Method for detecting defects in digital blocks

FIELD: measuring equipment.

SUBSTANCE: in turns, on each device, included in diagnosed block, feeding voltage amplitude is decreased in steps from nominal value Enom to threshold value Ethri with step ΔEn, while on each step of decreasing of amplitude of feeding voltage of device pseudo-random multi-digit code sets are sent to inputs of diagnosed block, consisting of logical zeroes and ones with even possibility of appearance of logical zero or logical one in each digit, received logic levels are recorded on outputs of diagnosed digital block and compared to standard levels, and when error frequency Fc appears, voltage value Ethri is recorded (functioning threshold) for each device and its functioning area is calculated on basis of feeding voltage ΔEpi. Defective (potentially malfunctioning) device is detected on basis of lowest value in functioning area ΔEpi, which is selected on basis of comparison of functioning areas of all devices, included in diagnosed digital block.

EFFECT: higher precision, higher efficiency.

1 dwg

 

The invention relates to measuring technique and can be used to detect and indicate a potentially faulty (potentially unreliable, defective devices included in the digital block, cerebrosides method (i.e. has only access to the input and output diagnosed digital unit).

The known method of finding defects in digital blocks that form a multi-bit pseudo-random code sets, consisting of logical zeros and ones with a given probability of occurrence of logical zero or logical units in each category, and submit them for information correcting inputs diagnosed digital unit, register the received logic levels on the outputs diagnosed digital block and compare them with the reference levels, record the validity diagnosed digital block when matching the received logic levels from reference [1].

Also known way of finding defects in digital blocks containing bidirectional bus, after the filing of this multi-bit code set for control and information inputs diagnosed digital unit interval of time required for completion of transition processes in diagnosed digital block, measure the voltage level on each of Dun is aimed tires diagnosed digital block and if this bi-directional bus level is set to logical one or zero, his record, if bi-directional tires set to levels corresponding to the high-impedance state or breakage, the bidirectional data bus serves multi-bit pseudo-random code set consisting of logical zeros and ones with a given probability of occurrence of logical zero or logical units in each category, if this bi-directional bus level is set in the range between acceptable levels of logic zero and one, believe diagnosed digital block worthless, compare registered on bi-directional tires diagnostic object logic levels with a reference and consider diagnosed digital unit fit the coincidence of the received logic levels on the outputs and bi-directional tyre object diagnostic reference [2].

There is also known a method of rapid diagnosis of multi-channel digital blocks, namely, that affect the test signal on the test object, record the responses of the object of control, compares the reference and registered the feedback from the test object, ask in a digital code information is a valuable amplitude and time values of the test signals and the reference response of the test object, generate test signals defined in the digital code information-this is the major amplitude and time values in a given volume, exercise effects on corresponding inputs of a test object test signals with a predetermined time difference, record the deviation from the reference in the feedback from the test object in a temporary area on appropriate impact visualize at the end of the full volume of exposure to the types of deviations in the response object control, resume the formation of the test signal on the specified digital code information is a valuable amplitude and time values in a given volume to the first deflection and periodically repeat this impact to correct the deviation, visually displaying the decision on the results of diagnosis [3].

However, the known methods do not allow to detect and to indicate the place of the defective (potentially faulty) device diagnosed digital block as at nominal supply voltage defective device does not differ in the functional area from a known-good.

Now clearly see the tendency of intensive replacement of analog equipment to digital, which becomes embedded in the crucial areas of human activity. However, the problem of increasing its reliability is still relevant. Modern possibilities of digital equipment in the field of information processing allow to solve the problem is the prediction of the mean time between failures (MTBF) digital equipment at a qualitatively new level. The use of the proposed method for detection and location of defective (potentially faulty) devices in digital blocks will allow us to predict the average time between failures of digital equipment, for which you will be able to plan timely replacement of defective (potentially faulty) unit, which is included in its composition, more reliable, supporting the likelihood of digital equipment at the specified level.

The purpose of the invention is the detection and location of defective (potentially faulty) device diagnosed digital block.

