JP7188259B2 - Signal input device and signal detection method - Google Patents

Description

The present invention relates to a signal input device and a signal detection method for detecting the ON state and OFF state of an external switch.

Conventionally, in a control device for controlling facilities such as machine tools and plants, there are cases where it is necessary to detect the ON state and OFF state of an external switch with high reliability (for example, Patent Document 1 reference).

The safety circuit described in Patent Document 1 has a programmable logic circuit, and a part of this programmable logic circuit is configured as a test monitoring device that monitors whether or not there is a failure in the operation of an external switch using test pulses. ing. The test pulse is superimposed on the control signal of the evaluation circuit for evaluating the external switch, and if the external switch is operating as intended, the superimposed test pulse is detected at the feedback input.

JP 2011-530204 A

In the above configuration, for example, if the wiring between the external switch and the external switch is long, the pulse waveform may be dulled by stray capacitance or the like in this wiring, and it may not be possible to accurately determine whether the external switch operates normally.

Therefore, the present invention provides a signal input device and a signal detection method capable of accurately determining whether or not an external switch operates normally even if the wiring length between the device and the external switch is long. With the goal.

In order to achieve the above objects, the present invention provides a signal input device for detecting the ON state and OFF state of an external switch, comprising a voltage output state for outputting a voltage to the external switch and a voltage output state for outputting the voltage to the external switch. an intermittent section capable of switching between a voltage cutoff state that cuts off the voltage output state, a detection section that outputs a detection signal in response to an input voltage in which the voltage output in the voltage output state is input through the external switch, and the intermittent and a control unit capable of acquiring the detection signal, the control unit controlling the intermittent unit to change the voltage output to the external switch in a pulse shape, and within a predetermined time, the a confirmation mode for confirming that the detection signal changes; and an adjustment mode for adjusting the predetermined time in the confirmation mode based on the responsiveness of the input voltage when the voltage output to the external switch is changed. and a normal mode for detecting a change in the on/off state of the external switch when the detection signal changes in the voltage output state.

In order to achieve the above objects, the present invention also provides a signal detection method for detecting the ON state and OFF state of an external switch by a signal input device, wherein the voltage output from the signal input device to the external switch is detected by: a measuring step of measuring the time until the input voltage input to the signal input device through the external switch exceeds a threshold value after the change, and the voltage output to the external switch is changed in a pulse shape. and a confirmation step of confirming that the input voltage changes beyond the threshold value within a predetermined time set based on the time measured in the measurement step.

According to the signal input device and the signal detection method according to the present invention, it is possible to accurately determine whether or not the external switch operates normally even when the wiring length between the external switch and the external switch is long.

1 is a schematic configuration diagram showing a configuration example of a signal input device according to an embodiment of the present invention; FIG. (a) and (b) show an example of temporal changes in the control signal and the detection signal in the confirmation mode, (a) is the signal waveform during normal operation, and (b) is the signal when a short-circuit abnormality occurs. waveforms, respectively. (a) and (b) show examples of changes in the control signal, the input voltage, and the detection signal when the test pulse is generated. (a) shows the waveform when the first and second conductors are short, (b) shows waveforms when the first and second conductors are long. 5 is a graph showing examples of waveforms of control signals, input voltages, and detection signals in an adjustment mode; 7 is a graph showing an example of a test pulse waveform with a pulse width set based on the adjustment result in the adjustment mode;

[Embodiment]
An embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. It should be noted that the embodiment described below is shown as a preferred specific example for carrying out the present invention, and there are portions that specifically illustrate various technically preferable technical matters. , the technical scope of the present invention is not limited to this specific embodiment.

FIG. 1 is a schematic configuration diagram showing a configuration example of a signal input device 1 according to an embodiment of the present invention. This signal input device 1 is for detecting the on-state and off-state of external switches with high reliability. Detect off state. The signal input device 1 operates by being supplied with a DC voltage from a DC power supply 4 . In this embodiment, the output voltage of the DC power supply 4 is 24V.

