JP7230538B2 - Industrial equipment controller - Google Patents

Description

The present invention relates to a controller for controlling industrial equipment.

Conventionally, there is a controller that detects welding of a power cutoff relay that cuts off the drive current of a servomotor of a robot (industrial equipment) and outputs a welding detection signal to a safety PLC (external equipment) (see Patent Document 1).

Japanese Patent No. 5830755

By the way, the controller described in Patent Document 1 can detect an abnormality in an internal switch (for example, a power cutoff relay), but cannot detect an abnormality in an external device connected to the controller.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its main object is to use a circuit for detecting an abnormality in an internal switch in a controller for industrial equipment to detect an abnormality in an external device connected to the controller. to detect.

A first means for solving the above problems is a controller for industrial equipment,
a switch;
an external connection terminal connected to a power supply via the switch;
a driving unit that drives the switch with an on-pulse signal;
a voltage detection unit that detects a voltage at a detection point between the switch and the external connection terminal;
a detection unit that detects an abnormality in the switch and an abnormality in an external device connected to the external connection terminal based on the voltage detected by the voltage detection unit when the switch is driven by the drive unit;
Prepare.

According to the above configuration, the external connection terminal is connected to the power supply via the switch. Therefore, when the drive unit drives the switch with the on-pulse signal, the voltage from the power supply is applied to the external connection terminal in a pulse form. Then, the voltage detector detects the voltage at the detection point between the switch and the external connection terminal.

If the switch is normal when the drive section drives the switch with the on-pulse signal, the voltage detected by the voltage detection section becomes pulse-shaped. On the other hand, when the switch is stuck in the ON state (an abnormality occurs in which the switch is fixed in the ON state and does not move), the voltage detected by the voltage detection unit is a constant predetermined voltage (>0). Further, when the switch is stuck in the off state (abnormality occurs where the switch is fixed in the off state and does not move), the voltage detected by the voltage detection unit is 0 and constant. Therefore, the detection section can detect an abnormality of the switch based on the voltage detected by the voltage detection section when the switch is driven by the drive section.

Furthermore, when an external device is connected to the external connection terminal when the driving unit drives the switch with the on-pulse signal, the voltage applied to the external connection terminal is reflected by the resistance of the external device. Therefore, the voltage detected by the voltage detection unit is a voltage obtained by superimposing the voltage applied to the external connection terminal and the voltage reflected by the resistance of the external device. Also, when the external device is short-circuited, the voltage applied to the external connection terminal is not reflected. Therefore, the voltage detected by the voltage detection unit is the voltage applied to the external connection terminal. Therefore, the detection unit utilizes a circuit for detecting an abnormality in an internal switch to detect an external signal connected to the external connection terminal based on the voltage detected by the voltage detection unit when the switch is driven by the drive unit. Abnormality of equipment can be detected. Moreover, since the voltage at the detection point between the switch and the external connection terminal is detected by the voltage detection unit, it is possible to detect an abnormality in both the switch and the external device based on the voltage at one detection point. .

In the second means, the detection unit detects that the voltage detected by the voltage detection unit when the switch is driven by the drive unit can be regarded as equal to the voltage applied to the external connection terminal. If the voltage is less than the first voltage to be determined, it is detected that the external device is short-circuited.

If the external device connected to the external connection terminal is short-circuited when the driving unit drives the switch with the on-pulse signal, the voltage applied to the external connection terminal is not reflected. Therefore, the voltage detected by the voltage detection unit is approximately equal to the voltage applied to the external connection terminal. Therefore, when the voltage detected by the voltage detection unit when the switch is driven by the drive unit is less than the first voltage for determining that the voltage is equal to the voltage applied to the external connection terminal, the detection unit , it can detect that an external device is short-circuited.

In the third means, the voltage detected by the voltage detection unit when the switch is driven by the drive unit is set higher than the voltage applied to the external connection terminal. When the second voltage is exceeded with a delay from the rise of the voltage detected by the voltage detection section, it is detected that the external device is disconnected.

When the driving unit drives the switch with the on-pulse signal, if the external device is not connected to the external connection terminal, the voltage applied to the external connection terminal is reflected by the external connection terminal. Therefore, the voltage detected by the voltage detection unit is a voltage in which the voltage applied to the external connection terminal is superimposed with the voltage reflected by the external connection terminal at the same time as the voltage rises. On the other hand, when the external device connected to the external connection terminal is broken, the voltage applied to the external connection terminal is reflected at the broken portion of the external device that is farther from the external connection terminal. Therefore, the voltage detected by the voltage detection unit is a voltage in which the voltage applied to the external connection terminal is superimposed with the voltage reflected by the disconnection portion of the external device with a delay from the rise of the voltage applied to the external connection terminal. Therefore, when the switch is driven by the driving unit, the voltage detected by the voltage detecting unit detects the second voltage set higher than the voltage applied to the external connection terminal by the voltage detecting unit. It can be detected that the external device is broken if it exceeds the voltage with a delay from the rise of the applied voltage.

