JP2011244348A - Proximity sensor and i/o module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a proximity sensor with a self-diagnosis function in which the number of transmission wires of a detection signal and a self-diagnosis signal to a PLC being an example of a signal-receiving side from the proximity sensor is reduced.SOLUTION: The proximity sensor is wired to a PLC-side input contact and outputs a sensor output. The sensor output is variable to at least two levels of first and second levels according to whether an object to be detected is detected or not, and is variable to a third level according to the result of self-diagnosis.

Description

  The present invention relates to a proximity sensor with a self-diagnosis function and an I / O module that uses this as an input device to connect to an input contact of a programmable controller (hereinafter referred to as PLC) by input wiring.

  Proximity sensors can detect the presence or movement of a detection target by replacing it with an electrical signal in a non-contact state with the detection target, and there are many types and various uses.

  For example, there are a high-frequency oscillation type in which a detection target is a metal, and a capacitance method that can be detected even if the detection target is not a metal.

  Such proximity sensor signal output forms include analog output and on / off output. And a proximity sensor is used as one of the input devices which detect and input the state of a control device to PLC, for example (refer patent document 1).

  In the proximity sensor described above, a sensor output is output from the sensor output unit in accordance with whether or not the detection target is detected. In this case, the proximity sensor is connected to an input contact of the input module, for example. Wiring between the proximity sensor and the input contact includes power supply wiring, detection signal transmission wiring, and the like.

  On the other hand, a proximity sensor that has a self-diagnosis function, self-diagnose the sensor state, and transmits the diagnosis result to the input module has already been proposed (see Patent Document 2, etc.). When such a proximity sensor with a self-diagnosis function is connected to an input module, it is necessary to connect a wiring for self-diagnosis signal transmission to the input module as the transmission wiring in addition to the wiring for detection signal transmission. The I / O module includes an input module, an output module, an input / output module, a high-function module such as communication, positioning, and a counter.

JP2002-076871 JP2008-301158

  As described above, in proximity sensors with a self-diagnosis function, it is necessary to connect a wiring for self-diagnosis signal transmission in addition to a wiring for detection signal transmission as a signal transmission wiring. Extra effort is required. Further, more input lines are required because the number of input points increases.

  Therefore, the problem to be solved by the present invention is that in the proximity sensor with a self-diagnosis function, it is possible to reduce the number of wirings for transmitting the detection signal and the self-diagnosis signal and to reduce the labor of wiring between the proximity sensor and the PLC such as the input module. Is to be able to do it.

The proximity sensor according to the first aspect of the present invention relates to a first signal related to the presence or absence of proximity of a detection target via a wiring connected to the signal receiving side, and a self-diagnosis of the sensor state to determine whether the sensor state is normal or abnormal. In proximity sensors that transmit and output two signals,
Among the above signals, the level of the first signal is changed to at least two levels according to the detection and non-detection of the detection target, and transmitted to a single wiring. It is possible to convert at one of the above two levels when normal, or at a level different from these levels when abnormal, and transmit it to the single wiring. It is characterized by.

  In the first aspect of the present invention, for example, logic when the proximity of the detection target is present and the self-diagnosis result is normal, logic when there is no proximity of the detection target and the self-diagnosis result is normal, proximity of the detection target and self There are combinations of logic when the diagnosis result is abnormal and logic when there is no proximity of the detection target and the self-diagnosis result is abnormal. When the self-diagnosis result is normal, priority is given to transmission of the detection signal to be detected. In addition, when the self-diagnosis result is abnormal, priority is given to transmission of a signal of the self-diagnosis result.

  Then, in these logics, in the logic, when the self-diagnosis result is normal, the control circuit transmits two detection signals having different electrical levels as detection of the proximity of the detection target. When the self-diagnosis result is abnormal, the self-diagnosis result signal is transmitted as an electric level different from that of the two detection signals. Therefore, as a single wiring for transmission, the self-diagnosis result is normal unless the signal level in the transmission is an electrical level different from the level of the two detection signals, and the detection target depends on the level of the two detection signals. The proximity state can be determined on the transmission receiving side, and if the signal level in the transmission is an electric level different from the levels of the two detection signals, it is possible to determine that the proximity sensor is abnormal on the signal receiving side. .

  Therefore, in the proximity sensor according to the present invention, the transmission of at least two signals with and without proximity described above and the transmission of the signal of the self-diagnosis result can be transmitted to the receiving side with a single wiring, A proximity sensor that simplifies wiring with the receiving side can be provided.

  Preferably, in the first aspect of the present invention, each level is a voltage level. In this case, the first signal and the second signal are input to the input port, the first and second signals are logically combined, and the logical signal is output from at least two output ports corresponding to the combination. A control circuit that converts the signals into signals having different voltage levels corresponding to the logic signals output from the two output ports of the control circuit, and an output circuit that outputs the converted signals. It is preferable to include.

  Preferably, in the first aspect of the present invention, each of the levels is a level due to a current. In this case, the control circuit which inputs the first signal and the second signal to the input port, logically combines the first and second signals, and outputs the logic signal from the output port corresponding to the combination. And an output circuit for converting each signal into a signal having a different current level corresponding to a logic signal output from the output port of the control circuit, and outputting the converted signal.