The signal input device 1 is used, for example, as an input module of a programmable controller, which is a control device for controlling equipment such as machine tools, and outputs detection results of on/off states of external switches to a CPU module, which is a host controller. The external switch is, for example, an emergency stop switch for immediately stopping the operation of equipment to be controlled. In this embodiment, the signal input device 1 detects the on/off state of two external switches (first and second external switches 2 and 3). The number of is not particularly limited, and may be one or three or more.

The signal input device 1 includes, for example, a control unit 11 implemented by a CPU (arithmetic processing unit) executing a program stored in advance in a nonvolatile memory, first and second switching elements 12 and 13, and a second switching element. It has first and second photocouplers 14 and 15 and first to fourth resistors 16 to 19 . Note that the control unit 11 may be realized by hardware such as ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array).

The first switching element 12 and the first photocoupler 14 are components of the first detection circuit section 1A for detecting the ON/OFF state of the first external switch 2 . The second switching element 13 and the second photocoupler 15 are constituent elements of the second detection circuit section 1B for detecting the ON/OFF state of the second external switch 3 . The first external switch 2 is connected to the signal input device 1 by first and second conductors 51, 52 and the second external switch 3 is connected to the signal input device 1 by third and fourth conductors 53, 54. It is connected to the.

In the present embodiment, first switching element 12 is a transistor having a base, a collector, and an emitter, and control signal Vcs1 is output from control section 11 to the base of first switching element 12 . When the control signal Vcs1 is supplied from the control unit 11, the first switching element 12 becomes conductive between the collector and the emitter. A power supply voltage Vcc is supplied to the collector of the first switching element 12 via a first resistor 16 . The emitter of the first switching element 12 is connected to the output terminal 101 of the signal input device 1 .

Similarly, the second switching element 13 is a transistor having a base, a collector and an emitter, and a control signal Vcs2 is output from the controller 11 to the base of the second switching element 13 . The second switching element 13 becomes conductive between the collector and the emitter when the control signal Vcs2 is supplied from the control section 11 . The collector of the second switching element 13 is supplied with the power supply voltage Vcc through the third resistor 18 . The emitter of the second switching element 13 is connected to the output terminal 103 of the signal input device 1 .

The first external switch 2 includes a pair of electrodes 21 and 22, a contactor 23 made of a metal conductor that contacts and separates from the pair of electrodes 21 and 22, and a housing that accommodates the pair of electrodes 21 and 22 and the contactor 23. It has a body 24 and an operation unit 25 for operation by an operator or the like. The second external switch 3 similarly accommodates a pair of electrodes 31 and 32, a contactor 33 made of a metal conductor that contacts and separates from the pair of electrodes 31 and 32, and a pair of electrodes 31 and 32 and the contactor 33. and an operation unit 35 for operation by an operator or the like.

In the first external switch 2, the contactor 23 is urged against the pair of electrodes 21 and 22 by an elastic body (not shown). shorted by Further, when the operating portion 25 is pushed toward the housing 24, the contactor 23 is separated from the pair of electrodes 21 and 22, and the conduction between the pair of electrodes 21 and 22 is interrupted. The same applies to the second external switch 3 as well.

One electrode 21 of the pair of electrodes 21 and 22 of the first external switch 2 is connected to the output terminal 101 of the signal input device 1 via a first conductor 51, and the other electrode 22 is connected to a second conductor 52. is connected to the input terminal 102 of the signal input device 1 by the . One electrode 31 of the pair of electrodes 31 and 32 of the second external switch 3 is connected to the output terminal 103 of the signal input device 1 by the third conductor 53, and the other electrode 32 is connected to the fourth electrode. It is connected to the input terminal 104 of the signal input device 1 by a conductor 54 .

The first and second photocouplers 14 and 15 are configured by optically coupling light emitting diodes and phototransistors. In the first photocoupler 14, the anode of the light emitting diode is connected to the input terminal 102, and the collector of the phototransistor is supplied with the power supply voltage Vcc. In the second photocoupler 15, the anode of the light emitting diode is connected to the input terminal 104, and the collector of the phototransistor is supplied with the power supply voltage Vcc. The emitter of the phototransistor of the first photocoupler 14 is electrically grounded via the second resistor 17 . The emitter of the phototransistor of the second photocoupler 15 is electrically grounded through the fourth resistor 19 . The cathodes of the light emitting diodes of the first and second photocouplers 14, 15 are electrically grounded.

