CH660926A5 - MONITORING SYSTEM. - Google Patents

Description

The present invention is intended to develop a monitoring system as defined in the preamble of claim 1 in such a way that the addressing time is shortened, but nevertheless each of the reporting units can be addressed in a targeted manner.

According to the invention, this object is achieved by a monitoring system according to patent claim 1.

With the monitoring system, the addressing signals and the signaling signals are nested in time. The signaling units are all acted upon by the pulses continuously generated by the addressing circuit, the address of a selected signaling unit under consideration resulting from the number of the total number of pulses sent. Thus, a single pulse additionally given by the addressing circuit to the signal rail can effect the switching from one signaling unit to the next signaling unit; it is not necessary to put a complete address on the signal rail. By temporally stretching a pulse or a pulse gap, a measuring time is obtained within which the respectively addressed signaling unit modulates the signal level on the signal rail during the measuring time in accordance with the signal to be transmitted. With this transmission of the signal signals, there is therefore no retroactive effect on the addressing of the signaling units, because the amplitude shift in the signal signal via660926

averaging is small compared to the amplitude swing when addressing.

This temporal nesting of addressing signals and signaling signals results in a very short addressing time overall with the individual signaling units still freely addressable in any order.

According to the same principle (interleaving of addressing signals with a large amplitude swing and signals with a small amplitude swing), the central unit can also issue commands to the individual transponders, which trigger predetermined functional sequences in them, for example testing a sensor. Such sensors can be, for example, ion probes, photoelectric measuring devices, alarm-triggering switches, etc.

In the monitoring system, if one of the signaling units is working incorrectly, the work of the other transponders remains unaffected.

With the development according to claim 2, it is possible to transmit different messages from one transponder to the central unit with the same amplitude deviation of the message signals.

With the development according to claim 3 it is achieved that the individual transponders need not have their own power supply.

In a monitoring system according to claim 4, on the one hand, if the controllable switch of the transponder is working incorrectly, appropriate feedback can be received from the central unit; on the other hand, the message signals of the other connected transponders can still be evaluated in this case. The central unit can thus "read over" a short circuit in one of the transponders.

The development of the system according to claim 6 is advantageous with regard to a fine resolution of the phase position of the signal edges in the signal signals. On the one hand, this increases occupational safety and, on the other hand, opens up the transmission of a larger number of different measurement signals with a short measurement time overall.

The development of the system according to claim 8 is advantageous with regard to the adjustment of the individual transponders, which in practice can be far from the central unit. The sensitivity can be set entirely at the location of the signaling unit.

With the development of the system according to claim 9, long-term changes in the transponders can be automatically taken into account.

The development of the system according to claim 10 is advantageous with regard to the detection of incorrect operation of a transponder.

In the case of a system according to claim 12, an active function of a transponder can be requested by stretching an addressing pulse, without any retroactive effect on the addressing of the signaling units.

A monitoring system, for example, is explained in more detail below with reference to the drawing. In this show:

Figure 1 is a block diagram of a monitoring system with several individually addressable active transponders.

2 shows the circuit diagram of part of the central unit of the monitoring system according to FIG. 1 and of a transponder;

3 and 4 show the time course of signals on the signal rail of the monitoring system according to FIG. 1;

5A, 5B and 5C show enlarged sections from FIGS. 3 and 4;

6 shows a more detailed block diagram of an active transponder;

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7 shows the circuit diagram of a practical exemplary embodiment for an active transponder;

8 shows the block diagram of an integrated circuit of the active transponder according to FIG. 7;

9, 10 and 11 are graphical representations which are used to explain the evaluation of the message signals transmitted from the transponders to the central unit;

12 shows the circuit diagram of an alarm signal evaluation circuit of the central unit; and

13 to 15 are graphical representations, on the basis of which the information exchange between message units and central unit is explained.

In the monitoring system shown in FIG. 1, a plurality of active transponders 25 are connected to a central unit 26 via a signal rail which has two conductors 27, 28. Such transponders (transmitters / responders) can be addressed by the central unit 26 in any order and recognize not only their address but also other data provided by the central unit on the signal rail, e.g. Commands for self-control of the transponders or the control of various devices assigned to the transponders. In addition, the transponders transmit data, e.g. Sensor signals and a response identification signal back to the central unit. The transponder 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 that branch off from the conductors 27, 28 do not have a line termination. It can be seen that such branch lines can be provided regardless of the spatial arrangement of the transponders or the order in which they are addressed.

FIG. 2 shows the essential part of the central unit 26 connected to the conductors 27, 28 and an active transponder 25. The central unit 26 operates with a direct voltage V, which is present between conductors 35 and 36. The conductor 35 is connected via a resistor Ri 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 Si is placed in parallel with the resistor Ri. The conductors 37 and 36 are connected by a resistor R2, which together with the parallel connection of the resistor Ri and the switch Si forms a voltage divider. A measuring line 41 is connected to its center tap.

The transponder 25 contains a resistor R3, which is connected to the conductor 27. Its second terminal is connected to the conductor 28 via a further switch S2. In the exemplary embodiment considered here, the resistors Ri, R2 and R3 have the same value. A command circuit 42 controls the opening and closing of the switch Si. Similarly, the transponder 25 contains circuits, not shown in FIG. 2, for controlling the switch S2.

The information is transmitted between the transponders and the central unit by opening and closing the switches Si and S2. When the switch Si is closed, the conductor 27 is pulled up to the full supply voltage V, and the corresponding pulse reaches all transponders 25 via the conductors 27, 28. Both the closing time of the switch Si and the number of opening and closing cycles this switch is monitored in the individual reporting units, as will be described in more detail below.

If the resistors Ri, R2 and R3 have the same value and if the switches Si and S2 of FIG. 2 are both open, the voltage on the measuring line 41 is equal to half the supply voltage V. Conversely, if the voltage V / is on the measuring line 41 2, the switch Si is open. During this open time of the switch Si, the signal is transmitted from the transponder 25 to the central unit 26. For this purpose, the switch S2 is closed while the switch Si remains open. Then the resistor R3 is parallel to the resistor R2, this parallel connection being in series with the resistor Ri. 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 S2 can easily be determined.

