the "turn-on signal" be present, which, as mentioned earlier, is itransmitted from the processor 5 to the display 6 on the occurrence of a fault. The display may be alphabetic and/or numeric.

If, for example, the light-emitting component (light-emitting diode) forming part of the optical sensor in the coin-checking device BI is defective, "Blb" could be indicated on the display 6. The maintenance person can then see from a checklist that "Bl" is the coin-checking device, and "b" the light-emitting component of the optical sensor. It is also possible, of course, to use an exclusively numeric or an exclusively alphabetic display to indicate the faulty sub-assembly or component.

If the actual signals Sist transferred from the selectiontirnuit 1 to the comparator 2 not only are checked for presence but also must lie within specified limits, an analog-to-digital converter 9 may be provided so that the difference between the reference signal Ssoll and the actual signal Sist can then be evaluated in the detector 4. The actual signals Sist can thus be monitored asfto whether they lie within specified limits. To accomplish this, the direct voltage values of the respective actual signals to be tested may be ;binary-coded, for example.The associated reference signal is then a code word corresponding to the binary code of the associated reference direct voltage value. In the simplest case, the actual signals Sist provided by the components or sub-assemblies may be direct voltages which are either at logic "0" level or at logic "1" level. If, for example, the actual signal is at "0" level, and the associated reference signal at "1" level, a fault indication ensues.

In the simpler case of the check on the actual signals Sist, however, the analog-to-digital converter 9 and the detector 4 are not required. In this case, a check is made only to determine whether a difference exists between Ssoll and Sist. In this simpler case, the comparator 2 doubles as a fault detector, i.e., it delivers control signals directly to the processor 5, which indicate either the correctness of an actual signal Sist or a fault In the preferred embodiment, the display Bds also used to display the amount of credit remaining to the customer. With a switch 10 located inside the coin telephone, the maintenance person can switch from the coin telephone mode to the test mode. In the coin telephone mode M, the display-6 acts as the credit display. In the test mode P, any faults or faulty sub-assemblies or components and the number of the respective test step are shown on the display 6. The switch 10 may be mounted so as to be in the position M, "coin-telephone mode", when the housing of the coin telephone is closed.

It should be noted that the present invention can also be used in other computer-controlled automatic machines, such as vending and service machines.

Claims (14)

1. A method of fault diagnosis for computer controlled apparatus, and particularly for computer-controlled coin telephones comprising several sub-assemblies, such as push-button set, coin-checking device, and credit display, wherein the sub-assemblies are tested successively, wherein during the testing of a sub-assembly, actual signals generated by said sub-assembly or by the component contained therein are compared with associated reference signals stored as fixed values in the computer-controlled apparatus, and wherein in the event of an inadmissable difference between an actual signal and an associated reference signal, the identity of sub-assembly or the associated component associated with said signal is displayed in alphabetically and/or numerically coded form.

2. A method as claimed in claim 1, wherein the various sub-assemblies are assigned predetermined test steps which can be performed to check either one or more sub-assemblies.

3. A method as claimed in claim 2, wherein the respective desired test step is set in coded form, wherein a number assigned to the test step is displayed, wherein a sequence of operations or a manipulation associated with the test step is then performed, and wherein the identity of any faulty sub-assembly or component is then displayed in coded form, or if no fault has occurred the readiness for the next test step is displayed.

4. A method as claimed in claim 1, 2 of 3, wherein a plurality of static actual signals occurring in the coin telephone are first automatically prechecked, whereafter the separate test steps assigned to given sequences of operations are performed.

5. A method as claimed in claim 1, 2, 3 or 4, wherein the information for the coded alphabetic and/or numeric display of the faults is stored so that it can be called up and displayed later if desired.

6. A method as claimed in claim 1, 2, 3, 4 or 5, wherein the actual signals and the reference signals are coded.

7. An arrangement for performing fault diagnosis on computer-controlled coin telephones with several sub-assemblies, particularly for carrying out the method of claim 1, wherein the sub-assemblies are connected to the input of a selection circuit to permit transfer of the actual signals, which circuit has its output coupled to a comparator whose other input is connected to a read-only memory and which, in the event of an inadmissible difference between an actual signal and a reference signal, provides a "fault" signal to a processor which, in turn, causes a display to indicate the faulty sub-assembly and/or the faulty component.

8. An arrangement as claimed in claim 7, wherein a desired test step is entered as a combination of numbers and/or letters through an input device with its output connected to the processor which delivers control signals or addresses to the read-only memory and the selection circuit to connect the respective input to the comparator and to apply the associated reference signals stored in the read-only memory to the comparator, and wherein the processor prepares the display to indicate the sub-assembly and/or the component under test via a code translator connected to the processor, which enables or inhibits the display via a separate connection.

9. An arrangement as claimed in claim 7 or 8, wherein an analog-to-digital converter is inserted between the selection circuit and the comparator, and the comparator is connected to the processor via a detector.

10. An arrangement as claimed in claim 7, 8 or 9, wherein the input device is the push-button keyboard for entering the telephone numbers.

11. An arrangement as claimed in claim 7, 8, 9 or 10, wherein the display is the credit display provided in coin telephones.

12. An arrangement as claimed in claim 7, 8, 9, 10 or 1 1, wherein a switch is provided which is not accessible from outside and, depending on its position, causes the processor to control the test mode or the coin-telephone mode.

13. An arrangement as claimed in claim 7, 8, 9, 10 or 1 1, wherein when the handset is replaced, the processor is switched to the coin-telephone mode via the hookswitch.

14. A method of fault diagnosis for computer controlled apparatus, substantially as described with reference to the accompanying drawing.

1 5. Apparatus for fault diagnosis for computer controlled apparatus, substantially as described with reference to the accompanying drawing.