EP0254125B1 - Danger signalling system - Google Patents

Abstract

Danger alarm system with a control centre (Z) with an analyser and several two-wire signalling leads (ML) to which a plurality (i) of individually identifiable detectors (Mi) are connected in a chain arrangement; each of these has a controllable switch (STi) in one of the two wire leads (b). The detectors (Mi) are scanned cyclically from the control centre for their current status, each detector (Mi) switching the next detector (Mi + 1) through to the signalling lead (ML) after a time delay (ZG) dependent on its measured value and sends a current pulse on the signalling lead. In the analyser, the detector address and its measured value are determined from the respective time of the current pulse (li) and from these an alarm or malfunction indication is obtained. In accordance with the invention, a number of status scanning cycles (ZAZ) are carried out in sequence by the control centre (Z) and, in the case of a change of status or for any other reason, regular scanning cycles (RAZ) are carried out in which the detector address is also determined. The status scanning cycle uses a scan voltage (U3) which deviates from the scan voltage (U2) used for the regular scanning cycle (RAZ). For the status scanning (ZAZ), each detector (Mi) has additionally a comparator element (K) which switches the following detector (Mi + 1) through with no time delay. <IMAGE>

Description

The invention relates to a hazard alarm system according to the preamble of patent claim 1.

In the case of hazard detection systems, in particular intrusion or fire detection systems with manually operated detectors, for example push-button detectors, it is necessary to recognize an alarm as quickly as possible. In alarm systems that work according to the so-called pulse-signaling principle (DE-C-25 33 382), all detectors connected to a signaling line successively send measuring current pulses to the control center in a known manner when the line is queried. Usually, several lines are connected to a central module, which are queried one after the other. The query time of a detector thus depends on the number of lines and the number of detectors per line. Normally after this time at the earliest, the status change of the relevant detector, ie the alarm triggering detector, can be recognized. When this detector is alarmed, the address is given at the same time, the evaluation for both detector sizes is carried out and displayed in the control center. This means that an evaluation and statement about a change in detector status only takes place after a complete query cycle. Even if the individual polling cycles are relatively short, it may still be necessary to recognize a fire report or an attack report in the case of an intrusion protection system as quickly as possible.

The object of the invention is therefore to shorten the alarm detection time in a hazard alarm system described at the outset.

This object is achieved according to the invention in a hazard alarm system operating on the pulse-reporting principle with the characterizing features of claim 1.

With the invention, it is possible to determine within a considerably shorter time whether a detector has changed its state on a line, ie has switched from rest to alarm or fault. In this case, the determination of the reporting location is of secondary importance, so that a longer time may be required for this. The rapid alarm detection is achieved according to the invention in that the control center executes status polling cycles in quick succession and, in the event of a status change or if there is any other requirement, regular polling cycles. If a change in detector status is detected on a line, a regular polling cycle is then carried out for this line, in which the detector address is also determined. In this context, it can also be called an address polling cycle, although this is a conventional pulse detector polling cycle in which both the analog detector measured value and the detector address are recorded. The status query is carried out with a query voltage that differs from the query voltage in the regular query cycle. Accordingly, according to the invention, each detector is additionally provided with a comparison device which switches the subsequent detector on without delay, ie immediately, when the status is queried.

Since the detectors are mostly in the idle state in hazard alarm systems, the status query according to the invention has the advantage that the alarm detection time is considerably shortened because only a change in status is checked. The query time is therefore independent of the number of detectors per line. The longer regular polling cycle (address polling cycle) is carried out either when a change in status has been detected on the detection line or when there is another need, for example to check the function of the connected detectors. Furthermore, the regular polling cycle is required if control commands are transmitted to certain detectors or control elements which are assigned to certain detectors, as already known from DE-C-25 33 354.

Further refinements and advantages of the invention result from the subclaims.

The invention is described in detail below with reference to the drawing. Show

1 shows the known connection of the detectors to a control center,

2 shows a basic circuit of a detector according to the invention,

3a and 3b voltage and current diagrams and

Fig. 4 shows an embodiment of the detector according to the invention.

