WO2009046686A1

WO2009046686A1 - Method for checking the first check relay and second check relay of the cyclical code coding unit for railway interlocking system equipment and the cyclical code coding unit for implementing the method

Info

Publication number: WO2009046686A1
Application number: PCT/CZ2008/000111
Authority: WO
Inventors: Antonin Faran; Stanislav Srb; Radek Dobias
Original assignee: Azd Praha S.R.O.
Priority date: 2007-10-08
Filing date: 2008-09-19
Publication date: 2009-04-16
Also published as: CZ2007694A3; SK500192010A3

Abstract

The method for checking the first check relay (X) and second check relay (Y) of the coding unit (C) according to this invention consists in that, the check circuit (CCC) of the cyclical codes periodically, after the repeating control time (TSC) elapses, looks for an intersection of the common state, when the cyclical codes (CC1, CC2, CC3, CC4), generated simultaneously in both the first branch (B1) and in the second branch (B2) all have zero voltage (UO) in the first branch (B1) and, at the same time, in the second branch (B2). Immediately after detecting this instant the cyclical code check circuit (CCC) initialises an impulse to the diagnostic circuit (DC) for the period of the testing time (TT), to interrupt, through the diagnostic switches (d1, d2), the driving circuits of the check relays (X, Y), whose armatures are released for a short period after the testing time (TT). After the testing time (TT) elapses, the diagnostic circuit (DC) connects, through the diagnostic switches (d1, d2), the driving circuits of the check relays (X, Y), whose armatures attract, if they have a failure-free state. In this case the result switch (S) of the output switching circuit (OS) is not dropped, because its armature is belatedly released after the time (TD) of delay, during the interruption of its excitation, where the time (TD) of delay is longer than the testing time (TT), thus during a failure-free state during the test there is no interruption to the distribution of the cyclical codes (CC1, CC2, CC3, CC4) over the output switching circuit (OS) and return conductor (RCC) to the interlocking system equipment (IS), under the condition, that there has been no long-term jamming of the contacts of either the first check relay (X) or the second check relay (Y), in the operating or rest position. Because, in this case, this would lead to the constant drop of the relevant faulty relay, i.e. either of the first check relay (X) or second check relay (Y), due to the interruption of power to the first branch (B1) or the second branch (B2) as a result of the incompatible state of the connection of the second contact (x2), third contact (x3) of the first check relay (X) or the second contact (y2) and third contact (y3) of the second check relay (Y) which, in this case, causes the droppage of the result switch (S) and the function of the coding unit (C) is interrupted, until the arrival of the operator and until the elimination of the fault and until the initialisation of the activation button (ABU), by which the fault of thefirst check relay (X) or the second check relay (Y) is transferred in a safer direction, and moreover this failure state is monitored by the diagnostic circuit (DC), which arranges for the operator to be called. The contact of the activation button (ABU) can alternatively be replaced by a contact or switch of an automatic starter (AST).

Description

Method for Checking the First Check Relay and Second Check Relay of the Cyclical Code Coding Unit for Railway Interlocking System Equipment and the Cyclical Code Coding Unit for Implementing the Method

Technical Field

The invention concerns the method for checking the first check relay and second control relay of the cyclical code coding unit for railway interlocking system equipment, where the individual cyclical codes are generated in two branches of the electronic coding system.

The invention also concerns the cyclical code coding unit for railway interlocking system equipment for the implementation of this method of checking. The cyclical code coding unit is made up of a cyclical code check circuit, a starting circuit, diagnostic circuit, output switching circuit and a first and second branch.

Background of Invention

Until now coding units that generated cyclical codes so that the oscillator frequency was given the requested frequency by frequency dividers have been used for coding railway interlocking system equipment signal circuits and track circuits. It is necessary to safely check the cyclical code frequency obtained in this manner so, that it does not result in a change and in the transmission of a false signal aspect, which could seriously threaten traffic safety. The greatest disadvantage of this method is the fact, that it is not possible to implement an arbitrary set of signal codes without an unacceptable error of some of the cyclical codes occurring, so it is not possible to implement a universal cyclical code coding unit in this manner. It is very unfavourable economically.