The closing time of the switch S2 with the switch S1 open at the same time serves 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 is intended to bring other information from the transponder 25 to the central unit 26. By measuring the duration of the closing time of the switch S2, the data represented by the original message signal can be recovered. Certain commands can also be transmitted from the central unit 26 to the transponder 25 via the closing time of the switch S1, as will be described in more detail later.

The central unit 26 retrieves the information desired by the transponder 25 from the message signals by monitoring the closing of the switch S2, that is to say checking when a voltage of the magnitude V / 3 is present on the measuring line 41. The central unit 26 can determine whether only one signaling unit or a plurality of signaling units simultaneously provide signaling signals on the conductors 27, 28 which are generated by closing their switches S2 in a phase-controlled manner. 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 voltage divider, generally designated 44, with four resistors 45, 46, 47, 48, which is connected between the conductors 35, 36. A comparator stage, denoted overall by 50, contains three differential amplifiers 51, 52 and 53, each of which is connected to the measuring line 41 with one input, 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 S2. 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 at the same time, their switches S2 closing simultaneously and thus a corresponding number of resistors R3 being connected in parallel with the resistor R2. If one compares the signals on the conductors 54 and 55 at any time, and then there is a signal on the conductor 54, while no signal is received on the conductor 55, this indicates that exactly one transponder 25 is a signaling signal via the Leaves 27.28 to the central unit 26. A further differential amplifier 53 then outputs a signal to the command circuit 42 on a conductor 56 if 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

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Conductor 55 before, but the command circuit 42 is not switched off by a signal on the conductor 56, this indicates that two transponders 25 simultaneously transmit signal signals to the central unit 26.

In the exemplary embodiment according to FIG. 2, it is assumed that an evaluation circuit connected to the reproduced part of the central unit can simultaneously evaluate the level changes caused by two signaling units responding simultaneously on the conductors 27, 28, while such an evaluation cannot be carried out with three or more signaling units reporting simultaneously can be done.

Therefore, the conductors 54 and 55 are connected to this evaluation circuit, while the conductor 56 is connected to the command circuit 42. If the comparator stage 50 is generally constructed from n differential amplifiers, the outputs of the first n-1 differential amplifiers are correspondingly connected to the evaluation circuit, while the output of the nth differential amplifier is connected to the latter in order to switch off the command circuit 42.

FIG. 3 schematically shows the time course of the signal level on the conductors 27, 28 at the transition point between two polling cycles. In the exemplary embodiment considered here, a group of four pulses is used to switch from one signaling unit to the next signaling unit, but a different number of pulses can also be used to switch to the next signaling unit. An extended high-level pulse, which is shown in the drawing as address 31 and also extends beyond the first part of address O, serves to reset or initialize the various signaling units and, at the same time, to charge a charge storage device in the signaling units, which supplies them with energy serve. Each signaling unit contains a counter for adding up the total number of pulse groups delivered by the central unit, and the addressing and activation of the individual signaling units takes place according to this number. The high-level pulses from FIG. 3 following the stretched high-level pulse mentioned above are all of short duration, which means that the central unit does not provide a command on the conductors 27, 28, but rather only successive address signals which are predetermined by the number of pulse groups, issues.

FIG. 4 shows the manner in which a pulse group emitted by the central unit is modified in order to transmit a command to a specific one of the signaling units. Should e.g. If a command is sent to the 17th reporting unit, the high-level part of the second pulse of the associated pulse group is greatly expanded, e.g. 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 to and ti in FIG. 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 the function to be carried out for the signaling unit is also known from this. It is assumed that by extending the second pulse of a group, a command is coded which is used to switch on a light-emitting diode or a similar optical display unit. As soon as the high-level part of this pulse extends beyond time ti, the light-emitting diode is thus switched on and up to time t2. The signaling unit can execute various commands since different high-level pulses of a group can be stretched to different widths. The central unit 26 closes the switch S1 accordingly for this command transmission. So you get e.g. the stretched high-level pulse between the times to and ts mentioned above. After the waiting time ti has elapsed, 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 voltage switched on in this way is thus supplied from the central unit via the conductors 27 and 28; the energy supply for this consumer need not be carried out by the transponder. This will be explained later. In the same way, the transponder 25 outputs data to the central unit 26 by closing its switch S2 and generates a signal with the amplitude V / 3 by prolonged closing of the switch S2 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 the transponder to the central unit takes place when the switch S1 of the transponder is open by closing and opening the switch S2 of the transponder in accordance with the information to be transmitted. Each time the switch S2 is closed, the voltage on the measuring line 41 of the central unit assumes the level V / 3. The length of the period 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 S1) and on the transponder (closing time of switch S2). The closing time of switch S2 in turn depends on the output signal of a sensor assigned to the transponder (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 S2 of the transponder 25 will be described in more detail later.

FIG. 5a shows one of the pulse groups shown in FIG. 3 under the headings “Notification unit 1” and “Notification unit 2”, the scale being enlarged compared to FIG. FIG. 5A shows four pulses, with residual signals of low amplitude lying between the successive pulses, which are designated by 141, 142, 143 and 144. The fourth low-level residual signal 144 lies in a measuring period 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 increase 150 in the “good” time window 147, which indicates that the component in question (assigned or internal component of the reporting unit) is working properly, which generates the reporting signal for the central unit within the measuring period 145.

If, on the other hand, the signal transition 150 was in the first time window 146 of the measurement period, this could represent an indication of a fault in the sensor in question, while a position of the signal rise 150 in the last time window 148 can be used to code an alarm state. It goes without saying that the assignment of different time windows of a measurement period to certain states of the transponder can be selected differently for different sensors. Is e.g. If a temperature sensor is provided as a sensor, a signal transition in the time window 146 can be associated with a low temperature, a signal transition in the time window 147 with a medium or normal temperature and a signal transition in the time window 148 with a high temperature. 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, described above, results in a considerable improvement in the

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Noise behavior and measurement accuracy. (4.0 V) from the target voltage for this special sensor The measurement period 145 is deviated by stretching the open time in order to determine the switching state of the sensor, the switch S1, as well as from the amplitude value. This actual voltage of the residual signal emitted by the sensor can also be obtained 144 recognizable. Of course, each of the low-level residual signals 144, 142 or 143 of the same sensor could also be compared with a previously output, recorded voltage. If the lengthened previously in order to transmit information from the signaling unit to the measured voltage level for a long time (about a week or the central unit. In this case, more would be obtained), the comparison can then be used to display what was transmitted within the other measuring periods slow changes in the operation of the TransData of a different nature. In the embodiment ponder considered here, which is due to aging of the construction example, e.g. It is intended that the transponder may become part of the extension or dust may accumulate.

