SU656076A1 - Device for detecting faults in discrete objects - Google Patents

Description

The invention relates to the field of instrumentation technology and can be used to find multiple faults in discrete objects whose conclusions are independent (logically unrelated to each other). In particular, such objects include logical blocks of digital computers (digital computers).

A troubleshooting device is known that allows detection of multiple faults 1.

However, for this it is necessary to have a reference circuit. The closest technical solution is a device for troubleshooting in discrete objects 2. This device contains a pulse generator connected to the first input of the AND element and the control unit, the first output of which is connected to the pulse counter, the trigger of the last discharge of the counter, the OR element and the test generator , a stop trigger, a single input, which is connected to the second output of the control unit, and an output to the second input of the And element, the output of which is connected to the test generator and pulse counter, digits howl

an indicator connected to the outputs of the pulse counter bits, the single trigger output of the last bit also connected to the health indicator, and zero to the third input of the AND element, the mismatch elements whose inputs are connected to identical outputs of the blocks being checked, and the outputs to the mismatch indicators and through the OR element to the zero input of the stop trigger.

The drawback of the device is a significant hardware cost for checking the reference circuit.

The purpose of the invention is to expand the field of application of the device.

This goal is achieved by the fact that a two-input mismatch element with contact probes, connected to the mismatch indicator and the OR element, is introduced into the known device. This allows you to search for multiple faults in 2n-1

units to be checked and thereby reduce hardware costs by eliminating all nodes from the device that ensure the verification of the reference block. To extend the functionality, i.e.

troubleshooting without using a reference block, the device contains a two-input mismatch element, the output of which is connected to the mismatch indicator and the OR element, and the inputs to two contact probes.

Functional diagram of the device shown in the drawing.

The device contains 2p -1 checked blocks 1, test generator 2, pulse counter 3, element 4, digital indicator 5, trigger 6 of the last discharge of counter 3, fault indicator 7, stop trigger 8, pulse generator 9, control unit 10, performed, for example, on two locking buttons 11, 12, mismatch elements 13, mismatch indicators AND, element OR 15, two-input mismatch element 16 with mismatch indicator 17, contact probes 18.

The device operates as follows. Pressing button 11, the control unit 10 generates a command that initializes the tested blocks 1, test generator 2, counters 3, the last bit trigger 6 and the stop trigger 8. When the button 12 is pressed, block 10 generates a command The trigger 8 is transferred to the state "1 and opens the element AND 4. I. The pulses from the output of the generator 9 through the open element AND 4 begin to flow to the inputs of the counter 3 and the generator 2, which gives test influences to the inputs checked x blocks 1. In the case of serviceability of all tested blocks 1, the signals at identical outputs of these blocks coincide with each other, elements 13 do not generate pulses at their outputs, trigger 8 remains in the state "I, and element 4 4 is closed from the side of trigger 6 only when the counter reaches 3 the maximum number that is fixed by the digital indicator 5. The flip-flop from the zero to one state trigger 6 provides not only the operation of the I 4 element, but also the indicator 7. If at some kM output of any of the tested blocks 1 n The iM cycle appears as a signal that does not match the signals at the kx outputs of the remaining blocks 1 that are checked, then the kth element 13 is triggered. The output signal of the k-ro mismatch element 13 through the OR15 element tilts trigger 8 into "O, which closes AND 4 , thereby stopping the flow of clock pulses from the generator 9 to the nodes of the device. In this case, the digital indicator 5 fixes the number of the clock cycle, and the kth indicator 14 indicates the number of identical outputs on which the mismatch of the output signals of the tested blocks 1 was registered for the first time.

Now it is necessary to decide which of the tested blocks 1, and their 2n -1, is at this stage faulty. Since the scheme of the entire device is fixed at the moment when the output signals of the checked blocks 1 do not match, the outputs of the checked blocks 1 retain logical signals (O or 1), which characterize the state of each of the checked blocks 1. The task is simplified thanks to the kth indicator 14 , which indicates ke identical outputs of the checked blocks 1, on which a signal mismatch is registered. The connection of the contact probes 18 of the type "needle of the vacuum input element 16 to the inputs of the k-th element 13 allows the j-th input to be determined by means of the indicator 17, the signal value on which does not coincide with the values of the signals on the other inputs. The jth checked block 1 associated with the jth input of the kth element 13 is faulty at this stage.