For example the EK-1 type of coding unit - manufactured by Signal Mont s.r.o.,

Hradec Kralove, the Czech Republic - has been used for a number of decades by Czech Railways. It has an older component base and its further production is not prospective without considerable innovations.

The processors of the individual branches are used to generate cyclical codes for the powering of flashing lights and for coding the track circuits of an ABE -1 type electronic automatic block, used in the last six years on Czech Railway tracks. This solution pursuant to patent CZ 289 934 is unsuitable, however, due to the small application on secondary lines or for the reconstruction of railway lines. For foreign railway administrations the state is technically very similar as in the Czech Republic. In fact local mechanical coding units, in which an asynchronous motor controls a set of sensory springs through cams attached on the motor's shaft, with these springs interrupting the electronic circuit in the rhythm of the required cyclical code, have usually been used up until now. These coding units show low reliability, require demanding maintenance and thus they are already unsuitable at the current time.

A safe electronic code generator is described in US patent 4,234,870 from 1979, including a programable microprocessor, that works in that, the signal is divided by a rate selector after being generated by a crystal oscillator. The selection of the fixed frequency is used by tuned vital relay drivers. Feedback information from these drivers monitors their operation and checks the operation of output circuitry. External time delays are provided to check program delays within the system and to ensure against the generation of erroneous codes due to the cyclical resetting of the system. A rate selector provides permission of particular output code rates after division so, that the code is continually checked to ensure, that the system always generates the required code. Programming functions also provide self-checking, checking the microprocessor and checking the operations and operators against the impact of external components to provide system integrity and to achieve inherent reliability. Diversity and cycle checking are used by the by the arrangement of the system itself, by which it achieves functional safety and quality. The microprocessor system of the coding unit has a two- channel structure, while each channel is controlled by a relay driver and after being rectified, tuned and amplified the signal is optically divided. A disadvantage is that the check of the generated code's correctness is carried out continuously and by very complicated manner in analogue for each impulse code. Thus the system's reliability is apparently lower. The equipment is complicated, expensive and takes up an unnecessarily large enclosed space due to the obsolete analogue conception. The equipment can be expected to break down often. The use of microprocessors in the central unit requires, during regular revisions and repairs, the difficult replacement by components that are almost no longer manufactured.

Summary of the Invention

The method for checking the first check relay and second check relay of the cyclical code coding unit for railway interlocking system equipment according to this invention as well as the cyclical code coding unit for railway interlocking system equipment according to this invention removes or considerably limits the aforementioned disadvantages of the known solutions.

It concerns the use of a universal coding unit, for which the cyclical codes are generated on two electronic branches, with the use of the most modern electronic programming elements, for the checking of which the first check I relay and second check relay are used.

The coding unit according to this invention, created by the cyclical code check circuit, starting circuit, diagnostic circuit, output switching circuit and the first branch and second branch, has the coding unit's first check relay connected to the cyclical code check circuit and to return conductor in a series with the first diagnostic switch, and while the coding unit's second check relay is connected to the check circuit and to return conductor in a series with the second diagnostic switch. The diagnostic element is driven from the cyclical code check circuit. The first branch is powered from the main voltage in a series with the sixth contact of the result switch. The second branch is powered from the main voltage in a series with the seventh contact of the result switch. The starting circuit with the anti-repeat function is comprised of the starting element, either by an activation button for a manual start or an automatic starter for an automatic start, and then in a series of setting contacts for driving the result switch, specifically by the first contact of the first check relay, second contact of the second check relay and fifth contact of the result switch. The first to fourth contacts of the result switch connect the interlocking equipment to the coding unit outputs. The first branch's auxiliary circuits are powered by auxiliary voltage in a series with the second contact of the second check relay and also in a series with the third contact of the second check relay. Similarly the second branch's auxiliary circuits are powered by the auxiliary voltage in a series with the second contact and also in a series with the third contact of the first check relay.