  In the first aspect of the present invention, for example, logic when the proximity of the detection target is present and the self-diagnosis result is normal, logic when there is no proximity of the detection target and the self-diagnosis result is normal, proximity of the detection target and self There are combinations of logic when the diagnosis result is abnormal and logic when there is no proximity of the detection target and the self-diagnosis result is abnormal. When the self-diagnosis result is normal, priority is given to transmission of the detection signal to be detected. In addition, when the self-diagnosis result is abnormal, priority is given to transmission of a signal of the self-diagnosis result.

  Then, in these logics, in the logic, when the self-diagnosis result is normal, the control circuit transmits two detection signals having different electrical levels as detection of the proximity of the detection target. When the self-diagnosis result is abnormal, the self-diagnosis result signal is transmitted as an electric level different from that of the two detection signals. Therefore, as a single wiring for transmission, the self-diagnosis result is normal unless the signal level in the transmission is an electrical level different from the level of the two detection signals, and the detection target depends on the level of the two detection signals. The proximity state can be determined on the transmission receiving side, and if the signal level in the transmission is an electric level different from the levels of the two detection signals, it is possible to determine that the proximity sensor is abnormal on the signal receiving side. .

The proximity sensor according to the second aspect of the present invention relates to a first signal relating to the presence or absence of proximity of a detection target via a wiring connected to the signal receiving side, and a self-diagnosis of the sensor state to determine whether the sensor state is normal or abnormal. In proximity sensors that transmit and output two signals,
Among the above signals, the first signal is converted into at least two coded signals according to detection and non-detection of the detection target, and is transmitted and output to a single wiring. When normal, one of the above two coded signals is coded. When abnormal, these coded signals are converted into non-coded signals and transmitted to the single wiring. It is possible to do this.

  In the second aspect of the present invention, the first signal is changed into a coded signal corresponding to the presence / absence of detection of the detection target, and the second signal is determined whether the self-diagnosis result is normal or abnormal depending on whether the coded signal is normal or abnormal. Since it changes to the coded signal, any signal form can transmit the signal indicating the form in the same wiring, and as a result, the wiring for transmitting the sensor output to the input contact of the PLC, Single wiring is enough.

The proximity sensor according to the third aspect of the present invention includes a first signal related to the presence / absence of the proximity of the detection target via the wiring connected to the signal receiving side, and a self-diagnosis of the sensor state to determine whether the sensor state is normal or abnormal. In proximity sensors that transmit and output two signals,
Operates in either the detection target detection mode or self-diagnosis mode in conjunction with the input from the signal receiving side. In each mode, detection target detection or non-detection, or the sensor status self-diagnosis is normal diagnosis The signal level is changed according to whether the result is an abnormality diagnosis result or not.

  In the third aspect of the present invention, the detection target detection mode or the self-diagnosis mode operates in conjunction with the input from the signal receiving side, and in each mode, the detection target detection or non-detection or the self-detection of the sensor state is performed. Since the signal level changes depending on whether the diagnosis is a normal diagnosis result or an abnormal diagnosis result, the signal indicating the form can be transmitted in the same wiring regardless of the signal form as a signal. A single wiring is sufficient as the wiring for transmitting the signal to the input contact of the PLC.

  In the above, the PLC has a building block type classified into a plurality of modules by function. Examples of the module in this building block type include a CPU module and an I / O module. In addition, there is a unit type in which the modules are not integrated according to the function but integrated as a whole. The PLC of the present invention includes any type.

  According to the present invention, in the proximity sensor with a self-diagnosis function, it is possible to reduce the number of transmission lines of the detection signal and the self-diagnosis signal, thereby reducing the labor of wiring between the proximity sensor and the I / O module.

FIG. 1 is a diagram illustrating a proximity sensor according to a first embodiment of the present invention and a PLC to which the proximity sensor is connected to an input point. FIG. 2 is a diagram showing a circuit configuration of the proximity sensor of FIG. FIG. 3 is a time chart for explaining the operation of the proximity sensor having the circuit configuration of FIG. FIG. 4 is a diagram showing the operation logic and output logic of the first and second output transistors in the output circuit. FIG. 5 is a diagram illustrating an example of a PLC input circuit that inputs a signal from the proximity sensor according to the first embodiment. FIG. 6 is a diagram illustrating a circuit configuration of the proximity sensor according to the second embodiment. FIG. 7 is a time chart for explaining the operation of the proximity sensor according to the second embodiment. FIG. 8 is a diagram illustrating a circuit configuration of the proximity sensor according to the third embodiment. FIG. 9 is a time chart for explaining the operation of the proximity sensor according to the third embodiment. FIG. 10 is a diagram illustrating a circuit configuration of the proximity sensor according to the fourth embodiment. FIG. 11 is a time chart for explaining the operation of the proximity sensor according to the fourth embodiment.

