JPH11249733A - Controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To diagnose the operation of a photocoupler circuit for feeding the operating state of an output driving circuit for driving a load back to a control part based on a control output signal from the control part. SOLUTION: When a transistor Q11 for load driving of an output driving circuit 10a is turned off, a current flows to a photodiode PD 21 through the route of a load 9a, resistor R21 and photodiode PD 21, a phototransistor PT 21 is turned on, and signals at an L level are fed back to control parts 2 and 3. Based on a forced cut-off signal 7a, a primary side current cut-off part 8 cuts off power supply to the load 9a. The control parts 2 and 3 confirms the normal operation of a photocoupler circuit 11a based on the change of the output of the photocoupler circuit 11a into H level as a result after the current supply to the photodiode PD 21 is cut off by the forced cut-off signal 7a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system in which the operation state of an output drive circuit for driving a load is fed back to a control unit based on a control output signal, whereby the operation state of the output drive circuit is self-diagnosed. It concerns the device.

[0002]

2. Description of the Related Art JP-A-57-165856 discloses that
There is described a technique in which an output detection circuit is provided in parallel with an output drive circuit, and a failure is determined by examining a combination of an operation state of the output drive circuit and an operation state of the output detection circuit.

FIG. 5 is a circuit configuration diagram of the failure diagnosis circuit shown in FIG. 2 of the above-mentioned Japanese Patent Application Laid-Open No. 57-165856. 5, reference numeral 111 denotes an input circuit, 112 denotes a circuit in a printed circuit board, and 113 denotes an output circuit. The input circuit 111 includes a limit switch, a key switch, and the like 101.
a to 101 n. As the limit switches, key switches, etc., 101a to 101n have a normal make contact configuration.

The circuit 112 in the printed circuit board includes an output detection circuit (input state detection circuit) 103, an input circuit 104, and a CP.
U105, output latch circuit 106, output drive circuit 107
a to 107n, output detection circuits 108a to 108n, LE
It comprises a D display device 110. Output detection circuit 1
08a to 108n are composed of current limiting resistors Ra to Rn and photocouplers PCa to PCn. The output circuit 113 includes a DC power supply B and output drive circuits 107a to 107
and the load 109a to 109n connected between the load 109a and the load n.

To detect a failure on the output side, output detection circuits 108a to 108n connected in parallel to the output drive circuits 107a to 107n are used. In the following description, the output drive circuit 107a and the output detection circuit 108
a, a circuit having a load 109a.

(1) The output detection circuit 108a is off when an ON command is issued to the output drive circuit 107a, and the output detection circuit 108a is ON when an off command is issued to the output drive circuit 107a. If there is, the circuit on the output side, the input circuit 104, the CPU 105, and the output latch circuit 106 are all normal.

(2) If the output detection circuit 108a is off when an on command is output to the output drive circuit 107a, and the output detection circuit 108a is off when an off command is issued to the output drive circuit 107a. , Load 109a
Or, a broken wire, a poor connection of a connector (not shown), a trouble in an ON state of the output drive circuit 107a,
Alternatively, it is found that any one of the input circuit 104, the CPU 105, and the output latch circuit 106 has failed.

(3) If the output detection circuit 108a is ON when the ON command is output to the output drive circuit 107a, and the output detection circuit 108a is ON when the OFF command is output to the output drive circuit 107a. , Whether the output drive circuit 107a is in the off-state trouble or the input circuit 104, C
It can be seen that either the PU 105 or the output latch circuit 106 has failed.

(4) If the output detection circuit 108a is ON when the ON command is output to the output drive circuit 107a, and the output detection circuit 108a is OFF when the OFF command is output to the output drive circuit 107a. , Input circuit 1
04, one of the CPU 105 and the output latch circuit 106 has a fault.

The above-described failure mode is determined by the CPU 105 based on a signal fed back from the output detection circuit 108a to the input circuit 104.
It is displayed on the D display device 110.

