Safety switch

Abstract

The invention relates to a series circuit (1) having a plurality of safety switches (2). The series circuit (1) has wiring for connecting the safety switches (2). The safety switches (2) can output signals. Based on the recording of the signals by other safety switches (2) in the series circuit (1), it is detected whether the wiring is designed to connect a host (6) and whether such a host (6) is connected. The operation of the safety switches (2) is predetermined accordingly.

Description

Technical Field

[0001] The invention relates to a safety switch. Background Art

[0002] Safety switches are used in the field of safety technology, wherein they are used in particular for hazardous area protection of installations. The term “installation” also includes in particular machines, working devices and the like.

[0003] Such a safety switch can be operated, for example, by means of a transponder, wherein it can be detected on the basis of the transponder signal whether a separate protective device (for example a door as an access to the installation) is closed.

[0004] Such a safety switch usually has an input / output structure with an input and an output, which can be constructed redundantly in particular. The safety switch generates a switching signal output to the control device corresponding to the monitoring function of the safety switch, in particular according to the transponder signal, and controls the device to be monitored by means of the switching signal. If a non-dangerous state is detected by means of the safety switch, in particular the door to be monitored is closed and the entrance to the hazardous area (in which the device is arranged, for example) is blocked, then a switching signal (i.e. a release signal) with a switching state "on state" is generated corresponding to the activated safety condition. If the control device receives the release signal from the safety switch, the control device can put the device into operation or in operation. However, if the door is opened by means of the safety switch, the safety switch generates a switching signal with a switching state "off state" corresponding to the inactive safety condition. In this case, the safety switch shuts down the device to avoid a dangerous state.

[0005] In particular, in order to meet more complex monitoring tasks, a series circuit with multiple safety switches can be used. In this case, each safety switch can monitor, for example, a separate area for protecting the device. In this case, each safety switch generates a corresponding switching signal, which is associated with the read switching signal of the safety switch upstream in the series connection and then transmitted to the next safety switch. Only when all safety switches generate a release signal is the operation of the device released by the control device realized. Typically, the safety switches in the series circuit form slaves of a master-slave arrangement. In the case of such a master-slave arrangement, the diagnostic operation is usually realized in such a way that the master periodically or aperiodically queries data, in particular sensor data or switch data. Summary of the invention

[0006] The invention is based on the object of providing a series circuit of safety switches having an extended functionality.

[0007] In order to achieve this object, the features of the independent claim are provided. Advantageous embodiments and expedient developments are described in the dependent claims.

[0008] The invention relates to a series circuit with a plurality of safety switches. The series circuit has wiring to connect the safety switches. Signals can be output by the safety switches, wherein it is detected based on the recording of these signals by other safety switches in the series circuit: whether the wiring is designed to connect a host and whether such a host is connected and can communicate. The operation of the safety switch is predetermined accordingly.

[0009] Furthermore, the invention relates to a corresponding method.

[0010] The essential advantage of the invention is that the safety switch itself can autonomously determine the configuration of the series circuit by analyzing the readability of the signals of other safety switches and can set and execute its operation accordingly. This achieves a high functionality of the series circuit according to the invention.

[0011] Depending on whether the safety switch of the series circuit is connected to a master-slave system, different wirings are provided for connecting the series circuit of safety switches. Due to these different wirings, the readability of the signals of the safety switches to the other safety switches changes, which makes it possible to clearly identify whether the series circuit is designed for master-slave operation. In addition, by recording the signals of the master, which differ from the signals of the safety switch as a slave in the master-slave system, it is possible to clearly identify whether the master is connected to the safety switch.

[0012] Since the safety switch can detect these connection types and differentiate them from one another, the safety switch can autonomously adapt its operating method.

[0013] Since the safety switch is designed for safety technology, each safety switch has a redundant input and output structure, through which the switching signal generated in the safety switch can be transmitted. To form a series circuit, the redundant output of the safety switch is connected to the redundant input of the subsequent safety switch.

[0014] The switching signal is a safety-related signal whose switching state indicates the current monitoring state of a unit to be monitored, for example a separate protective device, in particular a protective door, by means of which access to a hazardous area can be closed.

[0015] The device protected by means of the safety switch is only operated when each safety switch generates a release signal as a switching signal. In this case, the safety switch generates its switching signal based on the current monitoring state and also based on the switching signal that has been generated by the upstream safety switch and has been read into this safety switch. The switching signal generated in the safety switch is then transmitted to the safety switch downstream in the series connection until finally the switching signal queued at the output of the series circuit is supplied to the control device.

