Patent ID: 12204326

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

<Serial Cascade Connector System (First Embodiment)>

FIG.1is a diagram illustrating a first embodiment of a serial cascade connector system. A serial cascade connector system200of the first embodiment includes a plurality of (eight in this drawing) safety switches210(1) to210(8), a power unit220, a safety controller230, a non-safety controller240, and a wire saving unit250.

Note that, in a case where matters common to the safety switches210(1) to210(8) are described, numerals in parentheses such as (1) to (8) following reference numerals can be omitted.

The safety switch210includes eight ports of a power terminal P21(VCC), a ground terminal P22(GND), OSSD output terminals P23and P24(OSSD1_O and OSSD2_O), OSSD input terminals P25and P26(OSSD1_I and OSSD2_I), a downstream communication terminal P27(COM_D), and an upstream communication terminal P28(COM_U).

Note that each of the safety switches210includes a switch body and an actuator (none of which are illustrated), and is arranged so as to detect an open or closed state of each corresponding door. Further, at least one of the safety switches210(1) to210(8) includes a lock portion (such as an electromagnet) that can lock movement of the actuator in response to a lock input.

Among the safety switches210(1) to210(8), the most upstream safety switch210(8) sends an OSSD output to the safety switch210(7) connected to the downstream side of the own switch based on the open or closed state of the door corresponding to the own switch.

Each of the intermediate safety switches210(0(where i=2, 3, . . . , 7) receives, as an OSSD input, an OSSD output that is output from the safety switch210(i+1) connected to the upstream side of the own switch, and sends an OSSD output to the safety switch210(i−1) connected to the downstream side of the own switch based on the OSSD input and the open or closed state of the door corresponding to the own switch.

The most downstream safety switch210(1) receives, as an OSSD input, the OSSD output that is output from the safety switch210(2) connected to the upstream side of the own switch, and sends an OSSD output to the wire saving unit250connected to the downstream side of the own switch based on the OSSD input and the open or closed state of the door corresponding to the own switch.

Note that the OSSD output from the safety switch210(1) to the wire saving unit250is set to an ON signal (=operation permission signal) when all the corresponding doors of the safety switches210(1) to210(8) are closed, and is set to an OFF signal (=operation non-permission signal) when at least one of the doors is not closed.

Further, the most downstream safety switch210(1) performs bidirectional communication with the wire saving unit250connected to the downstream communication terminal P27(COM_D), and performs bidirectional communication with the safety switch210(2) connected to the upstream communication terminal P28(COM13). Similarly, each of the intermediate safety switches210(i) performs bidirectional communication with the safety switch210(i−1) connected to the downstream communication terminal P27(COM_D), and performs bidirectional communication with the safety switch210(i+1) connected to the upstream communication terminal P28(COM13). In the bidirectional communication described above, an AUX output and a lock input in the conventional example (FIG.10) are transmitted and received as communication data.

When focusing on the AUX output, the most upstream safety switch210(8) outputs the AUX output based on the open or closed state, the locked state, an error state, and the like of the door corresponding to the own switch as downstream-facing communication data. The safety switch210(7) on the immediately downstream side superimposes its own AUX output on the communication data from the upstream side and outputs the communication data to the downstream side. Thereafter, similar signal processing is performed. As a result, downstream-facing communication data output from the most downstream safety switch210(1) to the wire saving unit250includes contents in which all the AUX outputs of the safety switches210(1) to210(8) are bundled into one.

The safety switch210(1) corresponds to a “first safety switch”. The safety switch210(2) connected to the upstream side of the safety switch210(1) corresponds to a “second safety switch”. The wire saving unit250connected to the downstream side of the safety switch210(1) corresponds to a “wiring unit”. The safety controller230connected to the wire saving unit250corresponds to a “safety control apparatus”.

The OSSD outputs (OSSD1_O and OSSD2_O) output from the safety switch210(1) to the wire saving unit250correspond to a “first safety signal”. The OSSD inputs (OSSD1_I and OSSD2_I) input from the safety switch210(2) to the safety switch210(1) correspond to a “second safety signal”.

The communication data output from the safety switch210(1) to the wire saving unit250, that is, communication data in which the AUX outputs (AUX1to AUX8) respectively indicating the states of the safety switches210(1) to210(8) are bundled into one corresponds to “first state information”. The communication data output from the safety switch210(2) to the safety switch210(1), that is, communication data in which the AUX outputs (AUX2to AUX8) respectively indicating the states of the safety switches210(2) to210(8) are bundled into one corresponds to “second state information”.

In the safety switch210(1), the OSSD input terminals P25and P26(OSSD1_I and OSSD2_I) correspond to a “first safety input terminal” configured to receive the OSSD input from the safety switch210(2). The OSSD output terminals P23and P24(OSSD1_O and OSSD2_O) correspond to a “first safety output terminal” configured to output the OSSD output to the wire saving unit250.

Further, in the safety switch210(1), the upstream communication terminal P28(COM_U) corresponds to an “upstream communication terminal” configured to receive the downstream-facing communication data (=AUX output) from the safety switch210(2) and to output upstream-facing communication data (=lock input) to the safety switch210(2). On the other hand, the downstream communication terminal P27(COM_D) corresponds to a “downstream communication terminal” configured to receive the upstream-facing communication data (=lock input) from the wire saving unit250and to output the downstream-facing communication data (=AUX output) to the wire saving unit250.

The wire saving unit250is provided between the most downstream safety switch210(1), and each of the power unit220, the safety controller230, and the non-safety controller240.

The wire saving unit250operates by receiving supply of an input voltage VCC and a ground voltage GND from the power unit220. Note that the wire saving unit250also functions as a power supply path from the power unit220to the safety switches210(1) to210(8).

Further, the wire saving unit250performs through-output of the OSSD outputs (OSSD1and OSSD2) received from the safety switch210(1) to the safety controller230. Note that the “through-output” here means that no logic processing is performed on the OSSD output. That is, it can be understood that the wire saving unit250performs “through-output” of the OSSD output even in a case where a buffer is provided on a signal path through which the OSSD output is transmitted, or even in a case where a bias is applied to the OSSD output.

Further, the wire saving unit250receives a lock instruction (LOCK) from the safety controller230, and outputs upstream-facing communication data (=lock input) to the safety switch210(1) based on the lock instruction (LOCK). Note that the lock input described above is sequentially transmitted from the most downstream safety switch210(1) to the most upstream safety switch210(8). Therefore, among the safety switches210(1) to210(8), those including the lock portion (such as the electromagnet) can lock the movement of the actuator in response to the lock input.

Furthermore, the wire saving unit250receives downstream-facing communication data (=bundle data of AUX outputs) from the safety switch210(1), separates this into the individual AUX outputs (AUX1to AUX8), and outputs the individual AUX outputs to the non-safety controller240. Therefore, the non-safety controller240can individually grasp the state of each of the safety switches210(1) to210(8).

In this manner, in the serial cascade connector system200of the present embodiment, as in the above-described conventional example (FIG.10), the number of wires for transmitting the OSSD output is integrated into one (inFIG.1, two wires for duplexing).

Further, the wire saving unit250has a function of performing bidirectional communication with the safety switch210(1) (eventually, all the safety switches210(1) to210(8)) via a single communication line. That is, in the above-described conventional example (FIG.10), sixteen (=LOCK×8+AUX×8) wires, laid between each of the safety controller130and the non-safety controller140and the safety switches110(1) to110(8), are integrated into one.

Therefore, the number of wires input to the wire saving unit250can be reduced with respect to the total number of the safety switches210(1) to210(8). As a result, wiring work for collectively controlling the safety switches210(1) to210(8) can be simplified.