In the fourth means, the voltage detected by the voltage detection unit when the switch is driven by the drive unit is set higher than the voltage applied to the external connection terminal. When the third voltage is exceeded at the same time as the voltage detected by the voltage detection section rises, it is detected that the external device is not connected to the external connection terminal.

When the driving unit drives the switch with the on-pulse signal, if the external device is not connected to the external connection terminal, the voltage applied to the external connection terminal is reflected by the external connection terminal. Therefore, the voltage detected by the voltage detection unit is a voltage in which the voltage applied to the external connection terminal is superimposed with the voltage reflected by the external connection terminal at the same time as the voltage rises. Therefore, the voltage detection unit detects the third voltage, which is set higher than the voltage applied to the external connection terminal, by the voltage detection unit when the switch is driven by the drive unit. It can be detected that an external device is not connected to the external connection terminal if the voltage exceeds the voltage at the same time as the voltage rises.

A fifth means is a controller for industrial equipment,
a switch;
an external connection terminal connected to a power supply via the switch;
a driving unit that drives the switch with an on-pulse signal;
a voltage detection unit that detects a voltage at a detection point between the switch and the external connection terminal;
The voltage detected by the voltage detection unit when the switch is driven by the drive unit detects a third voltage set higher than the voltage applied to the external connection terminal by the voltage detection unit. a detection unit that detects that an external device is not connected to the external connection terminal when the voltage exceeds the applied voltage at the same time as the voltage rises;
Prepare.

According to the above configuration, it is possible to obtain the same effects as those of the fourth means.

In the sixth means, a variable resistor is connected between the switch and the detection point, and the detection section detects the voltage detected by the voltage detection section when the switch is driven by the drive section. When the voltage exceeds a fourth voltage set higher than the voltage applied to the external connection terminal with a delay from the rise of the voltage detected by the voltage detection unit, the resistance value of the variable resistor is increased from the initial value, the maximum value of the voltage detected by the voltage detection unit when the switch is driven by the driving unit is set as a reference value, and after setting the reference value, the driving When the maximum value of the voltage detected by the voltage detection unit when the switch is driven by the unit is smaller than the reference value by an amount greater than a first predetermined value, it is determined that the external device is short-circuited. detect.

If an external device is connected to the external connection terminal when the drive unit drives the switch with the on-pulse signal, the voltage detected by the voltage detection unit will be higher than the voltage applied to the external connection terminal. After a delay, the voltage reflected by the resistance of the external device becomes the superimposed voltage. The magnitude of the voltage reflected by the resistance of the external device decreases when the resistance of the external device is relatively small with respect to the resistance between the switch and the detection point of the voltage detection section, and when it is relatively large growing.

According to the above configuration, when it can be estimated that an external device is connected to the external connection terminal, the resistance value of the variable resistor is increased from the initial value, and when the switch is driven by the drive unit, the voltage detection unit The maximum value of the voltage detected by is set as the reference value. When the external device is short-circuited after that, the maximum value of the voltage detected by the voltage detection section when the switch is driven by the drive section becomes smaller than the reference value. Therefore, after the setting of the reference value, the detection unit detects that the maximum value of the voltage detected by the voltage detection unit when the switch is driven by the drive unit is less than the reference value by an amount greater than the first predetermined value. In addition, it can detect that an external device is short-circuited.

In the seventh means, the voltage detected by the voltage detection unit when the switch is driven by the drive unit is set higher than the voltage applied to the external connection terminal. When the fourth voltage is exceeded with a delay from the rise of the voltage detected by the voltage detection section, it is detected that an external device is connected to the external connection terminal. According to such a configuration, it is possible to detect that an external device is connected to the external connection terminal.

In the eighth means, after setting the reference value, the detection unit detects the reference value as the maximum value of the voltage detected by the voltage detection unit when the switch is driven by the drive unit. If the amount of the voltage detected by the voltage detection unit that exceeds the rise of the voltage with a delay is greater than a second predetermined value, it is detected that the external device is disconnected.

If the external device is disconnected after setting the reference value, the maximum value of the voltage detected by the voltage detection unit when the switch is driven by the drive unit becomes larger than the reference value. Therefore, after setting the reference value, the detection unit determines that the maximum value of the voltage detected by the voltage detection unit when the switch is driven by the drive unit is higher than the rise of the voltage detected by the voltage detection unit. It can be detected that the external device is disconnected when the amount of exceeding with a delay is larger than the second predetermined value.

