EP0521180B1 - Danger signalling devices connected in a loop - Google Patents

Abstract

A multiplicity of primary signalling lines (MPL1,...) with respective hazard detectors (elements E1 to En) is connected at a signalling centre (Z) by means of a respective line switching unit (LAE). The respective end (e) of at least a plurality (m) of primary signalling lines (MPL1 to MPLm) is connected at its remote end to a loop connection element (SAE) which, in turn, is connected with only one primary signalling return line (MPRL) via an additional line connection unit (LAES) at the centre (Z). The loop connection element (SAE) exhibits a monitoring and control unit (KSE) which, when necessary, connects the relevant primary signalling line (MPL) by means of a line change-over switch (LU) to the primary signalling return line (MPRL) via an associated terminating element (EA). <IMAGE>

Description

The invention relates to a hazard detection system for loop operation with a message center to which a plurality of primary signal lines with respective hazard detectors are connected by means of a respective line interface unit.

Hazard detectors and sensors, e.g. for fire or intrusion detection, are usually connected to the control center via a two-wire primary signal line, generally as a branch line. A large number of such detectors or sensors or elements are connected to such a double wire, via which they are both supplied with energy and the information flow is handled. Such a stub usually ends with the last element. However, it is disadvantageous that in the event of a line fault, e.g. in the event of a wire break or a short circuit, the signal line is faulty and, depending on the design of the elements, the elements or at least some of them can no longer be queried.

In order to still be able to operate a faulty primary signal line, such lines are connected in a loop to the control center, so that the primary signal line can be queried from the other side up to the fault in loop operation and the individual elements can still deliver their data to the control center . The short circuit is also a critical case in loop operation, so here it is It has been proposed to locate the short circuit with the aid of measuring devices and to provide devices on the lines in order then to isolate the short circuit point.

Such loop systems have several disadvantages compared to stub lines. The primary signal line loop, which typically runs hundreds of meters through buildings and open spaces, also acts as an undesirable antenna for electromagnetic influences, which can result in high interference currents flowing through the loop, which can significantly impair the communication between the elements and the control center . In extreme cases, the primary reporting line can even be totally disturbed, so that no data transmission is possible. In order to avoid this, such loop arrangements are often operated from one side only in uninterrupted operation like a conventional stub line, which means that all elements are interrogated from the beginning of the line to the end. The loop end is returned to the control center, but is then not operational there. The return line is then only used in the event of a fault or possibly for test purposes, i.e. in this case the line is queried from the other end.

It has also been proposed to alternately scan primary signal lines in loop operation from the beginning or from the end and to provide a changeover switch, only one line interrogation unit being required for a loop, as is described, for example, in DE 36 37 681-A1 For strategic reasons, however, it is advisable to route the beginning and end of a primary signal line loop to different line interface units, the end being separable via a separate switch for EMC reasons.

In all of the previously known arrangements for loop operation, however, there is always the great disadvantage that a respective line must be returned from the last element of a respective primary signal line to the control center, which in the case of a large number of primary signal lines and at far ends from the control center results in a considerable additional Installation effort leads.

It is therefore the object of the invention to improve the loop operation in a hazard detection system, to reduce the installation effort and to reduce the interference effects which are in particular caused by the loop operation.

This object is achieved in a hazard detection system for loop operation of the type mentioned at the outset in that the respective end of at least a plurality of primary signal lines is led at its distal end to a loop connecting element which, in turn, is connected to the control center with only one primary signal return line via an additional line interface unit is.

With this arrangement according to the invention with only one loop connection element and a single primary signal return line for a large number of primary signal lines, considerably less installation effort is involved. In this way, existing hazard detection systems, which were originally only designed for branch lines, if the operator wishes it or existing regulations require it, can be retrofitted for loop operation. In addition, there is also the great advantage in existing systems that only a low hardware performance is required, but the control center can be converted in a simpler manner in terms of program.

In an expedient embodiment, the loop connection element has a control and control unit which, if necessary, by means of a line switch, the relevant primary reporting line via an associated terminating element, which is also arranged in the loop connecting element and for monitoring the line section between the loop connecting element SAE and the last element En of a primary reporting line MPL is used to connect to the primary reporting return line and thus to the control center. Advantageously, the line switch is opened in the trouble-free operation.