A voltage between the second resistor 17 and the emitter of the phototransistor of the first photocoupler 14 is input to the controller 11 as the detection signal Vds1 of the first photocoupler 14 . A voltage between the fourth resistor 19 and the emitter of the phototransistor of the second photocoupler 15 is input to the control section 11 as the detection signal Vds2 of the second photocoupler 15 . That is, the first and second photocouplers 14 and 15 output detection signals Vds1 and Vds2 to the control unit 11 by emitter outputs.

In the first detection circuit section 1A, the first switching element 12 has a voltage output state in which voltage is output to the first external switch 2 and a voltage cutoff state in which voltage output to the first external switch 2 is cut off. function as a switchable discontinuity. The first photocoupler 14 serves as a detection unit that outputs a detection signal Vds1 in response to an input voltage Vin1 that is input to the input terminal 102 via the first external switch 2, the voltage output in the voltage output state. Function. The detection signal Vds1 changes when the input voltage Vin1 changes beyond a predetermined threshold. In this embodiment, the threshold voltage is 7.2V.

In the second detection circuit section 1B, the second switching element 13 has a voltage output state in which voltage is output to the second external switch 3 and a voltage cutoff state in which voltage output to the second external switch 3 is cut off. function as a switchable discontinuity. The second photocoupler 15 serves as a detection unit that outputs a detection signal Vds2 in response to an input voltage Vin2 that is input to the input terminal 104 via the second external switch 3, the voltage output in the voltage output state. Function. The detection signal Vds2 changes when the input voltage Vin2 changes beyond a predetermined threshold. In the present embodiment, the threshold voltage is 7.2V as described above.

The control unit 11 can control the first and second switching elements 12 and 13 by the control signals Vcs1 and Vcs2 and can acquire the detection signals Vds1 and Vds2. The on/off state of the external switches 2 and 3 can be detected. Also, the control unit 11 operates in a plurality of operation modes. In this embodiment, the plurality of operation modes are confirmation mode, adjustment mode, and normal mode.

In the confirmation mode, the voltages output to the first and second external switches 2, 3 are changed in pulses by controlling the first and second switching elements 12, 13, and the detection signals Vds1, Vds1 and Vds1 are generated within a predetermined time. This is the mode for confirming that Vds2 changes. In this confirmation mode, when there is no abnormality in the wiring of the first to fourth conductors 51 to 54 and the operation section 25 of the first external switch 2 is operated, the detection signal Vds1 changes and the second This is for confirming that the detection signal Vds2 changes when the operating portion 35 of the external switch 3 is operated.

The adjustment mode is a mode for adjusting the predetermined time in the confirmation mode based on the responsiveness of the input voltages Vin1 and Vin2 when the voltages output to the first and second external switches 2 and 3 are changed. The necessity and specific procedure for adjusting the predetermined time in the confirmation mode will be described later.

In the normal mode, when the detection signals Vds1 and Vds2 change in the voltage output state in which the voltage is output from the output terminals 101 and 103 of the signal input device 1 to the first and second external switches 2 and 3, the first and second This is a mode for detecting that the ON/OFF states of the external switches 2 and 3 of 2 have changed. In other words, the control unit 11 determines that the ON/OFF state of the first external switch 2 has changed when the detection signal Vds1 changes during operations other than the confirmation mode and the adjustment mode, and determines that the ON/OFF state of the first external switch 2 has changed when the detection signal Vds2 changes. It is determined that the on/off state of the second external switch 3 has changed.

FIGS. 2A and 2B show an example of temporal changes in the control signals Vcs1, Vcs2 and the detection signals Vds1, Vds2 in the confirmation mode, where (a) is the signal waveform during normal operation, and (b) is the Signal waveforms are shown when a short-circuit abnormality occurs in which the second conducting wire 52 and the fourth conducting wire 54 are short-circuited.