  Hereinafter, a proximity sensor and a PLC according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[Embodiment 1]
A first embodiment of the present invention will be described with reference to FIGS. 1 shows a proximity sensor and a PLC to which the proximity sensor is connected as a signal receiving side, FIG. 2 shows a circuit configuration of the proximity sensor of FIG. 1, and FIG. 3 shows an operation of the proximity sensor having the circuit configuration of FIG. FIG. 4 shows the operation logic and output logic of the first and second output transistors in the output circuit.

  Referring to FIG. 1, the PLC in the embodiment is of a building block type in which a plurality of modules are classified by function. The building block type PLC 1 typically includes a CPU module, an I / O module, and the like.

  In the embodiment, an input module 3 is used as an I / O module, and an example in which the input module 3 and the proximity sensor 5 are connected by a wiring cable 7 is shown. Reference numeral 9 denotes a detection target. The wiring cable 7 includes at least a power supply wiring 7a, a ground wiring 7b, and a signal transmission wiring 7c.

  Referring to FIG. 2, the proximity sensor 5 according to the embodiment is, for example, a high-frequency oscillation / amplitude detection type proximity sensor that oscillates at a constant frequency and has an oscillation amplitude that is increased by approaching a detection target such as a metal body. Change is detected. This proximity sensor includes a power supply circuit 11, an oscillation circuit 13, a rectifying / smoothing circuit 15, a CPU 17, a self-diagnosis circuit 18, and an output circuit 19. The oscillation circuit 13 and the rectifying / smoothing circuit 15 can constitute a detection circuit that detects the proximity of the detection target 9.

  The CPU 17 inputs the detection signal generated by the detection circuit and the self-diagnosis signal from the self-diagnosis circuit 18 from the first and second input ports IN1 and IN2, respectively, and logically combines the above signals. A control circuit that outputs a logic signal corresponding to the combination can be configured. The CPU 17 receives power from the power supply circuit 11 at the third input port IN3.

  This proximity sensor includes a memory in which programs such as a basic operation program and a self-diagnosis program are stored, although not shown. The CPU 17 can access the memory, execute various programs, and control the operation of the proximity sensor.

  The oscillation circuit 13 is a circuit that oscillates at a high frequency. The oscillation circuit 13 has a built-in oscillation coil. When the detection target 9 made of a metal body or a magnetic body approaches the oscillation coil in the oscillation circuit 13, an eddy current loss occurs due to electromagnetic induction, and the impedance, which is the effective resistance value of the oscillation coil, changes. The oscillation output amplitude of 13 changes. The proximity sensor can detect the proximity of the detection target 9 using this oscillation output amplitude change.

  The oscillation output amplitude of the oscillation circuit 13 changes rapidly according to the proximity state of the detection target 9, and oscillates or stops oscillation. Therefore, the presence / absence of the detection target 9 can be determined by the change in the oscillation output amplitude. In this case, the detection output obtained by converting the output of the oscillation circuit 13 into a direct current by the rectifying / smoothing circuit 15 decreases as the detection target 9 approaches, and increases as the detection target 9 moves away. The CPU 17 detects the presence / absence of the proximity of the detection target 9 from the output of the rectifying / smoothing circuit 15 corresponding to the output of the oscillation circuit 13 and outputs the detection output to the output circuit 19.

  The output circuit 19 includes first and second output transistors TR1 and TR2, voltage dividing resistors R1 and R2, and bias resistors R3 and R4. Resistors R1 and R2 are connected between the collector terminal of the first transistor TR1 and the power source (DC 24V), and the connection midpoint between the resistors R1 and R2 is an output part of the proximity sensor. The collector terminal of the second transistor TR2 is also connected to the connection midpoint between the resistors R1 and R2. Reference numeral 21a denotes a power supply terminal, 21b denotes a ground terminal, and 21c denotes a signal output terminal. The power supply wiring 7 a is connected to the power supply terminal portion 21 a and supplies 24 V DC to the power supply circuit 11 and the output circuit 19. The ground wiring 7b is connected to the ground terminal portion 21b. The signal transmission wiring 7c is connected to the signal output terminal portion 21c.

  In the proximity sensor with the self-diagnosis function, it is usually necessary to transmit a self-diagnosis signal related to the result of the self-diagnosis to the input module 3 in addition to the detection signal related to the detection of the detection target 9. Two transmission lines are required for at least detection signal transmission and self-diagnosis signal transmission. In this embodiment, as described below, it is possible to transmit such a detection signal and a self-diagnosis signal by a single signal transmission wiring 7c, and thereby, the proximity sensor 5 and the input module 3 can be transmitted. The number of signal transmission wirings is reduced, and the labor for performing such signal transmission wiring work can be reduced.

  The operation of the proximity sensor 5 will be described with reference to FIGS. 3 and 4. FIG. 3 is a time chart for explaining the operation, and FIG. 4 shows the operation logic and output logic of the first and second output transistors TR1 and TR2 in the output circuit 19. Prior to time t0, the detection target 9 is not in proximity. At time t0 shown in FIG. 3, it is detected that the detection target 9 is approaching, and the detection state continues until time t2. A time t1 between the times t0 and t2 indicates a time when the self-diagnosis result is diagnosed as abnormal. Before the time t1, the self-diagnosis result is normal, and after the time t1, the self-diagnosis result is abnormal.