In the above-described failure judgment on the output side, the load 1
When the light-emitting diode 09a operates with a current larger than the current required to operate the light-emitting diode of the photocoupler PCa of the output detection circuit 108a, the current limiting resistor Ra is set to a large value within a range in which the light-emitting diode of the photocoupler PCa operates. When the output drive circuit 107a is off, the light emitting diode of the photocoupler PCa is operated without operating the load 109a. Further, when the output drive circuit 107a is turned on, the time during which the output drive circuit 107a is turned on is shortened so that a large current for operating the load 109a does not flow. In this way, the failure diagnosis can be performed without operating the load 109a.

For example, if the load 109a is a clutch or a solenoid, these loads are not driven mechanically unless a current of 200 mA (milliamperes) or more normally flows. On the other hand, the current required for the light emitting diode of the photocoupler PCa to operate is about 20 mA. Therefore, as the current limiting resistor Ra of the output detection circuit 108a, when the output drive circuit 107a is off, the photocoupler PC
The light emitting diode of a is selected to have a resistance value such that a current of 20 mA flows. When the failure diagnosis is performed by turning on the output driving circuit 107a, the output driving circuit 10
The time for turning on 7a is shortened. For example, the above-mentioned load such as the clutch or the solenoid does not operate mechanically unless a current of 200 mA normally flows for 5 ms (millisecond) or more. Therefore, the output drive circuit 107a
Is turned on by a signal from the CPU 105.
If the time is set to 1.5 ms, the failure diagnosis can be performed without operating the load 109a.

On the other hand, when the operation current of the load 109a is almost the same as the current for operating the light emitting diode of the photocoupler PCa of the output detection circuit 108a, a failure diagnosis circuit as shown in FIG. 6 is formed. In FIG. 6, reference numeral 114a denotes a load which operates with a current almost equal to the current required to operate the light emitting diode of the output detection circuit 108a, 115a denotes a switching element, for example, a switching transistor, and B and C denote DC power supplies.

In this failure diagnosis circuit, when the output drive circuit 107a is off, the switching transistor 11
5a is turned on, and a current flows through the light emitting diode of the photocoupler PCa. If the resistances R1 and R2 are appropriately selected, a current of about 2 mA flows through the light emitting diode and a current much smaller than 2 mA flows through the load 114a. Therefore, according to the above-described fault diagnosis circuit, fault diagnosis can be performed without operating the load that operates with a current of about 2 mA.

Japanese Patent Application Laid-Open No. 60-142407 discloses a control device for controlling the operation of a load device via a drive circuit based on a generated control signal. A changeover switch for selecting a voltage power supply; and a photocoupler inserted between the low-voltage power supply and the changeover switch to detect an energized state and generate a detection signal. Is described.

Japanese Unexamined Patent Publication No. Sho 60-252905 discloses a dual non-voltage contact output card system in which drive control of external devices is performed using a non-voltage contact output card. Are described as a set, a card is arranged between a CPU output and an external device, and the contact output of each non-voltage contact output card is fed back to the CPU side. .

FIG. 7 is a circuit configuration diagram of the failure diagnosis circuit shown in FIG. 2 of Japanese Patent Application Laid-Open No. 60-252905. 7, 201 and 301 are non-voltage contact output cards,
202 and 302 are flip-flops for storing data output from the CPU, 203, 303, 209, 309 and 2
11, 311 are current limiting resistors, 204, 304,
210 and 310 are photocouplers, 207 and 307 are surge absorbing diodes of relays, 205 and 305 are relay coils, 206 and 306 are relay contacts, and 208 is a relay power supply.

The flip-flops 202 and 302 have a CP
The data output by U is stored, and when the stored content is ON, the relay coils 205 and 305 are in the excited state, and when the stored content is OFF, the relay coils 205 and 305 are in the non-excited state. To check whether the CPU operates normally according to the output data of the CPU, the photocoupler 20
By using a configuration in which the outputs of 4,304 are fed back via the photocouplers 210,310 and read by the CPU, an abnormality of the card can be known.

