RU2368015C1 - Method for monitoring of condition and integrity of loop circuit - Google Patents

Abstract

FIELD: physics, alarm.

SUBSTANCE: method may be used in systems of fire and fire-security alarm, and is intended for monitoring of fire and security loop circuit condition, and also for monitoring of loop circuit integrity. To monitor condition of fire alarm boxes with the help of stated method, level of basic DC voltage is supplied to loop circuit with connected fire alarm boxes, which is used to generate multi-level information signal that varies its level in case of actuation of each fire alarm box connected into loop circuit, and which makes it possible to further discriminate the level that corresponds to actuation of single fire alarm box from the level in actuation of two and more fire alarm fire boxes and intended for multidigit analog-digital conversion, to which total voltage of loop circuit is exposed. In order to monitor integrity of the loop circuit itself, stated method provides for connection of active terminal device in the end of loop circuit, which, during arrival of basic DC voltage, generates signal of integrity in the form of sequence of periodically repeating single control pulses, period of which is identified bases on condition of maximum economy of electric energy in the loop circuit from one side and condition of permissible time of truthful definition of loop circuit integrity from the other side, and their duration is selected as shorter that maximum duration of pulses at the inlet of receiving-control instrument, not taken into account as alarm condition, on the one side, and on the other side higher than period of loop circuit voltage measurement by receiving-control device.

EFFECT: suggested method is more efficient by energy expenditures for process of monitoring.

10 dwg

Description

The invention relates to the field of automation, and in particular to fire and burglar-alarm systems, and is intended to monitor the status of a fire and security loop (i.e., the condition of fire detectors included in a fire and security loop), as well as to monitor the integrity of the loop ( i.e., the loop itself is intact). It should be clarified that the term “loop” means connecting wires along the entire length of the guarded circuit from the control panel to the last fire detector, and the term “control” in accordance with Ozhegov’s dictionary means “verification, as well as constant monitoring for verification or supervision of work ”in our case, the work of a fire and security loop (see S.I.Ozhegov and N.Yu.Shvedova“ Explanatory Dictionary of the Russian Language ”4th edition, supplemented, M .: Azbukovnik, 1997, p. 292).

A widespread method of checking the integrity of a loop is by applying a voltage (alternating or alternating) through the loop to the constant terminal resistor included at the end of the loop, while loop integrity is monitored continuously in time, and loop integrity is judged by the presence of current flowing through the loop a resistor in case of a loop working condition (see the fire alarm method described in the system’s work, author’s book FI Sharovar Fire alarm devices and systems. M .: Stroyizdat, 1985, p.205-222 ) In this system, various loop conditions (standby mode, open circuit, short circuit, fire detector operation) correspond to predetermined values of the loop resistance and, accordingly, the currents in it. The control panel analyzes the current value in the loop and switches to the corresponding “Normal”, “Fire”, or “Fault” mode. Such systems are simple in design and suitable for the protection of objects of simple layout. The main drawback in the operation of such a system is that the main part of the loop current flows through the terminal resistor and is used only to control the integrity of the loop, and not to power fire detectors, which limits the energy efficiency (efficiency) in such a loop by almost 50%, because the terminal resistor current flowing continuously during loop operation for reliable recognition by the control panel of the loop failure mode should be greater than the total total current of all fire detectors included in the loop.

The well-known "Method of protecting a loop with a terminal resistor of a security alarm control panel against unauthorized interference" (see the laid-out application for the invention of the Russian Federation No. 2003133434 from 5.11.2003, G08B 1/00). It should be noted that in security systems the issue of loop integrity is very relevant. In order to exclude the possibility of deliberately blocking the operation of such a loop for unauthorized entry into a protected room, in this method the integrity of the security loop is monitored in two ways, firstly, through the current through the terminal resistor, and secondly, using a special one external to the receiving -control instrument - Loop Status Monitoring Devices (hereinafter - UXSH) and an active terminal device. In the technical solution for the application for the invention of the Russian Federation No. 2003133434 to perform the task of reliable control of the integrity of the loop in both methods use one medium for exchanging information about the integrity of the loop - the loop itself. Therefore, transceivers are used to transmit and isolate signals in the process of exchanging UXSH information and an active terminal device. Since the method for monitoring the integrity of the loop over the current of the terminal resistor is considered above, let us dwell on the method with an active terminal device. To implement the loop integrity control method using the UXSH and the active terminal device, the following actions are performed:

1) in the Control Panel, to the terminals of the loop with the terminal resistor, connect the UXSH, and at the end of the loop in parallel with the terminal resistor, an active terminal device is connected;

2) between the UXSH and the terminal device there is a periodic exchange of Information Parcels via a loop in the following order:

a) in the UXSH, the Random Number Generator (block 4) forms the Information Parcel and transmits it to the Transmitter-Receiver (block 1), also located in the UXSH, which transmits this parcel to the loop and the UXSS Encryptor (block 2), which converts the Information Parcel with using the secret Key; from the output of the Encryptor, the changed Information Package gets into the Comparison Device (block 5), where it is stored for some time;

b) At the other end of the loop, the Transceiver, which is part of the active terminal device, receives the Information Parcel and transmits it to the Terminal Device Encryptor (similar to that in the UKSH), which converts the Information Parcel using a secret Key that matches the secret Key in the UKSH , - the results of the conversion to the UXSH and the terminal device should ultimately coincide. The resulting encrypted Information Parcel is sent back to the Transceiver of the terminal device, from there to the loop, and the transmission of the information sequence to the terminal device and then back to the UKSH is performed with a time shift, for time separation;

c) the information sequence encrypted in the terminal device through the loop enters the UXSH Transceiver, and from it to the UXSH Comparison Device (block 5), where the original information sequence encrypted in the UXSH is already stored (see a). Next, a comparison is made of the data stored and received from the terminal device, in case of coincidence, a conclusion is made about the integrity of the loop and the operability of the terminal device;

3) with a systematic mismatch of the compared data or the absence of response information sequences from the terminal device, the UXSH Control Unit (block 3) concludes that the loop is violated and sends a command to the UXSH Executive Unit (block 6) to generate an alarm signal in the loop;

4) control panel - the security device receives an alarm signal through a loop and goes into the "Alarm" state.

Having considered the method of protecting the loop from unauthorized interference using both a terminal resistor and an active terminal device that implement an increased degree of protection, we can conclude that it is highly reliable, however, such difficulties of the method lead to additional energy costs for the control process - increased even compared to an uneconomical method with terminal resistor. The method is undoubtedly very complicated, and its task does not include energy saving, which, of course, is justified in security systems, since with such a complex terminal device containing a terminal resistor and an active terminal device, it is possible to fundamentally increase the reliability of the alarm system (with using a large number of different secret keys). The share of energy consumption in this loop for integrity control is more than 50%, because control is carried out in two ways on the terminal resistor (50%) and, moreover, on the active terminal device. But, at high energy costs for controlling the integrity of the loop, it is unlikely that an unauthorized intervention in the operation of such a loop is possible, because you will have to try one of the following actions (to prove the justification of large> 50% of the energy consumption for loop integrity control, we list these actions):

1) select a terminal device with a secret code that matches the code of the terminal device installed in the loop, and switch the loops, however, it is possible to make the number of codes large enough, up to the complete elimination of the possibility of selection;

2) analyze the principle of encryption and reproduce it using external additional tools, although to complicate this task, you can choose one of the rather secure algorithms;

3) compile a list of responses of the terminal device to all possible UXSS messages, although to complicate this task, you can increase the length of the information message and, therefore, the number of possible different messages.

However, all these difficulties, which also lead to additional energy costs for the loop integrity control process, are not needed in the fire loop, where the task is to increase the number of fire detectors in the loop in order to provide control over large areas, for example, industrial premises. In fire loops, the issue of energy saving, which is usually spent on controlling the integrity of the loop, with its subsequent use to power additional fire detectors, is an acute issue.