[0016] Furthermore, each safety switch has a communication connection. Only in the case of a design for operation in a series circuit with a host computer, a line is led from each communication connection to the diagnostic line. Communication can be carried out bidirectionally.

[0017] Here, the master can be connected to the diagnostic line. The slaves are therefore wired in parallel with the master.

[0018] Both safety-related data and non-safety-related data are transmitted via the diagnostic link, which is used in particular in master-slave operation so that the master can control and / or in particular periodically or aperiodically query the slave formed by the safety switch.

[0019] According to the invention, the data transmitted via the diagnostic line are used in the safety switch to check whether the series circuit is designed for operation with a host computer.

[0020] Here, the following is utilized: In the case of a design for master-slave operation, the data transmitted by a safety switch via the communication connector are made available to the other safety switches via the diagnostic line. However, if the series circuit is not designed for master-slave operation, the communication connector is used as a message output and is not connected via the diagnostic line. The safety switch does not make message data and / or diagnostic data available to the other safety switches via the communication connector, but rather directly to an external unit, in particular a control device. Thus, it is possible to determine simply and reliably whether the series circuit is designed for master-slave operation by checking whether the data output by the safety switch via the communication connector is made available to the other safety switches.

[0021] According to an advantageous embodiment, during the start-up phase, a test pattern is generated by each safety switch, based on which the position of the respective safety switch in the series circuit is determined. This start-up phase is in particular the start-up acceleration phase at each start-up of the device before the start of the normal operation phase (so-called operating mode). The information in the test pattern (i.e. the information about the position value of the safety sensor in the series circuit) is used to determine the wiring.

[0022] The indication of the position value of the safety switch in the series circuit and thus the address of the safety switch in the series circuit is initiated by the safety switch itself in that the safety switch sends a test pattern in the form of pulses via at least one output, which is in particular designed as a safety output. After sending the pulses, each safety switch checks at at least one input, which is in particular designed as a safety input, whether pulses forming the test pattern have been received.

[0023] The first safety switch of the series circuit, whose input is connected to a bridge switch, for example, receives a static input signal at at least one of its inputs. The safety switch is therefore identified as the first safety switch of the series circuit and transmits a test pattern in the form of pulses as an output signal via at least one of its outputs to the next safety switch in the series circuit. The safety switch reads the pulses as a test pattern at at least one of its inputs, identifies the safety switch as the second safety switch in the series circuit, and accordingly transmits two pulses as a test pattern via at least one of its outputs to the next safety switch. This continues until each safety switch has been addressed according to its test pattern, i.e. its position in the series circuit as determined by the number of pulses. The information about the test pattern is then output via the communication connection of the respective safety switch.

[0024] Since the wiring of the series circuit and thus the structure of the series circuit is ascertained during the commissioning phase, which occurs before operational operation, based on the test pattern, it is also possible to adjust the operating mode of the safety switch during the commissioning phase, so that the safety switch of the series circuit can be adapted to the existing series circuit and the operation of the series circuit can be started without further adaptation. This makes it possible to replace the safety switch during operation of the series circuit.

[0025] In the event that the safety switch does not receive any information about the test pattern of the other safety switches during the commissioning phase, the safety switch autonomously switches to operation without a master and operates the communication connection as a message output.

[0026] Since the information about the test pattern of the safety switch is not detected by the other safety switches—preferably within a predefined pause time interval—it is detected that the communication connector is not connected to the diagnostic line, so that master-slave operation is not possible.

[0027] An autonomous reconfiguration of the communication connection as a message output then takes place in the safety switch, so that communication with an external unit (for example a control device which controls the installation to be protected) can be directly effected via the communication connection.

[0028] For the case in which information about the test pattern of the safety switch is received during the commissioning phase from other safety switches and a host connected to the diagnostic line, the position of the safety switch in the series circuit is monitored by the host.

[0029] In this case, the information about the test pattern or the signal usually provided to the diagnostic circuit not only identifies that the series circuit is designed for master-slave operation, but also that the master is also connected to the safety switch and is ready for communication.

[0030] In this case, the position value encoded in the information about the test pattern is transmitted to the host computer, so that the number of safety switches and their position within the series circuit are known in the host computer.