[0019]

In the conventional fault diagnosis circuit shown in FIG. 5, when the phototransistor side of the photocoupler PCa constituting the output detection circuit 108a becomes a short-circuit mode failure, the phototransistor side becomes short-circuit mode. Failure cannot be detected. For example, despite the command to turn on the output drive circuit 107a being supplied to the latch circuit 106, the collector of the phototransistor
If the emitter is in a conductive state, the output drive circuit 1
It is impossible to determine whether 07a is a failure that cannot be turned on or the output detection circuit 108a is a failure.

The conventional fault diagnosis circuit shown in FIG. 5 has a configuration in which the output detection circuit 108a is provided in parallel with the output drive circuit 107a. Therefore, when the output drive circuit 107a is in the off state, the output detection circuit 108a is connected via the load 109a. Thus, the current of the light emitting diode of the photocoupler PCa is supplied. For this reason, when the load 109a is activated by a current of about several milliamperes supplied to the light emitting diode, FIG.
As shown in (1), it is necessary to control the current of the light emitting diode of the output detection circuit 108a via the switching transistor 115a, which complicates the circuit configuration.

The failure diagnosis circuit described in Japanese Patent Application Laid-Open No. 60-142407 sets a failure diagnosis mode different from the actual operation state, and supplies a low-voltage power supply that does not operate the load device in this failure diagnosis mode. However, since the current flowing when the drive circuit is turned on is detected via the photocoupler, a failure cannot be detected in the actual operation state.

The fault diagnosis circuit shown in FIG. 7 has a configuration in which a series circuit of a photodiode and a current limiting resistor 211 is provided in parallel with a coil 205 of a relay as a load, so that the current of a light emitting diode is a load. It does not flow through the coil 205 of the relay. However, the operation of the photocoupler 210 that feeds back the output state cannot be checked. For example, photocoupler 2
When the collector output of the phototransistor No. 10 remains at the L level and does not change, whether the collector-emitter of the phototransistor of the photocoupler 210 forming the feedback loop has become a fault in the short-circuit mode, and configuring the drive circuit It is not possible to identify whether the short-circuit mode has occurred between the collector and the emitter of the phototransistor of the photocoupler 204.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a control device capable of checking whether or not a photocoupler circuit for feeding back an output state is operating normally. And Further, even when a circuit configuration in which a photocoupler circuit for feeding back the output state is connected in parallel to the output drive circuit is employed, the output drive circuit is not supplied with current through a load connected in series with the output drive circuit. An object is to provide a control device capable of detecting an output state.

[0024]

In order to solve the above-mentioned problems, a control device according to the present invention supplies a control output signal generated by a control unit to an output drive circuit to control a drive / non-drive state of a load. The ON / OFF operation state of the output drive circuit is fed back to the control unit via the photocoupler circuit, and the control unit feeds back the output drive circuit via the photocoupler circuit with the control output signal supplied to the output drive circuit. In a control device for diagnosing whether or not the operation of the output drive circuit is normal based on the on / off operation state of the power supply, the primary current flowing through the photodiode of the photocoupler circuit is forcibly cut off. A primary-side current cut-off unit, wherein the control unit is configured to switch off the primary-side current of the photocoupler circuit by the primary-side current cutoff unit; Output is characterized in that the operation of the photocoupler circuit based on the turned off state is configured to diagnose that it is normal.