A known method of addressing the survey of fire detectors included in the loop described in the work "Devices for fire alarms" (see Japan patent No. 3563254 B2, 11175859 A, G08B 17/00 from 12/11/1997). This method is implemented by a fire alarm device containing a loop with parallel-connected addressable fire detectors and a terminal device (element 9 in the figure of Japanese patent No. 3563254) and a control panel that interrogates them sequentially. The terminal device at the end of the line, like the fire detectors, gives an answer to the line at the request of the control panel. The decision on the integrity of the loop and on its condition is made if there are answers from the addressable fire detectors and from the active terminal device, moreover, the decision on the fire is made according to the responses from the fire detectors, and on the integrity of the loop - according to the response from the active terminal device. Undoubtedly, the advantages of the address-based method for monitoring the status and integrity of the loop include the cost-effectiveness of the loop integrity monitoring process and the high reliability of the analysis results, since the address-based monitoring method allows you to set the status of each loop sensor and at the same time identify its location at the address. The advantages of the method of targeted polling in the control process, in our opinion, include the simplicity of constructing a circuit device that implements this method. And the disadvantages include the high cost of fire detectors capable of implementing this method, and the complex exchange of information on the bus. In our opinion, if the exchange rate is large, the reliability of communication decreases and the influence of interference on the loop increases. If the exchange rate is small, then the period of cyclic interrogation of fire detectors will be unacceptably large, in addition, with this control method, the installation procedure of the system at the facility is complicated (usually all sensors are manually configured). Serious problems arise when the loop is broken / shorted, a large number of sensors immediately break down, to reduce this danger, separate parts of the loop are untied through special buffer amplifiers-coordinators in case if a fault occurs in any part, only part of the loop circuit will fail. .

The closest selected as a prototype is the "Signaling Method" according to the patent of the Russian Federation No. 2078376 from 07.15.1991, G08B 25/00, G08B 19/00. When checking the integrity of the loop in this way, an alternating signal is generated, it is fed to the active terminal device through the loop with fire detectors included, with which an additional signal is formed in the form of a pulse sequence, where pulses with a parameter other than a similar parameter are followed with a given period the remaining pulses in the period, while an additional signal from the terminal device is fed again through the signal loop to the control panel. When there is no additional signal generated by the active terminal device, an information signal is generated from the alternating signal received by the fire detectors of the loop, in which, depending on the state of the fire detectors included in the loop, the sequence of pulses changes, according to the results of which, a state opinion is formed a loop and fire detectors included in it.

To identify the differences between our proposed method and the selected prototype, consider the "Signaling method" according to patent No. 2078376 (prototype) in more detail. It should be noted that the “Alarm Method” adopted for the prototype includes both loop integrity monitoring and the status of fire detectors in it. Moreover, talking about monitoring the integrity of the loop makes sense only in the normal state of the loop, when fire detectors are passive, since any alarm state (fire, alarm) takes precedence over damage to the loop.

The integrity of the signal loop is monitored by periodically changing the shape of alternating pulses caused by the action of the active terminal device on the pulses arriving through the cable to the terminal device. For this (for periodically changing the shape of the pulses), the input loop voltage passed through the rectifier of the active terminal device (see FIG. 1 of patent No. 2078376, block 25) is supplied to the counter input (block 26), which causes cyclic changes in its state after arrival each half-wave voltage in the loop. The counter is organized in such a way that when every 3rd half-wave appears, it gives an enable signal to the transistor switch (block 28), which shortens the loop until the next half-wave appears. Thus, every 3rd half-wave in the loop is exposed to the terminal device (see Figure 2 of patent No. 2078376, timing diagram 3). In the control panel, according to the terminology of the "receiving panel" patent (see Figure 1 of patent No. 2078376, block 1), the voltage in the loop is rectified (See Figure 2 of patent No. 2078376, timing diagram 4) and sent to the input of the comparator ( see Figure 1 of patent No. 2078376, block 13), under the control of internal pulses of which are converted into a binary (only 2 levels are distinguished - 0 and 1) pulse sequence (see Figure 2 of patent No. 2078376, timing diagram 5). Further, this sequence is analyzed by coincidence elements (see FIG. 1 of patent No. 2078376, blocks 14-18) to identify pulses generated by the terminal device and to analyze the status of fire detectors included in the loop, which can also affect the voltage in the loop, leading to different signal modifications, which are all taken into account by the control panel that performs the analysis. Turning to the drawings of patent No. 2078376:

- at rest, the waveform is shown in Fig.2;

- when triggered by a fire detector - figure 3;

- when triggered by an active fire detector - figure 4;

- in case of a loop failure - in Fig. 5.

As you can see (see figure 2 of patent 2078376, timing diagram 3), to control the integrity of the loop, the active terminal device causes the flow of through current through the loop for 1/3 of the total control time, which leads to undoubtedly lower energy consumption for the task of controlling the integrity of the loop in comparison with the two analogues above, the first of which (the method according to the author’s book, FI Sharovar Fire alarm devices and systems. M .: Stroyizdat, 1985, p.205-222) contains a terminal resistor, and the second (“Protection MethodLeif EOL burglar alarm control panel from unauthorized intervention "refer a request for an invention of RF №2003133434 11.05.2003.) - comprises a complex terminal and to a terminal resistor, and an active element. But, nevertheless, even in comparison with the economical method adopted for the prototype, in our opinion, it is possible to optimize the integrity control mode, in the direction of reducing energy consumption for this mode and increasing the energy spent in the loop, for fire detectors, which makes it possible to increase the number fire detectors in one signal loop. We consider it necessary to clarify that the large energy consumption in the loop for monitoring its integrity entails the need to build a new loop or even several loops for the introduction of additional fire detectors, which may require an increase in the number of control panels necessary for processing signals from a given number of active fire detectors, and this increases the cost of equipment and maintenance costs of the fire complex. Therefore, the issue of reducing energy consumption for the loop integrity control process in all automatic fire safety control devices is very acute.

The informational pulse signal generated in the prototype method carries only two types of information:

1) there are distortions in the signal - there are fire detectors that have worked,

2) no distortion - no triggered detectors.

In its form and form, the pulsed information signal is intended for further single-bit processing on the comparator, as a result of which we can judge whether the detectors have triggered “yes” or “no” (triggering - switching to alarm state), the ability to distinguish between the triggering of several fire detectors of the same type such a detector, with such a conversion is not provided.

According to current standards, starting a fire extinguishing system by triggering one fire detector is unacceptable, because this can be a false alarm (either due to a false alarm of the fire detector, or due to local changes in the parameters of the protected environment). The main version of the standards is to consider the operation of two fire detectors as the "Fire" mode. And when more than two fire detectors went off, the probability of the occurrence of the Fire event increases all the more.

The type of the information signal generated in the prototype method does not provide the possibility of determining the number of triggered fire detectors in the loop, which does not allow the use of false alarm elimination algorithms in the control panel based on the processing of information about the number of fire detectors in the loop. As you can see, the question of determining the number of triggered fire detectors in the loop: one or many (two or more) in the prototype is not resolved, such a device is called single-threshold.

It will be fair to note that the prototype method is not applicable to the most common alarm loops, where a constant voltage is used to monitor the loop condition.

The purpose of the development of the proposed method is:

1. Reducing the power consumption of the loop integrity control process.

2. Making it possible to distinguish the transition of one fire detector to an alarm state from the transition to an alarm state of two or more fire detectors.

This goal is achieved by the fact that in the method of monitoring the status and integrity of the loop, based on the supply of the basic signal through the loop with the fire detectors turned on to the active terminal device, with the subsequent formation of an information signal about the state of the fire detectors in the loop, and a periodically repeating loop integrity signal generated active terminal device, and on the supply of both signals to the control panel via a loop - here in this claimed method, as a basic signal they supply a constant voltage, the information signal is formed by a multilevel one, changing its level depending on the number of fire detectors in the loop that have become alarmed, the loop integrity signal is generated as a sequence of single control pulses, the period of which is determined from the condition of minimum power consumption in the loop on one side and conditions allowable time for reliable determination of the integrity of the loop on the other, and their duration is chosen less than the maximum duration and pulses at the input of the control panel, which is not protected as an alarm condition, on the one hand, and on the other hand, is longer than the period of measuring the loop voltage by the control panel, consisting of a multilevel information signal and control pulses, the multi-bit is used as a processing tool analog-to-digital conversion, and according to its results distinguish the transition to the alarm state of one fire detector from the transition of two or more, and recognize the serviceability / malfunction of the loop .

We explain the essence of the invention in other words:

The purpose of the development of the proposed method is:

1. Reducing the power consumption of the loop integrity control process. The goal is achieved by increasing the repetition period and optimizing the duration of the control pulses.

2. Making it possible to distinguish the transition of one fire detector to an alarm state from the transition to an alarm state of two or more fire detectors.