In the ninth means, after setting the reference value, the detection unit detects the reference value as the maximum value of the voltage detected by the voltage detection unit when the switch is driven by the drive unit. It is detected that the external device is disconnected from the external connection terminal when the amount of the voltage detected by the voltage detection unit that exceeds the voltage at the same time as the rise is larger than a third predetermined value.

When the external device is disconnected from the external connection terminal after setting the reference value, the maximum value of the voltage detected by the voltage detection unit when the switch is driven by the drive unit becomes larger than the reference value. Furthermore, the voltage detected by the voltage detection unit is a voltage in which the voltage applied to the external connection terminal is superimposed with the voltage reflected by the external connection terminal at the same time as the voltage rises. Therefore, after setting the reference value, the detection section detects the maximum value of the voltage detected by the voltage detection section when the switch is driven by the drive section. When the exceeded amount is larger than the third predetermined value, it can be detected that the external device is disconnected from the external connection terminal.

The schematic diagram which shows a robot, a controller, and PLC. 4 is a time chart showing the voltage applied to the positive terminal of the external connection terminal; The time chart which shows the detection voltage in the case of no connection to an external connection terminal. The time chart which shows the detection voltage when there is a connection to the external connection terminal. 4 is a flowchart showing a procedure of abnormality detection; 4 is a time chart showing the detected voltage when the PLC is short-circuited after setting the reference value; 6 is a time chart showing the detected voltage when the PLC is disconnected from the external connection terminal after setting the reference value; 4 is a time chart showing the detected voltage when the PLC is disconnected after setting the reference value;

An embodiment embodied in a robot controller will be described below with reference to the drawings.

As shown in FIG. 1, controller 20 is connected to robot 10 . The robot 10 (industrial equipment) is, for example, an articulated robot, and performs work on a workpiece or the like. The motion of the robot 10 is controlled by the controller 20 .

The controller 20 is configured as a computer including a CPU, ROM, RAM, drive circuit, detection circuit, and the like. The controller 20 detects the state of the robot 10 and controls the robot 10 based on the detected state. The controller 20 realizes the functions of the driving section 21 , the voltage detecting section 22 and the detecting section 23 .

The controller 20 includes a power source 24, a switch 25, a variable resistor 26, external connection terminals 27, and the like. The power supply 24 may be a power supply circuit that transforms the voltage supplied from a commercial power supply, or may be a battery or the like. A power supply 24 supplies a predetermined voltage (for example, 24V). The switch 25 may be a semiconductor switching element, a relay, or the like. The variable resistor 26 (resistor) can change the magnitude of the resistance value according to a command from the detection unit 23 . The external connection terminal 27 is configured by a connector to which an external device can be connected.

Variable resistor 26 is connected to power supply 24 via switch 25 . A positive terminal of the external connection terminal 27 is connected to the switch 25 via the variable resistor 26 . That is, the positive terminal of the external connection terminal 27 is connected to the power supply 24 via the switch 25 . A negative terminal of the external connection terminal 27 is grounded. The switch 25 connects and disconnects the power source 24 and the variable resistor 26 and the positive terminal of the external connection terminal 27 . The switch 25 is driven by the driving section 21 .

The drive unit 21 drives the switch 25 with an on-pulse signal. As a result, the voltage V1 from the power supply 24 is applied to the positive terminal of the external connection terminal 27 in a pulse form, as shown in FIG. The drive unit 21 drives the switch 25 periodically, more specifically, in a constant cycle, by the on-pulse signal.

The voltage detection unit 22 detects the voltage at the detection point P between the switch 25 and the positive terminal of the external connection terminal 27 , more specifically, between the variable resistor 26 and the positive terminal of the external connection terminal 27 . The voltage detection section 22 sequentially detects the voltage at the detection point P and outputs the detected voltage to the detection section 23 .

The detection unit 23 detects an abnormality of the switch 25 based on the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 .

When the switch 25 is normal when the drive unit 21 drives the switch 25 with the on-pulse signal, the voltage detected by the voltage detection unit 22 is pulse-shaped. On the other hand, when the switch 25 is stuck in the ON state (an abnormality occurs in which the switch 25 is fixed in the ON state and does not move), the voltage detected by the voltage detection unit 22 is the voltage V1 (a constant predetermined voltage). Therefore, the detection unit 23 detects that the switch 25 is stuck on when the voltage detected by the voltage detection unit 22 is constant at the voltage V1 when the switch 25 is driven by the drive unit 21. .

Further, when the switch 25 is stuck in the off state (abnormal occurrence of the switch 25 being fixed in the off state and not moving), the voltage detected by the voltage detection unit 22 is 0 and constant. Therefore, when the voltage detected by the voltage detection unit 22 is constant at 0 when the switch 25 is driven by the driving unit 21, the detection unit 23 detects that the switch 25 is stuck off.