[0031] The position is received by the master as an address, at which the master regards the safety switch as a slave in a master-slave operation.

[0032] For the situation in which no host is connected to the diagnostic line during the commissioning phase or the connected host is not ready for operation and information about the test pattern of the safety switch is received from another safety switch, the selected safety switch monitors the position of the safety switch in the series circuit.

[0033] The design of the series circuit is therefore identified as a master-slave system based on the information about the test pattern output by the safety switch to the diagnostic circuit. However, during the commissioning phase no master is connected to the safety switch and / or no master is ready for operation.

[0034] In the case of such known master-slave systems, the master-slave system cannot be started without a master. In contrast, the functionality of the system according to the invention is expanded to the extent that the system can also be started without a master.

[0035] In this case, the selected safety switch temporarily assumes the master functionality, wherein the selected safety switch is expediently the safety switch which takes up the first position in the series circuit.

[0036] The selected safety switch records information about the test pattern of the other safety switches: how many safety switches are connected to the series circuit.

[0037] After the publication of the position has taken place, the selected safety switch sends the number of all safety switches as a broadcast signal, wherein the host receives the number as soon as it is connected to the series circuit and is ready for operation.

[0038] This procedure has the following advantages: When a master is connected to the series circuit, it can assume the control functions of the master as a master without interrupting the operation of the entire system. Since the master receives the broadcast signal from the selected safety switch, the number of connected slaves is known in the master, so that the master can periodically or aperiodically query the safety switch as a slave, wherein the slave, in particular the selected safety switch, only responds to the query of the master, that is, sends a signal via the communication connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention is described below with reference to the accompanying drawings. The accompanying drawings show:

[0040] Figure 1 An embodiment of a series circuit of a safety switch according to the present invention is shown;

[0041] Figure 2 ad shows according to Figure 1 Timing diagram of the test pattern of the safety switch in a series circuit. DETAILED DESCRIPTION

[0042] Figure 1 An exemplary embodiment of a series circuit 1 according to the invention is shown in a highly schematic manner, which consists of a multiple arrangement of safety switches 2 .

[0043] Here, Figure 1 A series circuit 1 of four identically designed safety switches 2 is shown. However, the safety switches 2 do not necessarily have to be identical. In general, the series circuit 1 can also have a different number of safety switches 2. Finally, a single safety switch 2 can also be used.

[0044] The safety switch 2 is used in the field of safety technology. The safety switch 2 is used to monitor, in particular, whether a separate protective device (e.g. a door, an entrance to a danger zone where dangerous equipment is arranged) is closed. In this case, the closed position of the door can be controlled according to a transponder signal. In this case, the transponder can be arranged in an actuator, which is arranged at the door and can move with the door. The safety switch 2 is then arranged at the frame that delimits the entrance. If the door is in the closed position, the transponder is in the reading area of ​​an RFID (radio frequency identification) reader, which is arranged in the safety switch 2, so that the RFID reader can receive the transponder signal of the transponder.

[0045] Each safety switch 2 has a redundant input structure with two inputs 3 and a redundant output structure with two outputs 4, through which switching signals generated in the safety switch 2 are transmitted as safety-related signals, according to which the device is released or shut down, so that these signals are processed in a higher-level control device. The inputs 3 are designed as safety inputs and the outputs 4 are designed as safety outputs.

[0046] In accordance with Figure 1 In the series circuit 1, the output end 4 of the safety switch 2 is connected to the input end 3 of the downstream safety switch 2 through the line 5. The output end 4 of the last safety switch 2 is connected to the host 6.

[0047] The host 6 can be designed, for example, as a safety relay or an I / O module (e.g., an I / O connection module). On the one hand, the host 6 is used to connect to a higher-level control device, which controls the operation of the device to be monitored. In addition, the host 6 controls a master-slave system, which, in addition to the host 6, also has a safety switch 2 as a slave. For this purpose, the safety switch 2 and the host 6 are connected via a diagnostic line 7. In this case, each safety switch 2 has a communication connection 10, from which a further line 8 leads to the diagnostic line 7.

[0048] During the operation of the series circuit 1, each safety switch 2 takes over the monitoring function of the safety switch and generates a switching signal accordingly, which is linked to the switching signal of the upstream safety switch 2 (if any) read via the line 5 and then transmitted to the next safety switch 2 via the line 5. The last safety switch 2 then transmits the switching signal to the host 6, which provides the switching signal to the control device. Only when all safety switches 2 of the series circuit 1 have generated a release signal, the control device releases the operation of the device.

