EP0602452A1 - Dispositif de sécurité avec microprocesseur - Google Patents

Dispositif de sécurité avec microprocesseur Download PDF

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Publication number
EP0602452A1
EP0602452A1 EP93119330A EP93119330A EP0602452A1 EP 0602452 A1 EP0602452 A1 EP 0602452A1 EP 93119330 A EP93119330 A EP 93119330A EP 93119330 A EP93119330 A EP 93119330A EP 0602452 A1 EP0602452 A1 EP 0602452A1
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EP
European Patent Office
Prior art keywords
microprocessor
safety device
measuring point
safety
assigned
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP93119330A
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German (de)
English (en)
Inventor
Karlheinz Beckhausen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
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Individual
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Filing date
Publication date
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Publication of EP0602452A1 publication Critical patent/EP0602452A1/fr
Withdrawn legal-status Critical Current

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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B21/00—Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for
    • G08B21/18—Status alarms
    • G08B21/182—Level alarms, e.g. alarms responsive to variables exceeding a threshold
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
    • G08B13/181—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using active radiation detection systems
    • G08B13/183—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using active radiation detection systems by interruption of a radiation beam or barrier
    • G08B13/186—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using active radiation detection systems by interruption of a radiation beam or barrier using light guides, e.g. optical fibres
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H47/00—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current
    • H01H47/002—Monitoring or fail-safe circuits
    • H01H47/004—Monitoring or fail-safe circuits using plural redundant serial connected relay operated contacts in controlled circuit

Definitions

  • the invention relates to a safety device, in particular for protecting people and / or objects, according to the preamble of patent claim 1.
  • DE-OS 42 10 848 discloses a safety device, in particular for protecting people and / or objects, which has an evaluation unit which is provided with at least one measuring point associated with at least one electrical termination, the measuring point being designed in particular as a tactile sensor at least consists of a comparison device, to which a signal that can be emitted by the measuring point can be fed and a switching device can be actuated as a function of the signal.
  • This safety device has the disadvantage that comparison values are fixed in the comparison device, so that several safety devices are required for each individual application or for different areas of use. Furthermore, this safety device has the disadvantage that an ohmic terminating resistor is electrically assigned to the measuring point and is terminated with this terminating resistor.
  • the object of the invention is to provide a safety device, in particular for protecting people and / or objects, with which sufficiently fast reaction times can be achieved and which can be used universally.
  • the safety device is characterized in that the evaluation unit is at least partially integrated in at least one microprocessor, the microprocessor being assigned a selection device for determining control functions of the microprocessor and being designed such that the electrical termination can be recognized automatically.
  • the safety device is constructed with a few components (microprocessor including a small amount of wiring), which reduces the production effort and the production costs and, due to the small number of components (in particular due to the avoidance of capacitors), a fast response time after actuation the measuring point (preferably in the millisecond range).
  • a selection device is also assigned to the microprocessor, with which control functions of the microprocessor can be determined.
  • Control functions are, for example, programs stored in the microprocessor, the definition of stored values and also the determination of operating modes of the microprocessor or the entire safety device.
  • the selection device can be, for example, jumpers or switches which enable the control functions to be determined manually.
  • the selection device can thus be used, for example, to determine the application for which the safety device is used. In this way, the selection device can be used to specify whether the safety device is to be operated in one or more channels.
  • Another advantage of the safety device according to the invention is that the microprocessor is designed in such a way that the electrical termination can be recognized automatically. This makes it possible to operate various electrical terminations on the safety device, thereby broadening the area of use of the safety device.
  • an electrical variable with which at least one measuring point can be acted upon can be controlled by the microprocessor.
  • the electrical variable can be optimally selected and controlled.
  • the electrical termination can be an ohmic resistance, and after recognizing the value of the ohmic resistance, a current (electrical quantity) impressed into the measuring point can be set to the correct value for this case.
  • the controllability of the electrical quantity is to be understood to mean that in the case of multichannel features (for example two measuring points), these can be queried cyclically (for example alternately).
  • the microprocessor is designed in such a way that there is a cyclic switchover between the two measuring points and the signals which can be output by the two measuring points are evaluated. Since this changeover can be controlled by the microprocessor, the frequency of the changeover can be chosen as desired. In particular, the choice of frequency in the KHz range makes sense, since this significantly reduces the response time of the safety device. The outlay on components is also reduced, since the at least two measuring points can be operated on a single energy source.
  • the electrical termination is a diode and the microprocessor is designed to detect the direction of the diode.