(Detection operation of detection object 9)
Before the time t0, since the detection target 9 is not close, the oscillation output amplitude of the oscillation circuit 13 is large, and an output corresponding to the oscillation output amplitude is output from the rectifying / smoothing circuit 15 to the CPU 17. The CPU 17 outputs the high level (Hi) voltage from the first output port OUT1 and the low level (Lo) voltage from the second output port OUT2, assuming that the detection target 9 is not in proximity from the output of the rectifying and smoothing circuit 15. Accordingly, as shown in FIG. 4, the first output transistor TR1 is turned on by applying a high level (Hi) voltage from the first output port OUT1 to the base, and the second output transistor TR2 is turned on from the second output port OUT2 to the base. Is turned off when a low level (Lo) voltage is applied. The resistors R1 and R2 are connected between the collector terminal of the first transistor TR1 and the power source, and the midpoint of connection between the resistors R1 and R2 is the output section of the proximity sensor 5, so that the output section voltage is both This is a divided voltage by the resistors R1 and R2. When the resistance values of both resistors R1 and R2 are the same, the output voltage from the output terminal portion 21c becomes a middle voltage (Mi) as shown in FIG. 3C, and this middle voltage (Mi) A non-detection signal (first level sensor output) is transmitted from the wiring 7c to the input module 3.

  Next, at time t 0, the detection target 9 approaches, the oscillation output amplitude of the oscillation circuit 13 is small, and an output corresponding to the oscillation output amplitude is output from the rectifying / smoothing circuit 15 to the CPU 17. The CPU 17 outputs a low level (Lo) voltage from both the first and second output ports OUT1 and OUT2, assuming that the detection target 9 is close to the output of the rectifying and smoothing circuit 15. As a result, the first and second output transistors TR1 and TR2 are both turned off as shown in FIG. 4, and the voltage of the output part OUT becomes a high level (Hi) voltage as shown in FIG. 3C. The high level (Hi) voltage is transmitted from the wiring 7 c to the input module 3 as a detection signal (first level sensor output) of the detection target 9.

  Next, at time t2, when the detection target 9 is not in proximity, the middle voltage (Mi) is transmitted from the wiring 7c to the input module 3 as a non-detection signal of the detection target 9 in the same manner as before time t0. The

  In FIG. 3C, the broken line after time t1 indicates the detection target at time t1-t2 when the self-diagnosis result is normal, and the detection target is close after time t2. Indicates no detection as no. In the next self-diagnosis operation, after time t1, since the self-diagnosis result is abnormal, the detection signals are in a high level (Hi) and the non-detection signals are not output in the middle (Mi).

(Self-diagnosis operation)
The CPU 17 self-diagnose the state of the proximity sensor 5 from the output of the self-diagnosis circuit 18 and determines whether it is normal or abnormal. For example, the self-diagnosis circuit 18 performs self-diagnosis on the state of the oscillation circuit 13 and the like, and inputs whether the self-diagnosis result is normal or abnormal to the CPU 17.

  When the CPU 17 self-diagnosis that the state of the proximity sensor 5 is normal before time t0, the detection operation of the detection target 9 is continued. In the above detection operation example, a high level (Hi) voltage signal is output from the first and second output ports OUT1 and OUT2 when the detection target is close, and a middle (Mi) voltage signal is output when the detection target is not close. .

  At time t1, when the CPU 17 makes a self-diagnosis that the state of the proximity sensor 5 is abnormal, the first and second output ports OUT1 and OUT2 are connected regardless of whether the detection target 9 is in proximity or not. 4 outputs a voltage for turning off the first output transistor TR1 and turning on the second output transistor TR2 as shown in FIG. 4, thereby forcing the output OUT voltage to be low as shown in FIG. Let it be level (Lo). This low level (Lo) voltage signal is transmitted from the wiring 7c to the input module 3 as a signal (third level sensor output) indicating that the proximity sensor is abnormal.

  As described above, in the proximity sensor according to the first embodiment, the voltage level of the sensor output changes, and the voltage first level indicating that the detection target 9 is not detected and the detection target 9 is detected. And a voltage different from the first level or the second level when the self-diagnosis result is normal, and when the self-diagnosis result is abnormal, the voltage different from the first level or the second level. It is possible to change to the third level. As a result, in the first embodiment, the detection / non-detection signal of the detection target 9 and the self-diagnosis signal can be transmitted to the input module 3 through the same wiring 7c. As a result, the proximity sensor 5 and the input module 3 can be transmitted. In this case, the wiring work can be simplified and the cost required for the wiring can be reduced.

  FIG. 5 shows an internal configuration of the input module 3 as an example of the signal receiving side. The input module 3 includes input circuits 3a and 3b and an internal circuit 3c that inputs the outputs of both the circuits 3a and 3b. The input circuit 3a includes resistors R1, R3, R5, R7, capacitors C1, C3, and a photocoupler P1. The input circuit 3b includes resistors R2, R4, R6, R8, capacitors C2, C4, and a photocoupler P2. A wiring 7c is connected to the input unit 23 (input point).

