DE3249787C2 - - Google Patents

Description

The invention relates to a monitoring system according to the Preamble of claim 1.

Such a monitoring system is in DE-OS 26 38 529 disclosed.

In such surveillance systems, the sensitivity can be speed of the sensors connected to the signaling units in the Change over time due to aging; can also tension conditions for operating these sensors or reference voltages to drift over time.

DE-OS 21 47 022 has already been proposed in one Monitoring system the alarm threshold depending on to update the actual values of previously received measurement signals. For this purpose, an average value calculator is used, which initially with the current output signal of a signaling unit is applied and this is continuously integrated. The The output signal of the mean value calculator is therefore a measure for slow changes in environmental conditions, under which a monitoring unit of the monitoring system works. This type of measurement signal setpoint update is then satisfactory when the alarm conditions are rapid level correspond to changes in the output signal of the signaling units, while the noise level changes are slow.

A monitoring system is also in DE-OS 27 13 640 described in which the resetting of an alarm threshold with averaging of the output signal of a sensor over long periods of time.

For other applications, especially fire monitoring However, systems must also be guaranteed to be slow changes in the output signal of a signaling unit  trigger an alarm. An example of this would be monitoring the temperature in a haystack, where the temperature is initially relatively slow grows.

Monitoring is therefore intended by the present invention System created according to the preamble of claim 1 in which, on the one hand, real aging-related Drifts are eliminated, on the other hand slow level changes conditions in the output signal of a signaling unit to trigger of an alarm.

According to the invention, this object is achieved by monitoring Plant according to claim 1, claim 2 or claim 5.

In the monitoring system according to the invention, a Taking into account real long-term changes in operations parameters without the operation of the monitoring system must be interrupted. The individual sensors of the message units can be remote from the central unit in real time be calibrated without the operation of the system is affected.

In a monitoring system according to claim 1 the reading of new alarm signal setpoints in the alarm signal Setpoint memory at fixed times, where the new setpoints using the at reading time actual values. In practice the updating of the target values to such discrete ones Times at which due to the environmental conditions it can be assumed that there are no disruptive factors (e.g. for climate control on Sunday morning).

In a monitoring system according to claim 2 an adjustment of the sensitivity of the signaling units assigned sensors only to fixed, from the central unit predetermined times, which in turn according to the above  described criteria can be selected.

In DE-OS 29 46 169 it is proposed by Simulators that act on a sensor to be tested, to bring about targeted alarm conditions, for which this Simu lators regarding the intensity of their influence physical size of the central unit of the super security system are controllable; the sensitivity of However, sensors cannot be used in this known system be put.

In a monitoring system according to claim 5, a Correction for the ongoing correction of a measurement signal signal at predetermined times from the output signal a reporting unit.

Advantageous developments of the invention are in Unteran sayings.

The invention will now be described with reference explained in more detail on the drawing. In this shows

Fig. 1 is a block diagram of a GE Überwachungsanla individually with a plurality of addressable active signaling units,

Fig. 2 is a circuit diagram of a portion of the central unit of the monitoring system of Fig. 1 and one of the signaling units,

FIGS. 3 and 4 shows the time history of signals on the signal bus of the monitoring system of Fig. 1,

Fig. 5A, 5B and 5C show enlarged sections of FIGS. 3 and 4,

Fig. 6 is a detailed block diagram of a signaling unit acti ven,

Fig. 7 shows the circuit diagram of a practical execution example of an active signaling unit,

Fig. 8 is a block diagram of an integrated circuit of the active signaling unit according to Fig. 7,

Fig. 9, 10 and 11 are graphs based on which the evaluation of the data transmitted from the monitoring units to the central unit status signals will be explained,

Fig. 12 shows the circuit diagram of an alarming signal evaluation circuit of the central unit,

Fig. 13 to 15 are graphical representations, de rer th based exchange of information between Meldeeinhei and the central unit will be explained, and

Fig. 16 is a block diagram of a portion of the central unit, which handles the compensation of long-term changes in system parameters.

In the monitoring system shown in Fig. 1, a plurality of active reporting units 25 are connected to a central unit 26 via a signal rail, which has two conductors 27, 28 . Such active reporting units are also referred to as "transponders" (transmitters / responders). They can be addressed by the central unit 26 in any order and recognize not only their addresses, but also other data that are provided by the central unit on the signal rail, e.g. B. Commands for Eigensteue tion of the reporting unit or the control of various ner, the reporting unit associated devices. In addition, the reporting units transmit data such. B. sensor signals and a response identification signal back to the central unit. The reporting unit 25 and the central unit 26 thus form a bidirectional data exchange system. The conductors 27, 28 and further pairs of conductors 31, 32 and 33, 34 which branch off from the conductors 27, 28 have no line termination. It is known that such branch lines can be provided regardless of the spatial arrangement of the signaling units or the order of their addressing.

Fig. 2 shows the essential part of the conductors 27, 28 connected to central unit 26 as well as one of the active signaling units 25. The central unit 26 works with a DC voltage V , which is applied between conductors 35 and 36 . The conductor 35 is connected via a resistor R ₁ to a conductor 37 which is connected to the conductor 27 via a connecting screw 38 . The conductor 36 is connected to the conductor 28 via a screw 40 . a switch S ₁ is placed in parallel with the resistor R ₁ . The conductors 37 and 36 are connected by a resistor R ₂ , which together with the parallel connection of the resistor R ₁ and the switch S ₁ forms a voltage divider. At its center tap, a measuring line 41 is ruled out.

The signaling unit 25 contains a resistor R ₃ , which is connected to the conductor 27 . His second terminal me is connected to the conductor 28 via a further switch S ₂ . In the exemplary embodiment considered here, the resistors R ₁ , R ₂ and R _{3 have} the same value. A command circuit 42 controls the opening and closing of the switch S ₁ . Similarly, the reporting unit 25 in Fig. 2 not shown circuits for control NEN of the switch S _2nd

The information transfer between the reporting units and the central unit takes place by opening and closing the switches S ₁ and S ₂ . By closing the switch S ₁ , the conductor 27 is pulled up to the full supply voltage V , and the corresponding pulse reaches the signaling units 25 via the conductors 27, 28 . Both the closing time of the switch S ₁ and the number of opening and closing games of this switch are monitored in the individual reporting units, as will be described in more detail below.

If the resistors R ₁ , R ₂ and R _{3 have} the same value and the switches S ₁ and S ₂ of FIG. 2 are both open, the voltage on the measuring line 41 is equal to half the supply voltage V. Conversely, if voltage V / 2 is on measuring line 41 , switch S _{1 is} open. In this open time of the switch S ₁ , the signal is transmitted from the signaling unit 25 to the central unit 26 . For this purpose, switch S _{2 is} closed, while switch S ₁ remains open. Then the resistor R _{3 is} parallel to the resistor R ₂ , this parallel connection was in series with the opposing R ₁ . The measuring line 41 therefore has a voltage level of V / 3. From the signal edges with which the signal on the measuring line 41 changes between the values V / 2 and V / 3, the number of opening and closing cycles of the switch S 2 can easily be determined.

The closing time of the switch S 2 at the same time ge open switch S 1 is used to encrypt a signal to be transmitted from the signaling unit to the central unit, which comes from a sensor not shown in FIG. 2 or to bring other information from the signaling unit 25 to the central unit 26 should. By measuring the duration of the closing time of the switch S 2 , the data represented by the original message signal can be recovered. About the closing time of the switch S 1 certain commands can also be transferred from the central unit 26 to the message unit 25 , as will be described in more detail later.

The central unit 26 regains the information desired from the reporting unit 25 from the reporting signals by monitoring the closing of the switch S 2 , that is to say when the measuring line 41 has a voltage of the magnitude V / 3. The central unit 26 can determine whether only one signaling unit or several signaling units simultaneously provide signaling signals on the conductors 27, 28 , which are generated by the closing of their switches S 2 controlled in the phase position. For this purpose, the central unit 26 must monitor when and by how much the voltage on the measuring line 41 drops below the value V / 3. To carry out this work, the central unit 26 contains a signal test circuit 43 . The latter includes a total of 44 voltage divider with four resistors 45, 46, 47, 48 , which is connected between the conductors 35, 36 . A total of 50 designated comparator stage contains three differential amplifiers 51, 52 and 53 , each of which is connected with one input to the measuring line 41 , while a second input is connected to an associated tap of the voltage divider 44 . The differential amplifier 51 then provides a signal on a conductor 54 when the signal on the measuring line 41 has the value V / 3 or a smaller value. This means that at least one of the reporting units 25 responds to addressing by the central unit 26 by closing its switch S 2 . The differential amplifier 52 then emits a signal on a conductor 55 when the level on the measuring line 41 has the value V / 4 or a smaller value. Such an output signal indicates that two or more signaling units respond simultaneously, their switches S 2 closing simultaneously and thus a corresponding number of resistors R 3 being connected in parallel with the resistor R 2 . If you compare the signals on the conductors 54 and 55 at any time and then a signal is present on the conductor 54 , while no signal is received on the conductor 55 , this indicates that exactly one signaling unit 25 has a signal delivers the conductors 27, 28 to the central processing unit 26 . Another differential amplifier 53 then outputs a signal to the command circuit 42 on a conductor 56 when the amplitude of the signal on the measuring line 41 has the value V / 5 or a smaller value. This means that three or more signaling units respond or there is a short circuit between the conductors 27, 28 . Under these conditions, the signal provided on the conductor 56 switches the command circuit 42 off and a fault indicator on. If there is a signal on the conductor 55 , however, the command circuit 42 is not switched off by a signal on the conductor 56 , this indicates that two signaling units 25 transmit signaling signals to the central unit 26 at the same time.