Further, the serial cascade connector system200of the present embodiment does not require a safety controller or a safety PLC having a function of communicating with a specific sensor. In a case where the safety PLC is introduced instead of the safety controller230and the non-safety controller240, it is necessary to program how to process signals from devices to be controlled (here, the safety switches210(1) to210(8)) by the safety PLC.

On the other hand, what kind of signal input/output processing (and display processing) needs to be performed between the safety switches210(1) to210(8) and each of the safety controller230and the non-safety controller240is set in advance in the wire saving unit250(particularly, an MCU built therein). Therefore, the safety controller230and the non-safety controller240can operate as if the safety switches210(1) to210(8) are directly connected to each of the safety controller230and the non-safety controller240.

Further, in a case where the safety PLC is introduced instead of the safety controller230and the non-safety controller240, an OSSD output (safety output) is input to the safety PLC in addition to an AUX output (non-safety output). In other words, the safety PLC intervenes in a signal system for transmission and reception of the OSSD output (safety output). In a safety system including a plurality of safety devices, a safety parameter of the entire safety system is evaluated based on failure rates of the respective safety devices constituting the safety system. Therefore, it can be said that the safety parameter is greatly affected when the safety PLC having a complicated function is incorporated in the safety system.

On the other hand, the wire saving unit250is not a device that performs reception and transmission after performing some logic processing on the OSSD output like the safety PLC, but performs the through-output of the OSSD outputs (OSSD1and OSSD2), input from the safety switch210(1), directly to the safety controller230. Therefore, even if the wire saving unit250is incorporated in the safety system, the influence on the safety parameter can be suppressed to the minimum. Further, as described later, the safety switch210can sense a failure occurring in the own switch and reflect such a failure sensing result in the OSSD output. Therefore, a failure sensing function of the safety switch210can be directly utilized.

Further, in the serial cascade connector system200of the present embodiment, it is possible to detect the states of the safety switches more than the number of input/output systems (terminals) of the AUX output, which is different from the related art disclosed in JP 2020-27772 A.

Note that it is sufficient for the number of signal lines connecting the safety switch210(1) and the wire saving unit250to be five or less as illustrated in this drawing. Therefore, it is possible to use a general-purpose M12connector cable.

<Consideration Regarding Lock Timing>

Meanwhile, in the serial cascade connector system200of the present embodiment, the lock input is transmitted to each of the safety switches210(1) to210(8) through the upstream-facing communication data output from the safety controller230.

At this time, if all of locks of the safety switches210(1) to210(8), which are input targets, operate simultaneously, depending on specifications of devices, an excessive current flows through a power line, or a normal operation cannot be performed due to a voltage drop in a cable resistor. In view of this, lock timings of the safety switches210(1) to210(8) are preferably controlled to be shifted from each other.

That is, the serial cascade connector system200is preferably configured such that a lock input for driving the lock portion of the upstream-side safety switch210(2) is input to the safety switch210(2) with a time difference at a timing different from a timing at which the lock portion in the downstream-side safety switch210(1) is driven when the wire saving unit250receives the lock instruction (LOCK) from the safety controller230. The same applies to the safety switches210(3) to210(8) further provided on the upstream side.

For example, a case where a batch of lock instruction bits is included in upstream-facing communication data output from the wire saving unit250is considered. In this case, unless some measures are taken, all the locks of the safety switches210(1) to210(8) can be operated almost at the same time.

Therefore, a delay function of a lock instruction bit may be incorporated in at least one of the safety switches210(1) to210(7) other than the most upstream side. As a technique for realizing this delay function, for example, a lock operation of the own switch may be started at a time point when it is recognized that the lock instruction bit is set to transmit a temporarily cleared lock instruction to the upstream side of the own switch, and then, a lock instruction bit may be set again and transmitted to the upstream side of the own switch at a time point when the lock operation of the own switch is completed. According to such a delay function, a timing at which the lock instruction bit is transmitted to the upstream side can be delayed, the lock timings of the safety switches210(1) to210(8) can be shifted from each other.

<Serial Cascade Connector System (Second Embodiment)>

FIG.2is a diagram illustrating a second embodiment of the serial cascade connector system. The serial cascade connector system200of the present embodiment includes the wire saving unit250provided with a plurality of systems of ports (two systems of a port A and a port B in this drawing) with the configuration of the above-described first embodiment (FIG.1) as a base.

Six safety switches210(A1) to210(A6) are serially cascade-connected to the port A of the wire saving unit250via connectors CNT1to CNT6and cables CBL1to CBL8. Note that each of the connectors CNT1to CNT6includes a downstream-side socket, an upstream-side socket, and a switch-side socket.

The port A of the wire saving unit250is connected to the downstream-side socket of the connector CNT1via the cable CBL1. The upstream-side socket of the connector CNT1is connected to the downstream-side socket of the connector CNT2via the cable CBL2. The upstream-side socket of the connector CNT2is connected to the downstream-side socket of the connector CNT3via the cable CBL3. The upstream-side socket of the connector CNT3is connected to the downstream-side socket of the connector CNT4via the cable CBL4. The upstream-side socket of the connector CNT4is connected to the downstream-side socket of the connector CNT5via the cable CBL5. The upstream-side socket of the connector CNT5is connected to the downstream-side socket of the connector CNT6via the cable CBL6. The upstream-side socket of the connector CNT6is connected to a terminator TM1(also referred to as a termination resistor or a dummy load).

The switch-side sockets of the connectors CNT1, CNT2, CNT5, and CNT6are directly connected to the safety switches210(A1),210(A2),210(A5), and210(A6), respectively. Note that each of the safety switches210(A1),210(A2),210(A5), and210(A6) includes a lock portion using an electromagnet. Therefore, the safety switches210(A1),210(A2),210(A5), and210(A6) can implement door locking in response to a lock input transmitted from the wire saving unit250.

The switch-side socket of the connector CNT3is connected to the safety switch210(A3) via the cable CBL7. The switch-side socket of the connector CNT4is connected to the safety switch210(A4) via the cable CBL8. Note that the safety switch210(A3) includes a lock portion using a spring lock. On the other hand, the safety switch210(A4) does not include any lock portion. Therefore, the safety switches210(A3) and210(A4) are not capable of implementing door locking even if receiving the lock input transmitted from the wire saving unit250.

Two safety switches210(B1) and210(B2) are serially cascade-connected to the port B of the wire saving unit250via connectors CNT7and CNT8and cables CBL9and CBL10, respectively. Note that each of the connectors CNT7and CNT8includes a downstream-side socket, an upstream-side socket, and a switch-side socket.

The port B of the wire saving unit250is connected to the downstream-side socket of the connector CNT7via the cable CBL9. The upstream-side socket of the connector CNT7is connected to the downstream-side socket of the connector CNT8via the cable CBL10. The upstream-side socket of the connector CNT8is connected to a terminator TM2.

The switch-side sockets of the connectors CNT7and CNT8are directly connected to the safety switches210(B1) and210(B2), respectively. Each of the safety switches210(B1) and210(B2) includes a lock portion using an electromagnet. Therefore, the safety switches210(B1) and210(B2) can implement door locking in response to the lock input transmitted from the wire saving unit250.

As described above, the maximum of eight safety switches in total can be connected to the ports A and B of the wire saving unit250in the serial cascade connector system200of the present embodiment. That is, in a case where x (where 0≤x≤8) safety switches are connected to the port A, the maximum of (8−x) safety switches can be connected to the port B.

The wire saving unit250operates by receiving supply of an input voltage VCC and a ground voltage GND from the power unit220. Note that the wire saving unit250also functions as a power supply path from the power unit220to each of the ports A and B.

Further, the wire saving unit250performs through-output of OSSD outputs (OSSD1_A/B and OSSD2_A/B), input from the safety switches210(A1) and210(B1) to the ports A and B, respectively, to the safety controller230.

