EP0212106B1 - Measured value transmission method - Google Patents

Abstract

1. A method of transmitting measured values in a surveillance system for the protection of buildings and having monitoring points (MS) which contain a measuring sensor (M), a measured value transducer (W) and a switch element (S) controlled by a monitoring unit (KE), and which, for the purpose of transmitting signals, are connected in a chain-like manner by way of signal lines (L) to first pairs of terminals (K1) of a signal exchange (Z) in which the signals are then combined to obtain differentiated fault or alarm signals, characterised in that the switching elements (S) provided in the monitoring points (MS) are conductive when put into operation, whereby the line signal on the signal line (L) arrives at all the monitoring points (MS) and permits the latter to synchronize to the synchronizing information contained in the line signal, that all the monitoring points (MS) are brought into a neutral state by a reset command from the signal exchange (Z), that the associated switching element (S) is momentarily opened by a control command of the monitoring unit (KE) at predetermined instant within the time raster defined by the synchronizing information, and that, as a result of this voltage interruption, all the monitoring points (MS), with the exception of the first monitoring point, receive a mark which indicates that the line signal received only serves for synchronization purposes and not for evaluation, and that the first monitoring point (MS1) is the only one to evaluate the signal, perform the corresponding command, give the reply and then switch on the switching element (S1) permanently, whereby the following monitoring point (MS2) receives a line signal without a mark and therefore in turn evaluates the signal, performs the corresponding command, gives a reply and then also switches on the associated switching element (S2) permanently, so that the operation can be repeated at the further monitoring points (MS) until the cycle is terminated at the last monitoring point (MSm) and a fresh cycle is started by a reset command by bringing all the monitoring points (MS) into the neutral state again.

Description

The invention relates to a method for the transmission of measured values in a monitoring system for protecting buildings according to the preamble of claim 1 (a method of this type is specified in EP-A 0 093 872).

To solve a variety of monitoring tasks, measuring points are distributed in extensive objects and connected to a signal center via a signal line. In this context, it is becoming increasingly important to know the exact origin of the measured values in order to satisfy the needs of intelligent signal processing, i.e. the measuring point must be identifiable.

There are three different ways of identifying the measuring points. The oldest known method, which is used very little today, is to pull a separate line from each measuring point to the signaling center. This solution is associated with a very high installation effort. Modern systems therefore use either the chain advancement principle, in which the measuring points are connected in series and the identification is made by counting corresponding advancing pulses (see Fig. 1), or individually addressed measuring points, which are connected in parallel to the line (Fig. 2). A method based on the indexing principle according to FIG. 1 is described in DE-AS 2,533,382.

• 1) Hoher Installationsaufwand, falls pro Meßstelle eine separate Ader zurückgeführt wird.
• 2) Die beim Kettenfortschaltprinzip entstehenden langen Pausen in der Stromversorgung der abgetrennten Meßstellen erfordern eine entsprechend leistungsfähige lokale Spannungsversorgung.
• 3) Beim Kettenfortschaltprinzip ist kein Signal vorhanden, welches die dauernde Synchronisation von Systemen erlaubt, die mit einem definierten Zeitraster arbeiten.
• 4) Das Kettenfortschaltprinzip reduziert die Uebertragungskapazität bei Systemen mit definiertem Zeitraster, da nach dem Zuschalten einer Meßstelle erst eine bestimmte Zeit zu deren Synchronisation verstreicht.
• 5) Unterschiedliche Meßstellen.

The main difference between the last two methods is that with the research principle all measuring points can be identical, while with the parallel system the measuring points differ by their address, which is achieved either by switches or other programming aids. It is clear that identical measuring points have decisive advantages both from the standpoint of large series production and maintenance and also eliminate the risk of confusion and incorrect addressing. The known methods for identifying measuring points in transmission systems have the following disadvantages.

• 1) High installation effort if a separate wire is returned for each measuring point.
• 2) The long pauses in the power supply of the separated measuring points that arise with the chain advancement principle require a correspondingly powerful local power supply.
• 3) With the chain advance principle, there is no signal that allows the continuous synchronization of systems that work with a defined time grid.
• 4) The chain advancement principle reduces the transmission capacity in systems with a defined time grid, since after a measuring point has been switched on it only takes a certain time to synchronize it.
• 5) Different measuring points.