In general, voltage reflection occurs at boundaries of different impedances. Therefore, when an external device is not connected to the external connection terminal 27 , the voltage applied to the positive terminal of the external connection terminal 27 is reflected by the positive terminal of the external connection terminal 27 . At this time, the voltage detected by the voltage detection unit 22 is, as shown in FIG. resulting in a superimposed voltage. Here, when the impedance changes from Z1 to Z2, the reflection coefficient .GAMMA. when the voltage is reflected is expressed by the following equation. That is, the magnitude of the voltage reflected by the impedance Z2 decreases as the impedance Z2 is relatively smaller than the impedance Z1, and increases as the impedance Z2 is relatively greater.

Γ=(Z2−Z1)/(Z2+Z1)
When no external device is connected to the external connection terminal 27, the impedance Z2 at the positive terminal of the external connection terminal 27 becomes infinite (extremely large value). Impedance Z1 is the resistance value of variable resistor 26 . Therefore, the reflection coefficient Γ=1, and as shown in FIG. becomes 2V1. In addition, since the distance between the detection point P and the positive terminal of the external connection terminal 27 is short (can be regarded as 0), the voltage V1 applied to the positive terminal of the external connection terminal 27 rises to the positive terminal of the external connection terminal 27 at the same time. The voltage V2 reflected at the terminals is superimposed.

Therefore, the detection unit 23 detects that the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 is set higher than the voltage V1 applied to the positive terminal of the external connection terminal 27. When Vr3 (third voltage) is exceeded at the same time as the voltage detected by the voltage detection unit 22 rises, it is detected that the positive terminal of the external connection terminal 27 is not connected to an external device. The voltage Vr3 is set based on the resistance value of the variable resistor 26, and is 1.5V1, for example.

A PLC (Programmable Logic Controller) 30 commands the controller 20 to operate and stop the robot 10 . The PLC 30 (external device) is connected to a host controller and the like (not shown). The PLC 30 includes a photocoupler 31, a resistor 32, a positive cable 33A, a negative cable 33B, a connector 34, and the like.

The photocoupler 31 includes a light emitting diode 31a and a phototransistor 31b. The anode of the light emitting diode 31a is connected via a resistor 32 to the positive electrode cable 33A. The cathode of the light emitting diode 31a is connected to the negative electrode cable 33B. Connectors 34 are attached to the ends of the positive electrode cable 33A and the negative electrode cable 33B.

A connector 34 is connected to the external connection terminal 27 of the controller 20 . Thus, the positive cable 33A is connected to the positive terminal of the external connection terminal 27, and the negative cable 33B is connected to the negative terminal.

Here, the positive electrode cable 33A may be short-circuited, or the cables 33A and 33B may be disconnected. Also, even if the connector 34 is apparently connected to the external connection terminal 27, the positive cable 33A may not be connected to the positive terminal, or the negative cable 33B may not be connected to the negative terminal.

In this embodiment, the detection unit 23 detects an abnormality of the PLC 30 based on the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 .

If the PLC 30 is connected to the external connection terminal 27 when the drive unit 21 drives the switch 25 with the on-pulse signal, the voltage V1 applied to the positive terminal of the external connection terminal 27 is reflected by the resistor 32 of the PLC 30. be done. Therefore, as shown in FIG. 4, the voltage detected by the voltage detection unit 22 is obtained by superimposing the voltage V1 applied to the positive terminal of the external connection terminal 27 and the voltage V3 reflected by the resistor 32 of the PLC 30. voltage. Then, the voltage applied to the positive terminal of the external connection terminal 27 is reflected by the resistor 32 of the PLC 30 that is farther from the external connection terminal 27 . Therefore, the voltage detected by the voltage detection unit 22 is a voltage obtained by superimposing the voltage V1 applied to the positive terminal of the external connection terminal 27 and the voltage V3 reflected by the resistor 32 of the PLC 30 with a delay from the rise of the voltage V1. becomes. Therefore, the detection unit 23 determines that the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 is a voltage Vr4 set higher than the voltage applied to the positive terminal of the external connection terminal 27 . When the (fourth voltage) is exceeded with a delay from the rise of the voltage detected by the voltage detection unit 22 , it is detected that the PLC 30 is connected to the external connection terminal 27 . The voltage Vr4 is set based on the resistance values of the variable resistor 26 and the resistor 32, and is 1.2V1, for example.