  • the use of a diode is also conceivable, which also represents an electrical termination. Since a diode must be operated with polarity, the microprocessor is used for direction detection (Polarity detection) of the diode. This has the advantage that the diode can be used in any way when the measuring point is installed, including the electrical termination. Incorrect installations are thus avoided in an advantageous manner.
  • the at least one measuring point is an optical waveguide which represents the tactile sensor and which has at its ends a converting device which has a light source on one side of the optical waveguide and on the other side of the optical waveguide is provided with a receiving and evaluating device, the receiving and evaluating device representing the electrical termination on the output side on one side of the optical waveguide.
  • the light source and the receiving and evaluating device are arranged on one side of the optical waveguide, while a deflection device (for example a mirror) is arranged on the other side of the optical waveguide.
  • a deflection device for example a mirror
  • the internal resistance of the evaluation device then represents the measuring resistance, which can be changed depending on the contact with the optical waveguide.
  • a watchdog is assigned to the microprocessor for function monitoring.
  • the watchdog which is integrated in the microprocessor or alternatively assigned to it externally, functions, for example, according to the counter principle, with the counter being reduced by 1 every clock period. If the counter counts to zero, it triggers a reset, as a result of which the program running in the microprocessor restarts.
  • the program provides for the counter to be cyclically set to a predeterminable value so that it does not count down to zero in the absence of errors. If zero is reached in the event of an error, the watchdog triggers the reset and starts the program again.
  • the microprocessor is designed to carry out a self-test or to perform a self-test that can be triggered manually.
  • This self-test has the advantage that a functional check of the safety device can be carried out automatically or manually. If the self-test is carried out independently, it is conceivable that this self-test is carried out in predefinable cycles. In addition, as an alternative or as a supplement to performing the self-test independently, it is conceivable to trigger it manually.
  • An implementation of the self-test is mentioned in the figure description and shown in the figures.
  • the microprocessor actuates a display device known per se depending on the signal that can be output by the measuring point. This makes it possible to display the functionality of the safety device.
  • the safety device can be networked with a superordinate or secondary system via an interface.
  • This makes it possible to output the signals which can be output by the measuring point (s) and further signals generated in the safety device via an interface (for example fieldbus interfaces such as Profibus or CAN) to a higher-level or secondary system (for example a control center).
  • the safety device according to the invention can be used, for example, in systems such as a programmable logic controller (PLC).
  • PLC programmable logic controller
  • each switching device is assigned to each processor in the case of multi-channel capability.
  • each microprocessor is assigned a pair of switching devices, which can be relays or power transistors, for example.
  • the electrical quantity can be generated in such a way that it has a positive level with respect to a mass of the voltage with which the safety device can be operated.
  • the at least one switching device can be actuated by the microprocessor in such a way that a safety-relevant state can be set or reached in the event that the measuring point emits a signal.
  • a safety-relevant state can be set or reached in the event that the measuring point emits a signal.
  • the microprocessor is assigned at least one monitoring device on the output side, the monitoring device acting on the at least one switching device.
  • the use of the monitoring device on the output side has the advantage that, on the one hand, the output of the microprocessor is monitored (in particular with regard to short-circuit or interruption), and at the same time that the monitoring device acts on the at least one switching device so that the monitoring device monitors itself.
  • the monitoring device can act on the at least one switching device, for example, in such a way that it provides the switching device with a potential (for example plus or minus a voltage supply).
  • the at least one switching device which in particular has a control transistor and a relay, can be monitored by the microprocessor and the monitoring device.
  • This arrangement has the advantage that in addition to monitoring the off course of the microprocessor and for monitoring the monitoring device, a function monitoring of a switching device is possible.
  • An embodiment of the monitoring device and its mode of operation is shown in the figures and described in more detail.
  • FIG. 1 shows a safety device according to the invention with resistance termination.
  • essential components of the evaluation unit are integrated in a microprocessor 1 in order to avoid a large number of discrete components.
  • These components are essentially AD converters arranged in the input circuit, a CPU in which control functions of the microprocessor 1 are stored, which, for example, emulate the comparison device, an internal watchdog and driver stages for a downstream switching device.
  • These components are available in terms of their safety-relevant function, in particular in duplicate, the simple existence of which is also conceivable.
  • the microprocessor 1 is supplied with power from an energy Source 2, which is designed such that any voltages (for example, mains voltage or battery voltage) can be used.
  • the microprocessor 1 is followed by a known display device 3.
  • the microprocessor 1 has a measuring point 4 which contains a terminating resistor RA and a measuring resistor RM and which is located in a circuit (between a DC voltage U and ground).