This goal was achieved due to the formation of voltage in the loop, consisting of control pulses and a multi-level information signal (changing its level depending on the number of fire detectors triggered) and intended for subsequent multi-bit analog-to-digital conversion, which allows further use of false alarm elimination algorithms. At the same time, the control panel distinguishes the situation when one fire detector (“Attention” mode) has tripped from the operation of two or more (“Fire” mode).

The idea of generating two signals - information about the status of fire detectors in the loop and the loop integrity signal generated by the active terminal device, consuming the loop current only during the formation of the loop integrity signal periodically repeating in time, is implemented in the analogue (application No. 2003133434), and prototype (patent No. 2078376). The gain in reducing energy consumption for loop integrity monitoring in the analogue (application No. 2003133434) is not quite compared to the uneconomical way of loop integrity monitoring with a passive terminal device - with a terminal resistor (method according to the author’s book F. F. Sharovar Fire alarm devices and systems M.: Stroyizdat, 1985, p.205-222), because a double integrity control method with a complex terminal device has been applied, which includes monitoring on both the passive and plus on the active terminal device. In the prototype (patent No. 2078376) - the gain is not so great compared to the same uneconomical way of controlling the integrity of the loop with a passive terminal device - terminal resistor (method according to the author’s book, F. Sharovar. Fire alarm devices and systems. M.: Stroyizdat 1985, p.205-222).

Let us explain in more detail, in the integrity control method with a passive terminal device - an end resistor, roughly speaking, the entire loop current is divided as follows: 50% (maximum) - to fire detectors and 50% (minimum) - to the terminal resistor. In the analogue (application No. 2003133434), where a sophisticated terminal device with double loop integrity control is justifiably used, fire detectors use even less loop energy in percentage terms, because to the current consumed by the passive terminal device - the terminal resistor, the current of the active terminal device is also added. In the prototype with an active terminal device (patent No. 2078376), the loop current is divided as follows: 66% (maximum) - for fire detectors and 33% (minimum) - for integrity control. In our claimed method, it was possible to reduce energy consumption for loop integrity control of the order of 1-5%, i.e. more than 95% of the loop current is used by fire detectors, which allows to increase their number in the loop one and a half to two times. In addition, having formed a multi-level information signal, which is expedient (since it is designed in its construction) to be subjected to multi-digit conversion to digital form, it is possible to distinguish the transition to the alarm state of one fire detector from the operation of several fire detectors. The formation of a multi-level information signal is very important for obtaining information about the real picture of the fire, and most importantly for the use in the control panel of algorithms for eliminating false alarms based on the processing of information about the number of fire detectors operating in one loop.

From the explanations made above, we can draw the following conclusions:

- in the claimed method significantly reduced power consumption of the loop integrity control process compared to the prototype, because the duration of the loop integrity monitoring pulse is about a percent of the length of the period of following single control pulses, i.e. the power consumption of the loop integrity control process is reduced to (1-5)% of the total energy consumed in the loop, which allows directing up to 95% of the loop energy to fire detectors, i.e. increase the number of fire detectors in the same loop in one and a half, two times;

- in the claimed method, in comparison with the prototype, it is possible to distinguish the triggering of one fire detector from the triggering of two or more fire detectors due to the nature of the multilevel information signal generated in the claimed method, changing its value (level) when each of the fire detectors is triggered - a tool to achieve this is a multi-bit analog-to-digital conversion (digitization), followed by application for the analysis of the results of digitization of algorithms for eliminating false revozhnyh signal receiving and control device;

- and, in addition, the use of a constant voltage as the basic signal in the method, unlike the prototype, firstly, does not require the formation of a complex basic alternating signal supplied to the loop and the terminal device, and secondly, determines the purpose of the method for the most common alarm loops, where a constant voltage is used to monitor the loop condition.

The inventive method is more economical in comparison with the prototype not because the prototype method according to patent No. 2078376 works on an alternating signal, but the inventive method on an alternating signal, but because the reduction in energy costs for the loop integrity control process is determined by the choice of period and duration control pulses, namely: the period of generation (issuance) of control pulses is increased, and their duration is optimized.

Thus, the claimed method differs from the known:

- firstly, by reducing energy costs for the loop integrity control process, which is due to the choice of the repetition period and the duration of single control pulses;

- secondly, by the type of information signal: it reflects the current state of fire detectors by a change in the constant voltage level, and not by the nature of the distortion of the base alternating signal in the loop, as was done in the prototype, which in the claimed method allows us to use “difference of operation one fire detector from two or more "multi-bit analog-to-digital conversion (digitization) with the subsequent application of algorithms for eliminating false alarms;

- thirdly, by the fact that for supplying via a loop to the active terminal device they do not form a complex alternating signal, but supply a constant voltage,

- fourthly, by the type of loop integrity signal - in the claimed method, these are single pulses, and in the prototype this is the presence of distortion in the group of pulses of the base signal.

The inventive "Method of monitoring the status and integrity of the loop" is presented in the drawings:

Figure 1. The block diagram of the alarm system that implements the method (option 1).

A block diagram of an alarm system implementing the proposed method with parallel activation of fire detectors and a terminal device in a loop is presented.

Figure 2. Scheme of the terminal device (option 1).

An electrical circuit diagram of one of the possible embodiments of an active terminal device is presented.

Figure 3. Timing diagrams of voltage on the elements of the terminal device (option 1) during the formation of the loop integrity signal.

The time diagrams of the voltage across the elements of the terminal device are presented. The operation of the terminal device in case of its execution according to the electrical circuit diagram shown in Figure 2 is considered.

Figure 4. Plots of voltage in a loop in various modes.

The time diagrams of the voltage in the loop for both versions of the alarm systems implementing the method are presented. In connection with the parallel connection of fire detectors and the terminal device in the loop (alarm system option 1), the voltage and timing diagrams at any point in the loop are the same, including, in particular, at the points where the loop is connected to the control panel. Possible modes of loop condition are considered depending on the triggered fire detectors. The stages of the formation of a multi-level information signal are presented.

When building a loop in series and parallel, as shown in option 2 of the alarm system, the voltages and timing diagrams are completely similar to option 1 with parallel connection of fire detectors with the clarification that when any fire detector is disconnected from the loop of option 2, the circuit breaks, the terminal device disconnects from the control panel and voltage plots in the loop correspond to the fault mode (open).

Figure 5. Summary diagram of the voltage in the loop in various modes.

For clarity of the method (process) of forming a multi-level information signal in the loop and for the clarity of the operation of the loop integrity control method, a summary time diagram of the voltage in the loop is presented for various possible modes indicated by the alarm control panel (option 1 and also option 2) that implements the inventive method .

6. The block diagram of the alarm system that implements the method (option 2).

A block diagram of the alarm system implementing the proposed method with series-parallel switching on of fire detectors and a terminal device in a loop is presented.

7. The electrical circuit diagram of the active terminal device (option 2).

Fig. 8. Timing diagrams of voltage on the elements of the terminal device (option 1) during the formation of the loop integrity signal.

Fig.9. Timing diagrams - an explanation of the choice of the duration of the control pulses.

Figure 10. Timing diagrams - an explanation of the choice of the period of follow-up of control pulses.

Consider the implementation of the proposed method in the process of operation of the alarm system, the first version of the block diagram of which can be presented, for example, in the following form (see Figure 1). As you can see, the alarm system contains a control panel (1), a loop (2) with parallel fire detectors (3), for example, type IP212-63 Danko, as well as an active terminal device (4) connected to the end of the loop, the electrical circuit diagram of the active terminal device may, for example, be as shown in FIG. In this case, the control panel contains a constant voltage source (5), a ballast resistor (6), which is designed to limit and determine the current in the loop through voltage measurement on the ballast resistor, a microcontroller (7) - type ATMEGA32 (-16AI), included in the standard scheme shown in the set of documents for the Atmega 32 (L) microcontroller (347pages, revision K, updated 08 | 07), available on the manufacturer’s website http://www.atmel.com/dyn/resources/prod_documents/doc2503.pdf.

The microcontroller contains an analog-to-digital eight-input 10-bit converter (8), hereinafter referred to as the ADC. A divider (9) is connected at the input of the ADC to match the real voltages in the loop (about 20-25 volts) with the permissible voltage at the input of the microcontroller (up to 5 volts).

Since the terminal device is not a standard element, let us consider in detail its construction. Option 1 of the circuit diagram of the electrical circuit terminal device (see Figure 1, position 4) is presented in Figure 2 and consists of a master oscillator (10), forming a sequence of pulses with the necessary time parameters, and an output key (11), forming control pulses in a loop.