If the positive cable 33A of the PLC 30 is short-circuited when the drive unit 21 drives the switch 25 with the on-pulse signal, the voltage V1 applied to the positive terminal of the external connection terminal 27 is not reflected. Therefore, the voltage detected by the voltage detector 22 is the voltage V1 applied to the positive terminal of the external connection terminal 27 . Therefore, the detection unit 23 determines that the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 can be considered to be equal to the voltage V1 applied to the positive terminal of the external connection terminal 27. If the voltage is less than the voltage Vr1 (first voltage) to be applied, it is detected that the positive electrode cable 33A of the PLC 30 is short-circuited. The voltage Vr1 is set based on the resistance value of the variable resistor 26, and is 1.2 V1, for example.

When at least one of the positive cable 33A and the negative cable 33B of the PLC 30 connected to the external connection terminal 27 is disconnected, the voltage V1 applied to the positive terminal of the external connection terminal 27 is applied to the positive terminal of the external connection terminal 27. is reflected at the disconnected portion of the PLC 30 that is more distant than the . Therefore, the voltage detected by the voltage detection unit 22 is a voltage in which the voltage applied to the positive electrode terminal of the external connection terminal 27 is superimposed with the voltage reflected at the disconnection portion of the PLC 30 with a delay from the rise of the voltage. . Therefore, the detection unit 23 detects that the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 is set higher than the voltage V1 applied to the positive terminal of the external connection terminal 27. When Vr2 (second voltage) is exceeded with a delay from the rise of the voltage detected by the voltage detection unit 22, it can be detected that the PLC 30 is disconnected. The voltage Vr2 is set based on the resistance values of the variable resistor 26 and the resistor 32, and is 1.5V1, for example.

FIG. 5 is a flow chart showing detailed procedures of abnormality detection. This series of processes is executed by the detection unit 23 in synchronization with the periodical driving of the switch 25 by the drive unit 21 .

First, the switch 25 is driven by the drive unit 21 (S10). The drive unit 21 drives the switch 25 with an on-pulse signal at a constant cycle. The voltage at the detection point P is detected by the voltage detector 22 (S11). Voltage detector 22 outputs the detected voltage to detector 23 .

Based on the detected voltage, it is determined whether or not the reflected voltage lags behind the rise of the detected voltage (S12). Specifically, as shown in FIG. 4, when the detected voltage exceeds the voltage Vr4 with a delay from the rise of the detected voltage, it is determined that the reflected voltage V3 is delayed from the rise of the detected voltage. On the other hand, as shown in FIG. 3, when the detected voltage exceeds the voltage Vr3 (>Vr4) at the same time as the detected voltage rises, it is determined that the reflected voltage V2 does not lag behind the rise of the detected voltage. As shown in FIG. 2, when the detected voltage does not exceed the voltage Vr4, it may be detected that the positive electrode cable 33A of the PLC 30 is short-circuited, and this series of processing may be terminated.

If it is determined in S12 that the reflected voltage does not lag behind the rise of the detected voltage (S12: NO), it is detected that the external device (PLC 30) is not connected to the external connection terminal 27 (S13). Then, this series of processing ends (END).

On the other hand, if it is determined in S12 that the reflected voltage lags behind the rise of the detected voltage (S12: YES), the resistance value of the variable resistor 26 is increased by a predetermined resistance value (S14). The initial resistance value of the variable resistor 26 is set to the minimum possible resistance value of the variable resistor 26 . The predetermined resistance value is preset based on the initial resistance value of the variable resistor 26 and the resistance value of the resistor 32 . The switch 25 is driven by the driving section 21 (S15), and the voltage at the detection point P is detected by the voltage detecting section 22 (S16).

Subsequently, it is determined whether or not the reflected voltage calculated from the detected voltage has decreased by half from the initial reflected voltage detected in the process of S11 (S17). The reflected voltage is calculated by subtracting the voltage V1 applied to the positive terminal of the external connection terminal 27 from the maximum detected voltage. In this determination, if it is determined that the reflected voltage is not halved from the initial reflected voltage (S17: NO), the process is executed again from S14.

On the other hand, if it is determined in S17 that the reflected voltage has halved from the initial reflected voltage (S17: YES), the maximum value of the detected voltage at that time is set as the reference value (S18). The switch 25 is driven by the drive section 21 (S19), and the voltage at the detection point P is detected by the voltage detection section 22 (S20).

Next, it is determined whether or not the amount of change in the maximum value of the detected voltage exceeds a predetermined value (S21). Specifically, when the amount by which the maximum value of the detected voltage is less than the reference value is greater than a first predetermined value, or when the amount by which the maximum value of the detected voltage is greater than the reference value is greater than a second predetermined value , determines that the amount of change in the maximum value of the detected voltage exceeds a predetermined value. The first predetermined value and the second predetermined value are set in advance based on the initial reflected voltage, and are set to 1/4 of the initial reflected voltage, for example. The first predetermined value and the second predetermined value are not limited to 1/4 of the initial reflected voltage, and the first predetermined value and the second predetermined value may be different. In this determination, if it is determined that the amount of change in the maximum value of the detected voltage does not exceed the predetermined value (S21: NO), the process from S19 is executed again.