[0049] Alternative Figure 1 In the variant shown in which the series circuit 1 forms a master-slave system, the communication connector 10 of the safety switch 2 is also not connected to the diagnostic line 7 but is directly connected via the line 8 to an external unit, in particular a control device.

[0050] During a startup acceleration phase (hereinafter referred to as a startup phase, which is before the working operation (ie, normal operation phase)) at each startup of the device, the addressing of each safety switch 2 in the series circuit 1 is performed.

[0051] The indication of the position value of the safety switch 2 in the series circuit 1 and thus the address of the safety switch 2 in the series circuit 1 is initiated by the safety switch 2 itself in that the safety switch sends a test pattern in the form of pulses via at least one output 4, which is in particular designed as a safety output. After sending the pulses, each safety switch 2 checks at at least one input 3, which is in particular designed as a safety input, whether the test pattern in the form of pulses has been received.

[0052] The first safety switch 2 of the series circuit 1 (at Figure 1 ) - the input of the first safety switch is connected to a bridge switch, for example - a static input signal is received at at least one input of the first safety switch. Therefore, the safety switch 2 is identified as the first safety switch 2 of the series circuit 1 and sends a test pattern in the form of pulses as an output signal to the next safety switch 2 in the series circuit 1 through at least one output 4 of the safety switch. The safety switch 2 reads the pulses as a test pattern at at least one input 3 of the safety switch, which is identified as the second safety switch 2 in the series circuit 1 and correspondingly sends two pulses as a test pattern to the next safety switch 2 through at least one output 4 of the safety switch. This continues until each safety switch 2 is addressed according to the test pattern of the safety switch, i.e., the position in the series circuit 1 determined by the number of pulses. Figure 2 Test patterns for the individual safety switches 2 are shown in ad. Information about these test patterns is then output via the communication connection 10 of the respective safety switch 2.

[0053] According to the invention, different configurations of the series circuit 1 are detected autonomously by the safety switch 2 during the commissioning phase. For this purpose, information about the test pattern is used, which is output via the communication connector 10 of the individual safety switches. This information contains the position of the respective safety switch.

[0054] If the series connection 1 does not form a master-slave system, that is, the communication connector 10 is not connected to the diagnostic line 7, then no information about the test pattern is provided via the diagnostic line 7. After a safety switch 2 has not received a test pattern from another safety switch 2 within a predetermined pause time interval, all safety switches 2 switch the configuration of the communication connector 10 to the message output, so that they can communicate directly with external units.

[0055] If the series circuit 1 - such as Figure 1 As shown in FIG. 1 , a master-slave system is formed, which is then detected by the safety switches 2 during the startup phase by virtue of the fact that these safety switches are respectively detected by the other safety switches 2 during the startup phase.

[0056] For the following situation - during the commissioning phase, the host 6 is connected to the series circuit 1 (such as Figure 1 ), the master 6 monitors the position release of the safety switch 2 and subsequently uses this position as an address at which it regards the safety switch 2 as a slave in master-slave operation.

[0057] For the following situation - during the commissioning phase, the host 6 has not yet been connected to the series circuit 1 or the host is not ready for operation (such as in Figure 1 As explained by interrupt 9 in the figure), the operation of the series circuit 1 can be started (ie even without the host 6).

[0058] In this case, the position release of the safety switches 2 is monitored by the first safety switch 2 in that it records and stores information about the test pattern of the other safety switches 2. The first safety switch 2 thus temporarily takes over the host functionality as the selected safety switch 2.

[0059] After the selected safety switch 2 has recorded the positions of all safety switches 2 connected to the series circuit 1, which is determined by the fact that no new information about the test pattern enters after a predetermined time, the selected safety switch 2 sends the number of safety switches in the series circuit 1 as a broadcast signal to the diagnostic line 7. As soon as the host 6 is connected to the series circuit 1 and the acceleration is started, the host receives the number of connected safety switches 2 and also takes over the host function in the series circuit 1. The host 6 then periodically or aperiodically queries the safety switch 2 for the address (i.e., position) of the safety switch, and the safety switch 2, as a slave, notifies the host 6 of the position. The slave, in particular the selected safety switch 2, then only responds to the query of the host 6.