The generator includes a current source (transistors VT1 and VT2), a storage capacitor C1, in which the charge from the current source is accumulated, and a voltage comparator on capacitor C1 with hysteresis on transistors VT3, VT4 and VT5, diode VD1 and LED VD3. The output key consists of a zener diode VD2, which limits the voltage in the loop during the formation of control pulses, as well as the LED VD3 and transistor VT5, which are also part of the generator.

Presented in figure 1, the first version of the security and fire system that implements the inventive "Method of monitoring the status and integrity of the loop", works as follows. The tasks of the control panel (1), in addition to monitoring the status of fire detectors included in the loop, include continuous monitoring of the integrity of the connecting wires forming the loop (2), along the entire length of the loop from the control panel to the last fire detector (3), included in this loop. We focus on the fact that the status of fire detectors is monitored by an information signal that is generated using the state of fire detectors in a loop from a constant base voltage, changing its level by changing the current passed through fire detectors when they go into alarm state (triggered); depending on the number of triggered fire detectors, the voltage level in the loop changes - the level of the information signal. To control the integrity of the loop at the end of the loop, a terminal device (4) is installed, with the help of which control pulses are generated, their presence at the input of the control panel serves as a confirmation of the health of the loop.

After turning on the control panel, the basic constant voltage from the output of the constant voltage source (5) through the ballast resistor (6) enters the loop (2), where fire detectors (3) and the active terminal device (4) start working from this voltage.

During operation, fire detectors located in the premises of the guarded object monitor a characteristic environmental parameter, for example, temperature, smoke content and so on, depending on the type of fire detector, and in the absence of alarm signs, in other words, in the absence of deviations of the monitored parameters from the set norm , fire detectors pass through (consume) only a small standby current necessary for the fire detector to operate, and the active terminal device “signals” (more precisely, it generates single control pulses with a given period and duration) about the integrity of the entire loop, because the terminal device is connected at the end and only with the integrity of the entire loop to the terminal device is the base voltage supplied.

Suppose that the system described above that implements the claimed method is in standby mode, i.e. the fire detectors (3) included in the loop (2) consume only a small standby current and do not significantly affect the voltage level in the loop of the information signal in the loop, this loop condition corresponds to the “Normal” mode on the control panel. The timing diagram of the "Normal" mode is presented in Fig.4a), where:

- U _BAZ - voltage at the output of a constant voltage source (5), in fact, this is the level of constant base voltage in the loop supplied to the loop and through the loop to fire detectors and terminal device;

- U _INF - voltage on the loop in the pauses between the control pulses in the "Normal" mode, in fact it is an information signal about the status of fire detectors in the loop;

- U _THRESHOLD - a change in the voltage in the loop by an amount exceeding U _THRESHOLD for the duration of the control pulse duration, the control panel considers a sign of the presence of a control pulse;

- U _NORM - this is the level of the information signal below U _BAZ , but above U _FIRE , when the voltage of the information signal in the loop below this level, the control panel switches to the “Attention” state;

- U _FIRE - this is the level of the information signal, below which the control panel goes into the “Fire” state;

- U _NEISP - voltage threshold in the loop between the conditions of "Fire" and "Fault (C)",

- U _IMP - level of control pulses.

As can be seen from Fig.4a), when all fire detectors in the loop are in standby state, the voltage of the information signal (equal to the voltage during pauses between the control pulses) is between the thresholds U _NORM and U _BAZ .

Since all fire detectors (3) and the terminal device (4) are connected in parallel in the loop, the currents flowing through them are added and the resulting loop current forms a voltage drop on the ballast resistor (6), which is directly proportional to the total current in the loop; how much the voltage drop across the ballast increases - by how much the voltage drops in the loop. The voltage in the loop (2), equal to the voltage difference at the output of the constant voltage source (5) and the voltage at the ballast resistor (6), linearly decreases with increasing current in the loop. Therefore, under the influence of a pulse increase in the current through the terminal device (4), voltage pulses appear in the loop, the voltage in the loop decreases for the duration of the control pulses.

Throughout the entire life of the system and regardless of the state of the fire detectors, the active terminal device (4) operates in a pulsed mode. The main part of the time it consumes from the loop only a small current (of the order of 50-100 microamps), necessary for the terminal device to operate, and only for the duration of the pulse duration the current of the terminal device increases stepwise.

Consider the process of forming a sequence of single control pulses, reflected in the operation of the active terminal device, option 1 of the circuit diagram of which is presented in figure 2. Initially, in the absence of a constant base voltage in the loop connected to the device through the contacts of connector X1, all transistors and diodes are closed, the storage capacitor C1 (see Figure 2) is completely discharged. There is no voltage in the loop.

From the moment that the voltage is supplied to the loop, it is completely supplied to the current source of the terminal device (see Fig. 2 VT1 and VT2). Due to this voltage, a current begins to flow through the resistor R1, which enters the base of the transistor VT2 and opens the collector junction of this transistor, while its emitter current increases. When this current creates enough voltage on resistor R2 to turn on transistor VT1, this transistor opens and picks up a part of the base current of transistor VT2, which limits the emitter current of this transistor to a level that is barely enough to create a trigger voltage on resistor R2 for transistor VT1. When the emitter current of transistor VT2 decreases, the base-emitter voltage of transistor VT1 decreases, it starts to close, and its collector current drops. In this case, the base current of the transistor VT2 increases, returning its emitter current to a stable value. Thus, the current through the transistor VT2 is stabilized and little depends on the voltage at the current source (transistors VT1 and VT2).

The output current of the current source enters the storage capacitor C1 and causes a linear increase in voltage across it (see Fig. 3a). As this voltage increases, the base-emitter voltage of the VT3 transistor grows (see Fig. 3b), formed by a resistor divider formed by a resistor R3 on the one hand and R4-R5-R8-R9 on the other hand. When this voltage reaches the threshold value (see Fig. 3b, moment t ₁ ), the transistor VT3 will begin to open and its collector current will open the transistor VT4. In turn, an increase in the collector current of the VT4 transistor will cause an increase in the voltage on its collector, which will cause a current through the resistor R5 to the base of the transistor VT3 - positive feedback will lead to an avalanche-like opening of both transistors (VT3 and VT4).

The fully opened transistor VT4 will cause the voltage of the capacitor C1 to appear on the collector of the transistor VT4 (see Fig.3c), which will cause a current through the resistor R8 to the base of the transistor VT5, which will fully open. In this case, the voltage on its collector will drop to almost zero, which will cause current to flow through the VD3 LED. This current consists of two parts. Firstly, through the resistor R10 and the opened diode VD1, the discharge current will flow from the capacitor C1 to the ground. Secondly, through the Zener diode VD2, current will flow from the loop. This will cause a decrease in the voltage in the loop (see Fig. 3d) to a value determined by the voltage drop across the Zener diode VD2 and the LED VD3.

The value of the discharge current through the resistor R10 is much larger than the charge current from the current source. This will cause a fast discharge of the capacitor C1 and a voltage drop across it (see Fig. 3a). As the capacitor discharges, the input voltages and currents of the transistors VT2 and VT3 will decrease until one of them starts to close (see Fig.3b, moment t ₂ ).

As soon as this happens, an avalanche-like process of closing both transistors under the influence of positive feedback through resistor R5 will begin. Which will lead to the closing of the transistor VT5, diode VD1, Zener diode VD2 and LED VD3.

Further, the process will be repeated, only the initial conditions of subsequent cycles differ from the conditions at the time the base voltage was applied to the loop, so the period of steady oscillations of the generator will be equal to the time interval from time t ₁ to time t ₃ in FIG. 3. The duration of the control pulses - the first (from time t ₁ to time t ₃ see FIG. 3) and all subsequent ones (for example, from time t ₃ to time t ₄ see FIG. 3) will coincide.

As we can see, at regular intervals, the terminal device jumps in stepwise increases the current passing through it by the time determined by the duration of the control pulses with a given period, thus forming the loop integrity signal - voltage U _IMP , and the duration of these current pulses is much less than the period of their following and the period itself is determined by the choice of elements R2, C1, R3, R4, R5, R8 and R9, and is determined, first of all, from the condition of admissible time for a reliable determination of the fault of the loop, as well as from the conditions saving energy consumed by the terminal device.

Each control pulse is accompanied by a flashing of the VD3 LED, which gives an additional opportunity to visually control the integrity of the loop and the operation of the terminal device.