Checking the correct operation of the first check relay and second check relay of the cyclical code coding unit for railway interlocking system equipment, according to this invention, is realised in that, an intersection of the common state is periodically sought using the cyclical code check circuit after a repeating check time elapses; when the first cyclical code, second cyclical code, third cyclical code and fourth cyclical code, generated simultaneously, in both the first branch and in the second branch, all have zero voltage in the first branch and, at the same time, in the second branch of the coding unit, then the cyclical code's voltage impulse is not generated. Immediately after detecting this instant the cyclical code check circuit initialises an impulse to the diagnostic circuit, through the first diagnostic switch of the diagnostic element and through the second diagnostic switch of the diagnostic element, for the period of the testing time, to interrupt the driving circuit of the first check relay and also to interrupt the driving circuit of the second check relay, whose armatures are released for a short period after the testing time. The diagnostic circuit registers this and after the testing time is finished it connects, through the first diagnostic switch of the diagnostic element and the second diagnostic switch of the diagnostic element, the driving circuits of the first check relay and the second check relay, whose armatures are attracted, if the first check relay and the second check relay have a failure-free state. In this case the result switch of the output switching circuit is not dropped, because its armature is belatedly released after the time of delay during the interruption of its excitation. The time of delay is longer than the testing time, so in a failure-free state during the test the distribution of the first cyclical code, second cyclical code, third cyclical code and fourth cyclical code, over the output switching circuit and return conductor to the interlocking system equipment is not interrupted under the condition, that there has been no long- term jamming of the contacts of either the first check relay or the second check relay in the operating or rest position. Because this would lead to the constant drop of the relevant faulty relay, i.e. either of the first check relay or second check relay, due to the interruption of the power to the decisive circuits of the first branch or the second branch, as a result of the incompatible state of the connection of the second contact and third contact of the first check relay or the second contact and third contact of the second check relay. Which in this case causes the permanent dropping of the result switch and the function of the coding unit until the arrival of the operator and until the elimination of the fault and until the initialisation of the activation button, or until the implementation of the automatic start, by which the fault of the first check relay or the second check relay is transferred in a safer direction. This failure state is moreover monitored by the diagnostic circuit, which arranges for the operator to be called.

In the event that the coding unit user would be interested in the alternative of starting the coding unit without the impact of the starter element, by the responsible employee, this problem can be resolved, for example, by connecting a contact or automatic starter switch (instead of the contact of the starting element), safely controlled by the first segment of the diagnostic circuit, which cheks the first branch and second segment of the diagnostic circuit, which checks the second branch so, that these segments of the diagnostic circuit coincidently evaluate, whether the coding unit's droppage was the result of a dangerous failure. In that case the diagnostic circuit permanently stops the coding unit's activity until the maintenance employee arrives. In the event the coding unit drops out due to a slight failure, for example due to an outage of the power voltage, the diagnostic circuit will allow the automatic start of the coding unit after the protective delay period elapses so, that the contact or switch of the automatic starter is closed. In locations, where there are frequent outages of power voltage, it would be necessary, without the aforementioned measure, to perform frequent interventions by the maintenance personnel after each outage of power voltage. It would be especially necessary for them to make frequent trips to what are often distant detached locations, where the coding unit is located. The main advantage of the new method for checking and the new local reliable coding unit according to this invention is the use of the most modern electronic programmable elements to replace the local old coding unit. The solution according to this invention is especially meant for application on secondary lines or for the reconstruction of railway lines. Cost savings on the reconstruction or construction of railway interlocking system equipment occur with the use of this invention.

The method for checking the first check relay and second check relay of the cyclical code coding unit for railway interlocking system equipment according to this invention makes it possible to use the newest programmable electronic elements for the generation of cyclical codes in the first branch and in the second branch, especially block fields, which are capable of generating an arbitrary cyclical code and therefore the coding unit conceived in this manner is universal. If a block field is used in the first and second branches instead of microprocessors, it is easier to program and the exchange during revisions and repairs after a certain period is especially easier.