In the embodiment of FIG. 2 is under that an evaluation unit connected to the reproduced part of the central unit, which can evaluate level changes caused by two simultaneously responding signaling units on the conductors 27, 28 , while evaluating such from three or more reporting units reporting at the same time cannot take place. Therefore, the Lei ter 54 and 55 are connected to this evaluation circuit, while the conductor 56 is connected to the command circuit 42 . If the comparator 50 generally constructed conference amplifiers of n Dif, the outputs of the first n -1 differential amplifiers are respectively connected to the evaluation circuit, during the off transition of the n-th differential amplifier is to cut off the command circuit 42 connected to the latter.

Fig. 3 shows schematically the temporal course of the signal level on the conductors 27, 28 at the transition point between two polling cycles. For switching from one signaling unit to the next signaling unit, a group of four pulses is used in the exemplary embodiment considered here, but a different number of pulses can also be used for switching to the next signaling unit. An extended high-level pulse, which is shown in the drawing under "Address 31" and extends beyond the first part of "Address 0", serves to reset or initialize the various signaling units and at the same time to charge a charge store in the Reporting units which serve to supply them with energy. Each signaling unit contains a counter for summing up the total number of pulse groups emitted by the central unit, and the addressing and activation of the individual signaling units takes place in accordance with this number. On the above-mentioned stretched high-level pulse following hochpegeli gen pulses of Fig. 3 are all short-lived, which means that the Zentraleiheit no command on the conductors 27, 28 provides, but only consecutive address signals by the number of pulse groups are specified, outputs.

Fig. 4 shows the manner in which a pulse group emitted by the central unit is changed to transmit a command to a particular one of the reporting units. Should z. B. a command to the 17th reporting unit are transferred, the hochpe gelige part of the second pulse of the associated pulse group in the stretched, z. B. for a time of 40 milliseconds. The exact period of time is not critical because the individual reporting units contain a pulse length discriminator, which responds when a pulse has been high for a period of time that is longer than a predetermined period of time. The latter corresponds to the distance between the times t ₀ and t ₁ in FIG. 4. In practice, this time threshold is approximately 20 msec. The signaling unit also recognizes that the temporal expansion was carried out on the second pulse of a group, and from this the function to be performed is known for the signaling unit. It is assumed that a command is encoded by extending the second pulse of a group, which is used to turn on a light emitting diode or similar optical display unit. As soon as the high-level part of this pulse extends beyond time t ₁ , the light-emitting diode is thus switched on, namely up to time t ₂ . The signaling unit can carry out various commands since different high-level pulses in a group can be stretched to different widths. For this command transmission, the central unit 26 closes the switch S 1 accordingly long. You get z. B. the above-mentioned ge stretched high-level pulse between times t ₀ and t ₂ . After the waiting time t ₁ , the consumer requested by the respective command (light emitting diode, relay or other consumer) is switched on as long as the full supply voltage is on the conductors 27, 28 . The consumer thus switched on is thus supplied with the voltage from the central unit via the conductors 27 and 28 ; the energy supply of this consumer need not be carried out by the reporting unit. This will be explained in more detail later. In the same way, the reporting unit 25 outputs data to the central unit 26 by closing its switch S 2 and generates a reporting signal with the amplitude V / 3 by prolonged closing of the switch S 2 shown in FIG. 2 . This will now be explained in more detail with reference to FIGS. 5A, 5B and 5C.

As already indicated above, the data transmission from a signaling unit to the central unit takes place with the switch S 1 of the signaling unit open by closing and opening the switch S 2 of the signaling unit in accordance with the information to be transmitted. Each time the switch S 2 is closed, the voltage on the measuring line 41 of the central unit assumes the level V / 3. The length of the time span over which the voltage on the measuring line 41 remains at the value V / 3 depends both on the central unit (open time of switch S 1 ) and on the signaling unit (closing time of switch S 2 ). the closing time of the switch S 2 in turn depends on the output signal of a sensor assigned to the signaling unit (e.g. amplitude of the sensor output signal) or on other data to be transmitted back from the signaling unit. The control of the switch S 2 of the reporting unit 25 will be described in more detail later.

Fig. 5A shows one of the pulse groups, which are shown in Fig. 3 under the headings "Notification unit 1" and "Notification unit 2", the scale compared to Fig. 3 is enlarged. In Fig. 5A there are four pulses as shown, with residual signals of low amplitude between 141, 142, 143 and 144 between the successive pulses. The fourth low-level residual signal 144 lies in a measuring time space 145 . In the exemplary embodiment considered here, this is divided into three time windows 146, 147 and 148 . Within the fourth low-level residual signal, there is a signal rise 150 which lies in the middle of the time window 147 . The signal rise 150 lies in the "good" time window 147 , which indicates that the component in question (assigned or internal module of the signaling unit) is working properly, which generates the signaling signal for the central unit within the measuring time period 145 .

On the other hand, if the signal transition 150 were in the first time window 146 of the measurement period, this could represent an indication of a fault in the sensor concerned, while a position of the signal rise 150 in the last time window 148 can be used for coding an alarm state. It goes without saying that the assignment of different time slots to a measuring time can be selected differently for certain states of the signaling unit for different sensors. Is z. B. a sensor is provided as a sensor, a signal transition in the time window 146 of a low temperature, a signal transition in the time window 147 of an average or normal temperature and a signal transition in the time window 148 of a high temperature can be assigned. Details of the determination of the position of the signal rise 150 with respect to the start of the measurement period 145 will be presented later. In general, the coding of the information to be transmitted provides a considerable improvement in the noise behavior and the measuring accuracy.

The measurement period 145 is obtained by extending the furnace time of the switch S 1 , as can also be seen from the amplitude value of the residual signal 144 . Of course, any other of the low-level residual signals 144, 142 or 143 could also be extended in order to transmit information from the signaling unit to the central unit. In this case, the data transmitted within the other measurement periods would be of a different nature. In the embodiment considered here, for. B. provided that the signaling unit when extending the first low-level residual signal 141 transmits its entire calibration data based on a reference voltage to the central unit. If the second low-level residual signal 142 expands, the signaling unit transmits data to the central unit for identifying the sensor or another component connected to the signaling unit. An extension of the low-level residual voltages 143 or 144 allows the signaling unit to transfer data to the central unit which are derived from an analog sensor output signal. Although it is assumed in FIG. 5A that only a single low-level residual signal is extended, namely the residual signal 144 , several low-level residual signals can thus also be expanded analogously to create corresponding measuring time periods. Conversely, if no data is to be transferred from a signaling unit under consideration to the central unit, none of the low-level residual signals is expanded by the central unit. It can thus be stretched with zero, one, two, three or four of the low-level residual signals in the pulse group shown in FIG. 5A, the four successive pulses together in the exemplary embodiment under consideration for the switching from one just activated signaling unit to the next serve to activate the reporting unit.

Because the first two low-level residual signals 141, 142 fall below line 430 of FIG. 5A, but do not reach line 431 there, the central unit can see from the voltage level on measuring line 41 that at these times switch S 2 of the signaling unit was closed. By closing this switch, the voltage level V / 3 is set up on the measuring line 41 , which lies within the amplitude range delimited by lines 430 and 431 . At the point in time at which the third low-level residual signal 143 was present, the switch S 2 is open. A level V / 2 on the measuring line 141 shows that, at the point in time under consideration, the switch S 2 is not closed either in the signaling unit just addressed or in another signaling unit.