1 shows the known connection of the individual detectors M1 to Mn to a detection line ML with the line wire pair a, b at the control center Z. The detectors are connected in a chain and each have a controllable switch ST1, ST2, etc. in the b-wire. When the interrogation voltage is applied, the subsequent detectors are switched on to the signaling line with a time delay in normal operation. This is known and need not be explained in detail.

A detector according to the invention for the status query is shown in a block diagram in FIG. The circuit is partly known from the conventional pulse detector. A timing element ZG is connected to the detection line, ie to line wire a and line wire b, the duration of which is determined by the measured value of the detector. In the case of automatic fire detectors, the analog detector measurement value determines the running time. This switching example is based on a manually operated detector. The detector status depends on the position of switch S1, R corresponds to the rest position, A corresponds to the alarm position and S corresponds to a fault, which each cause different delay times. The output from the timing element ZG causes a current pulse via the transverse transistor TQ and the transverse resistor RQ via the pulse generator IG. This current pulse is measured and evaluated in a known manner in the control center. Furthermore, the output of the timing element ZG controls the switch ST via the OR link OR, which is closed after the timing element ZG has expired and switches the detection line b through to the next detector (b) in a known manner. Normal pulse detectors are connected to the line one after the other and send their measuring current pulses IL one after the other via the detection line a, b to the control center Z.

According to the invention, a comparator K is provided in each detector Mi, which immediately closes the switch ST for the status query when the query voltage for the status query is on the message line ML. For this purpose there is a reference voltage Uref at the comparator K which is less than the query voltage for the status query. The interrogation voltage UL reaches the second input of the comparator K via the signal line ML. If the voltage on the signal line exceeds the Uref specified at the comparator input, the output of the comparator K emits a signal via the OR gate OR, so that the switch ST is closed and a transfer to the next detector regardless of the running time of the timing element ZG he follows.

eingestellt sein. Damit schalten mit der Abfragespannung U3, die am zweiten Eingang aller Komparatoren anliegt, über die Oder-Verknüpfung OR die Schalter ST sofort durch. Damit ist die b-Ader bis zum letzten Melder Mn durchverbunden. Alle Melder hängen parallel an der Meldeleitung und alle Zeitglieder ZG starten gleichzeitig. Sind alle Melder im Ruhezustand, so senden sie ihre Meßstromimpulse Ii bis In gleichzeitig zum Zeitpunkt tR, wie dies in Fig.3b gezeigt ist.Figures 3a and 3b show a voltage and a current diagram. 3a shows the line voltage UL as a function of time t. The line current IL measured in the control center is plotted below the time t accordingly. Each polling cycle begins with the start signal U0, ie the line voltage UL is reduced to the value 0. This short start signal ensures that all detectors are switched off by the signaling line. At time t0, the interrogation voltage is switched to the signaling line. For example, a query voltage U3 is applied for the status query cycle ZAZ. This query voltage is higher than the query voltage U2 for the regular query cycle RAZ. The reference input Uref of the comparator K in the respective detector (Mi) can be based on the value

be set. Thus, with the interrogation voltage U3, which is present at the second input of all comparators, the switches ST immediately switch through via the OR link OR. The b-wire is connected through to the last detector Mn. All detectors are connected to the alarm line in parallel and all ZG timers start at the same time. Are all detectors in the idle state, they send their measuring current pulses Ii to In simultaneously at the time tR, as shown in FIG. 3b.

In the second status query cycle ZAZ2, for example, one detector sends an alarm, another detector a fault, i.e. A measuring current pulse I2 comes at time tA, another measuring current pulse I3 comes later, at time tS. The other detectors simultaneously emit their quiescent current pulses at time tR. This is shown in Fig.3b. The evaluation device in the control center can distinguish between the alarm, fault and Ruheim pulses, but it cannot recognize the number of the detector (detector address).

For this purpose, the relevant detector addresses are determined in the subsequent regular query cycle RAZ1. This regular polling cycle is a completely normal pulse detector polling cycle with the regular polling voltage U2, which is lower than the polling voltage U3 for the state change. The respective comparators do not switch with this voltage on the signal line, i.e. the individual switches STi are only closed after the associated time elements ZGi have expired. The detectors thus send their measuring current pulses one after the other in a known manner. With this query, e.g. Control signals are transmitted to the detector M2, as is done in a known manner by reducing the voltage to U1.