Further, the wire saving unit250receives two systems of lock instructions (LOCK_A/B) from the safety controller230, and outputs the lock instructions to the safety switches210(A1) and210(B1) from the ports A and B, respectively, as upstream-facing communication data.

Furthermore, the wire saving unit250receives downstream-facing communication data input to each of the ports A and B from the safety switches210(A1) and210(B1), separates this into individual AUX outputs (AUX1to AUX8), and outputs the individual AUX outputs to the non-safety controller240.

As described above, the wire saving unit250basically operates similarly to that of the first embodiment (FIG.1) except that the two systems of the ports A and B are included. Therefore, it is possible to simplify wiring work for collectively controlling the safety switches210(A1) to210(A6),210(B1), and210(B2).

FIG.3is a diagram illustrating an application example of the serial cascade connector system200according to the second embodiment. As illustrated in this drawing, a case in which four sides of a hazard source (such as a machine tool) are surrounded by isolation walls, and a plurality of doors are provided on different side surfaces, respectively, is considered. In this case, it can be said that wires for safety switches respectively provided on the doors desirably branch into a plurality of systems from the wire saving unit250in terms of wiring work.

With reference to this drawing, the safety switches210(A1) to210(A3) arranged on the isolation wall on the front side on the paper surface are cascade-connected to the port A of the wire saving unit250. On the other hand, the safety switches210(B1) and210(B2) arranged on the isolation wall on the back side of the paper surface are cascade-connected to the port B of the wire saving unit250.

Further, in addition to the above-described wiring reason, there may be a case where it is desired to individually set input/output control (for example, lock control) of each of safety switches provided in each of a door for workers and a door for maintenance. For this purpose, the wire saving unit250desirably includes a plurality of systems of ports with the OSSD output and the lock input being independent for each of the systems.

<Wire Saving Unit>

FIG.4is a view illustrating an appearance of the wire saving unit250according to the second embodiment. With reference to this drawing, the wire saving unit250includes switch connection connectors251A and251B, OSSD indicator lamps252A and252B, switch state indicator lamps253, and setting changeover switches254.

The switch connection connector251A is a connector corresponding to the port A. As illustrated inFIG.2, the cable CBL1is connected to the switch connection connector251A. For example, the switch connection connector251A may be provided on the right side of an upper region in a front view of the wire saving unit250as illustrated in this drawing.

The switch connection connector251B is a connector corresponding to the port B. As illustrated inFIG.2, the cable CBL9is connected to the switch connection connector251B. For example, the switch connection connector251B may be provided below the switch connection connector251A in the front view of the wire saving unit250as illustrated in this drawing. In the present embodiment, the port A and the port B are configured using the switch connection connector251A and the switch connection connector251B, respectively, provided in a housing of the wire saving unit250, but may be configured using connectors provided at a tip of a cable by providing the cable that extends from the inside to the outside of the housing of the wire saving unit250.

The OSSD indicator lamp252A is turned on and off according to the OSSD outputs of the safety switches210cascade-connected to the port A. According toFIG.2, the OSSD indicator lamp252A is lit in green when all the OSSD outputs of the safety switches210(A1) to210(A6) are ON, and is turned off when at least one of them is OFF. For example, the OSSD indicator lamp252A may be provided at an upper right corner of the switch connection connector251A in the front view of the wire saving unit250as illustrated in this drawing.

The OSSD indicator lamp252B is turned on and off according to the OSSD outputs of the safety switches210cascade-connected to the port B. According toFIG.2, the OSSD indicator lamp252B is lit in green when all the OSSD outputs of the safety switches210(B1) and210(B2) are ON, and is turned off when at least one of them is OFF. For example, the OSSD indicator lamp252B may be provided at an upper right corner of the switch connection connector251B in the front view of the wire saving unit250as illustrated in this drawing.

The switch state indicator lamps253display states of the maximum of eight safety switches210, respectively, based on the downstream-facing communication data (=bundle data of the AUX output) input to each of the ports A and B. For example, eight switch state indicator lamps253may be vertically aligned in an array on the left side of the upper region (=the left side of each of the switch connection connectors251A and251B) in the front view of the wire saving unit250as illustrated in this drawing.

Note that the eight aligned switch state indicator lamps253correspond to the safety switches210connected to the port A in order from the top, and the safety switches210connected to the port B in order from the bottom. According toFIG.2, among the eight switch state indicator lamps253, six in order from the top indicate the states of the safety switches210(A1) to210(A6), and two in order from the bottom indicate the states of the safety switches210(B1) and210(B2). With such an array, it is easy to distinguish state displays of the safety switches210(A1) to210(A6),210(B1), and210(B2) connected to the ports A and B with the minimum number of indicator lamps.

The correspondence relationship between an on/off state of the switch state indicator lamp253and the safety switch210is as follows. For example, when the safety switch210has detected and locked the actuator212, the corresponding switch state indicator lamp253is lit in green. When the safety switch210has detected and unlocked the actuator212, the corresponding switch state indicator lamp253blinks in green. When the safety switch210has not detected the actuator212, the corresponding switch state indicator lamp253is lit in red. When the safety switch210is in an error state, the corresponding switch state indicator lamp253blinks in red. When the safety switch210is not connected, the switch state indicator lamp253is turned off.

In this manner, the switch state indicator lamp253has more display types (=lighting in green, blinking in green, lighting in red, blinking in red, and turning off) than the above-described OSSD indicator lamps252A and252B.

The setting changeover switch254is a switch configured to switch between various settings of each of the safety switches210cascade-connected to the ports A and B. For example, five setting changeover switches254may be aligned vertically in a lower region in the front view of the wire saving unit250as illustrated in this drawing.

Note that examples of setting parameters switchable by the setting changeover switch254include an OSSD output format (PNP/NPN), an OSSD output condition (linkage with locking/linkage with opening or closing), fixing turn-off of a large indicator lamp, turning off green of the large indicator lamp, and changeover of a latch force of an electromagnet lock. An input result of the setting changeover switch254may be included in the upstream-facing communication data output from the wire saving unit250as a setting changeover command.

FIG.5is a diagram illustrating functional blocks of the wire saving unit250according to the second embodiment. The wire saving unit250of the present configuration example includes a plurality of external terminals P31to P48and P49(1) to P49(8) (VCC, VCC_A, VCC_B, GND, GND_A, GND_B, OSSD1_I_A, OSSD2_I_A, OSSD1_O_A, OSSD2_O_A, OSSD1_I_B, OSSD2_I_B, OSSD1_O_B, OSSD2_O_B, COM_A, COM_B, LOCK_A, LOCK_B, and AUX1to AUX8) as tools configured to establish electrical conduction with the outside of the unit.

The VCC terminal P31is a power input terminal configured to receive the input voltage VCC from the power unit220. The VCC_A terminal P32is connected to the VCC terminal inside the wire saving unit250, and is a power output terminal configured to output the input voltage VCC to the port A. The VCC_B terminal P33is connected to the VCC terminal inside the wire saving unit250, and is a power output terminal configured to output the input voltage VCC to the port B.

The GND terminal P34is a ground input terminal configured to receive the ground voltage GND from the power unit220. The GND_A terminal P35is connected to the GND terminal inside the wire saving unit250, and is a ground output terminal configured to output the ground voltage GND to the port A. The GND_B terminal P36is connected to the GND terminal inside the wire saving unit250, and is a ground output terminal configured to output the ground voltage GND to the port B. The VCC terminal P31and the GND terminal P34function as a power input unit that inputs power to the wire saving unit250. Both the VCC terminal P31and the GND terminal P34are provided at a tip of a cable extending from the housing of the wiring unit250. That is, the power input unit configured to input the power to the wiring unit250is the cable.