5A, only the use of three time windows of calibration data based on a reference voltage is discussed in order to simplify the explanation. One transmitted to the central unit. When the more precise evaluation of the position of the signal rise 150 is expanded, the second low-level residual signal 142 is transmitted, which later describes the transponder data for identifying the sensor or is described in greater detail with reference to FIG. 12.

5B shows the same signal transmission from one to the central unit. An extension of the low-level transponders to the central unit, as the residual voltages 143 or 144 in FIG. 5A permit repeated signaling, is given with the only exception that at the same time the data is to be transferred to the central unit which switch S2 does not addressed transponders are derived in short from an analog sensor output signal. 20 closing position has failed. Since there is always another one in FIG. 5A, it is assumed that only one resistor R3 of a signaling unit is extended in parallel via the negative low-level residual signal, namely the stand R2, the low-level residual signals are residual signal 144 thus analogously also reduced in size several times. Thus, the residual signal 141 is a twofold residual signal to create corresponding measurement times - see the line 431 lying between V / 3 and V / 4 and spaces are expanded. Conversely, if no data is to be received from a line 432 lying between V / 4 and V / 5. The same as a transponder under consideration is transmitted to the central unit for the residual signal 142. The residual signal 143 and also that are provided, none of the central units Residual signal 144 only have the level V / 3. Stretched regardless of low-level residual signals. Thus, zero, of the short circuit in the unaddressed transponder one, two, three or four of the low-level residual signals in FIG. 5, the information is correctly extended from the transponder to the pulse group shown in FIG. 5A, since the information is at a distance the four successive pulses when considering the signal rise 150 from the beginning of the measurement period 145 together for the relaying. 5C illustrates the conditions at the same time that one of the signaling units that has just been activated is used for the transmission of signaling signals from two transponders to the next transponders to be activated. The switch S of the additional feedback signal is due to the fact that the first two low-level residual transponders are not short-circuited. In this signal 141, 142 too, fall below line 430 of FIG. 5A, but if the first two low-level residual signals do not reach line 431 there, the zen can have the value V / 4, since the switches S2 of the two transponders now match the voltage level Close on the measuring line 41 simultaneously. Neither of the two switches S2 is taken to mean that at these times switch S2, which was closed during the third low-level residual signal 143 transponder, was closed. By closing this switch 40 it is concluded, from which the central unit can conclude that the voltage level V / 3 and the second transponder is not directed to the measuring line 41, which is short-circuited which contains within lines 430 and switches S2, rather both transponders is 431 limited amplitude range at the same time. Deliver data for that. The switch S2 was open within the measurement period 145 obtained by stretching the low-level time at which the third low-level residual signal 144 residual signal 144 was present. A level V / 2 at 45 a low-level signal 160 of size V / 4. Measuring line 141 shows that, at the point in time under consideration, this is followed by a first signal rise 161 and a signal V / 3 of low magnitude, neither in the currently addressed nor in any other trans. Then the switch S2 is closed. This is followed by a second signal rise 163 and a low level signal to the transponder, a linear signal 164 of size V / 2 designed as an ion probe. If the signal increases 161 smoke detectors are connected, the stretched down and 163 both in the "good" time window 147, the central level residual signal 144 knows, which pre-unites the measurement period 145, that there is no alarm state. If one of the following is used for data transmission: If there are signal increases in the alarm time window 148, it knows that the entire measurement period has a duration of 32 ms for the central unit that a transponder is at the alarm level, and this total Period of time, however, the alarm-giving transponder should not be assigned the same amplitude range from 0 to 8 volts. 55. The period designated 165 in FIG. 5C is a. Thus, every millisecond of the measurement period represents a measure of the lower of the voltage value of 0.25 V that is returned by the transponders. In this embodiment, the analog voltages reported, the time cycle shown there extends that first time window over 12 ms and provides space 166 for the higher of these analog voltages.

represents a voltage of 3 V. The second time window 147 has FIG. 6 shows details of a transponder. The conductor has a duration of 8 ms and represents a voltage of 60 27.28 of the signal rail, a signal / network switch 60 is attached-2 V. The third time window closed again with a duration of 12 ms. This transfers a DC supply voltage and is assigned to a voltage of 3 V. If, therefore, one line 61 to the individual components of the actual signal rise 150 occurs at the point shown in FIG. 5 A, then the transponder and via a line 62 on the transponder, the transponder notifies the central unit that the associated component is passing on. It goes without saying that the sensor associated with the suffering transponder (as an ion probe device 61 can consist of several conductors, for example a smoke detector) a signal with a level of 4.0 V ground conductor, a conductor of 5 V against ground, a is present. The central unit then uses this conductor to determine 12 V relative to ground, etc. The voltage values from the conductors, how far the current actual voltage 27, 28 are present are determined by the signal / network

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switch 60 forwarded 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 transponder. The comparator of the activation circuit 64 then generates, on a line 67, an activation signal for the input / output circuit 68 and the output command control circuit 65 when the total number of groups of large amplitude pulses obtained via the busbar 63 matches the address set by the switch bank 66.

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 command Establish the required circuit connections. A first analog signal “A” is present on the input / output circuit 68 via a line 70, which is O V in the exemplary embodiment considered here. The input / output circuit 68 receives a second analog signal from a sensor 72 via a line 71. 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 on the busbar 63 a correspondingly coded signal, which is sent via the signal / network switch 60 to the conductors 27, 28 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 of the transponder. The setting of the switches can e.g. characterize the type of sensor 72 assigned to the transponder (ion probe smoke detector, photoelectric smoke detector, air speed sensor, temperature sensor, mechanical switch of a manually operated train detector, short-time switch for blowing off halon). A current surge relay 75 is controlled by the command output control circuit 65 via a line 76, the contacts 77 of which are switched from the position shown in FIG. 6 to the second position (erase position) when the signal is applied. 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 can have a signal lamp 81, e.g. a light emitting diode.