Let us turn to the consideration of the formation of an information signal in the “Failure” mode of the loop. In the event of a break in the loop and in the standby state of all fire detectors, the timing diagram is presented in Fig.4b. Voltage

U _BAS is not supplied to the terminal device, while the terminal device does not generate control pulses. The level of the information signal U _INF as in the “Normal” mode is higher than the threshold U _NORM .

When the wires in the loop are shorted, the voltage in it drops to zero, the time diagram in the short circuit mode of the loop, see Figure 5 - mode "short circuit". The control panel, in case of breakage and short circuit of the loop, displays the “Fault” mode.

Next, we continue to consider the process of generating an information signal in the “ATTENTION” mode. If alarming fire signs are detected, for example, an increase in temperature or the appearance of smoke, but in the presence of control pulses confirming the integrity of the loop, when only one of the fire detectors (3) jumpwise increases and fixes the current passed through itself, the time diagram will take the form shown in Fig. 4c). As you can see, the level of the information signal drops (we observe the process of forming a multi-level information signal, in this mode - the level of the information signal drops by an amount determined by the increase in current through the triggered fire detector and the resistance of the ballast resistor), the level of the information signal U _INF at the transition of any fire detector in a loop in alarm mode is between the values of U _NORM and

U _FIRE , i.e. became less than U _NORM , but still more than U _FIRE .

The control panel enters the “Attention” state and takes actions aimed at reducing the probability of issuing a false “Fire” signal. Depending on the settings of the device, this may be one of the following options:

- disconnecting the base voltage from the detectors for a time sufficient to reset the fire detectors, with the subsequent restoration of this voltage and waiting for a predetermined time (for example, 1 minute) to re-operate the detectors in the loop - the so-called "reconnaissance" or "interrogation";

- delay in the transition to the “Fire” state until the second detector is triggered (automatic or manual, in the same or adjacent loop) with the formation of warning sound and light indicators, but no signals to the automatic fire extinguishing systems.

Thanks to these measures, it is possible to avoid false fire alarms and the damage caused by automatic fire extinguishing systems to people and property in this case.

Let us consider the process of generating an information signal in the “FIRE” mode, when two fire detectors in the same loop worked (went into an alarm state), the time diagram of the voltage is shown in Fig. 4d).

As you can see, the level of the information signal has become even lower, now it is less than U _FIRE and is located between the values of U _FIRE and U _NORMAL . The control panel enters the “Fire” state and generates a triggering signal to the automatic fire extinguishing systems.

With three or more triggered fire detectors in the loop, the voltage of the information signal U _INF becomes even lower, but it is still within the same limits as in the case considered earlier. The control panel distinguishes only the transition of one fire detector into an alarm state from two or more, two or more are perceived equally to them.

For clarity, to illustrate the process of generating integrity signals and the status of the loop, we consider it expedient to give a summary diagram of the voltage in the loop at various possible modes, located one after another sequentially in time (see Figure 5). We first focus on the fact that in the total voltage of the loop there is always a multilevel information signal, which, depending on the change in the state of the detectors in the loop, can change from a level close to U _BAZ to zero (with a short circuit of the loop), and (in case loop health) in the total loop voltage simultaneously with a multilevel information signal there is a pulse signal of loop integrity (control pulses).

Suppose that when applying the basic voltage to the loop, the loop (see Figure 1) turned out to be open in some section, so that the U _BAZ “does not reach the terminal”, there are no control pulses (there is no signal of loop integrity), but all fire detectors, which received U _BAZ voltage to the loop break section, are in standby mode, the information signal level is close to U _BAZ , which is reflected in the summary diagram in the "Loop break" mode (see Figure 5).

Then the operator found the place of the loop breakage and fixed the malfunction, the terminal device started working and control pulses appeared in the total voltage on the loop. Suppose that all fire detectors are in standby mode, while the information signal has changed due to the current consumption of all fire detectors of the loop now, and not just those that were located to the point where the loop breaks. This loop condition is reflected on the summary diagram in the "NORMAL" mode (see Figure 5).

Then one of the fire detectors worked (went into an alarm state), the loop is intact - control pulses are present, the information signal level has fallen, it is between U _NORMAL and U _FIRE , this loop condition is reflected on the summary diagram in the ATTENTION mode (see Fig. .5).

When two or more fire detectors go into alarm mode, the level of the information signal still drops, now it is located between U _FIRE and

U _NEISP ; this loop condition is reflected on the summary diagram in the “FIRE” mode (see Figure 5).

And finally, with a short-circuited loop, the voltage across it turns to zero, which is reflected in the summary diagram in the "KZ" mode.

Having considered the process of generating a loop integrity signal in the form of a sequence of single pulses (see Figure 3) and an informational, multi-level signal on the status of fire detectors in a loop (see Figure 4), we can imagine that in a loop, if it is in good working order, there are two signals: a pulsed loop integrity signal and an information signal that changes its level depending on the state of fire detectors in the loop, therefore we call this signal multi-level (see Figure 4, Figure 5).

Note the following, the information signal in the prototype (see patent No. 2078376, Fig.2-3) is not intended for multi-bit ADC, because the basic information is transmitted not by the voltage value (only 2 levels are distinguished - “presence” and “absence” of the signal), but by a pulse train (a variant of a binary serial code) and the use of a multi-bit ADC is impractical (it makes no sense), since it does not add useful status information a loop.

The multi-level information signal generated in the claimed method is designed for multi-bit analog-to-digital conversion and, moreover, multi-bit digitization serves as a tool to achieve the goal: providing the ability to distinguish the transition (possibly random) in the alarm state of one fire detector from the transition of two or more fire detectors . Having such an opportunity to distinguish, we reduce the likelihood of false alarms and malfunctions of the control panel.

In our opinion, undoubtedly, one of the advantages of the proposed method is, in particular, not that it uses a multi-bit ADC (although this is also a difference from the prototype), but that in the method, in contrast to the prototype, a multi-level information signal, due to which it became expedient to use a multi-bit ADC as a tool, as after multi-digit digitization, it is possible to use algorithms for reducing the probability of “False alarms” in the control panel, which provides a gain in comparison with the prototype — increasing the reliability of the results of the analysis of the fire situation at the security facility.

Since the inventive "Method for monitoring the state and integrity of the loop" includes the formation of voltage in the loop, which, unlike the prototype, is designed for multi-bit analog-to-digital conversion and allows you to use more complex algorithms for analyzing the state of the loop, which improves the reliability of the analysis results digitized voltage in the loop (the difference between the operation of one, from two or more fire detectors), so far we will provide a brief discussion of the process of multi-bit analog phase transformation, without claiming to be original, but only to demonstrate the purpose of nature of the complex voltage formed in the loop, consisting of a multi-level information signal and control pulses, for this procedure.

Next, we consider the process of multi-bit analog-to-digital conversion of a multi-level information signal using the analog-to-digital converter built into the microcontroller.

Both generated when applying a constant base voltage of the signal (one is formed by the terminal device, as described above, and the other is formed by the fire detectors themselves, depending on their condition) make up the loop voltage, and through the loop enter the inputs 1 and 2 (see Figure 1) the ADC built into the microcontroller, for example, PA0 (ADC0) (this is the name of the inputs in the technical documentation for the Atmega 32 (L) microcontroller (347 pages, revision K, updated 08 | 07), available on the manufacturer’s website http: //www.atmel. com / dyn / resources / prod_documents / doc2503.pdf).

To match the voltage level in the loop with the ADC input, it may be necessary to use an additional resistor divider (9) in the control panel (see Figure 1).

The ADC is configured to work in the necessary modes during the execution of the main program of the control panel.

Periodically during the execution of the main program on the ADC from the microcontroller commands are issued to conduct voltage measurements at its inputs 1; 2 - PA0 (ADC0) (see figure 1), in fact, in the loop. After the measurements are completed, the ADC output register called ADC (ADC is the name of the output register in the set of documents on the MK, as well as ADC is the designation of the same name), the ADC value appears, determined by the formula given in the above technical documentation for the microcontroller:

ADC = (V _in · 1024) / V _ref ,

where 1024 = 2 ¹⁰ , where 10 is the number of bits of the ADC,

V _ref - reference voltage of the ADC (measurement limit),

V _in - real voltage at the input of the ADC, taking into account the divider:

V _in = U _ШС · К,

where U _AL - voltage in the loop,

K is the transfer coefficient of the matching resistor divider (9) (see Figure 1); if there is no divisor, then K = 1.