The OSSD1_I_A terminal P37and the OSSD2_I_A terminal P38are safety input terminals configured to receive the OSSD outputs (OSSD1and OSSD2), respectively, of the safety switch210connected to the port A. The OSSD_O_A terminal P39and the OSSD2_O_A terminal P40are respectively connected to the OSSD1_I_A terminal and the OSSD2_I_A terminal inside the wire saving unit250, and are safety output terminals configured to perform through-output of the OSSD output of the port A to the safety controller230. The OSSD_O_A terminal P39and the OSSD2_O_A terminal P40are provided at a tip of a cable extending from the housing of the wiring unit250. That is, a safety output unit configured to perform through-output of the OSSD output of the port A is the cable.

The OSSD1_I_B terminal P41and the OSSD2_I_B terminal P42are safety input terminals configured to receive the OSSD outputs (OSSD1and OSSD2), respectively, of the safety switch210connected to the port B. The OSSD_O_B terminal P43and the OSSD2_O_B terminal P44are respectively connected to the OSSD_I_B terminal and the OSSD2_I_B terminal inside the wire saving unit250, and are safety output terminals configured to perform through-output of the OSSD output of the port B to the safety controller230. The OSSD_O_B terminal P43and the OSSD2_O_B terminal P440are provided at a tip of a cable extending from the housing of the wiring unit250. That is, a safety output unit configured to perform through-output of the OSSD output of the port B is a cable.

The COM_A terminal P45is a wiring unit communication terminal configured to receive downstream-facing communication data (=bundle data of AUX outputs in the port A) from the safety switches210connected to the port A and outputting upstream-facing communication data (=lock input of the port A).

The COM_B terminal P46is a wiring unit communication terminal configured to receive downstream-facing communication data (=bundle data of AUX outputs in the port B) from the safety switches210connected to the port B and outputting upstream-facing communication data (=lock input of the port B).

The LOCK_A terminal P47and the LOCK_B terminal P48are lock instruction input terminals that receive the lock instructions of the ports A and B, respectively, from the safety controller230. The LOCK_A terminal P47and the LOCK_B terminal P48are provided at a tip of a cable extending from the housing of the wiring unit250. That is, a lock instruction input unit that receives the lock instructions is the cable.

The AUX1terminal P49(1) to the AUX8terminal P49(8) are non-safety output terminals configured to individually output, to the non-safety controller240, the AUX outputs (AUX1to AUX8) respectively corresponding to the maximum of eight safety switches210connected to the ports A and B. The AUX1terminal P49(1) to the AUX8terminal P49(8) are provided at a tip of a cable extending from the housing of the wiring unit250. That is, an information output unit configured to individually output the states of the safety switches210is the cable. Note that each of the power input unit configured to input the power to the wiring unit250, the safety output unit configured to perform the through-output of the OSSD outputs of the port A and the port B, the lock instruction input unit configured to receive the lock instructions, and the information output unit for individually outputting the states of the safety switches210is the cable in the present embodiment, but may be configured using a terminal block including corresponding terminals.

Further, the wire saving unit250includes, as functional blocks thereof, an MCU250a, a lock input unit250b, a voltage regulator250c, an OSSD monitor unit250d, an AUX output unit250e, and a light emitting diode [LED]250f.

The MCU250a(=corresponding to the wiring unit MCU) individually grasps the respective states of the maximum of safety switches210cascade-connected to the ports A and B based on the downstream-facing communication data (=bundle data of the AUX outputs in the ports A and B) received via the COM_A terminal P45and the COM_B terminal P46, respectively.

Then, the MCU250aperforms external output control and display output control (=switch state display control) according to the respective states of the safety switches210by controlling each of the AUX output unit250eand the LED250f. Note that the MCU250aalso has a function of performing display output control (=OSSD display control) in response to an OSSD output monitoring result from the OSSD monitor unit250d.

Further, the MCU250aoutputs the upstream-facing communication data (=lock inputs of the ports A and B) from the COM_A terminal P45and the COM_B terminal P46based on the lock instructions received from the LOCK_A terminal P47and the LOCK_B terminal P48via the lock input unit250b.

Note that the above-described signal input/output processing (and display processing) may be programmed in advance in the MCU250a.

The lock input unit250breceives the lock instructions of the ports A and B from the safety controller230via the LOCK_A terminal P47and the LOCK_B terminal P48, and sends these lock instructions to the MCU250a.

The voltage regulator250creceives supply of the input voltage VCC (for example, DC+24 V) and the ground voltage GND (for example, 0 V) from the power unit220via the VCC terminal P31and the GND terminal P34, and supplies power to each unit of the wire saving unit250. For example, a DC-DC converter is used as the voltage regulator250c.

The OSSD monitor unit250dcorresponds to a safety signal monitor unit that monitors the OSSD output transmitted inside the wire saving unit250and outputs the monitoring result to the MCU250a. For example, the OSSD monitor unit250dmay monitor one OSSD output (OSSD1) of the duplexed OSSD outputs (OSSD1and OSSD2).

With reference to this drawing, the OSSD monitor unit250dtakes out and monitors the OSSD output (OSSD1_A) of the port A from a safety output line laid between the OSSD1_I_A terminal P37and the OSSD1_O_A terminal P39, and takes out and monitors the OSSD output (OSSD1B) of the port B from a safety output line laid between the OSSD1_I_B terminal P41and the OSSD1_O_B terminal P43.

Note that the OSSD monitor unit250dmay include: a transmission unit that transmits a monitoring signal based on the OSSD outputs (OSSD1_A and OSSD1B) to be monitored; and a reception unit that receives the monitoring signal through isolated communication with the transmission unit and outputs the monitoring signal to the MCU250a.

For example, the transmission unit may transmit a non-electrical monitoring signal (for example, an optical signal) based on the OSSD outputs (OSSD1_A and OSSD1B) to be monitored. In this case, a photocoupler including a light emitting element (such as a light emitting diode) and a light receiving element (such as a phototransistor) can be suitably used as the transmission unit and the reception unit.

Of course, a scheme of the isolated communication inside the OSSD monitor unit250d(=between the transmission unit and the reception unit described above) is not limited to any optical isolation scheme, and a transformer isolation scheme, a capacitive isolation scheme, or the like may be adopted.

As described above, in a safety system including a plurality of safety devices, a safety parameter of the entire safety system is evaluated based on failure rates of the respective safety devices constituting the safety system. Therefore, it is preferable that as few constituent elements as possible can affect the OSSD output.

In view of this, the MCU250ais desirably isolated from the safety output line through which the OSSD output is transmitted. According to this configuration, the OSSD output itself can pass over the wire saving unit250through the dedicated safety output line, and the MCU250dcan monitor the OSSD output while ensuring the independence of the OSSD output.

Note that a best mode in which the OSSD output is affected by nothing is not to provide the OSSD monitor unit250d. However, existing safety switches also include a safety switch not having a function of outputting a safety state (≈door open or closed state) as communication data, and it is also possible to assume a case where such a safety switch is connected to the wire saving unit250. Therefore, it is necessary to provide the OSSD monitor unit250din the wire saving unit250in order to grasp at least safety states for each port and perform display output and the like.

The AUX output unit250eindividually outputs the AUX outputs (AUX1to AUX8) of the respective safety switches210to the non-safety controller240in response to an instruction from the MCU250d.

The LED250fperforms OSSD display and switch state display in response to an instruction from the MCU250d. Note that the LED250fcan be understood as, for example, the OSSD indicator lamps252A and252B and the switch state indicator lamp253inFIG.4.