[0060] List of reference numerals:

[0061] (1) Series circuit

[0062] (2) Safety switch

[0063] (3) Input terminal

[0064] (4) Output terminal

[0065] (5) Line

[0066] (6) Host

[0067] (7) Diagnostic circuit

[0068] (8) Line

[0069] (9) Interruption

[0070] (10) Communication connection terminal

Claims

1. A series circuit (1), comprising a plurality of safety switches (2), wherein: The series circuit (1) has a wiring for connecting the safety switches (2), wherein a signal can be output by the safety switches (2), characterized in that it is detected based on the signals provided by the other safety switches (2) in the series circuit (1) via a diagnostic line (7) whether the series circuit (1) is designed for master-slave operation, wherein each safety switch (2) has a communication connection (10), wherein only in the case of the series circuit (1) designed for operation with a master (6), a line (8) leads from each communication connection (10) to a diagnostic line (7), wherein the master (6) can be connected to the diagnostic line (7), wherein by recording the signals of the master (6) it is detected whether the master (6) is connected to the safety switch (2), and the operation of the safety switch (2) is accordingly predetermined.

2. The series circuit (1) according to claim 1, characterized in that A signal output in one safety switch (2) via the communication connection (10) is supplied to the other safety switch (2).

3. The series circuit (1) according to claim 1 or 2, characterized in that In the case of a design for operation without the host computer (6), the communication connection (10) of the safety switch (2) is operated as a message output.

4. The series circuit (1) according to claim 1 or 2, characterized in that During a startup phase, a test pattern is generated by each safety switch (2), based on which the position of the corresponding safety switch (2) in the series circuit (1) is determined, wherein information about the test pattern is used to determine the wiring of the series circuit (1).

5. The series circuit (1) according to claim 4, characterized in that Information about the test pattern is transmitted via the diagnostic line (7), wherein the information is used to determine the wiring.

6. The series circuit (1) according to claim 5, characterized in that The safety switch (2) autonomously switches to operation without the host (6) and the communication connection (10) operates as the message output in the case that during the start-up phase the safety switch (2) receives no information about test patterns of other safety switches (2).

7. The series circuit (1) according to claim 5 or 6, characterized in that Monitoring of the position of the safety switch (2) in the series circuit (1) by the host (6) is published in the following case: during a start-up phase, information about a test pattern of the safety switch (2) is received by the other safety switches (2) and the host (6) connected to the diagnostic line (7).

8. The series circuit (1) according to claim 7, characterized in that The selected safety switch (2) monitors the position release of the safety switch (2) in the series circuit (1) for the following situation: during a start-up phase, none of the host computers (6) is connected to the diagnostic line (7) and information about a test pattern of the safety switch (2) is received from the other safety switches (2).

9. The series circuit (1) according to claim 8, characterized in that The selected safety switch (2) is the safety switch (2) which occupies the first position in the series circuit (1).

10. The series circuit (1) according to claim 7, characterized in that After the publication of the position is achieved, the selected safety switch (2) sends the number of all safety switches (2) as a broadcast signal, wherein the host (6) receives the number as long as the host (6) is connected to the series circuit (1).

11. The series circuit (1) according to claim 4, characterized in that The test pattern for each safety switch (2) comprises a pulse sequence having a number of pulses encoding the position of the corresponding safety switch (2) in the series circuit (1).

12. The series circuit (1) according to claim 1 or 2, characterized in that Each safety switch (2) has a redundant input and output structure, via which a switching signal generated in the safety switch (2) can be transmitted, wherein, in order to form the series circuit (1), the redundant output (4) of the safety switch (2) is connected to the redundant input (3) of the downstream safety switch (2).

13. A method for operating a series circuit (1) having a plurality of safety switches (2), wherein: The series circuit (1) has a wiring for connecting the safety switches (2), wherein a signal can be output by the safety switches (2), characterized in that it is detected based on the signals provided by the other safety switches (2) in the series circuit (1) via a diagnostic line (7) whether the series circuit (1) is designed for master-slave operation, wherein each safety switch (2) has a communication connection (10), wherein only in the case of the series circuit (1) designed for operation with a master (6), a line (8) leads from each communication connection (10) to a diagnostic line (7), wherein the master (6) can be connected to the diagnostic line (7), wherein by recording the signals of the master (6) it is detected whether the master (6) is connected to the safety switch (2), and the operation of the safety switch (2) is accordingly predetermined.

Images