On the other hand, if it is determined in S21 that the amount of change in the maximum value of the detected voltage exceeds the predetermined value (S21: YES), it is determined whether the maximum value of the detected voltage has increased (S22). In this determination, if it is determined that the maximum value of the detected voltage has not increased (S22: NO), it is detected that the external device has short-circuited, and that effect is reported (S23). That is, as shown in FIG. 6, when the amount by which the maximum value of the detected voltage falls below the reference value is greater than the first predetermined value, it is detected that the positive electrode cable 33A of the PLC 30 is short-circuited after setting the reference value. After that, this series of processing ends (END).

If it is determined in S22 that the maximum value of the detected voltage has increased (S22: YES), it is determined based on the detected voltage whether or not the reflected voltage lags behind the rise of the detected voltage (S24). . In this determination, if it is determined that the reflected voltage does not lag behind the rising edge of the detected voltage (S24: NO), it is detected that the external device is disconnected from the external connection terminal 27, and that fact is notified (S25). That is, as shown in FIG. 7, when the amount by which the maximum value of the detected voltage exceeds the reference value is greater than the second predetermined value and the reflected voltage does not lag behind the rise of the detected voltage, the PLC 30 is connected to the external connection terminal. 27 is detected. In other words, after setting the reference value, the maximum value of the voltage detected by the voltage detection unit 22 when the drive unit 21 drives the switch 25 is the reference value, and the rise of the voltage detected by the voltage detection unit 22 is the reference value. At the same time, when the exceeded amount is larger than the second predetermined value (=third predetermined value), it is detected that the PLC 30 is disconnected from the external connection terminal 27 . After that, this series of processing ends (END).

On the other hand, if it is determined in S24 that the reflected voltage lags behind the rise of the detected voltage (S24: YES), it is detected that the external device has disconnected, and that effect is reported (S26). That is, as shown in FIG. 8, when the amount by which the maximum value of the detected voltage exceeds the reference value is greater than the second predetermined value and the reflected voltage lags behind the rise of the detected voltage, the positive electrode cable 33A of the PLC 30 and at least one of the negative cable 33B is disconnected. In other words, after setting the reference value, the maximum value of the voltage detected by the voltage detection unit 22 when the drive unit 21 drives the switch 25 is the reference value, and the rise of the voltage detected by the voltage detection unit 22 is the reference value. When the amount exceeding the second predetermined value is larger than the second predetermined value, it is detected that at least one of the positive electrode cable 33A and the negative electrode cable 33B of the PLC 30 is disconnected. After that, this series of processing ends (END).

The embodiment detailed above has the following advantages.

The detection unit 23 uses a circuit (power source 24, drive unit 21, and voltage detection unit 22) that detects an abnormality in the internal switch 25 to detect the voltage detection unit when the switch 25 is driven by the drive unit 21. Abnormality of switch 25 can be detected based on the voltage detected by 22 . Specifically, when the voltage detected by the voltage detection unit 22 is constant at the voltage V1 when the switch 25 is driven by the drive unit 21, the detection unit 23 determines that the switch 25 is stuck on. can be detected. Further, when the voltage detected by the voltage detection unit 22 is constant at 0 when the switch 25 is driven by the drive unit 21, the detection unit 23 can detect that the switch 25 is stuck off. can.

If the PLC 30 is connected to the external connection terminal 27 when the drive unit 21 drives the switch 25 with the on-pulse signal, the voltage applied to the external connection terminal 27 is reflected by the resistor 32 of the PLC 30 . Therefore, the voltage detected by the voltage detection unit 22 is a voltage obtained by superimposing the voltage V<b>1 applied to the external connection terminal 27 and the voltage reflected by the resistor 32 of the PLC 30 . Also, when the PLC 30 is short-circuited, the voltage applied to the external connection terminal 27 is not reflected. Therefore, the voltage detected by the voltage detection section 22 is the voltage V1 applied to the external connection terminal 27 . Therefore, the detection unit 23 can detect an abnormality in the PLC 30 connected to the external connection terminal 27 based on the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 . Moreover, since the voltage at the detection point P between the switch 25 and the external connection terminal 27 is detected by the voltage detection unit 22, based on the voltage at one detection point P, an abnormality in both the switch 25 and the PLC 30 can be detected. can be detected.

The detection unit 23 determines that the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 can be considered to be equal to the voltage V1 applied to the external connection terminal 27. A first voltage If it is less than (reference value-first predetermined value), it can be detected that the PLC 30 is short-circuited.