FIG. 7 shows the circuit diagram of a practical exemplary embodiment of a transponder 25. Two screw terminals 83, 84 connect the conductors 27, 28 to conductors 85, 86 of the transponder. An overvoltage protection 87 is connected between the conductors 85, 86 and protects the components of the transponder against transients from the network. A diode 88 is connected between the conductor 85 and a main supply conductor 90 of the transponder. 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 cathode 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 (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 connected between the collector and the base of transistor 92, the base also being connected to conductor 86 via a zener diode 95. A resistor 96 is connected to the main supply conductor 90 and connects via a conductor 99 to a terminal «10» of an integrated circuit ICI. The numbered terminals of this integrated circuit are 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 ICI. 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 receive a low-level pulse at its terminal «17», the level on the conductor must be

27 be low (go to V / 2) for at least half a second before this pulse is recognized as a clock signal for the ICI integrated circuit. The level on a conductor 110 connected to the output of the low-pass filter is compared in the integrated circuit ICI with the level on conductor 99, that is to say with the line voltage supplied via the conductors 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, that is to say a change in the mains voltage by a factor of 2.

The address switch bank 66 and the sensor identification switch bank 74, which are combined to form a single switch bank, provide further input signals for the integrated circuit ICI. Their switches «1» to «5» represent the address switch bank, while 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 surge 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 this relay is energized, creating a break contact group

104 this relay is closed. A line 79 is connected to the terminal “8” of the integrated circuit IC 1, via which a NPN transistor 100 is driven. If the latter controls it, a resistor 89, which has 4.7 kOhm in the exemplary embodiment under consideration, is connected between the conductors 85 and 86, as a result of which the amplitude of the voltage present on the conductors 27, 28 and thus on the central unit 26 is reduced. It can be seen that the transistor 100 corresponds in function to the switch S2 in FIG. 2, its opening and closing taking place as a function of the control signals on the line 79. It can also be seen that the resistor 89 shown in FIG. 7 corresponds to the resistor R3 explained with reference to FIG. 2 in terms of its mode of operation.

A command to turn on transistor 100 is only generated on line 79 if on conductors 27,

28 is a low level residual signal. The other tax

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Signals for switching on or switching off the surge relay 75 or for switching on the signal lamp 81 are only generated when the signal on the conductors 27, 28 is high-level. The signaling unit can thus obtain energy for operating these consumers via the conductors 27, 28 without having to resort to the energy stored in the capacitor 91, which energy is used to operate the components of the signaling unit that perform logic functions. A potentiometer 105, a fixed resistor 106 and capacitors 107 and 108 are also connected to the integrated circuit ICI, as can be seen in the drawing.

FIG. 8 shows a block diagram of the integrated circuit ICI, the square-framed terminal numbers corresponding to the terminal numbers shown in FIG. 7. The addressing pulses of the central unit, which are transmitted to a signaling unit, reach the terminal “17” of the integrated circuit ICI via a conductor 110 and from there to a clock pulse generator 111. A second input of the latter is connected to the conductor 99. The clock pulse generator 111 contains a pulse shaping circuit, e.g. a differential amplifier that compares the voltage levels on conductors 110 and 99. The output signal of the clock pulse generator III is applied to a 2-bit counter 112 and to a clock signal identification circuit 113. A clock reference signal is applied to the latter via a resistor 106, a capacitor 108 and the supply conductor 93. A 5-bit counter 114 receives the overflow pulses of the 2-bit counter 112 via a conductor 115.If an incoming addressing pulse remains high for a predetermined period of time (20 ms in the exemplary embodiment), a stretched clock identification pulse arrives at one via a conductor 117 2/4 line decoder 118. If the incoming address pulse remains high for a very long time (80 ms in the exemplary embodiment under consideration), the clock signal identification circuit 113 generates a reset pulse for the two counters 112 and 116 on a conductor 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 goes to the 2/4 line decoder 118, an analog 4-channel multiplexer 122 and a switching control circuit 123. The latter represents an external memory for the switching cycles of two request cycles of the transponder if the external switch for a period of time is actuated, which is less than two request cycles. In the exemplary embodiment considered here, a request cycle takes

namely, the time period between two successive activation pulses, which are provided at the output of a comparator 131, 3 seconds. The storage period of the switching control circuit 123 is therefore 3 to 6 seconds, depending on the frequency with which 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 switch 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 ICI are connected. These terminals are connected to the sensor identification switch bank 74. If the switch bank 74 is set such 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 terminals «18», «19» and «20» lead to switching on the control circuit 123, i.e. 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 switch control circuit 123 receives the signal on the line 70 via the terminal “6” and the line 119, a signal for a special switching state being generated from this signal, which voltage reaches the multiplexer 122 via the line 129. In the other six settings of the switch bank connected to terminals "18", "19" and "20", switching control circuit 123 ensures direct connection between 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 produce 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 fed to an analog 8-channel multiplexer 126 via a data rail 125, which comprises several conductors. 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. The multiplexer 122 also has the output signal of the sensor 72 via the line 71 and the analog signal “A” (see FIG. 6) via the line 70, the latter then running over the conductors 119 and 129 when the connection through the Switching control circuit 123 is closed. 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 lower right 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 bank 66. If the address specified by the latter matches 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 the output signal of the clock pulse generator 111 transmitted via a conductor 139 is high, 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 assigned amplifier of an output driver stage 135 and is output from the integrated circuit ICI via terminal «8». This results in the transistor 100 shown in FIG. 7 being turned on, which is equivalent to closing the switch S2 shown in FIG. 2.

To another of the output terminals 136 («1», «2», «3»

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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 on 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 signal lamp 81 should be switched on. If terminal «3» is selected, current surge relay 75 is set, and if terminal «4» is selected, current surge relay 75 is deleted. The evaluation of the message 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 signaling signal pulse returning to the central unit, which is comparable to the modulated low-level residual signal 144 from 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 denotes 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 measurement period of 32 ms can be assigned to a measurement 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 message signals 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.

10 shows the effect of line capacities on the shape of real impulses. A first falling edge 192 of the signal standing on the conductors 27, 28 does not fall vertically, but rather follows an essentially logarithmic curve. Likewise, the signal rise 184 is also not exactly rectangular, but rather a curved rising edge 193 is obtained. In order to be able to measure the distance between the signal edges 192 and 193 exactly, it is advantageous to have one in those areas of the time scale within which these edges occur Nonius reading with increased accuracy. A time scale 194 for the rough measurement with a division of 1 ms is entered in FIG. Within the vernier range designated 195, the time units are selected to be smaller, e.g. 1/2 or 1/4 ms.