If a smoke detector designed as an ion probe were connected to the reporting unit, the extended low-level residual signal 144 , which specifies the measuring period 145 , could be used for data transmission as follows: It is assumed that the entire measuring period has a duration of 32 ms , wherein this entire period should be assigned to a measurement amplitude range of 0 to 8 volts. Thus, every millisecond of the measurement period represents a voltage value of 0.25 V. In this exemplary embodiment, it extends the first time window over 12 ms and represents a voltage of 3 V. The second time window 147 has a duration of 8 ms and represents a span voltage of 2 V. The third time window again has a duration of 12 ms and is assigned a voltage of 3 V. Thus, when the signal rise 150 occurs at the point shown in FIG. 5A, the signaling unit notifies the central unit that a signal with a level of 4.0 V is present from the sensor assigned to the signaling unit (smoke detector designed as an ion probe) . The central unit then determines, based on this voltage value, how far the current actual voltage (4.0 V) deviates from the target voltage for this special sensor in order to determine the switching state of the sensor. In addition, this actual voltage output by the sensor can be compared with a previously output, recorded voltage of the same sensor. If the previously measured voltage level has been obtained for a long time (about a week or more), the comparison can be used to obtain an indication of slow changes in the operation of the signaling unit, which can result from aging of components or accumulation of dust.

In Fig. 5A, only the use of three time windows is addressed in order to simplify the explanation. A more precise evaluation of the position of the signal rise 150 will be described in more detail later with reference to FIG. 12.

Fig. 5B shows the same signal transmission from egg ner reporting unit to the central unit, as shown in Fig. 5A, with the only exception that the switch S 2 of an unaddressed reporting unit has failed in the short-circuit position. Since a further resistor R 3 of a signaling unit is now constantly connected in parallel via the resistor R 2 , the low-level residual signals are continuously reduced in size. Thus, the residual signal 141 lies between the line 431 between V / 3 and V / 4 and a line 432 between V / 4 and V / 5. The same applies to the residual signal 142 . The residual signal 143 and also the residual signal 144 only have the level V / 3. Irrespective of the short circuit in the unaddressed signaling unit, the information is however correctly transmitted from the signaling unit to the central unit, since the information is at a distance from the signal increase 150 from the start of the measuring period 145 .

Fig. 5C illustrates the conditions with simultaneous transmission of message signals from two reporting units, the switch S of the additional reporting unit is not short-circuited. In this case too, the first two low-level residual signals have the value V / 4, since the switches S 2 of the two signaling units now close at the same time. However, neither of the two switches S 2 is closed during the third low-level residual signal 143 , from which the central unit can conclude that the two te signaling unit does not contain a permanently short-circuited switch S 2 , but rather both signaling units deliver data simultaneously. Within the measurement period 145 obtained by stretching the low-level residual signal 144 , one first has a low-level signal 160 of size V / 4. This is followed by a first signal rise 161 and a second low-level signal of size V / 3. This is followed by a second signal rise 163 and a low level signal 164 of size V / 2. If the signal increases 161 and 163 both fall in the "good" time window 147 , the central unit knows that there is no alarm state. If one of the signal rises falls into the alarm window 148 , the central unit knows that one of the signaling units is at the alarm level, but cannot identify the alarming unit of the signaling units. The period designated in FIG. 5C with 165 is a measure of the lower of the analog voltages reported by the reporting units, the period 166 shown there for the higher of these analog voltages.

Fig. 6 shows details of one of the reporting units. A signal / network switch 60 is connected to the conductors 27, 28 of the signal rail. This supplies a DC supply voltage via a line 61 to the individual modules of the actual reporting unit and via a line 62 to the reporting unit associated modules (z. B. a reporting device). It is understood that the line 61 may consist of several conductors, e.g. B. a ground conductor, a conductor of 5 V to ground, a conductor with 12 V to ground, etc. The signals present from the conductors 27, 28 are forwarded by the signal / network switch 60 to a busbar 63 , to which an activation circuit 64 , an output command control circuit 65 and an input / output circuit 68 are connected. The activation circuit 64 comprises an address counter and a comparator and is connected to an address switch bank 66 . Their switches are simple on / off switches, the position of which together specifies the address of the signaling unit under consideration. If the address switch bank 66 contains five switches, one of 32 different addresses can be assigned to the signaling unit. The comparator of the activation circuit 64 generates, when the total number of groups of large amplitude pulses obtained via the busbar 63 matches the address set by the switch bank 66 , on line 67 an activation signal for the input / output circuit 68 and the output command control circuit 65 .

As will be explained in more detail later with reference to FIG. 8, the input / output circuit 68 contains circuits which respond when the central unit 26 provides a command (stretched high-level pulse) on the conductors 27, 28 and then that of the respective one Establish command required circuit connections. A first analog signal "A" is present on the input / output circuit 68 via a line 70 , which is 0 V in the exemplary embodiment considered here. Via a line 71 , the input / output circuit 68 receives a second analog signal from a sensor 72 . If the input / output circuit 68 is instructed to transmit data assigned to the analog signal on the line 71 to the central unit, the input / output circuit 68 generates a correspondingly coded signal on the busbar 63 , which signal via the signal / network switch 60 the conductors 27, 28 are given and from there to the central unit. A reference voltage reaches the input / output circuit via a line 73 . The latter can be provided by a Zener diode. The reference voltage can also be reported to the central unit on request.

A switch bank 74 is also connected to the input / output circuit 68 , the simple on / off switches of which together provide a digital identifier for the signaling unit. The setting of the switches can z. B. characterize the type of the sensor 72 assigned cha cha characterize (ion probe smoke detector, photoelectric smoke detector, air speed sensor, temperature sensor, mechanical switch of a manually operated train detector, short-time switch to blow off Ha lon). Via a line 76 is controlled by the command output control circuit 65, a surge relay 75 , the contacts 77 are switched when the signal is applied from the position shown in Fig. 6 in the second position (extinguishing position). Via a line 78 , the contacts 77 can be switched to the ON position shown in FIG. 6. Finally, the command output control circuit 65 via a line 80, a signal lamp 81 , z. B. turn on a light emitting diode.

Fig. 7 shows the circuit diagram of a practical embodiment of a signaling unit 25th Two screws clamp 83, 84 connect the conductors 27, 28 to conductors 85, 86 of the signaling unit. An overvoltage protection 87 is connected between the conductors 85, 86 , which protects the components of the signaling unit against transients from the network. A diode 88 is connected between the conductor 85 and a main supply conductor 90 of the signaling unit. One terminal of a capacitor 91 is connected to the conductor 86 , the other terminal to the node between the main supply conductor 90 and the Ka method of the diode 88 . If there is a long rising pulse on the signaling unit, the capacitor 91 is charged via the diode 88 . The charge on capacitor 91 maintains the voltage on main supply conductor 90 for those periods in which conductors 27, 28 are low level ( V / 2 level or less). The voltage on the main supply conductor 90 is present at the collector of an NPN transistor 92 , which is connected as a series regulator, so that a regulated supply voltage is obtained on a supply conductor 93 . A resistor 94 is placed between the collector and the base of the transistor 92 , the base also being connected to the conductor 86 via a Zenerdiode 95 . An opposing stand 96 is connected to the main supply conductor 90 and connects via a conductor 99 to a terminal "10" of an integrated circuit device IC 1 . The numbered terminals of this integrated circuit is referred to in Fig. 8 with the same terminal numbers.

If the level on the conductors 27, 28 changes , a corresponding change in amplitude is obtained at the terminal "17" of the integrated circuit IC 1 . A low-pass filter, which consists of a resistor 97 and a capacitor 98 , filters out high-frequency noise pulses. In order for the integrated circuit IC 1 to hold a low-level pulse at its terminal "17" , the level on the conductor 27 must be low-level (go to V / 2) for at least half a second before this pulse acts as a clock signal for the integrated circuit IC 1 is recognized. The level on a conductor connected to the output of the low-pass filter 110 is compared in the integrated circuit IC 1 with the level on the conductor 99 , that is to say with the line voltage supplied via the conductor 27, 28 , which serves as a reference signal. This comparison determines whether the clock signal is high or low. This also compensates for large fluctuations in the mains voltage. In the exemplary embodiment considered here, the monitoring system also functions in the event of mains fluctuations of 15 to 30 V, i.e. a change in the mains voltage by a factor of 2.

Additional input signals for the integrated circuit IC 1 provide the address switch bank 66 and the Füh leridentification switch bank 74 , which are combined into a single switch bank. Their switches "1" to "5" represent the address switch bank, while the switches "6" to "8" represent the sensor identification switch bank 74 .