The open circuit voltage UR is connected to the line in a known manner after the query time AZ. This (UR) is greater than the interrogation voltage U3 and serves to supply energy to the detectors, in particular also Charging the energy buffer capacitors provided there.

Figure 4 shows an embodiment of the detector according to the invention. During the short start time SZ with the start signal U0 = 0, the capacitors C1 and C2 discharge, the transistor T3 is blocked. So all detectors are switched off by the reporting line.

The timing element ZG consists of the resistors R1, R2, R3, the capacitor C1 and the transistor T1. After applying the interrogation voltage, for example U2 for the regular interrogation cycle RAZ to the detector terminals a, b, the capacitor C1 charges in the idle state of the detector via R3, in the alarm state AL, i.e. when the switch S2 is closed, via the parallel connection of R3 and R2. The transistor T1 becomes conductive with a delay. Via the pulse generator IG, which consists of the capacitor C2 and the resistors R4, R5 and the transistor T2, the measuring current pulse Ii is generated via the resistor R6. Via the diode D1 and the resistor R7, the (switching) transistor T3 becomes conductive, which switches the line b to b 'to the next detector. With the regular interrogation with the lower interrogation voltage U2, the Zener diode ZD1 remains ineffective. In contrast, when the higher interrogation voltage U3 for the state interrogation is present, the transistor T3 becomes conductive via the Zener diode ZD1 immediately after the voltage is applied, that is to say regardless of the running time of the timing element.

The invention also has the advantage that an alarm detection can be ensured in a simple manner in the case of conventional pulse signaling lines if the central evaluation device fails. It can are only recognized on line alarm, but the alarm triggering detector is not identified. With this status query according to the invention, an alarm can also be recognized if one of the switching transistors T3 or the switch ST remains closed, for example due to a lightning effect. In this case too, alarm detection of the relevant message line is possible.

Claims (3)

1. Danger signalling system having the following features:

   a) a plurality of signal lines (ML), which each have a two-wire line (a, b), are connected to a central station (Z) with an evaluation device;

   b) connected in each signal line (ML) in the manner of a chain are a multiplicity (i) of individually identifiable detectors (Mi) which each have a controllable switch (STi) in one of the two wire lines (b);

   c) the detectors (Mi) of each signal line (ML) are cyclically interrogated by the central station for their respective detector status, each detector (Mi) connecting the following detector (Mi+1) with a time delay (ZG) to the signal line (ML) in accordance with its measured value and bringing about a current pulse (Ii) on the signal line;

   d) each interrogation cycle (AZi) consists of a short start time (SZ) with an interrogation voltage (U0) which approximately has the value 0, of an interrogation time (AZ) with a given interrogation voltage (U2) and of a rest time (RZ) with an open-circuit voltage (UR);

   e) the respective line current (IL) is measured in the central station (Z) in the evaluation device, the detector address and the detector measured value being determined from the respective instant of the current pulse (Ii), and alarm or fault signals being derived therefrom, characterized in that the danger signalling system is designed in such a way that:

   f) a plurality of successive status interrogation cycles (ZAZ) are carried out by the central station (Z), and in the event of a status change or if otherwise required, regular interrogation cycles (RAZ), in which also the detector address can be determined, are carried out;

   g) during the status interrogation cycle an interrogation voltage (U3) is generated which deviates from the interrogation voltage (U2) during the regular interrogation cycle (RAZ);

   h) and that, for the status interrogation (ZAZ), each detector (Mi) additionally has a comparing element (K) which connects the following detector (Mi+1) without delay.
2. Danger signalling system according to Claim 1, characterized in that there is arranged in the detector (Mi), in addition to the timing element (ZG) and the pulse generator (IG), a comparator (K), at the first input of which a reference voltage (Uref) is present and at the second input of which the line voltage (UL) is present, and the output of which controls the switch (ST) via an OR element (OR).
3. Danger signalling system according to Claim 1 or 2, characterized in that the interrogation voltage (U3) for the status interrogation (ZAZ) is greater than the interrogation voltage (U2) for the regular interrogation (RAZ), and in that the value of the reference voltage (Uref) lies between the two interrogation voltages (U2 and U3).

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