For this reason the coding unit can be produced in large series, it is possible to store a minimum number of space parts and as a result the coding units manufactured in this manner are inexpensive for the customer.

Brief Description of the Drawings

The invention is further described in the detailed example implementation, clarified in the attached schematic drawings.

The block scheme of the coding unit implementation is schematically displayed in Fig. 1.

An example of an implementation of cyclical codes is presented in Fig. 2 with the testing time and the repeating control time highlighted. An example of the manual starting of the coding unit with the use of the starting element, specifically the manual activation button, is presented in Fig. 3a. An example of the automatic starting of the coding unit with the use of the automatic starting element, specifically the automatic starter, is presented in Fig. 3b.

Detailed Description of the Embodiments The method for checking the first check relay X and second check relay Y of the cyclical code coding unit C for railway interlocking system equipment IS is apparent from the example of the implementation, which is presented in Figures 1, 2 and 3.

A coding unit C comprised of a cyclical code check circuit CCC, starting circuit ST. diagnostic circuit DC, output switching circuit OS, and a first branch Bi and a second branch B2 were chosen for this method.

The first control relay X of the coding unit C of cyclical codes CC1 - CC4 is connected to the check circuit CCC of the cyclical code CC1-CC4 and the return conductor RCC in a series with the first diagnostic switch di..

The second check relay Y of the coding unit C of cyclical codes CC1 - CC4 is connected to the check circuit CCC and the return conductor RCC in a series with the second diagnostic switch d2.

The diagnostic element D is driven from the cyclical code CC1-CC4 check circuit CCC.

The first branch Bl is powered from the main voltage MV in a series with the sixth contact §6 of the result switch S.

The second branch B2 is powered from the main voltage MV in a series with the seventh contact §7 of the result switch S.

The starting circuit ST with the anti-repeat function is comprised of the starting element, either by an activation button ABU for a manual start or an automatic starter AST for an automatic start, and then in a series of setting contacts for driving the result switch S, specifically the first contact x1_ of the first check relay X, second contact y_1. of the second check relay Y and fifth contact §5 of the result switch S. The first to fourth contacts si., §2, §3, §4 of the result switch S connect the interlocking equipment IS to the coding unit C outputs. The first branch's BJ. auxiliary circuits are powered by auxiliary voltage AV in a series with the second contact γ2 of the second check relay Y , and also in a series with the third contact γ3 of the second check relay Y.

Similarly the second branch B2 is powered by the auxiliary voltage AV in a series with the second contact x2 and also in a series with the third contact x3 of the first check relay X. Checking the correct operation of the first check relay X and second check relay Y_of the cyclical code CC1-CC4 coding unit C for interlocking system equipment IS is realised in that, an intersection of the common state is periodically sought using the cyclical code control circuit CCC after a repeating control time TSC elapses; when the first cyclical code CC1 , second cyclical code CC2. third cyclical code CC3 and fourth cyclical code CC4. generated simultaneously in both the first branch Bi and in the second branch B2, all have zero voltage UO in the first branch BJ. and, at the same time, in the second branch B2 of the coding unit C, then the cyclical code's CC1-CC4 voltage impulse is not generated. Immediately after detecting this instant, the cyclical code check circuit CCC initialises an impulse to the diagnostic circuit DC, through the first diagnostic switch dj. of the diagnostic element D and through the second diagnostic switch d2 of the diagnostic element D for the period of the testing time TT, to interrupt the driving circuit of the first check relay X and also to interrupt the driving circuit of the second check relay Y, whose armatures are released for a short period after the testing time TT, which the diagnostic circuit DC registers.