  When a high level (Hi) signal is input to the input unit 23, the high level (Hi) signal is divided by the voltage dividing ratio of the resistors R1 and R3 in the input circuits 3a and 3b, and the photocoupler P1 is turned on. Since the photocoupler P2 is turned on by dividing by the voltage dividing ratio of the resistors R2 and R4, the internal circuit 3c receives a detection signal indicating that there is a detection target from the proximity sensor 5 by the ON output from both the photocouplers P1 and P2. 7c is transmitted.

  When a middle (Mi) signal is input to the input unit 23, the middle (Mi) signal is divided by the voltage dividing ratio of the resistors R1 and R3 in the input circuits 3a and 3b, respectively, and the photocoupler P1 is turned off, and the resistor R2 , R4 and the photocoupler P2 is turned on. As a result, the internal circuit 3c knows that the non-detection signal indicating that there is no detection target has been transmitted from the proximity sensor 5 from the wiring 7c by the outputs from both the photocouplers P1 and P2.

  When a low level (Lo) signal is input to the input unit 23, the low level (Lo) signal is a photocoupler in each of the input circuits 3a and 3b according to the voltage dividing ratio of the resistors R1 and R3 and the voltage dividing ratio of the resistors R2 and R4. Both P1 and P2 are turned off. Thereby, the internal circuit 3c knows that the self-diagnosis signal has been transmitted from the proximity sensor 5 from the wiring 7c by the OFF output from both the photocouplers P1 and P2.

  As described above, in the first embodiment, two signals of the signal related to detection of the detection target and the signal indicating the self-diagnosis result can be transmitted to the single wiring 7c, and the wiring 7c to the input module 3 can be transmitted. The connection work can be simplified.

[Embodiment 2]
A second embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 6, in the second embodiment, the output circuit 19 inputs an output from the third output port OUT3 of the CPU 17 to one input unit based on the operational amplifier (op amp) A1 and the output of the operational amplifier A1. And pnp type output transistors TR1 and TR2 and a resistor R1 which both output current and output. The output transistors TR1 and TR2 have collectors connected in common and are connected to the output unit 21c. The base of the output transistor TR1 is connected to the emitter of the output transistor TR2. The emitter of the output transistor TR1 is connected to the power supply via the resistor R1 and is connected to the other input portion of the operational amplifier A1.

In the proximity sensor 5 of the second embodiment having the above configuration, the output circuit 19 is configured as an analog current output circuit.
The operation of the proximity sensor according to the second embodiment will be described with reference to FIG. Here, FIGS. 7A, 7B, and 7C correspond to FIGS. 3A, 3B, and 3C, respectively.

(Detection operation of detection object 9)
Before the time t0, since the detection target 9 is not close, the oscillation output amplitude of the oscillation circuit 13 is large, and an output corresponding to the oscillation output amplitude is output from the rectifying / smoothing circuit 15 to the CPU 17. The CPU 17 outputs a middle (Mi) voltage from the third output port OUT3 to one input portion of the operational amplifier A1, assuming that the detection target 9 is not in proximity from the output of the rectifying / smoothing circuit 15. The operational amplifier A1 outputs to the base of the output transistor TR2 an output corresponding to the difference (difference voltage) between the middle (Mi) voltage of one input unit and the voltage of the other input unit. In this case, since the differential voltage is intermediate, the current output from the common collector of the output transistors TR1 and TR2 to the current output unit 21c is, for example, 10 mA as the current first level. This first current level signal is transmitted from the wiring 7c to the input module 3 as a non-detection signal (first level sensor output) of the detection target 9.

  Next, at time t 0, the detection target 9 approaches, the oscillation output amplitude of the oscillation circuit 13 is small, and an output corresponding to the oscillation output amplitude is output from the rectifying / smoothing circuit 15 to the CPU 17. The CPU 17 outputs a high level (Hi) voltage from the third output port OUT3 to one input portion of the operational amplifier A1, assuming that the detection target 9 is close to the output of the rectifying / smoothing circuit 15. The operational amplifier A1 outputs an output corresponding to the difference (difference voltage) between the high level (Hi) voltage of one input unit and the voltage of the other input unit to the base of the output transistor TR2. In this case, since the difference voltage is small, the current output from the common collector of the output transistors TR1 and TR2 to the current output unit 21c is, for example, 20 mA as the current second level. This current second level signal is transmitted from the wiring 7c to the input module 3 as a detection signal of the detection target 9 (second level sensor output).

(Self-diagnosis operation)
The CPU 17 self-diagnose the state of the proximity sensor 5 from the output of the self-diagnosis circuit 18 and determines whether it is normal or abnormal. For example, the self-diagnosis circuit 18 performs self-diagnosis on the state of the oscillation circuit 13 and the like, and inputs whether the self-diagnosis result is normal or abnormal to the CPU 17.
Until time t1, when the CPU 17 performs self-diagnosis that the state of the proximity sensor 5 is normal, the detection operation of the detection target 9 is continued. In the above detection operation example, a current signal of 20 mA is output from the output point 21c when the detection target is close, and a current signal of 10 mA is output when the detection target is not close.