  • the microprocessor 1 is connected to a selection device 5 with which the control functions which the CPU contains (for example in the form of a stored software) can be determined.
  • the selection device 5 is, for example, jumpers or switches, the control functions being determinable depending on the switching state of the switches, for example (switch closed, in particular against ground, or switching open).
  • a watchdog 6 is shown, which is assigned externally to the microprocessor 1 and monitors its functional sequence.
  • a switching device 7 is connected downstream of the microprocessor 1, the switching device 7 being operable as a function of the signal that can be output by the measuring point 4.
  • the evaluation unit shown in FIG. 1 works as follows:
  • the selection device 5 which can contain any number of switches, for example, comparison values (maximum and minimum values) are predefined in the microprocessor 1, which can be selected from a large number of values stored in the microprocessor 1.
  • a current flowing through the measuring point 4 is compared with the predetermined limit values with the interposition of, for example, the AD converter arranged in the input circuit of the microprocessor 1. If it is a safety device monitored by quiescent current, an interruption of the measuring point 4 is indicated on the display device 3 when the minimum value is undershot. If the maximum value is exceeded, the measuring point 4 is short-circuited, which can also be displayed via the display device 3. In this case, the switching device from the microprocessor 1 7 actuated, since the measuring point 4 has been actuated.
  • the watchdog 6 operates according to the counter principle, so that errors in the program sequence can be identified and displayed.
  • Figure 2 shows a safety device according to the invention, which is multi-channel.
  • FIG. 2 shows a multichannel and redundant embodiment of the safety device according to the invention.
  • the essential components shown in FIG. 1 (in particular all components shown in FIG. 1, with the exception of energy source 2) are duplicated.
  • Two microprocessors 1.1 and 1.2 are each assigned a measuring point 4.1 and 4.2 and a selection device 5.1 and 5.2.
  • the two Microprocessors 1.1 and 1.2 operate in the same way as in the manner shown and described in FIG. 1 that each microprocessor monitors its assigned measuring point or, alternatively, the measuring point of the other microprocessor.
  • both the microprocessor 1.1 cyclically monitors the two measuring points 4.1 and 4.2 and also the microprocessor 1.2 also cyclically monitors the two measuring points 4.1 and 4.2. Furthermore, it is conceivable that a single measuring point is present, the signal of which can be switched to both microprocessors 1.1 and 1.2.
  • FIG. 3 shows a safety device according to the invention with a diode termination.
  • the measuring point 4 shown in FIG. 3 consists of the measuring resistor RM, the measuring point 4 being terminated with a diode D.
  • the diode D as well as the terminating resistor RA can be integrated in the measuring point.
  • the arrangement in the input circuit of the microprocessor is also conceivable if the generation of the voltage U is also integrated therein.
  • the safety device shown in FIG. 3 has a single-channel structure, the microprocessor 1 monitoring the measuring point 4 and being equipped with a direction detection of the diode D, which will be described later.
  • the functions of the microprocessor 1 are monitored by the watchdog 6.
  • the procedure for monitoring the measuring point 4 and the processing of the signal which can be output by the measuring point 4 in the microprocessor 1 is carried out analogously to the procedure as described for FIGS. 1 and 2.
  • switching devices 8.1 and 8.2 are provided, which are arranged in the circuit of the measuring point 4 and can be actuated by the microprocessor 1.
  • the voltage U (alternating voltage) can also be controlled by the microprocessor (frequency change).
  • an electronic switch at each connection of the measuring point 4, which is implemented, for example, by the switching devices 8.1 and 8.2.
  • a positive operating voltage U is supplied to the anode or the cathode of the diode D. Since here, too, the voltage U is positive against ground, ent there is a galvanic separation of the voltage at the measuring point 4. Since the voltage U (or generally a signal source of any kind) is therefore always at one end of the measuring point 4 and an input of the microprocessor 1 at the other end, this is depending on the position the switching devices 8.1 and 8.2 the direction of the diode D independently. The switching devices 8.1 and 8.2 are actuated by the microprocessor 1 (connections AA and BB). Furthermore, test devices 9.1 and 9.2, which are implemented by means of buttons, are assigned to measuring point 4. With the help of these test devices 9.1 and 9.2, it is possible to carry out a self-test.