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 switched on, which works for the first 2 ms of a signal signal pulse fed back to the central unit. The corresponding operating mode is marked with “3” in FIG. 11. After the falling signal edge 192 has been measured, the subsequent time measurement can be carried out with a coarser grid up to half of the measurement period

(16 ms) work. This operating mode is labeled «2». In the exemplary embodiment considered here, the alarm threshold lies in the subsequent time period of 4 ms, and therefore a switch is made to vernier measurement (operating mode “3”) for the time period between 60 and 20 ms. For the rest of the measurement period (20 to 32 ms)

the time measurement can then again take place in a coarse grid (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 operating modes “1”, “2” and “3” correspond to the switch positions of switches 204 and 205, which are described below with reference to FIG. 12.

12 shows in a simplified form the evaluation circuit of the central unit 26, which examines the low-level residual signals modulated by the transponders 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 V / 3 by closing its switch S2 (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 switches 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 reaches a frequency divider 210 via a line 208, which divides the frequency by a factor of 4. The output of the frequency divider 210 is connected via a line 212 to the contact “2” of the switch 204. 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 of the AND gate 203 reaches a coarse counter 220 via a line 218. Its output is connected via a line 221 to a multiplier circuit 222 which quadruples the counter reading. The output signal of the multiplier circuit 222 is fed via a line 223 to a second input of the adder 224. The output signal of the adder 224 is passed via a line 225 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 the adder 226 provided on the line 207 thus represents the length of time of the low-level signal section 180 with the level V / 3 in the message signal transmitted from the message unit to the central unit.

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The evaluated signal is passed to the fine counter 216 via the line 207, the AND gate 202. This on a line 230 and from there to a comparator 231, counting is via line 217 to adder 224

which then gives an alarm signal on an output line 232. These 8 pulses are made available to the one previously received if the evaluated signal is greater than the number “58”, so that those from the adder 224

a reference signal which is a total of 66 calculated from a multi-position s. From the time

Switch 233 is provided. The latter can be one of three of 18 ms lies on the line 54 and thus also on the

Provide reference signals «65», «75», «85», with line 201 no longer receiving a signal, so that none of the AND

Bridge of the multi-position switch 233 through a sensitivity circuit 202, 203 more counting pulses can be adjusted Lichkeits-control unit 234 is adjusted. The latter can over can. After 20 ms, the switches 204, 205 are again controlled into a line 235 by a program, in the coarse count position “2”, the AND gate 203

which is stored in the memory of a digital computer, can no longer forward pulses to the coarse counter or via a line 236 from a keypad 220. The signal on line 225 can be controlled. The sensitivity now characterizes the adder 226. With the aid of the numbers "65", "75" and "85" switching thresholds compensation stage 228 can now do that from the adder 224

on a scale that ranges from "0" to "128". provided gross result can be changed. If

The evaluated message on line 207, for example the last query of the signaling unit under consideration, is also connected to another via line 240, which revealed that a reference voltage due to aging of components

Comparator 241, which shares a line 242 or other long-term changes in the monitoring

Receives reference signal. The comparator 241 then generates a monitoring system which has risen from 4.0 V to 4.6 V, then a signal indicating a fault can be output on an output line 2 'from the raw result' 66 'on line 225.

243, if the evaluated signal on line 207 is subtracted the number "1", so that a compensated

less than or equal to the reference signal on the line based measured value «65», which is used for the alarm and

242 is. Fault control in comparators 231 and 241

For the description of the functioning of the surveillance is used. The evaluation circuit system shown in FIG. 12 is initially assumed that the central unit 26 25 has converted the analog signal signal on line 201 to an addressed transponder, converting data into a digital signal signal with very high accuracy,

to report back. Here, the command circuit 42 moves to which is provided on line 207. This itself

Start of the measurement period of the switch 200 in the figure when the fine count only for 2 ms when it arrives

12 position shown. Switches 204 and 205 are used to carry out a fine measurement on their contacts “3” 30 of the measurement period for a message signal and for 4 ms in the vicinity of the center.

closed. Under these conditions, the transponders connected to the central unit, generated by the clock generator 206, arrive via line 211 and can be remotely calibrated. This can be done so that the switch 205 and the line 214 to the one input of each transponder have the address switch bank 66 set to that of the AND gate 202. As well as the fourth low-level residual address “31” is set. The central unit then checks signal begins, lies on line 201 the calibration voltage from the differential 35, which returns from this transponder,

Amplifier 251 generates second input signal for the AND and the latter is within permissible limits, it shows

Links 202 and 202 in front, so that now counting pulses through this by lighting up the signal lamp 81 of the transponder

Line 215 to the fine counter 216. Reaches that. Other activities of the transponder, e.g. the falling signal edge 192 of Figure 10 level V / 3 after pulling the current surge relay 75 can indicate this

1.5 ms (6 counting steps on the vernier scale 195), then 40 serve that the calibration voltage is within permissible limits, the remaining two clock pulses of the fine counting lie. If, on the other hand, that which has been reported back to the central unit is likewise via the AND gate 202 to the fine counter 216. calibration signal is not within predetermined limits, then

This is because the command circuit 42 switches 204, 205 on the transponder the potentiometer shown in FIGS.

readjusted in position tiometer 105 during the first 2 ms of the measuring period until the correct calibration span

"3" keeps closed. After that, the bridges of the 45 voltage is set, which is indicated by the signal lamp lighting up

Set switches 204 and 205 to position «2», in which 81 can be recognized. After adjusting the calibration chip

a rough measurement takes place. Now receives the AND gate 202 voltage, the switches of the addressing switch bank 66th

no more clock pulses, while the AND gate 203 returns to its original position,

switch 204 with the output of frequency divider 210. Referring now to FIGS

connected is. The divided clock pulses thus reach the versatility of the monitoring described above.

clarified via line 213, the AND gate 203 and the line chungsanlage. The signal curves shown there

218 on the coarse counter 220. The latter now counts with one are not exactly to scale, roughly puts

Frequency from 1 kHz upwards. However, since the switches 204 and 205 each represent a distance of 2.5 cm on the abscissa, a period of 32 ms during the interval between 2 and 16 ms of the measuring time.

remain in position "2", a total of 14 ss are shown in Figure 13, a total of five pulses, of which

Pulses via line 218 to the coarse counter 220 four pulses belong to a pulse group, which is given. Its counter reading is multiplied by the number 4 by multiplying the addressing of a transponder and the feedback from circuit 222, so that you can control the data from this reporting unit to the central unit.