<Safety Switch (Application Example)>

FIG.6is a view illustrating an application example of the safety switch210. This drawing illustrates a guard300surrounding a hazard source such as a machine tool. The guard300is an example of safety protection using isolation, and a part (particularly, around a door where with a safety switch) of a surrounding box including an isolation wall is depicted in this drawing. However, the depiction of this drawing is merely an example, and it can be understood by replacing the isolation wall of this drawing with an iron fence or the like.

The guard300includes double doors301L and301R as movable guards that can be opened and closed. Each of the doors301L and301R may be made of a transparent resin, reinforced glass, or the like. A safety switch210L is provided at an upper right corner of the left door301L. A safety switch210R is provided at an upper left corner of the right door301R. Each of the safety switches210L and210R can be understood to correspond to the safety switch210described above.

Note that alphabets L and R following reference numerals are used to distinguish between a plurality of the same or similar members. The alphabets L and R are omitted when matters common to the plurality of members are described.

Each of a switch body211L of the safety switch210L and a switch body211R of the safety switch210R is fixed to a door frame302of the guard300. In this manner, the switch body211to which a cable is connected is desirably installed not on the door301that can be open and closed (moved) but on the fixed door frame302.

On the other hand, an actuator212L of the safety switch210L is fixed to a support member303L fixed to the door301L. Further, an actuator212R of the safety switch210R is fixed to a support member303R fixed to the door301R.

Note that, as a safety function contributing to a safety system, the safety switch210detects whether or not the actuator212is within a predetermined range with respect to the switch body211, and outputs a detection result as a safety signal (OSSD).

For example, when the door301of the guard300is closed, an RFID of the actuator212provided in the door301approaches a detection unit (antenna coil) of the switch body211provided in the door frame302. At this time, the switch body211detects that the actuator212is within the predetermined range with respect to the switch body211, that is, that the door301is closed since the RFID is identified by the detection unit.

On the other hand, when the door301of the guard300is open, the RFID of the actuator211provided in the door301is spaced apart from the detection unit (antenna coil) of the switch body211provided in the door frame302. At this time, the switch body211detects that the actuator212is not within the predetermined range with respect to the switch body211, that is, the door301is open since the communication between the detection unit and the RFID is not established.

In this manner, the safety switches210are arranged so as to detect the open or closed states of the respective corresponding doors301.

When at least one of the doors301L and301R (the door301L in this drawing) is open, a state is formed in which the operation of the machine tool surrounded by the guard300is prohibited. On the other hand, when both the doors301L and301R are closed, a state is formed in which the operation of the machine tool surrounded by the guard300can be permitted (=a state satisfying one of operation permission conditions) is formed.

In this manner, the safety switch210is a device configured as a protective measure against a moving device (mechanical hazard source). In particular, the safety switch210is a type of safety protection by stopping. In this type, an operation region where the hazard source operates is defined, and the operation of the hazard source is stopped when detecting that a human body is likely to enter such a movable region or the entry of the human body. In particular, in the safety system provided with the safety switch210, the hazard source is stopped when a state where the door301is closed transitions to a state where the door301is open.

That is, in a “safe state”, which is achieved while a state in which various conditions including the absence of an entry of a human body in the operation region and the like are satisfied is being maintained by closing of the door301, the safety switch210outputs an ON signal, and the hazard source operates. On the other hand, when the door301is moved from the “safe state” so that the operation region is opened, the safety switch210outputs an OFF signal, and the hazard source stops.

In the entire safety system, once the OFF signal is output from the safety switch210, the hazard source is not restarted even if the door301itself moves to a closed position, but is restarted when a reset signal is separately input. This is because, once the door301is opened, it is difficult to confirm the absence of an entry of a human body in the operation region even if the door301is closed thereafter.

Further, the safety switch210has a lock portion for restricting opening of the door301in addition to the safety function.

For example, the safety switch210drives an electromagnet of the switch body211when receiving a lock input output from an external device (for example, the safety controller230described above) in the state of detecting that the actuator212is within the predetermined range with respect to the switch body211(=that the door301is closed). At this time, an iron plate of the actuator212is magnetized. As a result, the opening of the door301is restricted by an attractive force between the electromagnet and the iron plate. Note that the safety switch210may be configured not to unlock the door301unless a specific signal is input from the external device. Further, as a mechanism of the lock portion, engagement between a bolt and a pin may be used instead of the attraction between the electromagnet and the iron plate.

With the safety switch210having a lock function, it is possible to prevent, in advance, trouble that the machine tool or the like (mechanical hazard source) stops based on the OSSD output every time a user opens the door301by mistake.

In this manner, the above-described lock function can be understood as an auxiliary function (=non-safety function) for maintaining smooth operation of the machine tool or the like. That is, the safety function of the safety system is realized only through the OSSD output of the safety switch210.

<Safety Switch (Functional Block)>

FIG.7is a diagram illustrating a functional block of the safety switch210. In the safety switch210of the present configuration example, the switch body211includes a control circuit410, an input/output circuit420, a switching device430, an OSSD monitoring circuit440, a power supply unit450, a communication unit460, a display unit470, and an electromagnet480. In this drawing, constituent elements (mainly constituent elements related to terminals) of a hinge type provided on the rearward side (back side) of the switch body211are collectively depicted on the left side of the block. Further, constituent elements of a hinge type provided on the forward side (front side) of the switch body211are collectively depicted on the right side of the block.

The control circuit410(corresponding to a safety switch MCU) includes a first MCU411and a second MCU412. The input/output circuit420includes a first safety input unit421, a second safety input unit422, an upstream communication unit423, and a downstream communication unit424. The switching device430includes a first safety output unit431and a second safety output unit432. The power supply unit450includes a power supply circuit451and a power supply monitoring circuit452. The communication unit460includes an antenna coil463. The display unit470includes an indicator lamp control unit471and an indicator lamp472.

Further, the actuator212includes a communication unit510in the safety switch210of the present configuration example. Note that the communication unit510includes an antenna coil511and a response circuit512.

The first MCU411and the second MCU412communicate with each other to monitor each other. The first MCU411and the second MCU412are connected to the antenna coil463.

The first MCU411drives the antenna coil463, and transmits a wireless signal from the antenna coil463to the communication unit510(in particular, the antenna coil511) of the actuator212. The communication unit510may be a wireless tag (RF-ID tag).

The response circuit512operates using an induced current generated in the antenna coil511as a power source. Further, the response circuit512demodulates the wireless signal received by the antenna coil511to acquire information, and further transmits the wireless signal (response signal) via the antenna coil511.

Each of the first MCU411and the second MCU412receives the wireless signal (response signal) transmitted from the antenna coil511of the actuator212via the antenna coil463.

The first MCU411includes a measurement unit411a, a demodulation unit411b, and a safety determination circuit411c. Further, the second MCU412includes a measurement unit412a, a demodulation unit412b, a safety determination circuit412c, and a display control unit412d.

Each of the measurement units411aand412ameasures the intensity of the wireless signal (response signal) received via the antenna coil463, and estimates an inter-coil distance d (and further, a distance from the switch body211to the actuator212) between the antenna coil463of the switch body211and the antenna coil511of the actuator212based on a result of the measurement. Note that the antenna coil463functions as the detection unit that detects that the actuator212is within the predetermined range with respect to the switch body211. Further, instead of the inter-coil distance d, the intensity of the wireless signal may be directly used to sense a position of the actuator212.

Further, the detection unit detecting that the actuator212is within the predetermined range with respect to the switch body211is not limited to the above-described technique using the antenna coil463. For example, a detection unit based on a detection principle in which a physical switch is provided in the switch body211, and the physical switch is pressed by a protruding member or the like provided in the actuator212when a door is closed and the actuator212approaches the switch body211may be adopted.

Each of the demodulation units411band412bdemodulates information conveyed by the wireless signal (response signal) received via the antenna coil463, and identifies the actuator212based on the information. Note that this information may include unique identification information (ID information).