Thus, the result of measuring the voltage at the input of the ADC is directly proportional to the voltage in the loop

ADC = (U _GC · K · 1024) / V _ref .

To analyze the loop condition, it is enough for the microcontroller to compare the voltage obtained at the ADC input as a result of the measurement with the threshold values determined in advance during the design of the control and reception device (K and V _ref values are known in advance when writing the microcontroller program). The threshold values themselves are calculated according to the above formula when substituting the corresponding voltages (U _NORM , U _FIRE and so on) instead of U _AL :

ADC _BA3 = (U _BAZ · K · 1024) / V _ref ,

ADC _NORM = (U _NORM · K · 1024) / V _ref ,

ADC _FIRE = (U _FIRE · K · 1024) / V _ref ,

ADC _NEISP = (U _NEISP · K · 1024) / V _ref ,

Where

U _BAZ - the base voltage of the loop from the output of a constant source

voltage (5), see Figure 1,

U _NORM - voltage threshold in the loop between the conditions of the "Norm" and

"Attention", see Figure 4,

U _FIRE - voltage threshold in the loop between the states of "Attention" and "Fire",

U _NEISP - voltage threshold in the loop between the conditions of "Fire" and

"Fault (KZ)",

ADC _BAZ - ADC value at the ADC output when measuring voltage in

a loop equal to U _BAZ ,

ADC _NORM - ADC value at the ADC output when measuring voltage in

loop equal to U _NORM ,

ADC _FIRE - ADC value at the ADC output for voltage measurement

in a loop equal to U _FIRE ,

ADC _NEISP - ADC value at the ADC output for voltage measurement

in a loop equal to U _NESIS .

Figure 4a) shows the form of the information signal in the normal state of the loop (all fire detectors are in standby state and the loop is operational, that is, it is not cut off and shorted). In this mode, the loop current, consisting of the sum of the standby currents of the fire detectors and the pulse current of the terminal device, creates two voltage values in the loop: between pulses, which is essentially an information signal U _INF on the status of the loop, or rather, the state of the fire detectors in it , and U _IMP during the control pulses, which are a signal of the integrity of the loop.

During the formation of the control terminal voltage of the pulses in the loop U _IMP reduced relative to the value U _{of IFN} by more than the threshold value U _THRESHOLD, which enables the microcontroller to identify the level control pulses from the data signal.

When all fire detectors in the loop are in standby mode, the voltage in the loop between the control pulses is in the range

_NORMAL U <U _IFN ≤U _bases.

In this case, after completing the measurements, the value corresponding to the following condition will be present in the output register of the ADC of the microcontroller:

АDC _NORM <ADC≤ADС _BAZ ,

which serves as a sign of the normal state of fire detectors in a loop.

If one of the fire detectors in the loop goes into an alarm state and abruptly increases the current passing through it (see Fig. 4c), then the voltage in the loop between the control pulses will be in the range

U _FIRE <U _INF ≤U _NORM , and then

ADC _FIRE <ADC≤ADC _NORM .

If two or more fire detectors go into alarm state in the loop (see Fig. 4d), then the voltage in the loop in the pauses between the control pulses will be in the range

U _NEISP <U _INF ≤U _FIRE and

ADC _NORMAL <ADC≤ADC _FIRE .

If, as a result of insulation failure, extraneous interference, or other reasons, the loop turns out to be short-circuited (shorted and inoperative), the voltage in it will drop below the U _level

0≤U _INF ≤U _NISP and

0≤ADC≤ADC _NULL

As described above, the control panel (microcontroller) receives information about the voltage and current in the loop. In the event that the measurement result at the ADC output falls into the same range of values for a sufficiently long time (longer than the delay time of the response of the control panel to a change in the state of the loop, which is determined during the development of this device), the control panel does the conclusion about the change in the status of the loop and accordingly changes its state depending on the fire tactics selected for this loop (the response of the device to the operation of one fire detector, several fire detectors lei and so on). Thus, there is a multi-bit conversion of a multi-level information signal into a digital form.

To identify signs of the presence of control pulses in the loop, the microcontroller remembers in its memory the value of the number obtained in the output register of the ADC last time. If the next value is less than the previous value by

ΔU> U _THRESHOLD and

ΔADC> ADC _THRESHOLD , where

ADC _THRESHOLD = (U _THRESHOLD · K · 1024) / V _ref ,

then the microcontroller considers this a sufficient sign of the control pulse from the terminal device. In this case, the corresponding microcontroller register is zeroed out, regularly incremented during the program execution. If there are no signs of control pulses for a long time (Fig. 4b), the value in this register will reach a threshold value, which will enable the microcontroller to make a conclusion about a fault in the loop (or terminal device, which is not important) and reproduce information on the fault on its display organs.

The inventive method for monitoring the condition and integrity of the loop allows you to build systems for its implementation, in which the formation of a signal to start automatic fire extinguishing systems can occur after analyzing the status of fire detectors in one loop (see NPB 88-2001 * - "FIRE FIGHTING AND ALARM SYSTEMS. NORMS AND DESIGN RULES ”, clause 13.3). According to the terminology of the specified standard, the control panel using our proposed method for monitoring the status and integrity of the loop is called a two-threshold, in contrast to the prototype, which is called a single-threshold in the standard.

When generating a signal for starting automatic fire extinguishing systems with a single-threshold control panel operating with signals generated in the prototype method, according to NPB 88-2001 *, it is necessary to analyze the status of three single-threshold fire loops, which limits the number of fire extinguishing directions served by one control panel , 1/3 of the number of fire loops. At the same time, the signals generated in our method make it possible to use the option of constructing a two-threshold fire loop, which allows generating signals to start automatic fire extinguishing systems for the number of directions equal to the number of fire loops in the device.

At the same time, it becomes possible to increase the area of the fire extinguishing zone served by a two-threshold control panel with a certain number of loops, in comparison with a single-threshold control panel, or to reduce the area corresponding to one direction of fire extinguishing (more accurate use of fire extinguishing means and reduced risk of harm to people and property from the launch of automatic fire extinguishing systems in areas where there is no fire).

In addition, to service a given number of directions of automatic fire extinguishing, approximately 3 times fewer two-threshold control panels will be required than single-threshold ones, which will reduce the total cost of creating and maintaining a fire complex. The reliability of such a system (with fewer elements) is usually higher than that of a system with a large number of elements (single-threshold control panels).

The inventive method can be implemented in the operation of several alarm systems, for example, FIG. 6 shows a second variant of a block diagram of an alarm system, which, like the first option (FIG. 1), implements the inventive method. As you can see, fire detectors are connected in a loop in a parallel-parallel manner, that is, fire detectors are included in the loop circuit break (input to the output of the previous detector or to the control panel, the input and output are connected inside the detector), and the terminal device is connected at the end of the loop (to the output of the last detector). This allows you to control not only the integrity of the loop wires, but also the presence of fire detectors (when removing any fire detector, the loop circuit is broken, the terminal device is disconnected from the control panel and ceases to issue control pulses to the cable, which causes the control panel to transition to the " Fault ”), and this significantly increases the reliability of the fire complex.

Since the terminal device is not a standard element, let us consider in detail its construction. 7 is a schematic electrical diagram of a second embodiment of a terminal device. The terminal device made according to option 2 (see Fig. 7) consists of a voltage stabilizer (12) (see Fig. 7, elements C1, DA1 and C2) and a generator (13) (see Fig. 7, elements VT1 , VT2, VD1). The generator is assembled according to an asymmetric scheme on transistors of different conductivity. The transistor VT1, due to the negative feedback through the resistors R1 and R2, operates in a mode close to the amplifier mode "A". Transistor VT2 works in key-amplification mode. Positive feedback from the collector of transistor VT2 through capacitor C3 turns the circuit into a generator. The VD1 LED is connected to the generator output, visually indicating the operation of the terminal device, as in option 1.

A serviceable cable constructed according to the second variant (Fig. 6), that is, with intact, not shorted wires of the cable and installed fire detectors, is completely similar from the electric point of view to the first version of the cable (Figure 1), therefore, all reasoning can be applied to it and diagrams (FIG. 4, FIG. 5) above. The only difference between the 2nd option of the loop from the 1st is the additional ability to control the presence of all fire detectors - when removing any detector in the loop there is a voltage characteristic of the "Fault (open)" mode (see Fig. 4b).

Since the second variant of the terminal device (Fig. 7) is constructed differently than the first (Fig. 2), we also consider in detail the process of generating control pulses during operation of the terminal device according to the second construction variant presented in Fig. 7.