The detection unit 23 detects a second voltage (reference voltage) in which the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 is set higher than the voltage V1 applied to the external connection terminal 27. value+second predetermined value) with a delay from the rise of the voltage detected by the voltage detection unit 22, it can be detected that the PLC 30 is disconnected.

The detection unit 23 detects a third voltage (reference voltage) in which the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 is set higher than the voltage V1 applied to the external connection terminal 27 . value + second predetermined value) at the same time as the voltage detected by the voltage detection unit 22 rises, the PLC 30 is not connected to the external connection terminal 27 (the PLC 30 is disconnected from the external connection terminal 27). can be detected.

・When it can be estimated that the PLC 30 is connected to the external connection terminal 27, the resistance value of the variable resistor 26 is increased from the initial value, and the voltage detection unit 22 detects the The maximum value of the detected voltage is set as the reference value. When the PLC 30 is short-circuited after that, the maximum value of the voltage detected by the voltage detection section 22 when the switch 25 is driven by the drive section 21 becomes smaller than the reference value. Therefore, after the reference value is set, the detection unit 23 determines that the maximum value of the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 falls below the reference value by the first predetermined value. , it can be detected that the PLC 30 has shorted.

- If the PLC 30 is disconnected after setting the reference value, the maximum value of the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 becomes larger than the reference value. Therefore, after setting the reference value, the detection unit 23 determines that the maximum value of the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 is the reference value. It can be detected that the PLC 30 is disconnected when the amount that exceeds the voltage with a delay from the rise of the voltage is larger than the second predetermined value.

・If the PLC 30 is disconnected from the external connection terminal 27 after setting the reference value, the maximum value of the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 becomes larger than the reference value. . Furthermore, the voltage detected by the voltage detection unit 22 is a voltage in which the voltage applied to the external connection terminal 27 and the voltage reflected by the external connection terminal 27 are superimposed at the same time as the voltage rises. Therefore, after setting the reference value, the detection unit 23 determines that the maximum value of the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 is the reference value. It can be detected that the PLC 30 is disconnected from the external connection terminal 27 when the amount that the voltage rises and exceeds is greater than the third predetermined value (=second predetermined value).

It should be noted that the above embodiment can be modified as follows. Parts that are the same as those in the above embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

The detection unit 23 performs at least one of detecting that the PLC 30 is short-circuited (short-circuited after setting the reference value) and that the PLC 30 is disconnected (disconnected after setting the reference value). can be anything. Further, after setting the reference value, the detection unit 23 determines that the maximum value of the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the driving unit 21 falls below the reference value by a fourth predetermined value. If it is larger than (<first predetermined value), it may be detected that the PLC 30 is about to short circuit. After setting the reference value, the detection unit 23 determines that the maximum value of the voltage detected by the voltage detection unit 22 when the switch 25 is driven by the drive unit 21 is the reference value. It may be detected that the PLC 30 is on the verge of disconnection when the amount that exceeds the rise of the voltage is greater than a fifth predetermined value (<second predetermined value).

- A fixed resistor may be used in place of the variable resistor 26 . In that case, the processing of S14 to S18 in FIG. Also, the variable resistor 26 can be omitted. Even in that case, the detection unit 23 can detect that the PLC 30 is short-circuited.

- The external connection terminal 27 may include only a positive terminal. The anode of the light emitting diode 31a may be connected to the positive terminal, and the cathode of the light emitting diode 31a in the PLC 30 may be grounded. The external connection terminal 27 is not limited to an external output terminal, and may be an external input terminal. In that case, the detection unit 23 may detect an abnormality in the PLC 30 (external device) during a period (period) in which no signal is input from the external input terminal.

- The external device connected to the external connection terminal 27 is not limited to the PLC 30, and may be a teaching pendant (teaching operator), a measuring instrument (sensor), or the like.

- The industrial equipment controlled by the controller 20 is not limited to the robot 10, but may be a machine tool, various manufacturing equipment, or the like.

DESCRIPTION OF SYMBOLS 10... Robot (industrial equipment), 20... Controller, 21... Drive part, 22... Voltage detection part, 23... Detection part, 24... Power supply, 25... Switch, 26... Variable resistor, 27... External connection terminal, 30... PLC (External equipment), 31... Photocoupler, 32... Resistor, 33A... Positive cable, 33B... Negative cable, 34... Connector.