If the signaling unit issues a command to control a connected consumer, the corresponding command signal reaches the unit to be controlled via one of the lines 76, 78, 80 also shown in FIG. 7. The line 78 is connected to a closing winding 101 of the impulse relay 75 , through which the normally open contact group 102 of this relay can be closed. When line 76 is applied, the turn-off winding 103 of this relay is energized, whereby a normally closed contact group 104 of this relay is closed. At the terminal "8" of the integrated circuit IC 1 , a line 79 is connected, via which an NPN transistor 100 is connected. Controls the latter by, a counter stood 89 , which has 4.7 kOhm in the embodiment under consideration, switched between the conductors 85 and 86 , whereby the amplitude of the conductors 27, 28 and thus on the central unit 26 voltage is reduced. It can be seen that the transistor 100 speaks in terms of function of the switch S 2 in FIG. 2, its opening and closing depending on the speed of the control signals on line 79 . It can also be seen that the resistor 89 shown in FIG. 7 corresponds to the resistor R 3 explained with reference to FIG. 2 from the mode of operation.

A command to turn on transistor 100 is only generated on line 79 if there is a low-level residual signal on conductors 27, 28 . The further control signals to turn on or turn off the impulse relay 75 or to turn on the signal lamp 81 are only generated when the Si signal on the lines 27, 28 is high. Thus, the signaling unit energy for operating these consumers can refer to the conductors 27, 28 without having to resort to the energy stored in the capacitor 91 , which is used to operate the logic functions components of the signaling unit. A potentiometer 105 , a fixed resistor 106 and capacitors 107 and 108 are also connected to the integrated circuit IC 1 , as can be seen in the drawing.

Fig. 8 shows a block diagram of the integrated circuit IC 1 , wherein the square-framed terminal numbers correspond to the terminal numbers shown in Fig. 7. The one reporting unit via addressing pulses of the central unit arrive via a conductor 110 to the terminal "17" of the integrated circuit IC 1 and from there to a pulse generator 111 . A second input of the latter is connected to conductor 99 . The clock pulse generator 111 ent holds a pulse shaping circuit, for. B. a difference ver stronger, which compares the voltage levels on the conductors 110 and 99 . The output signal of the clock pulse generator 111 is fed to a 2-bit counter 112 and to a clock signal identification circuit 113 . On the latter a Kon capacitor 108 and the supply conductor 93 through a resistor 106, a Taktge berbezugssignal on. A 5-bit counter 114 receives the overflow pulses of the 2-bit counter 112 via a conductor 115 . Remains an incoming address pulse for a predetermined period of time (20 ms in the embodiment) also goes high, thus reaches a stretched clock identification pulse over conductor 117 to ei s 2/4 line decoder 118th If the incoming addressing pulse remains high for a very long time (80 ms in the exemplary embodiment considered), the clock signal identification circuit 113 generates a reset pulse on a conductor 116 for the two counters 112 and 116 .

The 2-bit counter 112 outputs a clock decoding signal on output conductors 120, 121 . The latter specifies which of a plurality of different commands should be carried out by the reporting unit. The signal on the output conductors 120, 121 passes to the 2/4 line decoder 118 , an analog 4-channel multiple 122 and a switching control circuit 123 . The latter represents an external memory for the switching cycles of two request cycles of the signaling unit if the external switch is actuated for a period of time that is less than two request cycles. In the exemplary embodiment considered here, an inquiry cycle, namely the time span between two successive activation pulses, which are provided at the output of a comparator 131 , lasts 3 seconds. The storage duration of the switching control circuit 123 is therefore 3 to 6 seconds, depending on the frequency of the external switch works exactly. This external switch can be a mechanical momentary switch which gives a signal to the switching control circuit 123 via the line 70 and the terminal "6" and a conductor 119 . It should be emphasized that despite the presence of this switch and its actuation, the switching control circuit 123 does not store the switch actuation for the subsequent transmission to the multiplexer 122 unless the corresponding switch identification data are present over three conductors which are connected to the terminals "18". , "19" and "20" of the integrated circuit IC 1 are connected. These terminals are connected to the sensor identification switch bank 74 . If the switch bank 74 is set so that the switching control circuit 123 is activated, the latter forwards the data relating to the switch actuation (on the line 70 ) to the multiplexer 122 .

Certain settings of the switch bank connected to the terminals "18", "19" and "20" result in the activation control circuit 123 being switched on , ie they interrupt the connection between the conductor 119 and a conductor 129 , which leads to the multiplexer 122 . In the exemplary embodiment considered here, two of the eight possible switch settings are used to achieve this function. Under these conditions, the switching control circuit 123 receives the signal on line 70 via terminal "6" and line 119 , a voltage for a special switching state being generated from this signal, which voltage is passed to multiplexer 122 via line 129 . In the other six settings of the switch bank connected to the terminals “18”, “19” and “20” , the switching control circuit 123 ensures direct connection between the conductors 119 and 129 .

To explain the operation of the switching control circuit 123 , reference is made again to FIG. 5A. If the sensor identification signal corresponds to a two-position switch connected to line 70 , the data received via conductor 119 from the switch must be translated in order to identify one of the three possible switching states (not connected, open, closed). A temperature sensor connected to line 70 , on the other hand, would generate an analog output signal, and the sensor identification signal would result in direct forwarding of the sensor output signal without any implementation by the switching control circuit 123 .

A sensor circuit 124 generates the sensor identification signal and a calibration signal. The sensor identification signal is given via a data rail 125 , which comprises several conductors, to an analog 8-channel multiplexer 126 . The sensor identification signal at the output of multiplexer 126 passes via a conductor 127 to 4-channel multiplexer 122 , which also receives the calibration signal generated by transmitter circuit 124 via line 73 . At the multiplexer 122 is also on line 71, the output signal of the Füh lers 72 and line 70, the analog signal "A" (see FIG. 6), the latter then running on Lei ter 119 and 129 when the connection is closed by the switching control circuit 123 . The output signal of the multiplexer 122 passes via a line 128 to a voltage-controlled monostable multivibrator 130 , which is connected to the potentiometer 105 via the terminal "9" and to the capacitor 107 via the terminal "11" (cf. also the right one) lower part of Fig. 7).

The digital comparator 131 receives the output signal of the 5-bit counter 114 and the output signal of the addressing switch 66 . If the address given by the latter corresponds to the status of the counter 114 , the comparator 131 generates an activation signal on a conductor 132 for the voltage-controlled monostable multivibrator. This activation signal also reaches the 2/4 line decoder 118 via a conductor 133 . If this is set to a high level via a conductor 139 via the output signal of the clock pulse generator 111 , the voltage-controlled monostable multivibrator 130 is deleted. If the output signal of the clock pulse generator is low, it generates a second activation signal for the multivibrator 130 . If both activation signals are present, the voltage-controlled monostable multivibrator 130 generates an output activation signal on a conductor 134 , which is amplified by the associated amplifier of an output driver stage 135 and is output via the terminal "8" from the integrated circuit IC 1 . This leads to a control of the transistor 100 shown in FIG. 7, which is equivalent to the closing of the switch S 2 shown in FIG. 2.

To select another one of the output terminals 136 ( "1", "2", "3" or "4" ), the 2/4 line decoder 118 must provide a corresponding output signal on one of the conductors 137 connected to it. For this purpose, three input signals must be present at the 2/4 line decoder 118 : first, a clock decoding signal on the output conductors 120, 121 , which selects the output driver stage to be controlled; second, an activation signal on conductor 133 ; and third, an expanded clock signal on conductor 117 , which identifies the command that was issued. If terminal "2" is selected, this means that the signal lamp 81 should be switched on. If the terminal "3" is selected, the impulse relay 75 is set, and if the terminal "4" is selected, the impulse relay 75 is deleted. The evaluation of the feedback signals returning to the central unit 26 will now be described below with reference to FIGS . 9 to 11.

Fig. 9 shows in an idealized form a returning signal pulse to the central unit, which is comparable to the modulated low-level residual signal 144 of Fig. 5A. The low-level residual signal is stretched so that a measurement period 180 is obtained, the duration of which is 32 ms between the rising edge 181 of an addressing pulse and the rising edge 182 of the next addressing pulse. Within the measurement period 180 , the residual signal has a first low-level signal section 183 , a signal rise 184 , in which the signal rises from level V / 3 to level V / 2, and a subsequent signal section 185 . Line 186 indicates the alarm threshold, while lines 187 and 188 indicate a range of adjustable sensitivity.

In practice, the actual sensitivity corresponds to the difference between the signal increase 184 and the line 186 representing the alarm threshold. As already explained above, the measuring period of 32 ms can be assigned a measuring range of 8 V. The length of the signal section 183 is then a measure of the output voltage to be transmitted of the sensor assigned to the signaling unit. In practice, however, the Mel designale are not returned to the central unit with the idealized pulse shape shown in FIG. 9. Rather, the various edges are distorted by the components contained in the system, so that signal edges are obtained, as are generally shown in FIG. 10.