Some of the aforementioned disadvantages (high installation effort, different measuring points) are eliminated by the method specified in EP-A 0 093 872, which is based on the combination of the chain advancement principle and the parallel principle and also ensures reliable identification of the measuring points.

The object of the invention is to provide a method for transmitting measured values in a transmission system and a device for carrying out the method, which avoids the disadvantages mentioned above, and in particular to create a transmission system which, with little installation effort, reliably identifies the measuring points which Maintaining their synchronization to a defined time grid and the transmission of their measured values to a signaling center enables identical measuring points which are connected in a chain to the signaling center to be used.

A further object of the invention is to design the measuring points in such a way that they can be controlled from both sides by the signaling center via signal lines arranged in a loop.

This object is achieved in a method of the type mentioned by the characterizing features of claim 1. The invention is further developed by the features of the subclaims.

The method according to the invention avoids a major disadvantage of the chain indexing method, namely that the measuring points further away from the signaling center receive neither supply voltage nor signal for a long time.

The origin of the signals arriving from the measuring points in the signal center, i.e. Identification is possible using two methods: firstly by counting the commands sent and secondly by the measuring point address, provided that a cycle with special commands for setting an individual address in the address memory of a measuring point has been used. By combining both methods, according to EP-A 0 093 872, i.e. by comparing the number of commands sent with the individual address reported back from the measuring points to the signaling center, a very high degree of security of the measuring point identification can be achieved.

The measured values can now be transmitted as described in DE-AS 2,533,382, i.e. the switching elements are actuated with each polling cycle. However, the transmission can also be carried out as in a parallel transmission system, the switching elements remaining closed.

• Fig. 1 ein serielles, kettengeschaltetes Ueberwachungssystem nach dem Stand der Technik,
• Fig. 2 ein parallel adressiertes Ueberwachungssystem des Standes der Technik,
• Fig. 3 das Blockschaltbild einer Meßstelle MS zur Durchführung des erfindungsgemäßen Verfahrens und
• Fig. 4 eine Ausführungsform eines erfindungsgemäßen Ueberwachungssystems.

A device for carrying out the method according to the invention consists of measuring points which have a measured variable sensor, a measured value converter, a control unit, an address memory and a switching element. A preferred embodiment of the invention is explained in more detail below with reference to the figures. Show it

• 1 shows a serial, chain-connected monitoring system according to the prior art,
• 2 shows a parallel addressed monitoring system of the prior art,
• Fig. 3 shows the block diagram of a measuring point MS for performing the method according to the invention and
• Fig. 4 shows an embodiment of a monitoring system according to the invention.

Fig. 1 shows the structure of a conventional monitoring system according to the chain advance principle. One or more signal lines L emanate from a signal center Z, to each of which a number of measuring points MS are connected. The measuring points MSm essentially contain, in addition to the measuring sensors and transducers, a signal receiver, a sequence control, a signal generator and a switching element Sm. After the line voltage has been applied to the signal line L, a timing element begins to run in the measuring point MS1. After a certain delay, the switching element S1 closes and applies the line voltage to the second measuring point MS2, where a timer also starts to run again. In this way, all switches of the measuring points MSm of a signal line L close one after the other. This process can be repeated periodically, so that all measuring points MS of a line are queried cyclically. After the line voltage is applied to a measuring point Msm or when the relevant switching element Sm is closed, the measured value of the measuring sensor M can be transmitted to the signal center Z.

Storage capacitors located in the measuring points ensure the energy supply to the measuring point during any system-related voltage interruptions.

2 shows a conventional monitoring system addressed in parallel. As in FIG. 1, the individual measuring points MS of the entire system are distributed over different signal lines L and connected to the signal center Z via this signal line L. Each signal line L consists of a two-wire line to which all measuring points MS of a signal line L are connected in parallel. Each measuring point MS is characterized by a fixed address Am. By sending this characteristic address Am, the signal center Z can call up any measuring point MSm and, for example, cause it to deliver its measured value. The address signals can consist, for example, of a digital pulse sequence, a specific voltage, frequency or tone sequence, or of any combination of these elements. In the case of a larger number of measuring points MS per signal line L, practically only one digital pulse sequence can be used, because it can be used to implement almost any number of different addresses with elements that are easy to integrate and of modest accuracy. By means of further digital pulse sequences, complicated instructions can also be transmitted to the measuring point addressed in each case.

An obvious disadvantage of the parallel system described is the possibility of confusing measuring points or incorrect addressing that is difficult to find. In addition, a line short circuit disables an entire signal line.