With the help of the loop switching element, all primary reporting lines can be connected to the central alarm system via the primary reporting line. In a special embodiment of the invention, however, a plurality of loop interface elements can also be provided, with either each loop interface element being connected to the control center with its own primary primary return line, or the loop interface elements being connected in cascade fashion, so that only the first loop interface element with the center is connected via a single one Primary return line is connected.

With this arrangement it is possible to regularly monitor the primary signal lines from the last element to the loop switching element and the primary signal return line even in the case of trouble-free operation.

This arrangement according to the invention has proven to be expedient for hazard alarm systems which operate according to the chain synchronization principle, because the individual elements each have a switching element in one of the two-wire lines, at least for one interrogation direction.

• Fig. 1 eine Meldeprimärleitung als Stichleitung im ungestörten Betrieb,
• Fig. 2 eine Meldeprimärleitung als Stichleitung im gestörten Betrieb,
• Fig. 3 eine Meldeprimärleitung als Schleife im ungestörten Betrieb,
• Fig. 4 eine Meldeprimärleitung als Schleife im gestörten Betrieb,
• Fig. 5 eine bekannte Schleifenanordnung mit Trennelementen für den Kurzschlußfall,
• Fig. 6 mögliche Schleifenbetriebsarten wie sie bereits ebenfalls vorgeschlagen wurden und
• Fig. 7 die erfindungsgemäße Schleifenanordnung mit einem Schleifenanschaltelement.

The invention is explained in more detail below with reference to a drawing. Show

• 1 shows a primary signal line as a branch line in undisturbed operation,
• 2 shows a primary signal line as a stub line in disturbed operation,
• 3 shows a primary signal line as a loop in undisturbed operation,
• 4 shows a primary signal line as a loop in the disturbed operation,
• 5 shows a known loop arrangement with separating elements for a short circuit,
• Fig. 6 possible loop modes as they have also been proposed and
• 7 shows the loop arrangement according to the invention with a loop switching element.

1 and 2, a primary signal line is shown as a stub line. The signaling primary line MPL is connected to the control center Z as a two-wire line a, b via the line interface unit LAE. The hazard detectors or elements E1 to En are located on the primary signal line. If a fault ST now occurs, as shown in FIG. 2, for example as a line break between element E4 and element E5, elements E5 to En can no longer be queried . In this case, these elements could be queried if the reporting primary line were switched into a loop, as shown in FIG. 3.

3, the primary signal line MPL is connected at the beginning to the central station Z via a first line interface unit LAE1. The last element En is looped back to the central station Z and its end e is connected via a second line connection unit LAE2. In the above-mentioned fault case ST, when loop operation is present, as shown in FIG. 4, elements E5 to En can be queried from the end e of the primary signal line MPL, that is, from the central station Z via the line interface unit LAE2.

In the event of a short-circuit KZ, whether it has occurred on the signaling line or in an element, an interrogation is only possible during loop operation if special separating elements are provided between some elements, as shown in Fig. 5. At the central station Z, a signaling primary line MPL1 is connected with its start (on) to a first line interface unit LAE11 and the feedback, i.e. the signal primary line MPL1 is connected at its end (e) to a second line interface unit LAE12. A first separating element TE1 is provided between the elements E2 and E3. The line short-circuit KZ is assumed between the elements E3 and E4. A second separating element TE2 is provided between element E4 and element E5 (not specifically shown). With this known arrangement, in the event of a short circuit KZ, the short circuit point can be switched off by means of the separating elements TE1, TE2. The line section between the two separating elements TE1 and TE2 is thus disconnected in the event of a short-circuit. The elements E1 and E2 can be operated from the beginning (on) of the primary signal line MPL1, and the elements E5 to En can be operated from the end (e) of the primary signal line MPL1. Only the two elements E3 and E4 can no longer be queried.

Figure 6 shows two possible loop modes. At the central station Z, the start and the end e of a primary signal line MPL1 with the elements E1 to En are connected via a first line interface unit LAE1 by means of a changeover switch S1. In the second variant for loop operation, the start is at a second Signaling primary line MPL2 connected to the line interface unit LAE21. Here, the loop connections are shown in simplified form with only one line. Two-wire primary signal lines with multi-pole switches are usually used. In these two cases, ie signaling primary lines MPL1 and MPL2, a separate return conductor to the control center is required from the last element En, as already mentioned. If a fault is now detected, the loop can be queried alternately from the front or from the back using the switch S1. The second variant, known per se, is more expedient. There, the start and end of the primary signal line are routed to different line interfaces LAE21, LAE22, which may even be located on different modules. For the interrogation in loop operation from the end (e) of the primary detector line MPL2, the switch S2 is switched on. In the normal case it will be kept open for EMC reasons.