To achieve this goal alternately on each device that is part of the diagnosed unit, the amplitude of the supply voltage speed is reduced from the nominal values of EMr.up to a threshold of Eporincrements Δ Fpwhile at each step of reducing the amplitude of the supply voltage of the device to the inputs diagnosed digital unit served in a given amount of pseudo-random multi-bit code sets, consisting of logical ones and zeros with equal probability of occurrence of logical zero or logical units in each category, record the received logic levels on the outputs diagnosed digital block and cf is up their with the reference levels, when the failure frequency Fcrecord the voltage Epor(threshold function) for each device and calculate its area health supply voltage Δ FPIby the formula

where Δ Fpi- area health i-th device supply voltage;

EMr.- nominal voltage detection unit;

Eporthe threshold voltage of the first device, wherein the output detection unit have problems;

i - the number of the device.

Defective (potentially faulty) the device is determined by the lowest value of the field of health Δ FPIthat puts on the comparison of the areas of operability of all devices included in the composition diagnosed digital block.

The frequency of failure Pcdetermined by the formula

where m is the number of pseudo - random multi-bit code sets, during the passage through which the keypad has failed in its work;

n is the number of pseudo - random multi-bit code sets fed to the input of the digital block.

In the step of decreasing the amplitude of the supply voltage from the nominal value of EMr.up to a threshold of Eporpthe conditions for the improper functioning of the selected device. This clearly ensures that the distortion in the output responses diagnosed digital block.

According to the proposed method calculated the area of health supply voltage Δ FPIeach digital block is used as a generic and available for monitoring a parameter that has a fairly complex correlation with degrading parameters of the element base, difficult to observe.

The magnitude of the operational capability of the devices included in the diagnosed unit supply voltage, depends on the supply reliability of degrading components of their components.

Calculating the area of health on the supply voltage for each device included in the detection unit, from all devices select the device, which has the least area health supply voltage Δ FPI(figure 1). This device is considered defective (potentially faulty).

The essence of the method consists in the following.

Diagnosed digital unit, consisting of Z-device zapityvat voltage EMr.. In a given volume form multi-bit pseudo-random code sets consisting of logical ones and zeros with equal probability of occurrence of logical zero or logical units in each category, and submit them to the inputs diagnosed digital block.

The target multi-bit pseudo-random code sets depends on the number of inputs diagnosed digital block and is calculated using the method of synthesis of the tests according to the criterion of minimum length.

Register the received logic levels on the outputs diagnosed digital block and compare them with the reference levels. The results of this comparison determine the failure frequency Fcby the formula 1.

If the nominal supply voltage EMr.digital block failure frequency Fc0 (m≠ n), the diagnosed digital unit is considered defective and diagnosis stop to fix the problem.

If the nominal supply voltage EMr.the failure frequency Fc=0 (m=n), then diagnosed digital block is considered healthy and start to alternate the measurement threshold of the functioning of the devices included in its composition.

To do this, the Z-device included in the diagnosed unit, select the first device, which measured the threshold of the functioning of the supply voltage Epor.

With this purpose, the nominal supply voltage EMr.the first device is reduced by the amount Δ Fpon inputs diagnosed digital block serves in a given volume pseudos the tea multibit code sets, consisting of logical ones and zeros with equal probability of occurrence of logical zero or logical units in each category. Register the received logic levels on the outputs diagnosed digital block and compare them with the reference levels. The results of this comparison determine the failure frequency Fcby the formula 1.

If the supply voltage EMr.-k· Δ Epwhere k=1 failure frequency Fc=0 (m=n), then on the first device reduces the supply voltage to a value of EMr.-k· Δ Fpwhere k=2, the inputs diagnosed digital unit served in a given amount of pseudo-random multi-bit code sets, consisting of logical ones and zeros with equal probability of occurrence of logical zero or logical units in each category. Register the received logic levels on the outputs diagnosed digital block and compare them with the reference levels. The results of this comparison determine the failure frequency Fcby the formula 1.

The process step-by-step reduction of the nominal supply voltage EMr.the value of Δ Fpcontinue up until the failure frequency Fcwill not become greater than zero, i.e. Fc>0 (m≠ n). Upon occurrence of this event set the voltage (a threshold operation) for the first device is and E por=EMr.-k· Δ Epremember, where Eporthe threshold voltage for the first device, wherein the digital unit becomes inoperable, k is the number of the step.