After the testing time TT is finished it connects, through the first diagnostic switch th of the diagnostic element D and the second diagnostic switch d_2 of the diagnostic element D, the driving circuits of the first check relay X and the second check relay Y, whose armatures attract, if the first check relay X and the second check relay Y have a failure-free state. In this case the result switch S of the output switching circuit OS is not dropped, because its armature is belatedly released after the delay time JJD during the interruption of its excitation. Meanwhile the delay time TD is longer than the testing time TT. Thus in a failure-free state during the test, there is no interruption to the distribution of the first cyclical code CC1 over the first contact of the result switch §1, second cyclical code CC2 over the second contact of the result switch §2, third cyclical code CC3 over the third contact of the result switch s_3 and fourth cyclical code CC4 over the fourth contact of the result switch §4, i.e. over the output switching circuit OS and return conductor RCC to the interlocking system equipment IS, under the condition, that there has been no long-term jamming of the contacts of either the first check relay X or the second check relay Y in the operating or rest position.

Because this would lead to the constant drop of the relevant faulty relay, i.e. either of the first check relay X over the sixth contact of the result switch §6 or second check relay Y over the seventh contact of the result switch §7, due to the interruption of the power to the decisive circuits of the first branch BI or the second branch B2 as a result of the incompatible state of the connection of the second contact x2 and third contact x3 of the first control relay X or the second contact γ2 and third contact y3 of the second control relay Y. Which in this case causes the permanent dropping of the result switch S, because the driving circuit (which is closed through the fifth result switch §5, and also through the first contact xi of the first check I relay X and through the first contact yj of the second check relay Y), is disconnected.

And the function of the coding unit C is interrupted, until the arrival of the operator and until the elimination of the fault and until the initialisation of the activation button ABU. or until the implementation of the automatic start. Thus the fault of the first check relay X or the second check relay Y is transferred in a safer direction. This failure state is moreover monitored by the diagnostic circuit DC, which arranges for the operator to be called.

In the event that the coding unit C user would be interested in the alternative of starting the coding unit without the impact of the activation button ABU by the responsible employee, this problem can be resolved, for example, by connecting a contact or automatic starter switch AST instead of the contact of the activation button ABU. Its activity is safely controlled by the first segment of the diagnostic circuit DC1, which controls the first branch BJ. and second segment of the diagnostic circuit DC2, which controls the second branch B2 so, that these segments of the diagnostic circuit DC1, DC2 coincidently evaluate, whether the coding unit's C droppage was the result of a dangerous failure. In that case the diagnostic circuit DC permanently stops the coding unit's C activity until the maintenance employee arrives.

In the event the coding unit C drops out due to a slight failure, for example due to an outage of the power voltage UN, the diagnostic circuit DC will allow the automatic start of the coding unit C after the protective period of delay time TD. elapses so, that the contact or switch of the automatic starter AST is closed.

In the presented specific example implementation, they are like programmable elements, specifically in the first branch BJ. and in the second branch B2 of the coding unit C, and block fields are used instead of processors, because they are easier to program, and especially the exchange of the programmable elements during the revisions and repair of coding units after a certain period, are easier.

In locations, where there are frequent outages of power voltage UN, it would be necessary, without the aforementioned measure, to perform frequent interventions by the maintenance personnel after each outage of power voltage UN₁ It would be especially necessary for them to make frequent trips to what are often distant detached locations, where the coding unit C is located. An example of the implementation of the invention is given in Fig. 1 by continuous lines, where the start of the coding unit C is carried out by the impact of the activation button ABU. In the same diagram an example of the implementation is given by a dashed line, where the start of the coding unit is carried out automatically with the use of the automatic starter AST.

An example of the implementation of the cyclical codes CC1 - CC4 is given in Fig. 2, in which the code impulse amplitude UC is represented by a continuous line, while the zero voltage UO of the cyclical codes CC1 - CC4 is represented by a weak line. This figure represents the dependence of the cyclical codes CC1-CC4, i.e. of the first cyclical code CC1. second cyclical code CC2, third cyclical code CC3 and fourth cyclical code CC4, on time t with a display of the testing time TT, repeating control time TSC and protective delay TD.