Before the appearance of a constant base voltage in the cable connected via connector X1, the capacitors C1, C2 and C3 are discharged, all transistors are closed. When voltage appears in the loop, the voltage stabilizer DA1 starts working, charging the capacitor C2 to the rated output voltage of the stabilizer. In this case, the stabilizer passes current through itself from its input (from the loop) to the output (to the capacitor C2), the voltage difference at the input and output of the stabilizer is minimal. The voltage in the loop differs little from the voltage of the capacitor and increases with the charge of the capacitor C2 (see Fig.8g). At time t ₁ (Fig. 8), the voltage at the output of the stabilizer DA1 reaches the nominal value and the stabilizer reduces the current from input to output. In this case, the current at the input of the terminal device will decrease, which will cause an increase in the voltage in the loop to the value determined by the fire detectors.

Further, the stabilizer DA1 holds the voltage across the capacitor C2 due to the current consumed from the loop. The input current of the terminal device will be equal to the sum of the current consumption of the stabilizer DA1 and the current consumed by the generator.

After the voltage appears on the capacitor C2, a current appears, charging the generator feedback capacitor C3 (see Fig. 7) from the generator supply voltage (at the output of the stabilizer DA1, on the capacitor C2). This current flows from the output of the stabilizer DA1 through resistors R3, R4, R2, capacitor C3 and resistor R5 to a common wire (terminal 2 of connector X1). This current leads to the charge of the capacitor C3 and an increase in voltage on the left (in Fig. 7) lining of the capacitor C3 (see Fig. 8a).

When this voltage reaches the threshold value U _POR (see Fig.8a), at which the current through the resistor R1 to the base of the transistor VT1 will cause it to open and the current flows in the collector circuit (voltage on the collector VT1 see Fig. 8b), it will open transistor VT2. In this case, the voltage at the collector of transistor VT2 and the right tab of capacitor C3 will begin to increase, which will lead to an increase in voltage on the left side of capacitor C3. And this will lead to further opening of the transistor VT1, causing a further opening of the transistor VT2. Thus, both transistors will cascade into an open state. In this case, the voltage on the left side of the capacitor C3 will jumpwise increase by the value of the generator supply voltage (time t ₂ in Fig. 8a).

The opened transistor VT2 supplies voltage (voltage to the collector VT2 see Fig. 8c) from the output of the stabilizer DA1 to the LED VD1 through the resistor R6. The current flowing in this circuit causes the LED to glow. In this case, the capacitor C2 is discharged, the voltage on it decreases, which causes an increase in the current flowing from the input of the stabilizer DA1 (from the loop) to the output of the stabilizer (into the capacitor C2) until this current compensates for the current consumed by the generator (the main part of this current passes through LED VD1). And an increase in the input current of the stabilizer DA1 (from the loop) will cause a voltage drop in the loop (see Fig.8g). Thus, the beginning of the control pulse is formed.

Next, the capacitor C3 is recharged by the current flowing through the resistors R1 and R2 (the transistor VT1 is open and the voltages at its base and collector are close to zero) to ground. As the capacitor is recharged, the voltage on the left side of the capacitor C3 will gradually decrease (see Fig. 8a), moment t ₃ ) to the threshold value U _POR , at which the transistor VT1 starts to close, which will cause the transistor VT2 to close and reduce its collector current. In this case, the output voltage of the generator will begin to decrease (on the VT2 collector, resistors R4 and R5, the right side of the capacitor C3), which will cause a further decrease in voltage on the left side of the capacitor C3 (see Fig. 8a), which will lead to an avalanche-like closing of both transistors and termination current through resistors R5 and R6, the voltage at the collector of transistor VT2 drops to 0 (see Fig. 8c), LED VD1 goes out.

The termination of currents through transistors will cause a decrease to almost zero of the current consumed by the generator. In this case, the current consumed by the stabilizer DA1 from the loop will sharply decrease, which will cause an increase in the voltage in the loop, thus forming the end of the control pulse (see Fig. 8g).

Further, the process is repeated in the manner described above, except that the voltage at the junction of the resistors R1 and R2 with the capacitor C3 (see Fig. 8a) is not zero, but negative. This will cause a longer transient charge process of this capacitor to the threshold value for opening the transistors and changing the state of the generator (the beginning of the formation of the control pulse, moment t ₄ in Fig. 8a) than in the first cycle, but will not affect the duration of the control pulse (t ₄ -t ₅ in FIG. 8).

The temporal characteristics of the generated signals depend on the values of the circuit elements. The duration of the control pulse is directly proportional to the capacitance of the capacitor C3 and the total resistance of the parallel-connected resistors R1 and R2. The duration of the pause between the control pulses is directly proportional to the capacitance of the capacitor C3 and the total resistance of the series-connected resistors R2, R3, R4 and R5. The choice of ratings of these components ensure the operation of the circuit with the necessary time parameters.

Since a considerable technical effect from the use of the proposed method is to reduce the power consumption of the loop integrity control process, we justify the choice of the duration and period of repetition of single control pulses, which are the signal of the loop integrity.

Given the need to reduce the influence of pulsed noise, random in time and usually having a short duration, on the operation of the control panel, the microcontroller’s algorithm of operation, knowingly, when designing the alarm system, sets the time delay for the control panel to transition to another state when changing the input information of the microcontroller, i.e. either when impulse noise arrives at the input, or when the voltage in the loop changes.

The delay time is selected sufficient so that, according to the collected statistics, most impulse noise ends (in duration) during this time, while the control panel switches to another state only when, after the delay time has elapsed, the voltage at its input gives the beginning of the countdown of this time is still present, thus significantly reducing the likelihood of false alarms of the control panel from impulse noise.

Due to the peculiarities of the option of building a control panel using the ATMega32 microcontroller, which has several inputs and only one computing module, the process of processing information from several inputs can be performed only sequentially in time (see the description of the ATMega32 microcontroller). From this it follows that the process of processing information from one input (to which the loop is connected) will not occur continuously, but periodically.

When describing the principle of determining the fact of changing the state of the loop, we will use the concept of “impact”, meaning the change in voltage in the loop, and therefore the output values of the analog-to-digital converter, which goes beyond the values characteristic of the state that the microcontroller considers current for the loop. For example, if the microcontroller has previously determined that the loop is in the “Attention” state, then by the influence we will understand the voltage change in the loop outside the boundaries typical for the “Attention” state - that is, U _NORM and U _FIRE .

Given the periodic nature of the microcontroller measuring the voltage in the loop, the transition of the control panel to a new state is allowed only if the changed voltage in the loop is still present (falls into the same range of values) within the number specified at the design stage of the device N _IMP measurement periods T _ISM voltage in the loop.

- For further explanation, we turn to Figure 9. It shows the voltage plots in the loop corresponding to the effects of different durations. Vertical lines under the voltage diagram indicate the moments of measurement by an analog-to-digital voltage converter in a loop at the command of the microcontroller.

Figure 9a) shows an example of the effect of a short impulse noise on the loop, which outputs the voltage in the loop below the boundary U _FIRE at time t ₁ . The microcontroller will receive relevant information about this at time t ₃ , when the analog-to-digital converter gives the result of measuring the voltage in the loop. From this moment, the microcontroller will start the delay time. To calculate the time of influence on the loop, a separate memory cell (period counter) is used. If during subsequent measurements the voltage in the loop also turns out to be outside the boundaries of the current state (see Fig. 9a), moment t ₃ ), then the contents of the period counter is increased by 1 until it reaches the value of N _IMP . If, during the next measurement (see Fig. 9a), moment t ₅ ), the microcontroller receives information from the analog-to-digital converter that the voltage in the loop has returned to the current state (see Fig. 9a), time t ₄ ), then the contents the period counter is reset to zero without reaching the value of N _IMP . Thus, we see that short pulsed interference with a duration of t _OCH1 (from time t ₁ to time t ₆ ) less than t _{THRESHOLD 1} (from time t ₃ to time t ₆ ) does not lead to a change in the state of the control panel.

Figure 9b) shows an exemplary plot of the effect on the activation loop of a fire detector, in which at time t ₁ (see Fig. 9b), the voltage in the loop extends beyond the boundary U _FIRE . The microcontroller will receive the corresponding information from the analog-to-digital converter at time t ₂ and the contents of the period counter will become 1. With each subsequent measurement of the voltage in the loop, the contents of the period counter will increase by 1 until at time t ₃ it reaches the value of N _IMP . In this case, the microcontroller concludes that the loop state has really changed (activation of the second fire detector) and goes into the “Fire” state. Thus, we see that the impact on the loop of duration t _air2 (from time t ₁ to time t ₃ ), greater than t _{THRESHOLD 2} (from time t ₂ to time t ₃ ), leads to a change in the status of the control panel.

