SU208355A1 - TROUBLESHOOTING DEVICE - Google Patents

Description

Fault finding devices are known to include a test generator, a fault decoder, triggers, and valves. -: And

The proposed device is characterized in that in it the output of the monitored device is connected to the counting input of a parity trigger, a single output of which is connected to the control input of the single fault decoder through a permit valve, and the zero output is connected to a double fault indicator.

This makes it possible to increase the efficiency of finding faulty elements.

To clarify the operation of the proposed device, we consider a computational diagnostic test, which is used to determine faults.

The counting diagnostic test (TDS) for the device shown in FIG. 1, can be constructed by adding modulo 2 all the characters of each column in the table. one.

 O 1 1 O 1

Symbol of addition (i) i} R

10110 no modzlu

 0001

inserts the chains S, then one should find such a collection of chains that their sum modulo 2 is equal to S.

Table 1 Positions of defective items

ten

15

For computational diagnostic test table. 2 faults thus has the form.

table 2

From Table 2 it follows that for the circuit shown in FIG. 1, a test was compiled that has the property to form an even binary code at the output of the device under test if it contains at most one un-equal element. In fact, all columns contain an even number of ones. It is easy to make sure that if all the elements of the device are intact, then the code for the release / 1

the course of the device is equal to / i

i.e., it is also even. Suppose that in the described device breaks can occur in any pair of elements at the same time. At the same time, as follows from the scheme, all possible reactions of the device to the diagnostic test can be summarized in a table of double faults (see Table 3). A computed diagnostic test has the property of forming an odd code at the output of a monitored device if the device contains an arbitrary pair of elements with breaks (except for 1.2 and 4.5, which are not electrically distinguishable for this circuit).

Table 3

Controlled Outlet Reactions

yCTJ on C /

SDT

The construction of TDS is fundamentally possible for any discrete devices. So for the circuits shown in FIG. 2, 3, can be compiled SDT, are given in table. 4 and 5.

Table 4

Items are faulty. Ele.centos

Table 5

The counting diagnostic test has the property to form an odd output code even in 40 cases when a pair of faulty elements has different types of faults (open and short). For example, if the device contains a breakage of the first element and the second one is closed, then this fact manifests itself in the following way: OT Cl-TTi-ilTi TTT / - rr -ir rf1tf 1t is the same odd reaction of Rlo2: are electrically distinguishable. For example, breakage of the first and closure of the fourth elements lead to the formation of the output code n / and - 1 which is even. The considered properties of TDS distinguish it from known tests. 60 At the same time, the TDS has the property of diagnosing (finding) faulty elements, since it contains a diagnostic test (in the considered example it is 55) These tests consist of two parts: the minimum diagnostic test G "in and the additional part J pop Additional input the combinations ensure the parity of all the columns and can be found as follows: modulo 2 is added to all the symbols contained in the columns of the diagnostic part j The resulting sum is 5, representing i Ji is some binary The n-bit code, in general, cannot function as an input test combination (as was the case for the circuit in Fig. 1), since with such excitation of circuit elements it does not form a closed electrical circuit between the poles. However, this code, as a vector-dimensional space, on the basis of the corresponding theorem from the theory of vector spaces can be represented as a linear combination of basis vectors. If we take as the basis the largest set of linearly independent cycles passing through both poles and The source of power then it turns out that the binary code obtained above can be represented as a linear combination of cycles (closed circuits between poles). At the same time, according to Berge’s theorem, the number of cyclic input combinations does not exceed the cyclomatic number y n -, where n is the number of graph edges (in this case, the number of circuit elements), t is the number of vertices (t. e. number of nodes of the scheme).

To illustrate the proposed method in order to control a discrete device with -inputs and a single output, you can use the circuit shown in FIG. 4. In the circuit, there is a test generator (GT), which is a device that is capable of producing a Gd sequence of a D-bit binary codes (test) by a signal L.

An LDR with p-inputs and one output reacts to the test so that at its output a sequence of characters O and 1 (output binary code) appears. A decoding device (DL) contains a parity check node represented by trigger G with a counting input, a shift register P, and a single-fault decoder DON.

As a result of the test run, some binary code appears in the register, representing the diagnostic part of the response of the monitored device T

 min

At the same time, under the influence of the output code, trigger G is set to one of the following two states: if the output code is even, then a signal appears at its single output; if the output code was

odd, a signal appears at its zero output.

In the presence of a signal at a single trigger output, a polling signal B triggers a "enable" signal that unlocks the DON decoder. In this case, a signal appears at the output of the latter, indicating the position of the faulty element with high confidence. If the trigger T gives the signal from zero output, then this signal goes to the indicator of the presence of two failed elements. If necessary, it can also be used to unlock a decoder for double faults (not shown in the diagram).

Subject invention

A troubleshooting device containing a single fault decoder, a parity trigger, and a valve, characterized in that, in order to increase the efficiency of finding the faulty elements, the output of the monitored device is connected to the counting input of the parity trigger, whose single output through the enabling gate It is connected to the control input of the single fault malfunction detector, and the zero output is connected to the double fault indicator.

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