Line 223 receives a total of «56». The latter is these four pulses are those in FIGS. 5A to 5C

comparable in the adder 224 to the pulses previously received via line 217. In addition, a long

added output signal of the fine counter 216. stretched pulse shown, which corresponds to the addressing pulse «31»

16 ms after the start of the measurement period thus corresponds to that of FIG. 3. The low level residual signals from

Output signal of the adder 224 to the value "58", and the figure 13 are with the switch S1 open of the central unit

Switches 204, 205 are maintained by the command circuit 42 on the fine 26, while the high signal levels when closed.

Count position «3» reset. 6s senem switch S1 can be obtained. The rising and

If the signal rise 193 (see FIG. 10) takes place at 18 ms, falling pulse edges correspond to the closing or

then in the period between 16 and 18 ms 8 from opening switch S1.

Clock generator 206 generates pulses via switch 205 and in FIG. 13 the first rising pulse edge is obtained

at time to when switch S1 closes. As a result, the previously addressed transponder 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 transponder. The transponder 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 S1 remains closed for a predetermined minimum time (period between to and t2), 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 coded by stretching the second, third and fourth addressing pulse of FIG. 13 in time. Since the connection to the output "1" of the output driver stage 135 is not used at the time in question, the expansion of the first high-level addressing pulse beyond t2 has no further effect. At time t3, switch Fl is open, the signal on conductors 27, 28 becomes low again. In this way, the addressed transponder is commanded to end the signal at output “1” and to start transmitting the calibration data of this transponder. If the addressing pulse had already dropped at time ti, this would have meant that output "1" of the addressed transponder should not be switched on.

If the switch S1 of the central unit 26 remains open, after the time t3 the duration of the low-level residual signal between the times t3 and t4 (time axis interrupted!) Can be up to 32 ms because this is the duration of the measurement period selected in the exemplary embodiment under consideration. 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 need any feedback of calibration data of the addressed transponder, the switch S1 is closed again after only 1 or 2 ms, so that the time span between the times t3 and t4 of FIG. 13 would only be 1 or 2 ms.

It can be seen that in this way each rising edge of the pulse group contributes to the addressing of the various transponders and that commands can be transmitted to the respectively addressed transponder via the position of the falling edges of the addressing pulses.

At time t4, switch S1 is closed. Depending on the position of time t4, the transmission of calibration data is stopped or prevented by the rising signal edge. Due to the rising signal edge, the 2-bit counters 112 (compare FIG. 8) of all transponders are also incremented by one. The switch S1 opens again at the time ts, so that the signal on the conductors 27, 28 is low before the time t6 at which a persistent high-level addressing pulse would command the transponder to switch on the output “2”. The latter would have meant that the signal lamp 81 connected to the output “2” of the output driver stage 135 is switched on. However, the addressing pulse already became low at time ts, so that the output “2” of the output driver stage 135 and thus also the signal lamp 180 are not switched on. In the period between ts and t8, the transponder can report the sensor identification data to the central unit. If a high-level addressing pulse is received again shortly after the time ts, on the other hand, the transponder cannot report this data to the central unit.

At the time ts, the switch S1 closes again, whereby

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the transmission of sensor identification data is ended and the 2-bit counter 112 of all transponders is increased further. The third addressing pulse only remains high until t9. At this time the switch S1 is opened, that is again before the time tio up to which the high-level addressing pulse would have to be extended in order to command the transponder to switch on the output “2” of the output driver stage 135, as a result of which the current surge relay 75 would be switched on. Thus, opening switch S1 at time t9 is practically a command not to apply current surge relay 75. The addressing pulse remains low until tu, and in the measurement period thus obtained, the reporting unit can report 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 increase with respect to the beginning of the measurement period takes place as described above with reference to FIGS. 10 to 12. At the time ti2, the switch S1 closes again, as a result of which a further high-level addressing pulse is obtained, by means of which the feedback from the addressed transponder 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 ti2 and tu, so that the transponder switches on the output “4” of the output driver stage 135 and thus the current surge relay 75 is switched off. If the addressing pulse were already low level at time tn, the transponder would not switch off the surge relay 75. Between the times ti s and tió, the transponder tries to transmit a second analog voltage to the central unit, namely the output signal of the sensor 72 received via the line 71. However, since FIG. 13 assumes that the switch S1 returns after only 1 or 2 ms closes, the transponder is not commanded to report the output signal of the sensor 72 to the central unit. At time ti6, switch S1 closes again, and the rising signal edge prevents 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 transponder to the next transponder to be activated takes place together. This switchover to the next signaling unit takes place 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, at which the address of the addressing switch bank 66 also provided considered transponders. The transponder addressed next at time ti6 does not necessarily have to be the spatially closest transponder. At the end of a polling cycle, the fifth addressing pulse remains low beyond time t22. If this addressing pulse had become low by opening switch S1 at time tn, it would have instructed the newly addressed transponder not to switch on its output "1". However, since the addressing pulse remains high above tis, the command is given to control output «1». At time ti9, 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 t2i and t22, with all transponders recognizing at time t22 that this greatly extended, high-level addressing pulse is a reset pulse, by means of which the counters 112 and 114 in all transponders are cleared. Man

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recognizes that in the monitoring system described above, a large number of data and commands can be packed in and between the addressing pulses.

FIG. 14A shows a group of addressing pulses emitted by the central unit 26, while FIGS. 14B to 14F show the response of the signaling unit to each of the addressing pulses. The waveforms shown in FIGS. 14B to 14F correspond to the signals at the outputs “8”, “1”, “2”, “3” and “4” on the output side of the integrated circuit ICI on the right in FIG. 7 or on the one in FIG 8 right-hand output side of the output driver stage 135. The signal form in FIG. 14B shows when the output “8” of the integrated circuit ICI is switched on. This corresponds to the periods within which the transponder is activated to report signals to the central unit.