  At time t1, when the CPU 17 makes a self-diagnosis that the state of the proximity sensor 5 is abnormal, the output port OUT3 is connected to the operational amplifier A1 regardless of whether the detection target 9 is in proximity or not. (Lo) signal is output. As a result, a current signal of 0-5 mA indicating the result of self-diagnosis is output from the output point 21c.

  As described above, in the proximity sensor 5 according to the second embodiment, the sensor output changes at the current level, the first current level indicating that the detection target 9 is detected, and the detection target 9 is not detected. It changes at the current second level, and when the self-diagnosis result is abnormal, it changes at the current third level.

  Thus, in the second embodiment, detection / non-detection of the detection target 9 and the self-diagnosis result can be transmitted to the input module 3 by the same wiring 7c by the current signal, and as a result, the proximity sensor 5 and the input module are transmitted. The connection wiring with 3 can be completed by a single wiring, and the wiring work can be simplified and the cost required for the wiring can be reduced.

[Embodiment 3]
A third embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 8, in the third embodiment, the output circuit 19 includes an output transistor TR1, voltage dividing resistors R1 and R2, and a bias resistor R4. The base of the output transistor TR1 is connected to the fourth output port OUT4 of the CPU 17, the collector is connected to the power supply line via the voltage dividing resistors R1 and R2, and the emitter is connected to the ground line. Similarly to the first embodiment, the midpoint of connection between the voltage dividing resistors R1 and R2 is connected to the output unit 21c.

  In the proximity sensor 5 of the third embodiment having the above configuration, the output circuit 19 has a configuration of a coded signal output circuit.

  When the CPU 17 determines that there is proximity to the detection target based on the output of the rectifying / smoothing circuit 15, the CPU 17 outputs a logic signal of “10101010”, for example, as the first coded signal. The signal in this case is a low level (Lo) voltage if the logic is “1”, and a high level (Hi) voltage if the logic is “0”. When it is determined that there is no proximity to the detection target, for example, a logic signal of “11001100” is output as the second coded signal. Further, in the case of a diagnostic signal, a logic signal “00000000”, for example, is output as the third coded signal. The output transistor TR1 is turned off when a low level (Lo) voltage is input to the base as a logic “1”, and as a result, a high level (Hi) voltage is output as a logic “1” from the output unit 21c. . The output transistor TR1 is turned on when a high level (Hi) voltage is input to the base as a logic “0”, and as a result, a low level (Lo) voltage is output from the output unit 21c as a logic “0”. Is done.

  The operation of the proximity sensor according to the second embodiment will be described with reference to FIG. Here, FIGS. 9A, 9B, and 9C correspond to FIGS. 3A, 3B, and 3C, respectively.

(Detection operation of detection object 9)
Before the time t0, since the detection target 9 is not close, the oscillation output amplitude of the oscillation circuit 13 is large, and an output corresponding to the oscillation output amplitude is output from the rectifying / smoothing circuit 15 to the CPU 17. The CPU 17 detects that the detection target 9 is not close from the output of the rectifying and smoothing circuit 15 and outputs the first coded signal from the fourth output port OUT4 to the base of the output transistor TR1. The first coded signal is transmitted from the wiring 7c to the input module 3 as a non-detection signal of the detection target 9.

  Next, at time t 0, the detection target 9 approaches, the oscillation output amplitude of the oscillation circuit 13 is small, and an output corresponding to the oscillation output amplitude is output from the rectifying / smoothing circuit 15 to the CPU 17. The CPU 17 outputs the second coded signal from the fourth output port OUT4 to the base of the output transistor TR1, assuming that the detection target 9 is close to the output of the rectifying / smoothing circuit 15. The second coded signal is transmitted from the wiring 7c to the input module 3 as a detection signal for the detection target 9.

  In FIG. 9 (a), in order to correspond to FIG. 3 (a), the non-detection is indicated by a low level (Lo), and the detection is indicated by a high level (Hi). Or to detect.

(Self-diagnosis operation)
The self-diagnosis is shown in FIG. 9 (b). In FIG. 9 (b), the self-diagnosis result is low level (Lo) when normal and the high level (Hi) is normal because of the correspondence with FIG. 3 (b). Is shown.

  The CPU 17 self-diagnose the state of the proximity sensor 5 from the output of the self-diagnosis circuit 18 and determines whether it is normal or abnormal. For example, the self-diagnosis circuit 18 performs self-diagnosis on the state of the oscillation circuit 13 and the like, and inputs whether the self-diagnosis result is normal or abnormal to the CPU 17.

  Until time t1, when the CPU 17 performs self-diagnosis that the state of the proximity sensor 5 is normal, the CPU 17 outputs a third coded signal from the fourth output port OUT4 to the base of the output transistor TR1. The third coded signal when the self-diagnosis result is normal is a signal in which a high level (Hi) and a low level (Lo) are repeated in accordance with either the first or second coded signal. Further, the third coded signal when the self-diagnosis result is abnormal is at a low level (Lo) corresponding to the above “00...”. Furthermore, the number of third coded signals can be increased for each abnormal symptom of the self-diagnosis result.