The field of health on the supply voltage for the first device, diagnosed digital block is calculated by the formula

received it is remembered, and this device sets the nominal supply voltage EMr..

Then choose a second device included in the detection unit, for which the same sequence measure the threshold of its functioning Epor=EMr.-k·Δ Ep.The field of health on the supply voltage for the second device is calculated by the formula

also remember, this device sets the nominal supply voltage EMr.. The process of measuring the threshold of operation for each of the Z devices included in the diagnosed unit, in the same sequence repeated.

For the first device region health supply voltage is calculated by the formula

Thus, by measuring the area of health supply voltage is La each device, part of the diagnosed unit Δ FP1that Δ FP2...ΔEPIthat Δ Fzall Z-devices-choose a device which has the least area health supply voltage Δ FPI(figure 1).

This device is considered defective (potentially faulty).

Given that the average time between failures diagnosed digital block will be determined by the device that the field of health on the supply voltage the lowest found so potentially faulty device will determine the time to failure of the block in which it is located.

Thus, applying the method described in industrial and operations engineering the digital control blocks, it is possible to carry out detection and location of potentially defective devices in their composition, and the results of their calculations of the areas of health supply voltage Δ FPIat different points in time to predict the average time between failures diagnosed digital blocks.

The predicted mean time between failure (MTBF) of the keypad can be used for planning timely replacement of defective (potentially faulty) devices more reliable, topazolite to support the likelihood of digital block at the specified level.

Practical experience of the operation of digital hardware using the detection method and specify the location of the defective (potentially faulty) device in a digital block is allowed to increase its mean time between failures (MTBF) at 12-14%.

Literature

1. U.S. patent No. 3614608, CL G 01 R 15/12, 1971.

2. USSR author's certificate No. 840770, CL G 01 R 31/28, 1981.

3. The copyright certificate of the Russian Federation No. 2133479, CL G 01 R 31/28, G 06 F 11/26 1999 (prototype).

The way of finding defects in digital blocks based on input influence and comparison of the output response with its benchmark, characterized in that diagnosed the keypad turn on each device the amplitude of the supply voltage speed is reduced from the nominal values of EMr.up to a threshold of Eporincrements ΔFnwith each step reducing the supply voltage of the device to the inputs diagnosed digital unit served in a given amount of pseudo-random multi-bit code sets, consisting of logical ones and zeros with equal probability of occurrence of logical zero or logical units in each category, with the specified amount of code sets is determined by the number of inputs diagnosed digital block and is calculated using the method of synthesis of the tests according to the criterion of minimum length, compare the output of QCD is IKI with their reference levels, record the voltage Epor, which is the threshold operation, for each device when the failure frequency Fccalculate the area of health supply voltage ΔFPIand choose the defective device according to the smallest value of the field of health ΔFPIand the area health devices on the power supply ΔEpicalculated by the formula

where ΔEpi- area health i-th device supply voltage;

EMr.- nominal voltage detection unit;

Eporthe threshold voltage of the first device, wherein the output detection unit have problems;

i - the number of the device

and the failure frequency Fccalculated by the formula

where m is the number of pseudo - random multi-bit code sets, during the passage through which the keypad has failed in its work;

n is the number of pseudo - random multi-bit code sets fed to the input of the digital block.



 

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SUBSTANCE: in turns, on each device, included in diagnosed block, feeding voltage amplitude is decreased in steps from nominal value Enom to threshold value Ethri with step ΔEn, while on each step of decreasing of amplitude of feeding voltage of device pseudo-random multi-digit code sets are sent to inputs of diagnosed block, consisting of logical zeroes and ones with even possibility of appearance of logical zero or logical one in each digit, received logic levels are recorded on outputs of diagnosed digital block and compared to standard levels, and when error frequency Fc appears, voltage value Ethri is recorded (functioning threshold) for each device and its functioning area is calculated on basis of feeding voltage ΔEpi. Defective (potentially malfunctioning) device is detected on basis of lowest value in functioning area ΔEpi, which is selected on basis of comparison of functioning areas of all devices, included in diagnosed digital block.

EFFECT: higher precision, higher efficiency.

1 dwg

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