Fig. 10 shows the effect of line capacities on the form of real impulses. A first falling edge 192 of the signal standing on the conductors 27, 28 does not drop vertically, but rather follows an essentially logarithmic curve. Likewise, the signal rise 184 is also not exactly rectangular, rather a curved rising edge 193 is obtained . In order to be able to measure the distance between the signal edges 192 and 193 precisely, it is advantageous to carry out a vernier reading with increased accuracy precisely in those areas of the time scale within which these edges occur. In Fig. 10, a time scale 194 for the rough measurement with a division of 1 ms is entered. Within the area designated with 195 Noniusbe the time units are chosen smaller, z. B. ½ or ¼ ms.

Fig. 11 shows the setting of the various scaling factors for the time axis schematically: before the start of a measurement, the evaluation circuit is switched to mode "1" (no measurement). At time 0, a timer is turned on, which works for the first 2 ms of a signal signal pulse fed back to the central unit. The corresponding de operating mode is marked in FIG. 11 with "3". After the falling signal edge 192 has been measured, the subsequent time measurement can work with a coarser grid up to half of the measurement period (16 ms). This operating mode is marked with "2". In the exemplary embodiment considered here, the alarm threshold lies in the subsequent time period of 4 ms, and therefore the time period is switched between 60 and 20 ms to vernier measurement (operating mode "3"). For the rest of the measurement period (20 to 32 ms), the time measurement can then be carried out again in rough detent (operating mode "2"). For other voltage ranges to be transmitted and other accuracy when measuring the vernier, the vernier measuring ranges (operating mode "3") can be shifted accordingly. The above-mentioned modes "1", "2" and "3" correspond to the switch positions of switches 204 and 205 , which will be described below with reference to FIG. 12.

Fig. 12 shows in a simplified form the evaluation circuit of the central unit 26 , which looks for the low-level residual signals modulated by the signaling units 25 in a measurement period for the presence of an alarm condition or a fault condition. The evaluation circuit is connected via lines 54 and 55 to the outputs of the differential amplifiers 51 and 52 shown in FIG. 2. A signal is on line 54 when a signaling unit lowers the residual signal on conductors 27, 28 to level V / 3 by closing switch S 2 (corresponds to transistor 100 ). This signal passes through a switch 200 and a line 201 to the one inputs of two AND gates 202, 203 . The command circuit 42 controls the operation of the switch 200 as well as the operation of the two three-position switches 204 and 205 . The scarf ter 204 and 205 are mechanically coupled.

The switch positions of the switches 204 and 205 are designated "1", "2" and "3" as shown in FIG. 11. A clock generator 206 generates a sequence of pulses which can reach the AND gate 202 and the AND gate 203 via the switches 204 and 205 , but are only switched through by these as long as there is a signal on the line 201 , which indicates that a signal is being transmitted by a signaling unit.

The clock 206 runs at a frequency of 4 kHz, for example. Its output signal passes through a line 208 to a frequency divider 210 , which divides the frequency by a factor of 4. The output of the frequency divider 210 is connected to the contact "2" of the switch 204 via a line 212 . The output of the clock generator 206 is connected directly to the contact “3” of the switch 205 via a line 211 . The bridge of the switch 204 is connected via a line 213 to the second input of the AND gate 203 , while the bridge of the switch 205 is connected to the second input of the AND gate 202 via a line 214 . The output of the AND gate 202 is connected via a line 215 to a fine counter 216 , the counter reading of which is given via line 217 to an input of an adder 224 . The output signal from the AND gate 203 reaches a coarse counter 220 via a line 218 . Its output is connected via a line 221 to a multiplier 222 , which quadruples the count. The output signal of the multiplier circuit 222 is given via a line 223 to a second input of the adder 224 . Via a line 225 , the output signal of the adder 224 is given to an input of a further adder 226 , which receives a compensation signal provided by a compensation stage 228 at a second input via a line 227 . The output signal of adder 226 provided on line 207 thus represents the length of time of the low-level signal section 180 with the height V / 3 in the message signal transmitted from the message unit to the central unit.

Via the line 207 , the evaluated Mel designally reaches a line 230 and from there to a comparator 231 , which then provides an alarm signal on an output line 232 if the evaluated signal signal is greater than a reference signal, which is provided by a multi-position switch 233 . The latter can provide one of three reference signals "65", "75", "85", the bridge of the multi-position switch 233 being adjusted by a sensitivity control unit 234 . The latter can be controlled via a line 235 from a program which is stored in the memory of a digital computer, or can also be controlled via a line 236 from a keypad. The sensitivity characterizing numbers "65", "75" and "85" represent switching thresholds on a scale that ranges from "0" to "128".

The evaluated Mel designal standing on line 207 is also connected via line 240 to a further comparator 241 , which receives a reference signal via line 242 . The comparator 241 then generates a signal indicating a fault on an output line 243 if the evaluated mel designal on line 207 is less than or equal to the reference signal on line 242 .

For the description of the operation of the surveillance system, it is initially assumed that the central unit 26 has instructed an addressed reporting unit to report data back. Here the loading circuit 42 moves the switch 200 into the position shown in FIG. 12 at the beginning of the measurement period. The switches 204 and 205 are closed for the initially performed fine measurement on their contacts "3". Under these conditions, the pulses generated by the clock generator 206 pass through line 211 , switch 205 and line 214 to one input of AND gate 202 . And the fourth low-level residual signal starts, is located on the line 201, the second Eingangssi generated by the differential amplifier 251 gnal for the AND gates 202 and 202 before, so that now counts arrive on line 215 to the fine counter 216th If the falling signal edge 192 of FIG. 10 reaches the V / 3 level after 1.5 ms (6 counting steps on the vernier scale 195 ), the remaining two clock pulses of the fine counting also arrive at the fine counter 216 via the AND gate 202 . This is because the command circuit 42, the switch 204 is closed 205 during the first 2 ms the measurement period in the Stelung "3" holds. Then the bridges of switches 204 and 205 are placed in position "2", in which a rough measurement is carried out. Now the AND gate 202 no longer receives clock pulses, while the AND gate 203 is connected via the switch 204 to the output of the frequency divider 210 . The down-divided clock pulses pass through line 213 , AND gate 203 and line 218 to the coarse meter 220 . The latter now counts up with a frequency of 1 kHz. Since switches 204 and 205 remain in the "2" position during the interval between 2 and 16 ms of the measurement period, a total of 14 pulses are given to coarse counter 220 via line 218 . Whose counter reading is multiplied by the multiplication circuit 222 by the number 4, so that the total value "56" is obtained on line 223 . The last rer is added in adder 224 to the output signal of fine counter 216 previously received via line 217 . 16 ms after the start of the measurement period, the output signal of the adder 224 thus corresponds to the value "58" and the switches 204 and 205 are reset to the fine count position "3" by the command circuit 42 .

If the signal rise 193 (cf. FIG. 10) takes place at 18 ms, then 8 pulses generated by the clock generator 206 are transmitted to the fine counter 216 via the switch 205 and the AND gate 202 in the period between 16 and 18 ms. This count is given to adder 224 via line 217 . These 8 pulses are added to the previously obtained number "58" so that the total sum calculated by the adder is "66". From the point in time of 18 ms, there is no signal on line 54 and thus also on line 201 , so that none of the AND gates 202, 203 can allow more counting pulses to pass through. After 20 ms, the switches 204, 205 are switched back to the coarse counting position "2", but the AND gate 203 can now no longer transmit pulses to the coarse counter 220 . The signal on line 225 now passes to adder 226 . With the aid of the compensation stage 228 , the raw result provided by the adder 224 can now be modified. If, for example, the last query of the signaling unit in question showed that a reference voltage has risen from 4.0 V to 4.6 V due to the aging of components or other long-term changes in the monitoring system, then the raw result on line 225 may result "66" the number "1" are subtracted, so that a compensated measured value "65" is obtained, which is used for the alarm and fault control in comparators 231 and 241 .

The evaluation circuit shown in FIG. 12 converts the analog signal signal on line 201 with very high accuracy into a digital signal which is provided on line 207 . This even if the fine counting is only used for 2 ms when a message signal arrives and for 4 ms in the vicinity of the middle of the measuring period.