The safety determination circuit411cof the first MCU411determines whether the inter-coil distance d measured by the measurement unit411ais equal to or less than a threshold dth, and transmits a result of the determination to the second MCU412. Similarly, the safety determination circuit412cof the second MCU412determines whether the inter-coil distance d measured by the measurement unit412ais equal to or less than the threshold dth, and transmits a result of the determination to the first MCU411. Then, each of the safety determination circuits411cand412cdetermines that the actuator212is in a state (door closed state) of being within the predetermined range with respect to the switch body211when the determination result of the own unit coincides with the determination result of the counterpart (when both the units determine that the inter-coil distance d is equal to or less than the threshold dth).

In the input/output circuit420, the first safety input unit421and the second safety input unit422are input circuits configured for a serial cascade connection of the plurality of safety switches210. For example, the first safety input unit421and the second safety input unit422are connected to the first safety output unit431and the second safety output unit432, respectively, of another safety switch210provided on the upstream side.

The first MCU411is connected to the first safety input unit421. When the ON signal is input through the first safety input unit421, the first MCU411controls the first safety output unit431based on a proximity state of the actuator212(=the open or closed state of the door) and a locked state of the electromagnet480. On the other hand, when the OFF signal is input through the first safety input unit421, the first MCU411causes the first safety output unit431to output the OFF signal without depending on the proximity state of the actuator212and the locked state of the electromagnet480.

Similarly, the second MCU412is connected to the second safety input unit422. When the ON signal is input through the second safety input unit422, the second MCU412controls the second safety output unit432based on the proximity state of the actuator212and the locked state of the electromagnet480. On the other hand, when the OFF signal is input through the second safety input unit422, the second MCU412causes the second safety output unit432to output the OFF signal without depending on the proximity state of the actuator212and the locked state of the electromagnet480.

As a result, the plurality of safety switches210can be connected in a cascade. When any one of the plurality of safety switches210is not in the safe state, the OFF signal is output to the external device (for example, the safety controller230). Therefore, for example, in a case where a plurality of doors are provided for an iron fence surrounding a hazard source, the operation of the hazard source is not possible unless all the doors are in the safe state. On the other hand, when all of the plurality of safety switches210are in the safe state, the ON signal is output to the external device.

The upstream communication unit423is connected to another safety switch210provided on the upstream side, and transmits upstream-facing communication data (including the lock input) and receives downstream-facing communication data (including bundle data of AUX outputs).

The downstream communication unit424is connected to another safety switch210or the wire saving unit250provided on the downstream side, and transmits downstream-facing communication data (including bundle data of AUX outputs) and receives upstream-facing communication data (including the lock input).

For example, the control circuit410generates downstream-facing communication data based on communication data (=communication data obtained by bundling upstream AUX outputs) received via the upstream communication unit423and the own state of the safety switch210, and outputs the downstream-facing communication data from the downstream communication unit424.

The first safety output unit431and the second safety output unit432respectively output OSSD outputs (OSSD1_O and OSSD2_O) to another safety switch210or the wire saving unit250provided on the downstream side.

For example, the control circuit410outputs the OSSD outputs (OSSD1_O and OSSD2_O) from the first safety output unit431and the second safety output unit432, respectively, based on OSSD inputs (OSSD1_I and OSSD2_I) received via the first safety input unit421and the second safety input unit422, respectively, and a proximity state of the actuator212(=a detection result obtained by the detection unit).

In the switching device430, the first safety output unit431and the second safety output unit432can be configured as, for example, an open collector output circuit using a PNP transistor. In this case, when the PNP transistor is turned on, a positive-side power supply is connected to an output terminal, so that the ON signal (=high level) is output. On the other hand, when the PNP transistor is turned off, the output terminal is grounded via a pull-down resistor, so that the OFF signal (=low level) is output.

Note that each of the first safety output unit431and the second safety output unit432can also be configured as an open collector output circuit using an NPN transistor. In this case, output logic levels are reversed from the above. Specifically, the ON signal becomes a low level, and the OFF signal becomes a high level.

The OSSD monitoring circuit440may be connected to each of the first safety output unit431and the second safety output unit432. The OSSD monitoring circuit440is connected to the first MCU411and the second MCU412. The first MCU411monitors whether the operation of the second safety output unit432is normal through the OSSD monitoring circuit440. The second MCU412monitors whether the operation of the first safety output unit431is normal through the OSSD monitoring circuit440.

For example, each of the first safety output unit431and the second safety output unit432periodically shifts the output signal to OFF for a minute time when outputting the ON signal. The OSSD monitoring circuit440determines that the OSSD is normal if the OFF for the minute time can be detected during an output period of the ON signal, and determines that the OSSD is not normal if the OFF for the minute time cannot be detected. When it is determined that the OSSD is not normal, the OSSD outputs of the first safety output unit431and the second safety output unit432transition to OFF. In this manner, the OSSD monitoring circuit440senses a failure occurring in the switch body, and a sensing result of the failure is reflected in the OSSD outputs of the first safety output unit431and the second safety output unit432.

Note that a case where the ON signal continues is caused by a short circuit between the output terminal and the positive-side power supply. In this case, the safety determination circuits411cand412coutput control signals for outputting the OFF signal to the first safety output unit431and the second safety output unit432, respectively. As a result, the normal one of the first safety output unit431and the second safety output unit432outputs the OFF signal.

The external device (for example, the safety controller230) is in a state of being capable of permitting the operation of the hazard source only during a period in which both the first safety output unit431and the second safety output unit432output the ON signals. In other words, the external device does not permit the operation of the hazard source during a period in which at least one of the first safety output unit431and the second safety output unit432outputs the OFF signal. Note that the external device is configured not to react to the OFF for the minute time during the ON signal described above.

In the power supply unit450, the power supply circuit451is a DC-DC converter that receives supply of an input voltage VCC (for example, DC+24 V) and a ground voltage GND (for example, 0 V) from the outside and generates a desired output voltage VREG (for example, DC+10 V, +5 V, or +3.3 V). Note that the power supply circuit451supplies power to each unit (=all circuits that require power) of the switch body211.

Meanwhile, when the input voltage VCC or the output voltage VREG is not within a predetermined range, there is a possibility that the first MCU411, the second MCU412, and the like do not normally operate. Therefore, the power supply monitoring circuit452determines whether the input voltage VCC and the output voltage VREG are within the predetermined range, and outputs a determination result to the first safety output unit431and the second safety output unit432.

When receiving the determination result indicating that the power supply circuit451is not normally operating, each of the first safety output unit431and the second safety output unit432outputs the OFF signal without depending on the control signal output from each of the first MCU411and the second MCU412.

On the other hand, when receiving the determination result indicating that the power supply circuit451is normally operating, each of the first safety output unit431and the second safety output unit432outputs the ON signal or the OFF signal depending on the control signal output from each of the first MCU411and the second MCU412. In this manner, the power supply monitoring circuit452senses a failure related to a power supply of the switch body211, and a sensing result of the failure is reflected in the OSSD outputs of the first safety output unit431and the second safety output unit432.

Based on an instruction from the control circuit410(for example, the display control unit412dof the second MCU412), the indicator lamp control unit471turns on or off or causes blinking in green or blinking in red of the indicator lamp472(for example, a large indicator lamp) according to the proximity state of the actuator212(=the open or closed state of the door) and the locked or unlocked state of the electromagnet480.

Further, the indicator lamp control unit471turns on or off or causes blinking in green or blinking in red of the indicator lamp472(for example, a plurality of small indicator lamps) according to the OSSD output, an INPUT signal, the locked state or unlocked state, and the like. Note that the above OSSD output is an output signal of each of first safety output unit431and second safety output unit432.