Such a self-diagnosis signal is transmitted from the wiring 7c to the input module 3.
Thereby, in Embodiment 3, detection / non-detection of the detection target 9 and the self-diagnosis result can be transmitted to the input module 3 by the same wiring 7c by the coded signal, and as a result, the proximity sensor 5 and the input Connection wiring with the module 3 can be completed with a single wiring, so that the wiring work can be simplified and the cost required for the wiring can be reduced.

[Embodiment 4]
A fourth embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 10, in the fourth embodiment, the output circuit 19 includes an output transistor TR1, resistors R1, R2, R4, R5, and R6, and an input circuit 19a. The base of the output transistor TR1 is connected to the fifth output port OUT5 of the CPU 17, the collector is connected to the power supply line via the voltage dividing resistors R1 and R2, and the emitter is connected to the ground line. Similarly to the first embodiment, the midpoint of connection between the voltage dividing resistors R1 and R2 is connected to the output unit 21c.

  The input circuit 19a includes resistors R7 and R8 and a photocoupler P1. The output circuit 19 has an input unit 21d, and this input unit 21d is connected to the input module 3 side via a wiring 7d. A signal for switching and controlling the output signal from the proximity sensor 5 can be input from the input module 3 via the wiring 7d. In the figure, this signal is described as “PLC interlocking input IN”. When the PLC interlocking input IN is at a high level (Hi), the detection mode is switched to a detection mode for outputting a signal related to the presence / absence of detection target proximity. . When the high-level (Hi) PLC interlocking input IN to enter the detection mode is input to the input unit 21d, the photocoupler P1 in the input circuit 19a is turned OFF, and the OFF output is input to the fourth input port IN4 of the CPU 17. When the low-level (Lo) PLC interlocking input IN for entering the self-diagnosis mode is input to the input unit 21d, the photocoupler P1 is turned off, and the off-output is input to the fourth input port IN4 of the CPU 17.

  In response to the on / off output of the photocoupler P1, the CPU 17 outputs a detection signal, a non-detection signal, or a self-diagnosis signal from the fifth output port OUT5.

  The operation of the proximity sensor according to the fourth embodiment will be described with reference to FIG. Here, FIGS. 11A and 11B correspond to FIGS. 3A and 3B, respectively. FIG. 11C shows a high level (Hi) voltage input to the input circuit 19a in the output circuit 19 as the first mode, and a low level (second level) input to the input circuit 19a in the output circuit 19 as the second mode. Lo) voltage. FIG. 11D shows the signal level of detection or non-detection in the first mode and the signal level of whether the self-diagnosis in the second mode is normal or abnormal.

(Before time t0)
Before the time t0, the detection target is not detected as shown in FIG. 11A, and the self-diagnosis result is normal as shown in FIG. 11B. Further, as shown in FIG. 11C, a high level (Hi) voltage is input from the input module 3 to the PLC interlocking input IN, and a detection mode for detecting the proximity of the detection target is set. In this state, the CPU 17 outputs a low level (Lo) signal from the fifth output port OUT5 to the output circuit 19, thereby turning off the output transistor TR1. As a result, the output unit 21c receives FIG. 11 (d). A high level (Hi) signal indicating non-detection of the detection target is output as the sensor output OUT as indicated by. This signal is transmitted from the wiring 7c to the input module 3.

(Time t0-t01)
Next, at time t0-t01, the detection target 9 is detected as shown in FIG. 11A, and the self-diagnosis result is normal as shown in FIG. 11B. Further, as shown in FIG. 11 (c), a high level (Hi) voltage is input from the input module 3 as the PLC interlocking input IN, and the detection target proximity presence / absence detection mode is set. In this state, the CPU 17 outputs a high level (Hi) signal from the fifth output port OUT5 to the output circuit 19, whereby the output transistor TR1 is turned on. As a result, the output unit 21c receives FIG. 11 (d). As shown in FIG. 4, a low level (Lo) signal indicating detection target detection is output as the sensor output OUT. This signal is transmitted from the wiring 7c to the input module 3.

(Time t01-t02)
From time t01 to t02, the detection target 9 is detected as shown in FIG. 11A, and the self-diagnosis result is normal as shown in FIG. 11B. Further, as shown in FIG. 11C, a low level (Lo) voltage is input from the input module 3 as the PLC interlocking input IN, and the self-diagnosis mode is set. In this state, the CPU 17 outputs a high level (Hi) signal indicating that it is normal as a result of self-diagnosis from the fifth output port OUT5 to the output circuit 19, whereby the output transistor TR1 is turned on. As a result, as shown in FIG. 11D, the output unit 21c outputs a high level (Hi) signal indicating that the self-diagnosis result is normal as the sensor output OUT. This high level (Hi) signal is transmitted from the wiring 7 c to the input module 3.

(Time t02-t1)
At time t02-t1, the detection target 9 is detected as shown in FIG. 11A, and the self-diagnosis result is normal as shown in FIG. 11B. Further, as shown in FIG. 11C, a high level (Hi) voltage is input from the input module 3 as the PLC interlocking input IN, and the detection mode is set. In this state, the CPU 17 outputs a high level (Hi) signal from the fifth output port OUT5 to the output circuit 19, whereby the output transistor TR1 is turned on. As a result, the output unit 21c receives FIG. 11 (d). A low level (Lo) signal indicating the detection target proximity detection is output as the sensor output OUT as shown in FIG. This signal is transmitted from the wiring 7c to the input module 3.