The signaling units connected to the central unit can be remotely calibrated. This can be so successful that the address switch terbank 66 is set to the address "31" for each of the message units. The central unit then checks the calibration voltage returning from this signaling unit, and if the latter is within permissible limits, it indicates this by the signal lamp 81 of the signaling unit lighting up. Other activities of the reporting unit, e.g. B. the tightening of the impulse relay 75 can indicate that the NEN that the calibration voltage is within permissible limits. If, on the other hand, the calibration signal reported back to the central unit is not within predetermined limits, the potentiometer 105 shown in FIGS . 7 and 8 is readjusted until the correct calibration voltage is set, which can be recognized by the signal lamp 81 lighting up. After Einjustierung the calibration voltage, the switch of Adressierschalterbank then 66 put back in its original position.

The versatility of the above-described surveillance system is illustrated below with reference to FIGS . 13 to 15. The signal curves shown there are not exactly to scale, but roughly speaking, a distance of 2.5 cm on the abscissa represents a period of 32 ms.

A total of five pulses are shown in FIG. 13, four of which belong to a pulse group which control the addressing of a signaling unit and the feedback of data from this signaling unit to the central unit. These four pulses are comparable to the pulses shown in FIGS. 5A to 5C. In addition, an elongated pulse is shown which corresponds to the addressing pulse "31" of FIG. 3. The low-level residual signals of FIG. 13 are obtained with the switch S 1 of the central processing unit 26 open, while the high signal levels are obtained with the switch S 1 closed. The rising and falling pulse edges correspond to the closing or opening of switch S 1 .

In Fig. 13 is obtained the first rising pulse edge at the instant t _0, when the switch S 1 closes. As a result, the previously addressed message unit is switched off and the data transmission from it to the central unit is ended. In addition, the level of the counter contained in the activation circuit 64 (counter 114 of FIG. 8) is increased in each of the reporting units. The one of the signaling units whose addressing switch band 66 is set to the increased counter reading is now activated by its activation circuit 64 . As can be seen from FIG. 13, the switch S 1 remains closed for a predetermined minimum time (period between t ₀ and t ₂ ), so that the output "1" is switched on via the output driver stage 135 (cf. FIG. 8). The further outputs "2" to "4" are assigned output commands for the signaling unit, which would be encoded by the second, third and fourth addressing pulse of FIG. 13 being stretched in time. Since at the time in question the connection to the output "1" of the output driver stage 135 is not used, the expansion of the first high-level address pulse beyond t _{2 has} no further effect. At time t ₃ , switch F 1 is open, the signal on conductors 27, 28 becomes low again. As a result, the addressed signaling unit is commanded to end the signal at output "1" again and to start transmitting the calibration data of this signaling unit. If the addressing pulse had already dropped at time t ₁ , this would have meant that output "1" of the addressed signaling unit should not be switched on.

If the switch S 1 of the central unit 26 remains open, then after the time t ₃ the duration of the low level residual signal between the times t ₃ and t ₄ (time axis interrupted!) Can be up to 32 ms because this is the one selected in the exemplary embodiment under consideration Duration of the measurement period is. The low-level residual signal is continuously checked in the evaluation circuit of the central unit to determine whether there is a signal increase. The latter would be assigned to the actual value of the calibration data. If the central unit 26 does not require feedback of calibration data from the addressed reporting unit, the switch S 1 is closed again after only 1 or 2 ms, so that the time period between the points t ₃ and t ₄ of FIG. 13 is only 1 or 2 ms would be.

It can be seen that in this way every rising Edge of the pulse group for addressing the ver contributes to different reporting units and the location the falling edges of the addressing pulse commands who is sent to the addressed reporting unit that can.

At time t ₄ , switch S 1 is closed. Depending on the position of time t ₄ , the transmission of calibration data is ended or prevented by the rising signal edge. Due to the rising signal edge, the 2-bit counter 112 (cf. FIG. 8) of all signaling units is also incremented by one. The switch S 1 opens again at the time t ₅ , so that the signal on the conductors 27, 28 is low before the time t ₆ , at which a still high level addressing pulse of the signaling unit would command the output "2" to be switched on . The latter would have meant that the signal lamp 81 connected to the output "2" of the output driver stage 135 is turned on. The addressing pulse, however, was already low at time t ₅ , so that the output "2" of the output driver stage 135 and thus the signal lamp 180 are not switched on. In the period between t ₅ and t ₆ , the reporting unit can report the sensor identification data to the central unit. If a high-level addressing pulse is received again shortly after the time t ₅ , on the other hand, the reporting unit cannot report this data to the central unit.

At time t ₈ , switch S 1 closes again, as a result of which the transmission of sensor identification data is ended and the 2-bit counter 112 of all signaling units is further increased. The third addressing pulse remains high only until t ₉ . At this time, the switch S 1 is opened, again before the time t ₁₀ , up to which the hochpe gelige addressing pulse had to be extended to command the signaling unit to turn on the output "2" of the output driver stage 135 , whereby the impulse relay 75th would be turned on. Thus opening the switch S 1 at time t _{9 is} practically a command not to apply the impulse relay 75 . The addressing pulse remains low until t ₁₂ , and in the measurement period thus obtained, the signaling unit can measure the size of the analog voltage "A" on line 70 (see FIG. 6) to the central unit. The conversion of the analog level of this signal into the phase position of a signal rise with respect to the start of the measurement period takes place as described above with reference to FIGS . 10 to 12. At time t ₁₂ , switch S 1 closes again, where it is held by a further high level addressing pulse, by which the feedback from the addressed reporting unit is ended and all 2-bit counters 112 are increased.

The fourth addressing pulse must remain high for a certain period of time, which corresponds to the time between t ₁₂ and t ₁₄ , so that the signaling unit turns on the output "4" of the output driver stage 135 and thus the impulse relay 75 is switched off. If the addressing pulse were already low at time t ₁₃ , the signaling unit would not switch off the impulse relay 75 . Between times t ₁₅ and t ₁₆ , the signaling unit attempts to transmit a second analog voltage to the central unit, namely the output signal of sensor 72 received via line 71 . However, since in Fig. 13 it is assumed that the switch S 1 closes again after only 1 or 2 ms, the signaling unit is not commanded to report the output signal of the sensor 72 to the central unit. At time t ₁₆ , switch S 1 closes again, and the rising signal edge prevents the transmission of the sensor output signal, and all 2-bit counters 112 are incremented again.

The four addressing pulses mentioned above together represent a pulse group through which a switching from one considered, just activated signaling unit to the next signaling unit to be activated takes place together. This switchover to the next message unit is carried out by overflow of the various 2-bit counters 112 and the associated increase in the 5-bit counters 114 , which are connected to the comparator 131 , to which the addresses provided by the addressing switching bank 66 are also provided of the reporting unit under consideration. The signaling unit addressed as the next addressed at time t ₁₆ need not necessarily represent the spatially closest signaling unit. At the end of an interrogation cycle, the fifth addressing pulse remains low at time t ₂₂ . If this addressing pulse had never become the same level by opening switch S 1 at time t ₁₇ , it would have instructed the newly addressed signaling unit not to switch on its output "1". However, since the addressing pulse remains high beyond t ₁₈ , the command is given to control output "1". At time t ₁₈ in the exemplary embodiment under consideration, the clock generator circuit recognizes that output "1" of output driver stage 135 is to be switched off. The addressing pulse also remains high above t ₂₁ and t ₂₂ , with all signaling units recognizing at time t ₂₂ that this greatly extended, high-level addressing pulse is a reset pulse by which counters 112 and 114 are deleted in all signaling units. It can be seen that in the surveillance system described above, a large number of data and commands are packed in and between the addressing pulses.

In Fig. 14A is a group of the integrated Zentralein 26 emitted Adressierimpulsen shown currency rend in FIGS. 14B to 14F, the reaction of the signaling unit to a each of the Adressierimpulse give wiederge is. The waveforms shown in FIGS . 14B to 14F correspond to the signals at the outputs "8", "1", "2", "3" and "4" of the output side of the integrated circuit IC 1 and IC 1 on the right in FIG 8 on the right in FIG. 8, the output side of the output driver stage 135 . The waveform in Fig. 14B indicates when the output "8" of the IC 1 is turned on. This corresponds to the periods within which the reporting unit for the feedback of signals to the central unit is activated.

From Fig. 14A it can be seen that the switch S 1 is closed at time t ₀ , whereby the first addressing pulse is initiated. The switch S 1 remains closed until t ₁ , this period being so short that the output "1" of the integrated circuit IC 1 is not switched on. With the opening of the switch S 1 , the output "8" of the integrated circuit IC 1 is switched on, and the reporting unit 25 tries to report data, as the pulse 340 of FIG. 14B shows. At time t ₁ , however, switch S 1 is closed again, so that the first transmission is ended incorrectly and pulse 340 is accordingly switched off. Since the time period between t ₀ and t _{1 is} very small, the output "1" is not turned on, as shown in Fig. 14C.