It can be seen from FIG. 14A that switch S1 is closed at time to, which initiates the first addressing pulse. The switch S1 remains closed until ti, this time period being so short that the output “1” of the integrated circuit ICI is not switched on. When the switch S1 is opened, the output “8” of the integrated circuit ICI is switched on, and the transponder 25 attempts to report data, as the pulse 340 from FIG. 14B shows. At time ti, however, the switch S1 is closed again, so that the first send command is ended and the pulse 340 is switched off accordingly. Since the period between to and ti is very short, the output “1” is not switched on, as shown in FIG. 14C.

At time t2, switch S1 is closed again and remains closed beyond minimum time t3, which is required to switch on output “2”. The rising edge of a pulse 341 is therefore obtained at time t3, as shown in FIG. 14D. The signal lamp 81 is switched on by the pulse 341. This remains switched on from t3 until the switch S1 is closed again at time t4. After time U, the signaling unit again tries to transfer data to the central unit, as shown by pulse 342 in FIG. 14B. However, the period between U and ts is too short for the feedback of the sensor identification data, and the pulse 342 is ended when the switch S1 closes again at the time ts.

The third addressing pulse in the group shown in FIG. 14A remains high only for a short time, which is too short to cause output “3” to be switched on. The waveform shown in Figure 14E is thus consistently low level. At time t6, switch S1 is opened again, so that the third low-level residual signal is obtained on conductors 27, 28 (see FIG. 14A). However, this residual signal is not as low-level as the previous low-level residual signals between addressing pulses of the addressing pulse group under consideration. This is due to the fact that the third low-level residual signal comprises a period in which the first analog signal “A” is to be reported back from a connected device to the central unit. The low-level residual signal, which is only slightly reduced, indicates that no corresponding analog signal transmitter is connected to the transponder being 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 fr, switch S1 closes again, which initiates the fourth addressing pulse. This addressing pulse remains high beyond ts, so that output «4» is switched on. In the exemplary embodiment considered, this leads to the deletion of the assigned current surge relay 75. At time ts, pulse 343 is generated at output “4” (see FIG. 14F). The pulse 343 lasts until the time t <> at which the switch S1 of the central unit opens again. The fourth low-level residual signal begins at time t9, this residual signal being extended so long that the output “8” of the integrated circuit ICI is and remains high, so that the transponder can report data back to the central unit from the second analogue sensor assigned to it . Due to the transition to the fourth low-level residual signal, output «8» becomes low-level again, and this state remains until tu. At ti l a complete pulse group was obtained, the counter 114 from FIG. 8 is increased in all transponders and the next group of addressing pulses begins.

From the above description of FIGS. 14A to 14F, it can be seen that by stretching the addressing pulses, information can also be transmitted from the central unit to the transponders, 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, whereby the light duration could be shortened or extended in order to transmit different data. The duration of such a pulse can thus mean information either for units connected to the transponders or for the monitoring personnel.

How the switch S1 of the central unit 26 can be controlled for transferring data to the transponders 25 is explained below with reference to FIGS. 15A to 15F. FIG. 15A again shows four addressing pulses forming a group. The first addressing pulse becomes high at time to and remains so beyond time ti. The latter corresponds to the minimum switch closing time which is required to make the output «1» of the integrated circuit ICI high. Correspondingly, the rising edge of a pulse 345 is obtained at this output at time ti. This pulse remains high until time t2, at which switch S1 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-ready coded representation of an analog signal.

At time t2, switch S1 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 switch S1 is closed again after only 4 ms at time t3, output «8»

at this point, the level is low again and the intended data transmission of the transponder is ended. The second addressing pulse begins at the time t3.

The second addressing pulse remains high beyond time t4, which represents the minimum switch-on time of switch S1, which is necessary to switch on output «2» and thus to transmit a function command to the transponder. As a result, the rising edge of a pulse 346 is obtained at time t4, as shown in Figure 15D. The pulse 346 remains high until the time ts at which the switch S1 of the central unit opens again. When pulse 346 ends, output “8” of output driver stage 135 again goes high, and the reporting unit attempts to report further data back to the central unit. However, this attempt is ended at time t6 when switch S1 is closed again. Pulse 346 thus represents one

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32 ms long data pulse that is transferred to the addressed transponder.

The third addressing pulse remains high beyond time t7, 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. Pulse 347 ends after 8 ms at time ts at which switch S1 is opened again. The transponder then tries to report data back to the central unit between the times ts and t9, the amplitude of the residual signal on the conductors 27 and 28 now being somewhat larger than that of the previous residual signals, since there is no sensor connected to the transponder that is to be reported back Would provide analog signal.

The fourth addressing pulse is initiated at time t9. The switch S1 is kept closed beyond the time tio, 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. Output «4» remains high until time ti i, at which switch S1 of the central unit is opened. This ends pulse 348 after a data transmission time of 40 ms. At time ti i, output “8” also goes high again, so that the reporting unit sends a pulse 350 back to the central unit, which ends at time ti2. Since the switch S1 is still kept closed at this point in time, a signal rise on the conductors 27, 28 is obtained at the point in time ti2, which is evaluated 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 tu and the

Feedback of data is used. At time ti3, switch S1 is closed again, whereby the first addressing pulse of the next group of four is initiated.

s The following outstanding features of the monitoring system described have been dealt with above on the basis of exemplary embodiments:

1. Nonius evaluation of the signal signals generated by the transponders io in the central unit to increase the accuracy;

2. Exact evaluation of the data transmitted by a returning transponder even if another reporting unit is transmitting a radio at the same time.

15 has flaws;

3. Feedback of different data from a transponder in different measurement periods, which are obtained by stretching a low-level residual signal, which is in each case assigned to one of a plurality of address

20 sierimpulsen follows, which together form an addressing pulse group used to switch from one signaling unit to another transponder, e.g. Transmit sensor identification data, calibration data of the transponder and identification data for the transponder

Can be 25;

4. Compensation of the signal signals transmitted by the transponder with regard to long-term changes in system parameters;

5. Adjustment of transponders on site;

30 6. Power supply for the transponders and the sensors connected to them from the central unit via the two conductors, which are also used for signal transmission.