Claims (10)

a switch;
an external connection terminal connected to a power supply via the switch;
a driving unit that drives the switch with an on-pulse signal;
a voltage detection unit that detects a voltage at a detection point between the switch and the external connection terminal;
a detection unit that detects an abnormality in the switch and an abnormality in an external device connected to the external connection terminal based on the voltage detected by the voltage detection unit when the switch is driven by the drive unit;
with
The detection unit determines that the voltage detected by the voltage detection unit when the switch is driven by the drive unit is equal to the voltage applied to the external connection terminal. A controller for industrial equipment , which detects that the external equipment is short-circuited when . The detection unit detects a third voltage, which is set higher than the voltage applied to the external connection terminal, detected by the voltage detection unit when the switch is driven by the drive unit. 2. The controller for industrial equipment according to claim 1 , which detects that an external device is not connected to said external connection terminal when said voltage detected by said voltage detection unit exceeds said voltage at the same time said voltage rises. a switch;
an external connection terminal connected to a power supply via the switch;
a driving unit that drives the switch with an on-pulse signal;
a voltage detection unit that detects a voltage at a detection point between the switch and the external connection terminal;
a detection unit that detects an abnormality in the switch and an abnormality in an external device connected to the external connection terminal based on the voltage detected by the voltage detection unit when the switch is driven by the drive unit;
with
The detection unit detects a third voltage, which is set higher than the voltage applied to the external connection terminal, detected by the voltage detection unit when the switch is driven by the drive unit. A controller for industrial equipment that detects that an external device is not connected to the external connection terminal when the voltage detected by the voltage detection unit exceeds the voltage at the same time as it rises. The detection unit detects a second voltage, which is set higher than the voltage applied to the external connection terminal, detected by the voltage detection unit when the switch is driven by the drive unit. The controller for industrial equipment according to any one of claims 1 to 3, wherein the controller detects that the external equipment is disconnected when the voltage detected by the voltage detection unit exceeds the rise with a delay. a switch;
an external connection terminal connected to a power supply via the switch;
a driving unit that drives the switch with an on-pulse signal;
a voltage detection unit that detects a voltage at a detection point between the switch and the external connection terminal;
The voltage detected by the voltage detection unit when the switch is driven by the drive unit detects a third voltage set higher than the voltage applied to the external connection terminal by the voltage detection unit. a detection unit that detects that an external device is not connected to the external connection terminal when the voltage exceeds the applied voltage at the same time as the voltage rises;
A controller for industrial equipment, comprising: a switch;
an external connection terminal connected to a power supply via the switch;
a driving unit that drives the switch with an on-pulse signal;
a voltage detection unit that detects a voltage at a detection point between the switch and the external connection terminal;
a detection unit that detects an abnormality in the switch and an abnormality in an external device connected to the external connection terminal based on the voltage detected by the voltage detection unit when the switch is driven by the drive unit;
with
A variable resistor is connected between the switch and the detection point,
The detection unit is
The voltage detected by the voltage detection unit when the switch is driven by the drive unit detects a fourth voltage set higher than the voltage applied to the external connection terminal by the voltage detection unit. is detected by the voltage detection unit when the switch is driven by the drive unit by increasing the resistance value of the variable resistor from the initial value when the voltage exceeds the initial value after the rise of the voltage detected by the voltage detection unit. setting the maximum value of the voltage as a reference value,
After setting the reference value, the amount by which the maximum value of the voltage detected by the voltage detection unit when the switch is driven by the drive unit is less than the reference value is greater than a first predetermined value. and a controller for industrial equipment that detects that the external equipment is short-circuited. The detection unit detects a fourth voltage, which is set higher than the voltage applied to the external connection terminal, detected by the voltage detection unit when the switch is driven by the drive unit. The industry according to any one of claims 1 to 5, wherein it detects that an external device is connected to the external connection terminal when the voltage detected by the voltage detection unit exceeds the rise with a delay. equipment controller. a switch;
an external connection terminal connected to a power supply via the switch;
a driving unit that drives the switch with an on-pulse signal;
a voltage detection unit that detects a voltage at a detection point between the switch and the external connection terminal;
a detection unit that detects an abnormality in the switch and an abnormality in an external device connected to the external connection terminal based on the voltage detected by the voltage detection unit when the switch is driven by the drive unit;
with
The detection unit detects a fourth voltage, which is set higher than the voltage applied to the external connection terminal, detected by the voltage detection unit when the switch is driven by the drive unit. A controller for industrial equipment, which detects that an external device is connected to the external connection terminal when the voltage detected by the voltage detection unit exceeds the voltage with a delay from rising. After setting the reference value, the detection unit detects the maximum value of the voltage detected by the voltage detection unit when the switch is driven by the drive unit. 7. The controller for industrial equipment according to claim 6, wherein disconnection of said external equipment is detected when the amount exceeding said voltage with a delay from the rise of said voltage is greater than a second predetermined value. After setting the reference value, the detection unit detects the maximum value of the voltage detected by the voltage detection unit when the switch is driven by the drive unit. 10. The controller for industrial equipment according to claim 6, wherein said controller detects that said external equipment is disconnected from said external connection terminal when the amount of said voltage exceeded at the same time said voltage rises is larger than a third predetermined value.

Images