  • the safety device shown in FIG. 3 works as follows: After connection in any direction of the diode D, the switching device 8.1 is first actuated (closed) and the switching device 8.2 is opened, for example. Then the microprocessor 1 queries the levels present at the measuring point 4 on the input side. Subsequently, the switching devices 8.1 and 8.2 are operated in reverse, whereupon the levels are queried again. Due to the interrogation of the levels, a lower level is set in the reverse direction of the diode D at an input of the microprocessor 1 compared to the higher level, which represents the direction of flow of the diode D.
  • the switching devices 8.1 and 8.2 are actuated by the microprocessor 1 in such a way that the diode D is operated in the direction of flow.
  • the switching device 8.1 is closed, while the switching device 8.2 is open, so that the diode D is operated in the forward direction.
  • the duration of the direction detection (for example after the safety device has been started up), this can be indicated by means of the display device 3.
  • the switching device 7 is actuated in such a way that the system (or object) monitored by the safety device is in a safe state, so that malfunctions or dangers to persons are excluded.
  • monitoring can be carried out to determine whether there is an interruption or not.
  • An interruption can be determined in that a level at an input of the microprocessor 1 is smaller than a predeterminable level (limit value which is not shown by means of the made selection device 5 is predetermined).
  • the switching device 8.1 is placed cyclically for a short time at one input of the microprocessor 1. If the switchover device 8.2 is actuated in reverse, so that the voltage U is applied to the other input of the microprocessor 1 and the level is measured at one input of the microprocessor 1, when the measuring point 4 is actuated, a level is set which is above the limit value .
  • This actuation of the measuring point 4 and the signal which can be emitted by this measuring point 4 leads on the one hand to an actuation of the display device 3 and on the other hand to an actuation of the switching device 7, which influences the system (object) to be monitored in such a way that a safety state is achieved.
  • This can involve stopping a drive, for example.
  • the cyclic switching of the two switching devices 8.1 and 8.2 is advantageously asymmetrical, which prevents faults from leading to incorrect evaluations, since the voltage applied at measuring point 4 is always conducted synchronously with the safety device.
  • Figure 4 shows a switching device according to the invention, which is designed fail-safe.
  • the selection device 5 is connected to the microprocessor 1 via a data line. This ensures reliable transmission of the selection of the selection device 5 to the microprocessor 1, for example in digital form.
  • the microprocessor 1 is designed in such a way that its components, such as AD converters arranged in the input circuit, the CPU and driver stages for a downstream switching device are designed in duplicate, since they have safety-relevant functions. It is also conceivable to use two separate microprocessors.
  • the microprocessor 1 is followed by the two switching devices 7.1 and 7.2, the switching contacts of which are connected in series in the output circuit.
  • the driver stages integrated in the microprocessor 1 are designed such that in the event that the measuring point 4 emits a signal, both switching devices 7.1 and 7.2 are controlled by both driver stages.
  • both driver stages control the two switching devices 7.1 and 7.2, the two Switching devices 7.1 and 7.2 are arranged in parallel, so that in any case a switching device can be actuated in order to set a safe state in the event of a fault.
  • FIG. 5 shows a safety device according to the invention with a monitoring device, an embodiment of a switching device being shown in FIG. 6 in addition to the previous figures and to explain the functioning of the monitoring device.
  • the safety device according to the invention with the microprocessor 1 is shown in simplified form in FIG. The additional components to the microprocessor 1 shown in the previous figures are present, but not shown.
  • a driver stage integrated in the microprocessor 1 and not shown emits a signal both to a switching device 7.1 and to a monitoring device 10 in the event that the measuring point 4 (or 4.1, 4.2) is actuated.
  • the monitoring device 10 is connected on the output side to an input of the microprocessor 1 (or the second microprocessor) and again on the output side to the switching device 7.1 for acting on this switching device 7.1.
  • Two monitoring devices are used for two microprocessors.
  • the switching device 7.1 (or also the switching device 7.2) consists of a control transistor 11, which is controlled by a driver stage of the microprocessor 1 and which controls the coil of a relay 12.
  • the control transistor 11 is controlled by the microprocessor 1 and places the relay in the circuit (represented by the plus / minus signs). As a result, for example, the contacts of the relay 12 are closed, which enable the operation of an electrical machine.
  • the monitoring device 10 shown in FIG. 5 works in conjunction with the switching device 7.1 shown in FIG. 6 as follows:
  • the monitoring device 10, which is designed in particular as a mono-flop, is set by a driver stage of the microprocessor 1. This can be done cyclically, in particular, since if the microprocessor or its components fail, the switching device 7.1 must be actuated.
  • an output of the monitoring device 10 forms a ground potential (D or minus sign in FIG. 6) for the switching device 7.1.