As shown in FIG. 2A, in normal operation, when the control unit 11 changes the control signal Vcs1 into a pulse shape, the detection signal Vds1 changes in synchronization with the control signal Vcs1, and the control unit 11 changes the control signal Vcs1. When Vcs2 is changed in a pulse shape, the detection signal Vds2 changes in synchronization with this control signal Vcs2. On the other hand, when the second conducting wire 52 and the fourth conducting wire 54 are short-circuited, as shown in FIG. , Vds2 do not change. When such an anomaly occurs, the control unit 11 outputs an anomaly signal to notify the host controller of the anomaly. Hereinafter, the pulse-like changes of the control signals Vcs1 and Vcs2 in the confirmation mode are referred to as test pulses.

By the way, the length of the first to fourth conducting wires 51 to 54 may be long depending on the configuration of the equipment, for example. In such a case, changes in the waveforms of the input voltages Vin1 and Vin2 may become sluggish due to the influence of stray capacitance in the first to fourth conductors 51-54. If the waveforms of the input voltages Vin1 and Vin2 become blunted (blunt) in this way, the detection signals Vds1 and Vds2 do not change within a predetermined time in the confirmation mode, and there is a risk of erroneously detecting an abnormality.

3A and 3B show an example of changes in the control signal Vcs1, the input voltage Vin1, and the detection signal Vds1 when the test pulse is generated. (b) shows the waveforms when the first and second conductors 51 and 52 are long, respectively.

FIGS. 3A and 3B show a case where a test pulse is generated at time t0 and the signal state of the detection signal Vds1 is confirmed at time t1. In this illustrated example, the pulse width of the test pulse is 300 μs, and the interval between time t0 and time t1 is 200 μs.

When the first and second conducting wires 51 and 52 are short, as shown in FIG. 3(a), the input voltage Vin1 reaches the threshold Vsh (in the present embodiment) of the first photocoupler 14 before time t1. 7.2 V), and the detection signal Vds1 is changing. In this case, an abnormality is not erroneously detected in the confirmation mode. On the other hand, when the first and second conductors 51 and 52 are long and the input voltage Vin1 is greatly weakened by the stray capacitance, the voltage value Va of the input voltage Vin1 at time t1 is lower than the threshold value Vsh, as shown in FIG. is high, and the signal state of the detection signal Vds1 does not change until time t1. In this case, an abnormality is erroneously detected.

Therefore, in the present embodiment, in the adjustment mode, after the control unit 11 changes the voltages output to the first and second external switches 2 and 3, the input voltages Vin1 and Vin2 change beyond the threshold value Vsh. The time until the time is measured, and the predetermined time in the confirmation mode is set to a time equal to or longer than the measured time. Next, this specific example will be described with reference to FIGS. 4 and 5. FIG.

FIG. 4 is a graph showing an example of waveforms of the control signal Vcs1, the input voltage Vin1, and the detection signal Vds1 in the adjustment mode. FIG. 5 is a graph showing an example of a test pulse waveform with a pulse width set based on the adjustment result in the adjustment mode.

In the adjustment mode, the control unit 11 turns off the control signal Vcs1 and generates a pulse signal having a pulse width sufficient for the input voltage Vin1 to fall below the threshold Vsh. Further, the control unit 11 checks the signal state of the detection signal Vds1 at regular time intervals in the adjustment mode. In the illustrated example of FIG. 4, after turning off the control signal Vcs1 at time t0, the signal state of the detection signal Vds1 is checked every 200 μs at times t1, t2, t3, t4, and t5.

In the example shown in FIG. 4, the voltage value Vb of the input voltage Vin1 is higher than the threshold Vsh at time t2 after 400 μs from time t0, and the voltage value Vb of input voltage Vin1 is higher than the threshold Vsh at time t3 after 600 μs. lower than Therefore, the detection signal Vds1 changes between time t2 and time t3, and the control unit 11 detects that the detection signal Vds1 has changed at time t3. In this case, the measurement time in the control unit 11 is 600 μs.