3 shows the block diagram of a measuring point MS for use in the transmission method according to the invention. The measuring point MS can be a fire detector, e.g. B. an ionization detector, an optical smoke detector, a temperature detector or a flame detector, or a monitoring device in an intrusion protection system, e.g. a passive infrared detector, an ultrasonic detector or a noise detector, or any measuring point in a transmission system.

In each measuring point MS there is a directionally symmetrical (bilateral) switching element S which connects the two input / output terminals 1 and 2 to one another. A sensor M, a transducer W, a control unit KE, an address memory AR and a command memory BS are provided in module B.

The state of the switching element S is controlled by the control unit KE, which also contains means for signal detection. The measuring points are connected to one another and to the signal center Z via terminals 1 and 3A on the one hand and terminals 2 and 3B on the other hand, as shown in FIG. 4.

Since the switching element S is directionally symmetrical (bilateral), the measuring points MS can be supplied with current from both sides, i.e. the signal lines can be connected to terminals 1 and 3A as well as to terminals 2 and 3B of the measuring point MS, which simplifies and increases the safety during assembly.

The control unit KE also contains a line short-circuit detector for the left and right connection terminal. If a short circuit is detected, opening the switching element S prevents the voltage at the terminal which is not short-circuited from dropping below the necessary operating voltage. This makes it possible to maintain the operation of all measuring points MS up to the line short.

The measuring points MS are symmetrical with regard to the connection terminals, i.e. interchangeable. A preferred embodiment of the method according to the invention provides that the signal line L is returned from the last measuring point MS back to the signal center. The measuring point MS can now be monitored from two sides. This, in conjunction with the short-circuit detector mentioned, makes it possible to fully maintain the data traffic from and to the measuring points MS in the event of a line short-circuit or interruption, while simultaneously reporting the line fault. It is of great importance in this connection that the location of the line disturbance can easily be determined by the method according to the invention. This is a particular advantage because it is well known that finding line faults is very time consuming and time consuming.

FIG. 4 shows an embodiment of a transmission system according to the invention with measuring points MS which are controlled from the signal center Z. are. As in FIG. 1, all measuring points MSm are distributed over one or more signal lines L. The measuring points MS are constructed in accordance with FIG. 3, that is to say they contain a directionally symmetrical (bilateral) switching element S which can switch through the line signal arriving at one input / output terminal K1 to the other input / output terminal K2 and insert changes into the switched line signal and into the Modules B each have a measuring sensor M, a transducer W, a control unit KE, an address memory AR for storing the individual measuring point address and a command memory BS for storing the commands.

The changes inserted into the line signal by the switching element S are referred to as "markings". The marking is noticeable in the line going out from the measuring point MS as a current voltage interruption, which indicates to subsequent measuring points MS that the information coming from the signaling center Z may not be evaluated and may only be used for synchronization purposes. When commissioning, all switching elements S are conductive, so that all measuring points MS can synchronize with the synchronization information contained in the line signal. A reset command before the start of a cycle for querying measured values brings all m measuring points MS into a neutral state, which leads to all switching elements S, controlled by the associated control unit KE, at a defined point in time within the time frame given by the synchronization information, by means of a short time Open a current voltage interruption as a marking in the outgoing line signal, whereby all m - 1 measuring points following the first measuring point MS1 receive a signal with a marking, which they use exclusively for synchronization. Since the measuring points run synchronously, the voltage interruption is always impressed at the same point in time within the defined time grid, which allows the information to be transmitted without interference at the other times.

The first measuring point MS1 is the only one to receive a line signal without marking, which means that it is the only one to evaluate the signal, execute the corresponding command, respond, then no commands except the reset command and no longer inserting a mark by switching the switching element S on continuously leaves. The continuous switching on of the switching element S has the consequence that from now on the line signal coming from the signal center Z reaches the subsequent measuring point MS2 without marking, which means that after evaluation it executes the corresponding command, responds, then also only accepts the reset command and the associated one Switching element S switches on continuously. This has the effect that the next but one measuring point MS2 also becomes active because it receives a line signal without marking. The cycle continues until the described process has been carried out in succession at all measuring points MS present in the signal line L. After completion of the cycle, a reset command is sent to all measuring points MS to go into the neutral state and to reinsert their mark by briefly opening the switching element S. A new cycle can then be started.