  • the further output of the monitoring device 10 forms a potential which is different from the ground potential (in particular a positive potential), the two outputs of the monitoring device 10 normally having a different potential.
  • the switching device 7.1 is protected against a breakthrough to ground, since such a device drops the relay 12 which is normally actuated and a safety-relevant (harmless) state can thus be set.
  • the output of the microprocessor 1 is connected to a positive potential (in particular a supply voltage)
  • the ground potential is withdrawn from the relay 12, so that the relay 12 also drops out in this case.
  • the control transistor 11 is checked whether it is short-circuited to ground or to a positive potential. In the event that the control transistor 11 is short-circuited to ground, the relay 12 no longer picks up, which is indicated to the microprocessor 1 via the connection E. This malfunction can be detected in the microprocessor 1 and displayed on the display device 3.
  • the relay 12 In the event that the control transistor 11 is short-circuited to a positive potential (in particular supply voltage), the relay 12 still has a signal on the control transistor 11 despite the error message from the microprocessor 1. This is registered via an input of the microprocessor 1 and the microprocessor 1 switches the signal to ground at its output, so that the relay 12 drops out and this can be indicated by the display device 3.
  • the at least one measuring point is designed as a tactile sensor.
  • this is a rubber hose (rubber profile), in which an electrical cable (measuring resistor RM) is integrated along, this sensor can be terminated on the input or output side with a resistor or a diode. Because the value of this resistance depends on the length of the rubber hose or the electrical cable, it is provided according to the invention to detect the voltage present at the measuring point, which represents a value proportional to the length. On the basis of this value, adjusted comparison values (minimum and maximum values) are specified, which are stored in a memory in the at least one microprocessor.
  • This process can be repeated by the microprocessor, so that the length is queried at predetermined time intervals and can be carried out automatically when the comparison values change.
  • This adjustment of the comparison values makes it possible to keep the switching points (or actuation of the switching device) the same for different lengths. If an impermissible length is detected, it is conceivable to specify comparison values which correspond to a permissible length or to actuate the switching device (or the display device) in such a way that the entire system (system) assumes a predetermined, in particular a safe, state.
  • FIG. 7 shows an embodiment of a tactile sensor, the one measuring point 4 known at least from the previous figures having an optical waveguide 13.
  • This optical waveguide 13 can be touched in at least one partial area, so that the light emitted by a light source 14, which is integrated in the measuring point 4, is modulated (changed), this modulation (change) by a receiving device 15 and an evaluation device 16 connected to it can be determined.
  • the evaluation device 16 is in turn electrically connected to the microprocessor 1, the internal resistance of the evaluation device 16 representing the measuring resistor RM.
  • the combination of the receiving device 15 and the evaluation device 16 is a photodiode, which changes its internal resistance (measuring resistor RM) depending on the light fed in by the light source 14 and also depending on the contact of the optical waveguide 13, whereby this change in resistance can be detected by the microprocessor 1.
  • an AD converter is integrated in the evaluation device 16 which converts the analog signals emitted by the receiving device 15 into digital signals.
  • FIG. 7 also shows that at least the light source 14 is connected to the microprocessor 1 and can be controlled from the latter. At the same time, this connection can be used for energy transmission for the light source 14.
  • the control by the microprocessor 1 has the advantage that the light source 14 is only put into operation when the entire safety device is in operation.
  • the measuring point 4 shown in FIG. 7 can either be operated alone on a microprocessor 1 or, analogously to the embodiment shown in FIG. 2, can be operated at least twice on a microprocessor 1.1 and 1.2 or in addition to one of the measuring points described above. This has the advantage that the range of applications of the safety device according to the invention can be expanded.
EP93119330A 1992-12-18 1993-12-01 Dispositif de sécurité avec microprocesseur Withdrawn EP0602452A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4242936 1992-12-18
DE19924242936 DE4242936A1 (de) 1992-12-18 1992-12-18 Sicherheitseinrichtung mit Mikroprozessor

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EP0602452A1 true EP0602452A1 (fr) 1994-06-22

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DE4432971A1 (de) * 1994-09-16 1996-03-21 Markus Braunewell Vorrichtung zum Aufmerksammachen auf das Entfernen eines Gegenstandes
DE4438039A1 (de) * 1994-10-25 1996-05-02 Leon Helma Christina Elektronisches Schaltgerät für die Erfassung des Betätigungszustandes von taktilen Sensoren
DE19939568C1 (de) * 1999-08-20 2001-02-08 Pilz Gmbh & Co Verfahren zur Einstellung einer Datenübertragungsrate in einem Feldbussystem

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