At the time t ₂ , the switch S 1 is closed again and remains closed beyond the minimum time t ₃ , which is required to switch on the output “2”. The rising edge of a pulse 341 is therefore obtained at time t ₃ , as shown in FIG. 14D. The signal lamp 81 is switched on by the pulse 341 . This remains switched on before t ₃ until the switch S 1 is closed again at time t ₄ . After the time t ₄ , the signaling unit again tries to transfer data to the central unit, as the pulse 342 of FIG. 14B shows. However, the time span between t ₄ and t ₅ is too short for the feedback of the sensor identification data, and the pulse 342 is ended when the switch S 1 closes again at the time t ₅ .

The third address pulse in the group shown in FIG. 14A remains high only for a short time that is too short to cause output "3" to turn on. The waveform shown in Fig. 14E is thus consistently low level. At time t ₀ , switch S 1 is opened again, so that the third low-level residual signal on conductors 27, 28 is obtained (see FIG. 14A). However, this residual signal is not as low as the previous low-level residual signals between addressing pulses of the considered addressing pulse group. This is due to the fact that the third low level residual signal includes a period in which the first analog signal "A" should be reported back from a connected device to the central unit. The low level residual signal, which has only been reduced, indicates that no corresponding analog signal transmitter is connected to the signaling unit just addressed. If such an analog signal transmitter were connected, the third low-level residual signal would have the same level as the preceding low-level residual signals.

At time t ₁ includes the Schaltr S 1 again, thereby initiating the fourth address pulse. This addressing pulse remains high level t ₈ beyond, so that the output "4" is turned on. In the exemplary embodiment under consideration, this leads to the deletion of the associated impulse relay 75 . At time t ₈ , pulse 343 (see FIG. 14F) is generated at output "4". The pulse 343 lasts until the time t ₉ , at which the switch S 1 of the central unit opens again. At time t ₉ , the fourth low-level residual signal begins, this residual signal being stretched so long that the output "8" of the integrated circuit IC 1 becomes and remains high, so that the signaling unit data from the second assigned to it, working analogously Sensor can report back to the central unit. Due to the transition to the fourth low-level residual signal, output "8" becomes low-level again, and this state remains until t ₁₁ . At t ₁₁ a complete pulse group was obtained, the counter 114 of FIG. 8 is incremented in all reporting units and the next group of addressing pulses begins.

From the above description of FIGS. 14A to 14F it follows that information can also be transmitted from the central unit to the signaling units by rotating the addressing pulses, the switching on of the signal lamp 81 being described as an example. According to the pulse 341 shown in FIG. 14D, this light shone for 20 ms, and the light duration could be shortened or lengthened in order to transmit various data. The duration of such a pulse can thus mean information either for units connected to the signaling unit or for the monitoring personnel.

How the switch S 1 of the central unit 26 can be controlled for transferring data to the reporting units 25 will be explained below with reference to FIGS. 15A to 15F. In Fig. 15A, a group of four forming Adressierimpulse are shown again. The first addressing pulse becomes high at time t ₀ and remains so beyond time t ₁ . The latter corresponds to the minimum switch closing time which is required to make the output "1" of the integrated circuit IC 1 high. Accordingly, the rising edge of a pulse 345 is obtained at this output at time t ₁ . This remains high until time t ₂ , at which the switch S 1 in the central unit is opened again. The pulse 345 has a length of approximately 12 ms and can be a command to perform a specific function or a pulse-width-coded representation of an analog signal.

At time t ₂ , the switch S 1 opens, whereupon the output "8" of the output driver stage 135 goes high. The reporting unit now tries to report data back to the central unit. However, since the switch S 1 is closed again after only 4 ms at the time t ₃ , the output “8” becomes low again at this time, and the intended data transmission of the signaling unit is ended. The second addressing pulse begins at the time t ₃ .

The second addressing pulse remains high above the point in time t ₄ , which represents the minimum switch-on time of the switch S 1 , which is necessary for switching on the output "2" and thus for transmitting a function command to the signaling unit. As a result, the rising edge of a pulse 346 is obtained at time t ₄ , as shown in FIG. 15D. The pulse 346 remains high until time t ₅ , at which the switch S 1 of the central unit opens again. When pulse 346 ends, output "8" of output driver stage 135 again goes high, and the reporting unit tries to report further data to the central unit. However, this search is ended at time t ₆ when the switch S 1 is closed again. Pulse 346 thus represents a 32 ms data pulse that is transmitted to the addressed signaling unit.

The third addressing pulse remains high beyond time t ₇ , so that the output "3" of the output driver stage 135 is switched on and a pulse 347 is provided, as shown in FIG. 15E. The pulse 347 ends after 8 ms at the time t ₈ , at which the switch S 1 is opened again. Subsequently, the reporting unit tries to report data back to the central unit between the time t ₈ and t ₉ , the amplitude of the residual signal on the conductors 27 and 28 now being somewhat larger than that of the previous residual signals, since no sensor is connected to the reporting unit which would provide an analog signal to be reported.

At time t ₃ , the fourth addressing pulse is initiated. The switch S 1 is kept closed beyond time t ₁₀ so that the output "4" of the output driver stage 135 is pulled up and a pulse 348 is obtained as shown in Fig. 15F. The output "4" remains hochpe until the time t ₁₁ , at which the switch S 1 of the central unit is opened. This ends pulse 348 after a data transmission time of 40 ms. At the point in time t ₁₁ , the output “8” also becomes high, so that the signaling unit sends a pulse 350 back to the central unit, which is ended at the point in time t ₁₂ . Since the switch S 1 is still closed at this point in time, one receives at the point in time t ₁₂ a signal increase on the conductors 27, 28 which is determined by the evaluation circuit of the central unit in the manner described in more detail above with regard to its relative position at the point in time t ₁₁ is evaluated and serves the feedback of data. At time t ₁₃ , the switch S 1 is closed again, whereby the first addressing pulse of the next group of four is initiated.

Fig. 16 shows in the left part of the distribution of the pending signal 207 on various circuits, the signals to trigger an alarm, to indicate faults, to request maintenance work and to compensate for the aging of the calibration voltage sources and the sensors. To the line 207 , a sixteenth divider stage 260 is initially ruled out. If - as explained above - the number "128" is assigned to a voltage of 8 V, the number signal provided on a line 261 of the divider stage 260 obviously corresponds exactly to the voltage 8 V, that is to say the output signal of the signaling unit. If there is an alarm signal of size "67" on line 207 , the number 4.2 is obtained at the output of divider stage 260 , which corresponds to an output voltage of 4.2 V of the alarm unit. If, for example, a Zener diode is used to generate a calibration voltage of 4.0 V in the signaling unit, a signal of the size "64" is obtained on line 207 , which after division in division stage 260 results in a calibration voltage of 4.0 V on line 261 results. Another sixteenth divider stage 262 is connected via a line 263 to the switching bridge of the multi-position switch 233 , on which the measurement signal setpoint is provided. For the sake of explanation, let us assume that the multi-position switch 233 is in its middle position, in which the measurement signal setpoint is predetermined by the number "75". This measurement signal setpoint is given via line 263 to divider stage 262 , and the number 4.7 is then obtained on a line 264 connected to this, which corresponds to a voltage of 4.7 V. This number is given to the one input of a subtractor 265 . Its second input is connected to line 261 via a line 266 and thus receives the output signal of the first divider stage 260 , which corresponds to a voltage of 4.2 V under the special conditions specified above. The number "0.5", corresponding to a voltage of 0.5 V, is thus obtained on a line 267 connected to the output of the subtracting circuit 265. This difference is a measure of the sensor sensitivity, since it indicates how far the sensor is from the measurement signal Setpoint, i.e. the alarm threshold, is removed. If the voltage at the output of the subtracting circuit 265 increases by a further 0.5 V, the measurement signal actual value reaches the measurement signal setpoint and the alarm signal is provided on the output line 232 . By monitoring the long-term changes in the signal on line 267 that characterizes the sensitivity of the sensor, one can see in the log of the central unit changes 09726 00070 552 001000280000000200012000285910961500040 0002003249787 00004 09607gen that are caused by aging of components, dust and similar errors. The sensitivity value provided on line 267 represents important measurement information that is accessible at the central unit.