7 shows the loop arrangement according to the invention with a loop switching element SAE. At the center Z, the signaling primary lines MPL1 to MPLm are connected via their respective line interface units LAE1 to LAEm. In order to enable these stub lines, which usually end with the last element En, to operate in a loop, the last elements En of a respective primary signal line are now routed to a loop switching element SAE, which is located at the far end of the primary signal line. This is shown in FIG. 7 with the signaling primary lines MPL1e to MPLme. The loop interface element SAE is only led to a central Z with a single primary signal return line MPRL and connected there via an additional line interface unit LAES. In a simplified representation, the loop switching element SAE has a control and control unit KSE, as well as a line switch LU and termination elements EA, the number of connection elements corresponding to the number of signaling primary lines MPL, here there are m lines shown. The multi-pole primary signal lines and switches are again shown in a simplified manner as simple lines. The line changeover switch LU is open in trouble-free operation, which is shown in FIG. 7 by the switch position zero (0). Only when a fault has been detected on one of the signaling primary lines MPL by the associated line interface unit, the line switch LU is switched to the corresponding position via the control and control device KSE and the additional line interface unit LAES, so that the faulty signal line can be operated from the line end. If necessary, several loop connection elements (SAE) can be cascaded to increase the number of signaling primary lines that can be connected.

The arrangement according to the invention with a loop switching element has a number of advantages. No hardware worth mentioning is required in the control center for loop operation. Without loop operation, all existing line interface units can be used for normal stub line operation. If loop operation is required, in addition to the loop interface element SAE, only one additional line interface unit and one primary feedback line is required for each m primary signal line. This also has the advantage that only one return line from the loop switching element, which is arranged at the far end of the many primary reporting lines, has to be returned to the central, which brings considerable cost savings, in contrast to the return of each individual primary reporting line to the central. With the arrangement according to the invention, regulations or customer requests can also be easily met if loopable systems are desired. In normal operation, these loop systems designed according to the invention are then operated like normal stub lines, because in practice they are so common show no line faults. With the invention, therefore, such requirements can be realized at a reasonable cost, without the need for large upfront investments, which preload the large number of other systems without loop technology.

Claims (7)

1. Alarm indicating system for loop operation, having a central alarm station (Z) to which, by means of a respective line connection unit (LAE), there is connected a multiplicity of primary alarm lines (MPL1, ...) with respective alarm indicators (elements E1 to En), characterized in that at least a plurality (m) of primary alarm lines (MPL1 to MPLm) is led at its far end (e) to a common loop connection element (SAE) which, for its part, is connected using only one primary alarm return line (MPRL) via an additional line connection unit (LAES) to the central station (Z), and in that the loop connection element (SAE) has a monitoring and control unit (KSE) which, if need be, connects the relevant primary alarm line (MPL) by means of a line changeover switch (LU), via an associated termination unit (EA), to the primary alarm return line (MPRL), the line changeover switch (LU) being open during trouble-free operation.
2. Alarm indicating system according to Claim 1, characterized in that all the primary alarm lines (MPL) are connected to the loop connection element (SAE).
3. Alarm indicating system according to Claim 1, characterized in that a plurality of loop connection elements is provided.
4. Alarm indicating system according to Claim 3, characterized in that each loop connection element is connected to the central station using its own primary alarm return line.
5. Alarm indicating system according to Claim 3, characterized in that the loop connection elements are connected in cascade, only the first loop connection element being connected to the central station.
6. Alarm indicating system according to one of the preceding claims, characterized in that, even in trouble-free operation, the primary alarm lines (MPL1,2) from the last element (En) to the loop connection element (SAE), and the primary alarm return line (MPRL) are regularly monitored.
7. Alarm indicating system according to one of the preceding claims, characterized in that the alarm indicators are constructed using elements which operate according to the known chain synchronization principle.

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