As a result, the control unit 11 sets the predetermined time for performing the confirmation mode operation on the first external switch 2 to a time equal to or longer than the measurement time (here, 600 μsec). More specifically, the predetermined time in the confirmation mode is set to the same time as the measurement time (600 μs) or a time longer than the measurement time (eg 700 μs). In order to prevent erroneous detection of abnormality, it is more desirable to set the predetermined time in the confirmation mode to a time longer than the measurement time. The control unit 11 also sets the predetermined time for the second external switch 3 to operate in the confirmation mode in the same manner as described above.

The control unit 11 sets the pulse width of the test pulse to a time longer than the time set as the predetermined time in the confirmation mode. FIG. 5 shows an example of a test pulse waveform with a pulse width of 800 μs on the same time axis as in FIG. 4 .

The predetermined time set in the adjustment mode and the pulse width of the test pulse are stored in the non-volatile memory of the signal input device 1 . The adjustment mode operation may be performed, for example, once when the signal input device 1 is powered on, or the first and second external switches 2, 3 are switched by the first to fourth conductors 51 to 54 to the signal input device 1. may be performed only once when connecting to

In the adjustment mode, a process of measuring the time from when the voltage output from the signal input device 1 to the first and second external switches 2 and 3 is changed to when the input voltages Vin1 and Vin2 change beyond the threshold value Vsh. corresponds to the measurement step of the signal detection method according to the present invention. Also, in the confirmation mode, the voltages output to the first and second external switches 2 and 3 are changed in a pulse shape, and the input voltages Vin1 and Vin2 are detected within a predetermined time set based on the time measured in the measurement step. The process of confirming that V exceeds the threshold value Vsh corresponds to the confirmation step of the signal detection method according to the present invention.

(Actions and effects of the embodiment)
According to the embodiment described above, in the confirmation mode, it is confirmed that the detection signal changes within the predetermined time adjusted in the adjustment mode. is long, it is possible to accurately determine whether or not the first and second external switches 2 and 3 operate normally without erroneously detecting an abnormality.

(Appendix)
Although the present invention has been described above based on the embodiments, these embodiments do not limit the invention according to the scope of claims. Also, it should be noted that not all combinations of features described in the embodiments are essential to the means for solving the problems of the invention. Moreover, the present invention can be modified appropriately without departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1... Signal input device 11... Control part 12... 1st switching element (intermittence part) 13... 2nd switching element (intermittence part)
14... First photocoupler (detection unit) 15... Second photocoupler (detection unit)
2... First external switch 3... Second external switch

Claims (3)

A signal input device for detecting the ON state and OFF state of an external switch,
a switching unit capable of switching between a voltage output state in which voltage is output to the external switch and a voltage cutoff state in which voltage output to the external switch is cut off;
a detection unit that outputs a detection signal in response to an input voltage in which the voltage output in the voltage output state is input through the external switch;
A control unit that controls the intermittent unit and can acquire the detection signal,
The control unit
a confirmation mode in which the voltage output to the external switch is changed in a pulse shape by controlling the intermittent section, and confirmation is made that the detection signal changes within a predetermined time;
an adjustment mode for adjusting the predetermined time in the confirmation mode based on the responsiveness of the input voltage when the voltage output to the external switch is changed;
a normal mode for detecting a change in the on/off state of the external switch when the detection signal changes while in the voltage output state;
Signal input device. The detection unit changes the detection signal when the input voltage changes beyond a threshold,
The control unit measures the time from when the voltage output to the external switch is changed in the adjustment mode until the input voltage changes beyond the threshold, and the set a predetermined time,
The signal input device according to claim 1. A signal detection method for detecting the ON state and OFF state of an external switch by a signal input device,
a measuring step of measuring the time from when the voltage output from the signal input device to the external switch is changed until the input voltage input to the signal input device via the external switch changes beyond a threshold; ,
A confirmation step of changing the voltage output to the external switch in a pulse form and confirming that the input voltage changes beyond the threshold value within a predetermined time set based on the time measured in the measurement step. When,
A signal detection method comprising:

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