The case when, at the i-th cycle, the k-th element 13 registered a discrepancy in the output signals of several checked blocks 1, the separation of the checked blocks into working and faulty ones is carried out by the majority method. This case corresponds to the same faults in several checked blocks 1.

Further, the jth checked block 1 recognized at the given stage as the faulty one and one of the checked 2 blocks that are intact at this stage are examined further.

Relocating the contact probes 18d of the two-input mismatch element 16 along the identical elements of these checked blocks 1, starting with the k-ro output and further into the faulty node, allows to detect the location of the malfunction. Thus, all elements located between the faulty element and the k-M output will give a mismatch, recorded by the mismatch indicator 17, and elements located after the point of the fault will give a coincidence of signals. The element at whose outputs the sipals coincide with the signals of a similar element of another checked block 1, and at the outputs do not coincide - is faulty. Troubleshooting in combinational circuits is performed at the i-th cycle, fixed by indicator 5. In sequential circuits, the moment of fault detection in the depth of logic does not coincide with the moment of its manifestation in the form of a mismatch of signals at the outputs of the tested blocks 1 .. Therefore, it is necessary moving the contact probes 18 of the two-input element 16, perform repeated zeroing and triggering using the control unit 10. In this case, the signals of the two-input mismatch element 16 will be sent to the element OR 15 earlier than with the mismatch elements 13, and therefore, as we approach the place of the malfunction, the digital

indicator 5 will decrease. As soon as the contact probes 18 are moved to the elements of the tested blocks 1 located behind the fault location, then the mismatch signal from the two-input mismatch element 16 to the OR element 15 does not arrive, the stop trigger 8 will be rebroken with the mismatch signals pending from the k-ro mismatch element 13 , and digital indicator 5 will again fix the i-th cycle.

After the fault has been rectified, the procedure is repeated. The detection of the next fault in one of the tested blocks 1, in general, occurs in one of the following steps after the i-ro. Again, it is determined which of the tested blocks 1 is faulty at the new cycle. This is repeated until all the malfunctions in all the 2n1 monitored blocks 1 are eliminated. In this way, any number of faults can be eliminated.

Since there are no reference blocks in the device, and only faulty blocks are used, and their number is 2π -1 (n 1,2,3 ...), the process of detecting multiple faults is somewhat probabilistic in nature. The total number M of possible faults of one block is determined by the following formula

M -1, where L is the number of elements in the block;

S (- numbers; 1o possible single faults q-ro element of the block.

If we assume that all faults are uniform and uncorrelated, then the probability of the occurrence of the same faults at the same time in all 2n -1 checked blocks 1 and, consequently, the probability of their failure is equal to:

R

where n 1,2,3 ...

That is, as the number of checked blocks 1 increases, this probability decreases. AT

Depending on the serial production, it is advisable to operate with either three or five checked blocks 1.

The economic effect of introducing a single troubleshooting device depends on the number of blocks to be tested and the serial production. In general, hardware costs are reduced by a factor of 2-3.

Claims (2)

Invention Formula A device for troubleshooting in discrete objects, containing a pulse generator connected to the first input of the AND element and the control unit, the first output of which is connected to the pulse counter, the trigger of the last digit of the counter, the OR element and the test generator, a stop trigger whose single input connected to the second output of the control unit, and the output to the second input of the element I, the output of which is connected to the test generator and pulse counter, a digital indicator connected to the outputs of the bits of the pulse counter, the single trigger output of the last bit also connected to the health indicator, and zero - with the third input of the And element, e.1 mismatch elements, the inputs of which are connected to identical outputs of checked blocks, and the outputs to the mismatch indicators and through the OR element to the zero INPUT} stop trigger a, characterized in that, in order to expand the field of application of the device, a two-input mismatch element with contact probes is inserted into it, connected to the mismatch indicator and the OR element. Sources of information taken into consideration. Knowledge in the examination 1. USSR author's certificate M 238236, cl. G 06 F 15/46, 1967. 2. USSR author's certificate No. 533894, cl. G 01 R 31/28, G 06 F 15/46, 1976.