An example of the starting of the coding unit C with the use of the activation button ABU is given in Fig. 3a, where the result switch S is dropped after the outage of the power voltage UN after the time TD of delay expires immediately after which the first check relay X and second check relay Y are dropped. The example where the power voltage UN is restored after a certain time and when the impact of the activation button ABU does not occur is also given in Fig. 3a. As a result of this the coding unit C does not start UN, which is represented by a thin line in this time segment, or the dropping of the result switch S, successively of the first check relay X and second check relay Y.

On the contrary, the excitation of the aforementioned elements is represented by a thick line in Fig. 3a and in Fig. 3b, which occurs upon the correct activity of the coding unit C. An example of the automatic starting of the coding unit C with the use of the automatic starter AST is given in Fig. 3b. After the outage of the power voltage UN and after the delay time TD expires, the result switch S is dropped, followed immediately afterwards by the dropping of the first check relay X and second check relay Y. After the power voltage UN is restored, the first segment of the diagnostic circuit DC1 and the second segment of the diagnostic circuit DC2 coincidently verify, during the protective delay TP, whether or not a dangerous failure occurred in the coding unit.

In the event that the aforementioned dangerous failure did not occur, then after the protective delay TP elapses, the result switch S is excited followed by the excitation of the first check relay X and the second check relay Y, i.e. leading to the start of the coding unit C. In the event that the first segment DC1 of the diagnostic circuit and, coincidently, the second segment DC2 of the diagnostic circuit ascertain a dangerous failure, the excitation of the result switch S followed by the excitation of the first check relay X and the second check relay Y does not occur, by which the failure is passed in a safe direction.

In order for such a conceived coding unit C to take the least amount of room, it is recommended to use a miniature element as the first check relay X and as the second check relay Y, i.e. relays with the second level of reliability. Because these types of relays do not guarantee that the armature will drop away due to the impact of gravitational effects, it is necessary to verify the correct functionality of the first check I relay X and second check relay Y in a manner, that satisfies the demanding safety requirements placed on railway interlocking equipment. The solution according to the attached invention fulfils these requirements.

Moreover, the timely calling of an operator is resolved by the diagnostic circuit DC in the event, that a dangerous failure of the first check relay X or second check relay Y of the coding unit C, is detected. The fact that connecting the circuit driving the result switch S has an anti-repeating nature also contributes to this. The new start of the result switch S can only be carried out after the failure in the check relay's circuit is repaired and after the confirmation of this fact, either by the resulting impact of the activation button ABU by the responsible employee or automatically in cooperation with the diagnostic circuit DC.

The method for checking the first check relay X and second check relay Y also satisfies the analysis of the safety of the circuits in the sense that if, during the repeated tests of these check relays, which are always carried out after the repeating control time TSC elapses, a faulty extension of the interval of the cyclical code CC1- CC4 occurs due to the failure of either of the diagnostic switches cM or d2, i.e. the occurrence of zero voltage UO of the cyclical code CC1-CC4 generated by the coding unit instead of the code impulse amplitude UC, then in the worst case the signal will be presented, which represents a more prohibitive signal aspect.

Industrial Applicability

The method for checking the first check relay X and second check relay Y of the cyclical code CC1-CC4 coding unit C can be used for railway interlocking system equipment IS, both during the new construction of railway interlocking system equipment IS and for the reconstruction of existing railway interlocking system equipment IS. Since the coding unit C is conceived to be universal and an arbitrary set , _ ,

11 of up to four cyclical codes can be realised with it, it can be expected that it will find use in foreign railway administrations as well.