The time delay also affects the incoming signals from the detectors in the loop, so the delay time cannot be too long, because this can lead to the fact that the control panel will miss a real alarm signal from the detectors.

The delay time between the activation (transition to an alarm state) of detectors in a loop and the transition to a different state of most control panels currently manufactured is a fraction of a second, in particular, for devices manufactured by the applicant, a response delay time is typical the control device from the moment the voltage at its input changes - of the order of 0.25-0.35 seconds, in _Fig . 9 it is _THRESHOLD ; t _{THRESHOLD 2} .

In order for the control pulse (forming the integrity signal, see Fig. 9c) from the terminal device in the loop not to cause a false positive of the control panel, the duration of the control pulse should be less than the delay time described above _THRESHOLD1 , and with a margin. This margin will allow to avoid false triggering of the control panel in the case when, after the control pulse, the loop will be affected by a pulse interference (i.e., a control pulse can give a reference, and a pulse interference will end the delay time).

In order for the control panel to determine the presence of a control pulse in the loop, the microcontroller must measure the voltage in the loop during the action of this pulse at least once. And for this, the duration of the control pulse should be longer than the period of measuring the voltage in the loop, and with a maximum margin, otherwise the control pulse can be skipped by the microcontroller, as shown in Fig. 9d), where the pulse of duration t _{Rev. 4} is unnoticed, it slips between the moments of measurement .

To reduce the period of measuring the voltage in the loop - this means increasing the number of such measurements per unit time. And this will lead to an increase in the amount of information that the microcontroller must have time to process during this time. And this determines the need for faster and more expensive microcontrollers, which ultimately leads to a rise in the cost of the security system. Moreover, the real gain from this will consist only in approaching the moment when the control panel goes into alarm state by the moment the fire detectors are activated in the loop (the more often the voltage in the loop is monitored, the smaller the possible error in the response time of the control panel, which is equal to the voltage measurement period in loop T _ISM ). And since there are no high requirements that would be established by GOST or industry standards for the proximity of the response time of the device to the time that fire detectors go into the active state in the loop, it is enough to choose the period of measuring the voltage in the loop several (5-10) times less than this is the reaction time. Typically, in the control panels manufactured by the enterprise by the Applicant, the voltage measurement period in the T _IZ loop is 20-60 ms.

Thus, the duration of the control pulses forming the loop integrity signal must be within the limits justified above, in particular, in devices manufactured by the applicant company, this duration is in the range from 20 to 250 ms.

Consider the criteria for choosing the period of control pulses. The more often follow-up pulses from the terminal device follow, the greater the energy consumption for monitoring the integrity of the loop (with each pulse, current flows through the terminal device, which is actually taken from the fire detectors), and the less energy is left for fire detectors. The aim of the invention is to reduce the power consumption of the loop integrity control process. From the point of view of reducing energy consumption for the control process, it is advisable to increase the period of control pulses.

On the other hand, with an increase in the repetition period of the control pulses, the waiting time of the loop integrity signal by the control panel also increases. To reduce the influence of single interference and ensure increased reliability of determining the integrity of the loop, it is advisable to choose (see Fig. 10a) the waiting time by the control panel of these pulses

t _expected at least 2 times the repetition period of the control pulses T _UTI . In this case, even if one control impulse is lost for any reason (see Fig. 10b), this will not lead to a false detection of a loop break.

In addition, it is desirable to leave a margin to compensate for changes in the period of control pulses under the influence of various factors, for example, temperature or deviations from the norm of the real electrical parameters of the timing elements of the terminal devices. Therefore, the ratio of the repetition period of control pulses to the waiting time by the control panel of these pulses of the order of 1 can be considered sufficient: (2.5-3).

In the modern domestic regulatory framework that defines the requirements for control panels, there are no data on the maximum permissible time for determining a fire loop malfunction from the moment it occurred. As a starting point, you can take the requirements for control panels by European standards EN 54-2: 1997, where on page 15, chapter 8, clause 8.1.3 (see Appendix) there is a requirement for the time of transition of the control panel to the appropriate state within 100 seconds of the occurrence of the malfunction.

However, if we take into account the 2nd variant of constructing a loop of a system that implements the inventive method, where the presence of all fire detectors in the loop is actually controlled, it is advisable to issue a loop fault message to the control panel for a shorter time. This can help prevent unwanted actions by intruders that disable the fire safety system, for example by removing fire detectors.

Based on the above considerations, we can conclude that it is acceptable to consider the time that the control panel will determine the malfunction in the fire loop (and, in fact, the time that the control panel will wait for control pulses from the terminal device), which is on the order of several tens of seconds. And from this we can conclude that the repetition period of the control pulses T _IMP can be selected within up to a dozen seconds.

In this case, the ratio of the period and duration of the control pulses will be of the order of hundreds, which will ensure the efficiency of the fire loop of about 99%.

So, for example, in the above two variants of signal systems, the pulse repetition period is selected on the order of 5-10 seconds, the waiting time is on the order of 12-20 seconds. The pulse duration is about 0.1-0.2 seconds. Thus, with a significantly shorter waiting time for the control pulses from the terminal device by the control panel and allowed by the European standards EN54-2, and in connection with this, the control panel can detect a malfunction in the fire loop from the moment it occurs about a reliable (no doubt at a given moment in time) determination of this malfunction (see Fig. 10c).

The efficiency of our loop is approximately 98%, the gain in reducing the power consumption of the loop integrity control process in comparison with the prototype can be achieved by 3 or more times, which allows, as we explained above, to increase the number of fire detectors in the loop by 1, 5-2 times and make the loop of the alarm system that implements the method more capacious with a single control panel.

The inventive method is intended for use in alarm systems developed and intended for mass production at the enterprise of the Applicant. Currently, the development of systems is at the stage of production of an experimental batch.

Information sources

1. Book of the author F. Sharovar Devices and fire alarm systems. M .: Stroyizdat, 1985, Chapter IV. Control panels and centralized fire alarm systems (p.205-222) (analogue).

2. Application for the invention “Method of protecting a loop with a terminal resistor of a security alarm control panel against unauthorized interference”, RU, No. 2003133434, G08B 1/00 (analogue).

3. Japan's application for the invention of “Device for fire alarms” No. 3563254 B2 (11175859 A), G08B 17/00 from 12/11/1997 (device operation - analogue).

4. RF patent for the invention "Signaling method" No. 2078376 from 07.15.1991, (prototype).

5. European standards EN54-2 (the source is the fundamental document for determining the period of repetition of control pulses).

The invention of "A method for monitoring the status and integrity of the loop"

Specification for drawings Item Name Drawing number Control panel one Signal loop 2 Fire detector 3 Terminal device four DC voltage source 5 Ballast resistor 6 Microcontroller, e.g. ATMEGA 32 (-16A1) 7 Analog to digital converter 8 Resistor divider 9 The master oscillator of the terminal device (option 1 - Figure 2) 10 The output key of the terminal device (option 1 - Figure 2) eleven Terminal voltage regulator, option 2 12 Terminal Generator, option 2 13

Claims (1)

A method for monitoring the status and integrity of the loop, based on the supply of the basic signal through the loop with the fire detectors turned on to the active terminal device, with the subsequent generation of an information signal on the status of the fire detectors in the loop, and the periodically repeating loop integrity signal generated by the active terminal device, and on of both signals to the control panel via a loop, characterized in that a constant voltage, an information signal, is supplied as the base signal al is formed by a multilevel one, changing its level depending on the number of fire detectors in the loop, the loop integrity signal is generated in the form of a sequence of single control pulses, the period of which is determined from the condition of minimum power consumption in the loop on the one hand and the conditions for the admissible time for determining the loop integrity on the other hand, and their duration is chosen less than the maximum not protected by the control panel as an alarm condition, on the one hand and, on the other hand, it is longer than the measurement period of the loop voltage by the control panel, consisting of a multilevel information signal and control pulses, a multi-bit analog-to-digital conversion is used as a tool for processing the loop voltage, which distinguishes the transition to the alarm state of one fire detector from the transition two or more, and recognize the serviceability / malfunction of the loop.

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