B

8 sheets of drawings

Claims (5)

660926 2 PATENT CLAIMS voltage divider (SI, RI, R2) can be obtained if 1. Monitoring system with a central unit and one, two or even more of the second switches (S2) which are connected to a plurality of transponders (25) via a signal rail. snen, addressable, active transponders in which 6th system according to one of claims 2 to 5, characterized in that a) the signal rail comprises two conductors, characterized by the digital 5, that the evaluation circuit a phase data in a serial representation between the central unit fine discriminator (202,206,216 ) and a phase rough display and the transponders are exchanged, criminator (203, 206, 210, 220) and a computing circuit (222, b) the central unit has an addressing circuit for generating 224) a weighted combination of the two discriminations of addressing signals in a predetermined sequence and generator output signals. A system with the signaling signals generated by the transponders io 7. System according to claim 6, characterized in that the evaluation circuit acted upon and the fine discriminator and the gross discriminator in each case c) each have the transponders: an activation and an AND element (202, 203), the an input circuit which is assigned to the respective transponder with the level changes on the signal rail (27, addressing signal and 28 received via the signal rail) and whose second input compares with addressing signals and, if they match, is assigned to a clock generator (206; 206,210) is connected, an activation signal is generated, and an output circuit is switched by the latter, the frequencies of the two clock generators being switchable, the output side with the signal divider, and that into the connecting lines (211, 212) and the input side with at least one sensor - between the clocks and is assigned to the associated AND-Glie, characterized in that the switches (204, 205) are inserted, which from the d) with the addressing circuit (42, SI, Rl) continuously 20 addressing circuit (42, Sl, Rl) in a predetermined sequence of pulses are delivered, the transmitted number of being actuated. Pulses the address of the selected transponder (25) 8. System according to one of claims 1 to 7, characterized in that the transponder (25) has a setting e) with the addressing circuit (42, Sl, Rl) a pulse baren reference signal generator (105) and one of the Zen or a pulse gap between pulses to a 25 traleinheit (26) via the signal rail (27,28) controllable compared to the Have the control distance of the pulses large display device (81). Measuring time (145) is extended, and 9. System according to one of claims 2 to 8, characterized in that f) the respectively addressed transponder (25) is characterized in that the evaluation circuit has a drift measuring time (145) on the signal rail (27, 28) standing compensation circuit (226, 228) for correcting the addressing signals modulated by the pha signal level with the phase shift of the level change determined in comparison with the amplitude swing of the 30 transmit discriminator. on the signal rail (27, 28). 2. System according to claim 1, characterized in that 10. System according to one of claims 4 to 9, characterized in the modulation of the signal level on the signal rail (27, characterized in that the transponder (25) one with the 28) by the transponder ( 25) have a single level change counter (64) to which addressing pulses are applied (150), whereby different signals to be reported in a 35 that each of these addressing pulses in turn consists of a different phase of this level change to the plurality of individual pulses and that the level of the starting point of the measuring time (145) are implemented, and residual signals between these individual pulses from the off-that the evaluation circuit has a phase discriminator (202-evaluation circuit with regard to sticking control-228), which previously addressed the distance between the start of the bar switches (S2) Transponder (25) off measurement time and the occurrence of the level change (150) 40 is evaluated. netes output signal. 11. Plant according to claim 10, characterized in 3. System according to claim 1 or 2, characterized in that the counter (64) draws a pre-counter (112) with the number that the addressing circuit (42, Sl, Rl) in the pulse gaps corresponding to individual pulses per addressing pulse, a residual signal (141 -144) with zero capacitance and a level connected to its overflow terminal and the transponder (25) has this 45 which address counter (114), and that the output of the residual signal continues over part of the measuring time (145) reduced counter with a circuit (118, 122) for command deco ners. is connected. 4. System according to claim 3, characterized in that 12. System according to one of claims 3 to 11, characterized in that the addressing circuit (42, Sl, Rl) a parallel connection, that the central unit one of the individual from a first controllable switch (Sl ) and a first so pulse of an addressing pulse for outputting data at the resistor (R1), which extends between a DC-addressed transponder (25) and the transponder voltage source (V) and a conductor (27) of the signal rail (25) each one Circuit (113) is connected to detect, and that the transponders (25) each have a stretched individual pulses. circuit from a second controllable switch (S2) and a second resistor (R3), which have 55 the conductor of the signal rail (27, 28) is connected. 5. The system as claimed in claim 4, characterized in that the evaluation circuit has a plurality of differential amplifiers. The invention relates to a monitoring system according to the core (51-53), the one inputs of which have a central part. The preamble of claim 1. Tap (41) of a first voltage divider are connected, 60 Such a monitoring system is described in DE-OS which is controllable by the parallel connection from the first 2 638 529. It has a plurality of active mel switches (S1) and the first resistor (R1) as well as a unit as well as a central unit connected to a third rail connected via the signal rail conductors, the signaling units being in the order (R2) exists, and the second inputs of which are controlled by the central unit in a different order and which taps of a multiple voltage divider (45-48) can and can be queried. For this purpose, the central unit connects the unit with several bits (V) directly to the signal rail via the DC voltage source unit and its partial ratios are connected to the existing address signal by which the voltages are activated that activate the desired signaling unit at the center tap becomes. For this, the signaling units each hold a read-only memory for the address assigned to them and a comparator which compares the address signal present on the signal rail with the address signal preset in the signaling unit and activates the signaling unit when these signals match. The activated signaling unit then emits a digital signaling signal on the signal rail, which shows the status of the sensors assigned to the signaling unit, for example a smoke sensor. In this known monitoring system it is advantageous that the various signaling units can be connected to the signal rail in any spatial arrangement; the system can be expanded as required. However, the addressing of a reporting unit under consideration takes a relatively long time, since the central unit must provide all bits of the addressing signal on the signal rail. DE-OS 2 836 760 also describes a monitoring system in which a plurality of active signaling units are likewise connected to a signal rail and emit digital signaling signals in succession to a central unit. In this monitoring system, the central unit is initially connected to a first signaling unit, while the signal rail between this first signaling unit and the subsequent signaling unit is initially interrupted. The first signaling unit closes the signal rail to the second signaling unit only after its signal has been transferred to the central unit. If the latter has given its signal to the central unit, the signal rail to the third signaling unit is closed there, etc. Although this makes it possible to query the various signaling units more quickly overall, the query must follow the spatial arrangement of the signaling units along the signal rail. The individual active reporting units cannot be addressed independently, so that, for example, a particularly critical reporting unit cannot be queried several times within a long overall polling cycle. The expansion of such a monitoring system is also associated with considerable structural outlay. Finally, if the switch in an active signaling unit that connects to the next signaling unit is working incorrectly, no signal can be received from all the subsequent signaling units.