List of Abbreviations

X First Control Relay

Y Second Control Relay

C Coding Unit

CC 1 - CC4 Cyclical Codes

CC1 First Cyclical Code

CC2 Second Cyclical Code

CC3 Third Cyclical Code

CC4 Fourth Cyclical Code

IS Interlockinα System Eαuioment

CCC Cyclical Code Control Circuit

TC Startinq Circuit

D Diaαnostic Element

DC Diaαnostic Circuit

OS Output Switching Circuit

B1 First Branch

B2 Second Branch

TSC Repeating Control Time

UO Zero Voltage

UC Code Impulse Amplitude

UN Power Voltage

MU Main Voltage

AU Auxilliary Voltage d1 First Diagnostic Switch d2 Second Diagnostic Switch

TT Testing Time

S Result Switch s1 First Contact of Result Switch s2 Second Contact of Result Switch

S3 Third Contact of Result Switch s4 Fourth Contact of Result Switch s5 Fifth Contact of Result Switch s6 Sixth Contact of Result Switch s7 Seventh Contact of Result Switch

OS Output Switching Circuit

TD Time of Delay x1 First Contact of First Control Relay x2 Second Contact of First Control Relay x3 Third Contact of First Control Relay y1 First Contact of Second Control Relay y2 Second Contact of Second Control Relay y3 Third Contact of Second Control Relay

DC1 First Segment of Diagnostic Circuit

DC2 Second Segment of Diagnostic Circuit

ABU Activation Button

AST Automatic Starter

TP Protective Delay

T Time

RCC Return Conductor

Claims

C L A I M S

1. The method for checking the first check relay (X) and second check relay (Y) of the cyclical code (CC1-CC4) coding unit (C) with a return conductor (RCC) for railway interlocking equipment (IS), where the individual cyclical codes (CC1-CC4) are generated in two branches of an electronic coding unit (C) system, is characterised in that, the checking of correct operation of the first check relay (X) and second check relay (Y) of the cyclical code (CC 1 - CC4) coding unit (C) with a return conductor (RCC) for railway interlocking system equipment (IS), is realised, through a check circuit (CCC) of the cyclical codes, which periodically after the repeating checking time (TSC) elapses, looks for an intersection of the common state, when the first cyclical code (CC1), second cyclical code (CC2), third cyclical code (CC3) and fourth cyclical code (CC4), generated simultaneously in both the first branch (B1) and in the second branch (B2), compared to the potential of the return conductor (RCC), all have zero voltage (UO), at the same time, in the first branch (B1) and in the second branch (B2) of the coding unit (C), then, the cyclical code's (CC1-CC4) voltage impulse is not generated; while

- immediately after detecting this instant the cyclical code check circuit (CCC) initialises an impulse to the diagnostic circuit (DC), through the first diagnostic switch (d1) of the diagnostic element (D) and through the second diagnostic switch (d2) of the diagnostic element (D), for the period of the testing time (TT), to interrupt the driving circuit of the first check relay (X) and also to interrupt the driving circuit of the second check relay (Y), whose armatures are released for a short period after the testing time (TT), which the diagnostic circuit (DC) registers; and

- after the testing time (TT) is finished the diagnostic circuit (DC) connects, through the first diagnostic switch (d1) and the second diagnostic switch (d2) of the diagnostic element (D), the driving circuits of the first check relay (X) and the second check relay (Y), whose armatures attract the first check relay (X) and the second check relay (Y), if the first check relay and the second check relay have a failure-free state, and in this case the result switch (S) of the output switching circuit (OS) is not dropped, because its armature is belatedly released after the time (TD) of delay during the interruption of its excitation, while