To line 207, another subtractor 270 is connected, which also receives the subject on the line 207 via a line signaling signal 271st A memory 272 is also connected to the line 207 via a line 273 . When the monitoring system is installed for the first time, an initial calibration signal runs from the individual sensors back to the central unit via the transponders assigned to them. This initial calibration signal is stored in the memory 272 and forms a fixed point for later measurements. After that, the "Sunday morning query", a measurement that takes place at a quiet time when the rooms are low, e.g. B. is carried out on Sunday morning at 2 o'clock, passed a calibration signal via lines 207 and 271 to subtractor 270 . The subtracting circuit 270 receives at its second input via a line 274 also the initial calibration signal stored in the memory 272 and generates on a line 272 connected to its output a calibration signal compensation signal which is a measure of the long-term changes in the circuit electrical lines and other variables that affect the generation and transmission of the calibration voltage. The calibration signal compensation signal on line 275 and / or the sensor compensation signal on line 308 mentioned below can thus serve to change (amplify or attenuate) the measurement signal provided by a signaling unit. In this way, the normal sensitivity of the operation of the monitoring system is maintained.

A comparator 400 is also connected via a line 401 to the output of the subtracting circuit 270 and thus also receives the calibration signal compensation signal. The comparison element 400 receives a reference signal via a second line 402 , and if the calibration signal compensation signal exceeds the latter, a maintenance request signal is provided on a line 403 connected to the output of the comparison element 400 . Which of the signaling units is to be maintained can be seen from the signaling unit identification signal which is transmitted via line 207 and line 280 to a number of comparison elements 281-288 , only the first and last of which are shown. As stated above, each of the reporting units contains an address switch bank 66 and a sensor identification switch bank 74 (see FIGS. 6 and 7). The setting of the individual switches of the sensor identification switch bank 74 is converted in the 8-channel multiplexer 126 into a switch identification signal which is emitted via the line 127 to the central unit. The sensor identification signal on line 280 of FIG. 16 can thus represent one of eight different values, the respective present of these values being determined by considering the output signals of the comparators 281-288 . For example, a sensor identification signal of the value "type 1" can be assigned to a smoke alarm device designed as an ion probe, and when this signal reaches the decoding unit formed by comparators 281-288 via line 280 , one on an output-side line 292 shows received signal that the signaling unit currently working together with the central unit comprises a "Type 1" sensor. In this way, the signals generated by the various settings of the switches of the sensor identification switch bank 74 are decoded, so that one can recognize the particular reporting unit and the type of sensor that is currently reporting its data back to the central unit via the assigned transponder on the central unit.

The term "Sunday morning query" is meant to express bring that a serial interrogation of the transponder different reporting units and storage of the from there reported data with a polling frequency takes place, which is significantly lower than the normal Ab question frequency. This "Sunday morning query" is preferred wise made when the rooms to be monitored are practically not occupied and are therefore calm. To this At times the conditions in the have to be monitored the areas stabilized, and through a sample at these times, reference values can be obtained. So you can, for example, the measured output voltage of a sensor with the original one Compare the output voltage of this sensor and so change conditions in this signal.

In the lower part of FIG. 16, three further circuits are shown, which are used only for the rarely carried out "Sunday morning query". The first measurement signal received by the sensor under consideration in the first Sunday morning query after the monitoring system is switched on is passed via line 303 to a memory 300 in which this signal is permanently stored. This signal is then no longer changed. With each subsequent weekly union Sunday morning query, the measurement signal obtained via the line 207 via a further line 304 passes to a subtractor three hundred and first There the output measurement signal of the sensor, which is retrieved from the memory 300 , is subtracted from the newly determined measurement signal of the sensor, and the result, the sensor compensation signal, is provided on the line 308 connected to the output of the subtraction circuit 305 , which is described above was briefly addressed. A comparator 302 also receives the output signal of the subtracting circuit 301 via line 305 . The comparator 302 determines whether the output signal of the subtractor circuit 301 and thus the magnitude of the change in the measurement signal provided by the sensor is greater than a predetermined reference variable which is on a further input line 306 of the comparator 302 . If the change in the measurement signal is greater than this reference value, a signal is provided on a line 307 which indicates that maintenance is required. This signal can be used to control an optical display, for. B. to switch on a control lamp in a control panel. You can also operate an acoustic warning device or a mechanically operated visual warning device by the signal on line 307 . This draws attention to the need for maintenance before a malfunction or incorrect signal processing occurs.

Remote calibration of all signaling units can be carried out in such a way that the five switches of the address switch bank 66 of the signaling unit under consideration are set so that they correspond to the address "31". The central unit then checks the calibration voltage reported back by this reporting unit, and if this lies within acceptable limits, this is indicated by switching on the signal lamp 81 on this reporting unit. Other processes perceivable on the reporting unit, e.g. B. switching the impulse relay 75 can serve to indicate that the calibration voltage is in an acceptable range. If the calibration signal reported back from the signaling unit to the central unit is not within the predetermined limit values, the potentiometer 105 shown in FIGS . 7 and 8 is adjusted at the signaling unit until the calibration voltage is within the predetermined limits, which is due to lighting up the signal lamp 81 is reported. After setting the correct calibration voltage, the switches of the address switch bank 66 are then returned to their original position, in which they specify the address of the signaling unit under consideration.

From the functional description given above it can be seen that the setting in the monitoring system described Sensitivity far from the central unit neter reporting units continuously and under automatic control tion can perform, for. B. by a to a specific Time of day or a specific day of the week program. The sensitivity setting can also can be controlled manually via a keypad. One can also the different reporting units on the same or set different measurement signal setpoints, whereby these measurement signal setpoints for some or all of the sensors can be changed at any time.

Claims (9)

1. Monitoring system with a central unit and a plurality of addressable signaling units connected to this via a signal rail, each of which has a sensor measuring a parameter to be monitored, in which case

• a) the central unit has an addressing circuit for generating addressing signals in predetermined monitoring cycles and an evaluation circuit which is acted upon by the measuring signals generated by the signaling units, the latter containing a measuring signal setpoint value memory,
• b) the signaling units each have: an activation circuit which compares an addressing signal assigned to the respective signaling unit and the addressing signals received via the signal rail and generates an activation signal if there is a match, and an output circuit which can be switched on by the latter, the output side with the signal rail and the input side connected to the sensor,

characterized in that

• c) new measurement signal setpoints are read into the measurement signal setpoint memory in predefined, large calibration cycles compared to the monitoring cycles using the actual measurement signals then present.

2. Monitoring system with a central unit and a plurality of addressable signaling units connected to it via a signal rail, each of which has a sensor measuring a parameter to be monitored, in which

• a) the central unit has an addressing circuit for generating addressing signals in predetermined monitoring cycles and an evaluation circuit acted upon by the measuring signals generated by the signaling units, the latter containing a measuring signal reference value memory,
• b) the signaling units each have: an activation circuit which compares an addressing signal assigned to the respective signaling unit and the addressing signals received via the signal rail and generates an activation signal if there is a match, and an output circuit which can be switched on by the latter, the output side with the signal rail and the input side connected to the sensor,

characterized in that

• c) the sensors are adjustable sensors in their sensitivity,
• d) the sensitivity setting in fixed, compared to the monitoring cycles large calibration cycles, and
• e) the central unit ( 26 ) emits an acknowledgment signal to the signaling unit ( 25 ) when the measurement signal then received from the latter lies within predetermined limit values.

3. Monitoring system according to claim 2, characterized in that the central unit ( 26 ) comprises a device ( 233 ) with which the setpoint signal can be set under program control. 4. Monitoring system according to claim 2 or 3, characterized in that the signaling unit ( 25 ) has a display device ( 81 ) controlled by the acknowledgment signal. 5. Monitoring system with a central unit and a plurality of addressable signaling units connected to this via a signal rail, each of which has a sensor measuring a parameter to be monitored, in which case

• a) the central unit has an addressing circuit for generating addressing signals in predetermined monitoring cycles and an evaluation circuit which is acted upon by the measuring signals generated by the signaling units, the latter containing a measuring signal setpoint value memory,
• b) the signaling units each have: an activation circuit which compares an addressing signal assigned to the respective signaling unit and the addressing signals received via the signal rail and generates an activation signal if there is a match, and an output circuit which can be switched on by the latter, the output side with the signal rail and the input side connected to the sensor,

characterized in that

• c) a memory ( 272 or 300 ) reads in the measurement signal in fixed, compared with the monitoring cycles large calibration cycles,
• d) a subtraction circuit ( 270 or 301 ) forms the difference between the stored measurement signal and the current measurement signal, and
• e) the output signal of the subtracting circuit ( 270 or 301 ) is used to amplify or weaken the measurement signal.

6. Monitoring system according to claim 5, characterized in that a comparator ( 302 or 400 ) with the subtracting circuit ( 270 or 301 ) is connected and generates a maintenance request signal when the output signal of the subtracting circuit ( 270 or 301 ) is larger as a target level.