The electromagnet480generates a magnetic force by a drive current supplied from the control circuit410(for example, the second MCU412). At this time, the iron plate (not illustrated) of the actuator212close to the switch body211is magnetized. As a result, the door is locked by an attractive force between the electromagnet480and the iron plate.

<Terminal Function Switching>

Incidentally, the safety switch210may include a first operation mode in which the lock input and the AUX output are input or output in parallel as in the above-described conventional example (FIG.10), and a second operation mode in which the lock input and the AUX output are serially input or output via a communication line of one system as in the above-described first embodiment (FIG.1) and second embodiment (FIG.2).

As tools for realizing the first and second operation modes described above, for example, the safety switch210is provided with a first terminal switchable as a lock input terminal or a downstream communication terminal, and a second terminal switchable as an AUX output terminal or an upstream communication terminal.

Further, for example, the safety switch210(particularly, the control circuit410) may switch the first terminal and the second terminal from the first operation mode of being used as the lock input terminal and the AUX output terminal, respectively, to the second operation mode of being used as the downstream communication terminal and the upstream communication terminal, respectively, based on a switching signal input to the first terminal.

Note that the wire saving unit250(in particular, the MCU250a) may transmit the switching signal indicating a specific pattern instead of the lock input as the upstream-facing communication data when activated, for example.

The safety switch210of the present configuration example can be developed in the market as a dual-purpose model compatible with both cascade connection and non-cascade connection.

<Signal Processing>

FIG.8is a view illustrating an example of signal processing in the safety switch210. Note that Steps S101to S108in this drawing can be basically understood as software processing executed by the control circuit410of the switch body211.

In Step S101, the inter-coil distance d between the antenna coil463of the switch body211and the antenna coil511of the actuator212is measured.

In Step S102, it is determined whether or not the inter-coil distance d measured in Step S101is within a predetermined range (the threshold dth or less). Here, in a case where it is determined as YES, the flow proceeds to Step S103. On the other hand, in a case where it is determined as NO, the flow returns to Step S101described above. Further, in a case where it is determined as NO in Step S102, the display unit470may be lit in red.

In Step S103, a wireless signal (response signal) from the actuator212is demodulated, and identification information (ID) of the actuator212is acquired.

In Step S104, it is determined whether or not the ID acquired in Step S103coincides with an expected value. Here, in a case where it is determined as YES, the flow proceeds to Step S105. On the other hand, in a case where it is determined as NO, the flow returns to Step S101described above. Further, in a case where it is determined as NO in Step S104, the display unit470may be lit in red.

In Step S105, it is determined whether or not the electromagnet480of the switch body211and the iron plate of the actuator212are in close contact with each other. Here, in a case where it is determined as YES, the flow proceeds to Step S106. On the other hand, in a case where it is determined as NO, the flow returns to Step S101described above.

FIG.9is a view illustrating an example of a close contact determination process in Step S105, and a current control signal of the electromagnet480and inspection currents (without anchor plate/with anchor plate) flowing through the electromagnet480are depicted in order from the top.

During an ON period of the current control signal (a high-level period in this drawing), the inspection current flows through the electromagnet480. Note that a current value of the inspection current is lower than a current value of a drive current flowing at the time of locking and attraction. If an inspection current at the same level as the drive current for locking and attraction is applied, the door is difficult to open even though no lock input is given, which affects usability. Therefore, it is desirable to perform the close contact determination by flowing a minute inspection current so as not to generate an attractive force.

In the close contact determination process in Step S105, the current value of the inspection current flowing through the electromagnet480is monitored. When the iron plate (anchor plate) is in close contact with the electromagnet480, an inductance of the electromagnet480increases. Therefore, a response time of the inspection current (=time until the inspection current reaches a constant value from when the current control signal is set to ON) increases.

Therefore, whether the current value (AD value) of the inspection current exceeds a threshold is determined at an AD value confirmation timing after a lapse of a certain period of time from when the current control signal is set to ON.

For example, when the current value of the inspection current exceeds the threshold at the AD value confirmation timing, it can be said that the inductance of the electromagnet480is low and the response time is short. Therefore, it is determined that the iron plate is not in close contact. On the other hand, when the current value of the inspection current does not exceed the threshold at the AD value confirmation timing, it can be said that the inductance of the electromagnet480is high and the response time is long. Therefore, it is determined that the iron plate is in close contact.

In this manner, in Step S105, the close contact with the iron plate is determined based on a change in the inductance of the electromagnet480. Note that the electromagnet480is not driven even if the lock input is received before it is determined as YES in Step S105. On the other hand, the electromagnet480is driven in response to the lock input if it is determined as YES in Step S105.

When the electromagnet480is driven in a state in which the electromagnet480and the iron plate are not in close contact with each other, a foreign matter as a magnetic body is attracted. Therefore, it is desirable to include in a driving condition of the electromagnet480that the electromagnet480and the iron plate are in a close contact state.

Returning toFIG.8, the description of the flow will be continued. In Step S106, various input determination processes are performed. With reference to this drawing, in Step S106, whether or not the lock input from a control apparatus (such as the safety controller230) that controls the safety switch210is set to ON is determined as a first input determination. The first input determination is omitted in a safety switch (for example, the safety switch210(A4) inFIG.2described above) not having a lock function.

Further, in Step S106, as a second input determination, it is determined whether or not all the OSSD inputs from another safety switch210connected in a cascade on the upstream side are set to ON.

Note that it is sufficient to perform the above-described second input determination only when the plurality of safety switches210are connected in a cascade. Note that it is sufficient to perform a determination on the presence or absence of the cascade connection independently of the software processing of the control circuit410illustrated in the flow from Steps S101to S108. For example, the determination on the presence or absence of the cascade connection may be performed at determination processing timings (for example, Steps S102, S104, and S105) included in Steps S101to S108or at predetermined time intervals.

Further, display control according to a result of the input determination of Step S106may be performed in the display unit470. As an example of the display control, the display unit470may be lit in orange in a case where the lock input is ON and the safety input is OFF. On the other hand, the display unit470may blink in green in a case where the lock input is OFF and the safety input is ON. Further, the display unit470may blink in orange in a case where both the lock input and the safety input are OFF.

In Step S107, it is determined whether both the first and second input determinations in Step S106are ON, in other words, whether both the lock input and the OSSD input are ON. Here, in a case where it is determined as YES, the flow proceeds to Step S108. On the other hand, in a case where it is determined as NO, the flow returns to Step S107and the above determination process is continued.

In Step S108, the ON signal is output via the first safety output unit431and the second safety output unit432. That is, the OSSD output is set to ON. Such a safety output is used for the input determination process in another safety switch210connected in a cascade on the downstream side. Further, the display unit470may be lit in green to indicate that the OSSD output is set to ON.

Thereafter, the flow returns to Step S101described above in order to determine whether or not to maintain the ON state of the safety output. Note that the safety output is affected by the determinations in Step S101and Step S106in the present embodiment Therefore, Step S105may be omitted in the determination flow as to whether or not to maintain the ON state of the safety output.

<Conclusion>

Hereinafter, various embodiments described above will be comprehensively described.

For example, according to one configuration (first configuration), a wiring unit disclosed in the present specification is connected to a plurality of safety switches each including an actuator and a switch body that detects the actuator in a cascade connection. The wiring unit includes: a power input unit configured to receive power; a safety switch port that includes a pair of safety input terminals receiving a first safety signal, which is a pair of safety signals output by a first safety switch among the plurality of safety switches connected in a cascade, a pair of power output terminals configured to supply power received via the power input unit to the plurality of safety switches, and a wiring unit communication terminal configured to perform bidirectional communication with the first safety switch; a safety output unit internally connected to the pair of safety input terminals to through-output the first safety signal received via the pair of safety input terminals; a lock instruction input unit that receives a lock instruction for locking a safety switch capable of locking movement of the actuator with respect to the switch body in response to an instruction among the plurality of safety switches; an information output unit configured to individually output information indicating a state of each of the plurality of safety switches; and a wiring unit MCU that individually outputs information indicating a state of each of the plurality of safety switches based on information from the plurality of safety switches received via the wiring unit communication terminal, and outputs a lock input for instructing locking based on the lock instruction received via the lock instruction input unit to the safety switch capable of the locking. The safety output unit is internally connected to the pair of safety input terminals to enable failure sensing by a failure sensing function of the first safety switch.