- the time (TD) of delay is longer than the testing time (TT), so in a failure-free state during the test, there is no interruption to the distribution of the first cyclical code (CC1) over the first contact (s1) of the result switch (S), second cyclical code (CC2) over the second contact (s2) of the result switch (S), third cyclical code (CC3) over the third contact (s3) of the result switch (S) and fourth cyclical code (CC4) over the fourth contact (s4) of the result switch (S) and over the return conductor (RCC) to the railway interlocking system equipment (IS), under the condition, that there has been no long-term jamming of the contacts of either the first check relay (X) or the second check relay (Y), in the operating or rest position, because, in this case, - due to the interruption of the power supply, to the decisive circuits of the first branch (B1) or the second branch (B2), as a result of the incompatible state of the connection of the second contact (x2) and third contact (x3) of the first check relay (X) or the second contact (y2) and third contact (y3) of the second check relay (Y), this would lead to the constant drop of the relevant faulty relay, i.e. either of the first check relay (X) over the sixth contact (s6) of the result switch (S) or second check relay (Y) over the seventh contact (s7) of the result switch (S), what in this case causes permanent field suppression of result switch (S), because this leads to the disconnection of its driving circuit, which is closed through the fifth contact (s5) of the result switch (S), and also through the first contact (x1) of the first check relay (X) and through the first contact (y1) of the second check relay (Y); and the function of the coding unit (C) is interrupted, until the arrival of the operator and until the elimination of the fault and until the initialisation of the starting element, e.g. the activation button (ABU) for a manual start, by which the fault of the first check relay (X) or the second check relay (Y), is transferred in a safer direction and moreover this failure state is monitored by the diagnostic circuit (DC), which arranges for the operator to be called.

2. The method according to claim 1 is characterised in that,

- the starting element is a contact or switch of the automatic starter (AST), whose activity is safely checked by the first segment (DC1) of the diagnostic circuit (DC), which cheks the first branch (B1) and second segment (DC2) of the diagnostic circuit (DC), which cheks the second branch (B2) so, that these segments of the diagnostic circuit (DC1 , DC2) coincidently evaluate, whether the coding unit's (C) droppage was the result of a dangerous failure, in which case the diagnostic circuit (DC) permanently stops the coding unit's (C) activity until the maintenance employee arrives, while

- in the event the coding unit (C) drops out due to a slight failure, for example due to an outage of the power supply (UN), the diagnostic circuit (DC) will allow the automatic start of the coding unit (C) after the protective delay (TP) elapses so, that the contact or switch of the automatic starter (AST) is closed.

3. The coding unit (C) for the method of the checking for the first check relay (X) and second check relay (Y) of the cyclical code (CC1 - CC4) coding unit (C) in railway interlocking equipment (IS) according to claim 1 or claim 2, where the coding unit (C) is comprised of the check circuit (CCC) of the cyclical code (CC1- CC4), starting circuit (ST), diagnostic circuit (DC), output switching circuit (OS), first branch (B1) and second branch (B2), is characterised in that,

- the first check relay (X) of the coding unit (C) of cyclical codes (CC1 - CC4) is connected to the check circuit (CCC) of the cyclical code (CC1-CC4) and to the return conductor (RCC) in a series with the first diagnostic switch (d1), whereas

- the second check relay (Y) of the coding unit (C) of cyclical codes (CC1 - CC4) is connected to the check circuit (CCC) and to the return conductor (RCC) in a series with the second diagnostic switch (d2), while

- the diagnostic element (D) is driven from the cyclical code (CC1-CC4) check circuit (CCC) in that,

- the first branch (B1) is powered from the main voltage (MV) in a series with the sixth contact (s6) of the result switch (S), whereas the second branch (B2) is powered from the main voltage (MV) in a series with the seventh contact (s7) of the result switch (S), while - the starting circuit (ST) with the anti-repeat function is comprised of the starting element, either by an activation button (ABU) for a manual start or an automatic starter (AST) for an automatic start, and then in a series of setting contacts for driving the result switch (S), specifically the first contact (x1) of the first check relay (X), second contact (y1) of the second check relay (Y) and fifth contact (s5) of the result switch (S), so that the first to fourth contacts (s1 , s2, s3, s4) of the result switch (S) connect the interlocking equipment (IS) to the coding unit (C) outputs, while the first branch's (B1) auxiliary circuits are powered by auxiliary voltage (AV) in a series with the second contact (y2) of the second check relay (Y) and also in a series with the third contact (y3) of the second check relay (Y), similarly the second branch (B2) is powered by the auxiliary voltage (AV) in a series with the second contact (x2) and also in a series with the third contact (x3) of the first check relay (X).