The possibility of giving individual commands to each individual measuring point MS is used when the transmission system is started up in order to transmit to each measuring point MS an individual measuring point address which it stores in its address register AR. In this way, each measuring point MS receives an identification that distinguishes it from the other measuring points. This type of addressing avoids any manipulation at the measuring points themselves and allows both the advantages of the parallel system and those of the derailleur system to be exploited without having their disadvantages. Of course, in the event of a system failure, malfunction or maintenance, the addresses can be re-entered in the register at any time.

Reference numerals

• Address A
• Address memory AR
• Assembly B
• Command memory BS
• KE control unit
• Input / output terminal K1
• Input / output terminal K2
• Signal line L
• Measuring sensor M
• Measuring point MS
• Switching element S
• Transducer W
• Signaling center Z
• Terminals 1
• Terminals 2
• Terminals 3A
• Terminals 3B

Claims (9)

1. A method of transmitting measured values in a surveillance system for the protection of buildings and having monitoring points (MS) which contain a measuring sensor (M), a measured value transducer (W) and a switch element (S) controlled by a monitoring unit (KE), and which, for the purpose of transmitting signals, are connected in a chain-like manner by way of signal lines (L) to first pairs of terminals (K1) of a signal exchange (Z) in which the signals are then combined to obtain differentiated fault or alarm signals, characterised in that the switching elements (S) provided in the monitoring points (MS) are conductive when put into operation, whereby the line signal on the signal line (L) arrives at all the monitoring points (MS) and permits the latter to synchronize to the synchronizing information contained in the line signal, that all the monitoring points (MS) are brought into a neutral state by a reset command from the signal exchange (Z), that the associated switching element (S) is momentarily opened by a control command of the monitoring unit (KE) at predetermined instant within the time raster defined by the synchronizing information, and that, as a result of this voltage interruption, all the monitoring points (MS), with the exception of the first monitoring point, receive a mark which indicates that the line signal received only serves for synchronization purposes and not for evaluation, and that the first monitoring point (MS1) is the only one to evaluate the signal, perform the corresponding command, give the reply and then switch on the switching element (S1) permanently, whereby the following monitoring point (MS2) receives a line signal without a mark and therefore in turn evaluates the signal, performs the corresponding command, gives a reply and then also switches on the associated switching element (S2) permanently, so that the operation can be repeated at the further monitoring points (MS) until the cycle is terminated at the last monitoring point (MSm) and a fresh cycle is started by a reset command by bringing all the monitoring points (MS) into the neutral state again.

2. A method as claimed in claim 1, characterised in that address memories (AR) provided in the monitoring points (MS) are occupied by the addresses of the monitoring point (MS) in a predetermined sequence from the signal exchange (Z) by suitable commands.

3. A method as claimed in claim 2, characterised in that the address memory (AR) located in the monitoring point (MS) nearest to the signal exchange (Z) is the first to be occupied by the address associated with the monitoring point (MS).

4. A method as claimed in claim 2, characterised in that the address memory (AR) located in the monitoring point (MS) furthest from the signal exchange (Z) is the first to be occupied by the address associated with the monitoring point (MS).

5. A method as claimed in one of the claims 1 to 4, characterised in that the monitoring points (MS) are directionally symmetrical (bilateral) with respect to the connection to the signal lines (L).

5. A method as claimed in claim 5, characterised in that the signal lines (L) are led back from the last monitoring points (MS) to second pairs of terminals (K2) of the signal exchange (Z), and that the monitoring points (MS) may be triggered by the signal exchange (Z) by way of the pairs of terminals (K1) and also by way of the pairs of terminals (K2).

7. A method as claimed in one of the claims 1 to 6, characterised in that all the switching elements (S) are closed, and hence all the monitoring points (MS) of a signal line (L) are connected in parallel to the signal exchange (Z), after the address memories (AR) of all the monitoring points (MS) of the signal line (L) have been occupied.

8. A method as claimed in one of the claims 1 to 7, characterised in that the monitoring units (KE) provided in the monitoring points (MS) can detect a short-circuit of the pairs of terminals (1, 3A) or (2, 3B) by which the monitoring points (MS) are connected to the signal line (L).

9. A method as claimed in one of the claims 1 to 8, characterised in that the monitoring points (MS) contain measuring sensors (M) for the detection of combustion phenomena, or products of combustion, for the detection of injurious gases or vapours, or for the detection of intruders in a room to be sur- veilled.

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