(Time t1-t11)
At time t1-t11, the detection target 9 is detected as shown in FIG. 11 (a), and the self-diagnosis result is abnormal as shown in FIG. 11 (b). Further, as shown in FIG. 11C, a high level (Hi) voltage is input from the input module 3 as the PLC interlocking input IN, and the detection mode is set. In this state, the CPU 17 outputs a high level (Hi) signal from the fifth output port OUT5 to the output circuit 19, whereby the output transistor TR1 is turned on. As a result, the output unit 21c receives FIG. 11 (d). A low level (Lo) signal indicating the detection target proximity detection is output as the sensor output OUT as shown in FIG. This signal is transmitted from the wiring 7c to the input module 3.

(Time t11-t2)
At time t11-t2, the detection target 9 is detected as shown in FIG. 11A, and the self-diagnosis result is abnormal as shown in FIG. 11B. Further, as shown in FIG. 11C, a low level (Lo) voltage is input from the input module 3 as the PLC interlocking input IN, and the self-diagnosis mode is set. In this state, the CPU 17 outputs a low level (Lo) signal from the fifth output port OUT5 to the output circuit 19, whereby the output transistor TR1 is turned on. As a result, the output unit 21c receives FIG. 11 (d). As shown in FIG. 4, a low level (Lo) signal indicating that the self-diagnosis result is abnormal is output as the sensor output OUT. This signal is transmitted from the wiring 7c to the input module 3.

(After time t2)
After time t2, since the immediately preceding self-diagnosis result of the proximity sensor is abnormal, a low level (Lo) signal indicating this is output. This signal is transmitted from the wiring 7c to the input module 3.

  As described above, in each of the embodiments, a signal indicating the detection of the proximity of a detection target and a self-diagnosis signal can be transmitted to the PLC, so that the wiring can be simplified. be able to.

  In the present invention, the constituent elements in the plurality of embodiments may be arbitrarily combined without departing from the spirit of the invention.

1 PLC
3 Input module (signal receiving side)
5 Proximity sensor 7 wiring (7a power wiring, 7b ground wiring, 7c output wiring)
9 Detection Target 11 Power Supply Circuit 13 Oscillation Circuit 15 Rectification Smoothing Circuit 17 CPU (Control Circuit)
19 Output circuit

Claims (9)

Proximity sensor that transmits and outputs a first signal related to the proximity of the detection target and a second signal related to whether the sensor state is normal or abnormal through a wiring connected to the signal receiving side In
Of the above signals,
For the first signal, the level is changed to at least two levels according to detection and non-detection of the detection target, and transmitted to a single wiring, and then output.
For the second signal, when the self-diagnosis result is normal, it is converted at one of the above two levels, and when abnormal, it is converted at a level different from these levels and transmitted to the single wiring. Is possible,
Proximity sensor characterized by the above.   The proximity sensor according to claim 1, wherein the level is a voltage level. A control circuit for inputting the first signal and the second signal to an input port, logically combining the first and second signals, and outputting a logic signal from at least two output ports corresponding to the combination. When,
An output circuit for converting each signal into a signal having a different voltage level corresponding to a logic signal output from two output ports of the control circuit, and outputting the converted signals;
including,
The proximity sensor according to claim 2.   The proximity sensor according to claim 1, wherein the level is a current level. A control circuit for inputting the first signal and the second signal to an input port, logically combining the first and second signals, and outputting a logic signal from the output port corresponding to the combination;
An output circuit for converting each signal into a signal having a different current level corresponding to a logic signal output from the output port of the control circuit, and outputting the converted signals;
including,
The proximity sensor according to claim 4. Proximity sensor that transmits and outputs a first signal related to the proximity of the detection target and a second signal related to whether the sensor state is normal or abnormal through a wiring connected to the signal receiving side In
Of the above signals,
The first signal is converted into at least two coded signals according to detection and non-detection of the detection target, and is transmitted and output to a single wiring.
As for the second signal, when the self-diagnosis result is normal, it is a coded signal of one of the above two coded signals, and when abnormal, the coded signal is different from these coded signals or is not coded. It is possible to convert it to a signal and transmit it to the single wiring.
Proximity sensor characterized by the above. Proximity sensor that transmits and outputs a first signal related to the proximity of the detection target and a second signal related to whether the sensor state is normal or abnormal through a wiring connected to the signal receiving side In
Operates in either the detection target detection mode or self-diagnosis mode in conjunction with the input from the signal receiving side. In each mode, detection target detection or non-detection, or the sensor status self-diagnosis is normal diagnosis A proximity sensor, wherein the signal level is changed according to whether the result is an abnormality diagnosis result.   The proximity sensor according to claim 1, wherein the signal receiving side is a programmable controller.   8. An I / O module characterized in that the proximity sensor according to any one of claims 1 to 7 can respond to an input of a sensor output.

Images