Note that, the wiring unit according to the first configuration may have a configuration (second configuration) in which the wiring unit MCU is isolated from a safety output line including the safety input terminals and the safety output unit.

Further, the wiring unit according to the second configuration may have a configuration (third configuration) in which a safety signal monitor unit that monitors the first safety signal sent to the safety output line and outputs a monitoring result to the wiring unit MCU is provided, and the safety signal monitor unit includes a transmission unit that transmits a monitoring signal based on the first safety signal sent to the safety output line, and a reception unit that receives the monitoring signal by isolated communication with the transmission unit and outputs the monitoring signal to the wiring unit MCU.

Further, the wiring unit according to the third configuration may have a configuration (fourth configuration) in which the transmission unit transmits the monitoring signal, which is not electrical, based on the first safety signal sent to the safety output line.

Further, the wiring unit according to the first configuration may have a configuration (fifth configuration) in which a housing that accommodates the wiring unit MCU is provided, and the safety switch port is configured using a connector provided on the housing.

Further, the wiring unit according to the first configuration may have a configuration (sixth configuration) in which a housing that accommodates the wiring unit MCU and a cable extending to the outside of the housing are provided, and the safety switch port is configured using a connector provided in the cable.

Further, the wiring unit according to the first configuration may have a configuration (seventh configuration) in which a housing that accommodates the wiring unit MCU is provided, and the housing is provided with: a first safety switch port and a second safety switch port which serve as the safety switch port; and a first lock instruction input unit and a second lock instruction input unit which serve as the lock instruction input unit, the first lock instruction input unit being configured to receive a lock instruction for instructing the lockable safety switch connected via the first safety switch port to perform locking, and the second lock instruction input unit being configured to receive a lock instruction for instructing the lockable safety switch connected via the second safety switch port to perform locking.

Further, the wiring unit according to the first configuration may have a configuration (eighth configuration) in which, when a plurality of the lockable safety switches are connected as the plurality of safety switches, the wiring unit MCU supplies a same lock input to each of the plurality of lockable safety switches.

Further, the wiring unit according to the first configuration may have a configuration (ninth configuration) provided with: a housing that accommodates the wiring unit MCU; and an indicator lamp that is provided on the housing and individually displays a state of each of the plurality of safety switches based on information received from the plurality of safety switches via the wiring unit communication terminal.

Further, the wiring unit according to the first configuration may have a configuration (tenth configuration) provided with: a housing that accommodates the wiring unit MCU; and an OSSD indicator lamp that is provided on the housing and displays a state of the first safety signal received by the safety input terminals included in the safety switch port.

Further, the wiring unit according to the first configuration may have a configuration (eleventh configuration) provided with: a housing that accommodates the wiring unit MCU; and a cable as the safety output unit extending to the outside of the housing.

Further, the wiring unit according to the first configuration may have a configuration (twelfth configuration) provided with: a housing that accommodates the wiring unit MCU; and a cable as the lock instruction input unit extending to the outside of the housing.

Further, the wiring unit according to the first configuration may have a configuration (thirteenth configuration) provided with: a housing that accommodates the wiring unit MCU; and a cable as the information output unit extending to the outside of the housing.

Further, the wiring unit according to the first configuration may have a configuration (fourteenth configuration) provided with: a housing that accommodates the wiring unit MCU; and a cable as the power input unit extending to the outside of the housing.

Further, the wiring unit according to the first configuration may have a configuration (fifteenth configuration) in which at least one of the safety output unit, the lock instruction input unit, the information output unit, and the power input unit is configured using a terminal block.

Further, for example, according to a sixteenth configuration, a serial cascade connector system disclosed in the present specification includes: a first safety switch and a second safety switch as safety switches each including an actuator and a switch body that detects the actuator; and a wiring unit to which the first safety switch and the second safety switch are connected in a cascade connection. At least one of the first safety switch and the second safety switch is a lockable safety switch including a lock portion capable of locking movement of the actuator in response to a lock input. The first safety switch includes: a pair of first safety input terminals configured to receive a second safety signal that is a pair of safety signals output from the second safety switch; a pair of first safety output terminals configured to output a first safety signal, which is a pair of safety signals, to the wiring unit; a first terminal configured to perform bidirectional communication with the second safety switch; a second terminal configured to perform bidirectional communication with the wiring unit; a detection unit detecting that the actuator is within a predetermined range with respect to the switch body; a safety switch MCU that outputs the first safety signal based on the second safety signal received via the first safety input terminals and a detection result obtained by the detection unit, and outputs, via the second terminal, information indicating states of the first safety switch and the second safety switch based on information indicating the state of the second safety switch received via the first terminal; and a failure sensing unit that senses a failure of the first safety switch. The wiring unit includes: a safety switch port that includes a pair of safety input terminals receiving the first safety signal, a power input unit configured to receive power, a pair of power output terminals configured to supply the power received via the power input unit to the first safety switch and the second safety switch, and a wiring unit communication terminal configured to perform bidirectional communication with the first safety switch; a safety output unit that is internally connected to the pair of safety input terminals to perform through-output of the first safety signal received via the safety input terminals; a lock instruction input unit that receives a lock instruction for locking the lockable safety switch; an information output unit configured to individually output the information indicating the state of each of the plurality of safety switches; and a wiring unit MCU that individually outputs the information indicating the state of the first safety switch and the information indicating the state of the second safety switch based on information received via the wiring unit communication terminal, and outputs the lock input for instructing locking based on the lock instruction received via the lock instruction input unit to the lockable safety switch via the wiring unit communication terminal. The safety output unit being internally connected to the pair of safety input terminals to enable sensing of a failure by a failure sensing unit included in the first safety switch at a destination where the first safety signal received from the through-output performed by the safety output unit.

Note that the serial cascade connector system according to the sixteenth configuration may have a configuration (seventeenth configuration) in which, when the wiring unit MCU receives the lock instruction via the lock instruction input unit, the lock input for driving the lock portion of the second safety switch as the lockable safety switch is input to the second safety switch at a timing different from a timing at which the lock portion is driven in the first safety switch as the lockable safety switch.

Further, the serial cascade connector system according to the sixteenth configuration may have a configuration (eighteenth configuration) in which the wiring unit MCU transmits a switching signal to the first safety switch via the wiring unit communication terminal when activated, and the first safety switch switches an operation mode for two terminals of the first terminal and the second terminal, based on the switching signal, from a first operation mode in which one of the first terminal and the second terminal is used as a lock input terminal that receives the lock input and another terminal is used as a state information output terminal that outputs the information indicating the state of the first safety switch to a second operation mode in which the first terminal is used as an upstream communication terminal for bidirectional communication with the second safety switch and the second terminal is used as a downstream communication terminal for bidirectional communication with the wiring unit.

OTHER MODIFICATIONS

Note that, in addition to the above-described embodiments, various alterations can be applied to various technical features disclosed in the present specification within a scope not departing from the spirit of the technical creation. That is, it is to be understood that the above-described embodiments are illustrative in all respects and not restrictive, and the technical scope of the invention is defined by the claims, and includes all alterations falling within the meaning and scope equivalent to the claims.