Further, the control device according to the present invention supplies power to a series circuit of a photodiode and a current limiting resistor for limiting a current supplied to the photodiode, and
A direction in which current is supplied to the photodiode through the load between the connection point between the photodiode and the current limiting resistor and the connection point between the output drive circuit and the load, while supplying the secondary current. Characterized in that it is connected to

According to the control device of the present invention, the primary current for forcibly cutting off the primary current flowing through the photodiode of the photocoupler circuit for feeding back the ON / OFF operation state of the output drive circuit to the control unit. With the provision of the cutoff unit, the control unit is configured to perform the photocoupler operation based on the fact that the primary current of the photocoupler circuit is forcibly cut off by the primary current cutoff unit and the output of the photocoupler circuit is turned off. It can be diagnosed that the operation of the circuit is normal. Therefore, it is possible to detect that the phototransistor, the photodiode, and the like on the output side of the photocoupler circuit are in the short-circuit mode failure.

In addition, the control device according to the present invention supplies power to a series circuit of a photodiode and a current limiting resistor for limiting a current supplied to the photodiode, and
A direction in which current is supplied to the photodiode through the load between the connection point between the photodiode and the current limiting resistor and the connection point between the output drive circuit and the load, while supplying the secondary current. , It is possible to detect the output state of the output drive circuit without receiving current supply via a load connected in series with the output drive circuit.

[0028]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a specific example of the control device according to the present invention. The control device 1 shown in FIG. 1 includes a first control unit 2, a second control unit 3,
Control unit 4, relay drive circuit 5, power supply relay 6 for load, forced cutoff signal generation unit 7, primary current cutoff unit 8
A plurality of loads 9a to 9n, a plurality of output driving circuits 10a to 10n provided corresponding to the loads 9a to 9n,
It comprises a plurality of photocoupler circuits 11a to 11n provided corresponding to the respective output drive circuits 10a to 10n, and a plurality of pull-up resistors 12a to 12n provided corresponding to the respective photocoupler circuits 11a to 11n.

Reference numeral VC denotes a circuit power supply (for example, +5 volts), and reference numeral VB denotes a load power supply (for example, 12 volts, 2 volts).
4 volts, etc.). Each of the control units 2 and 3, the checking unit 4, and the forced cutoff signal generation unit 7 are configured to operate with the circuit power supply VC. In FIG. 1, the ground symbol for the equipment ground indicates the ground of the circuit power supply (VC).
The ground symbol for grounding indicates the ground of the load power supply (VB).

Each of the control units 2 and 3 is configured using a microcomputer system. Each of the control units 2 and 3 outputs control output signals 2a to 2n and 3a to 3n that specify the operation state of each of the loads 9a to 9n based on the control input information. Each of the control units 2 and 3 has the same control program. The checking unit 4 controls each control output signal 2 of each of the control units 2 and 3.
a to 2n and 3a to 3n are compared with each other, and when the respective control output signals 2a to 2n and 3a to 3n match, it is determined that the respective control units 2 and 3 are operating normally and the load is determined. 9
An operation permission signal (load power supply command signal) 4a for permitting the driving of a to 9n is output. When the control output signals 2a to 2n and 3a to 3n do not match, for example,
The first control unit 2 generates an output for driving the first load 9a (or an output for non-drive), while the second control unit 3 deactivates the first load 9a. When an output (or an output to be driven) is being generated, the output of the operation permission signal 4a is stopped, and the fact that an abnormality has occurred in the control operation is notified via a not-shown alarm device or the like. The operation permission signal 4a is supplied to the relay drive circuit 5 and the forced cutoff signal generator 7.

The relay drive circuit 5 comprises an NPN transistor 5a whose emitter is grounded, a base resistor 5b, and a base-emitter resistor 5c. The collector of the NPN transistor 5a is connected to one end of the exciting winding 6a of the load power supply relay 6. Power supply relay 6 for load
The other end of the exciting winding 6a is connected to a circuit power supply VC. When the H-level operation permission signal 4a is output from the checking unit 4, the NPN transistor 5 is output via the base resistor 5b.
a, the NPN transistor 5a is turned on, and the excitation winding 6 of the load power supply relay 6 is turned on.
The excitation current is supplied to a, and the contact 6b of the relay is closed. When the contact 6b of the relay is closed, the load power supply VB is connected to each of the loads 9a to 9n via the primary side current interrupting unit 8.
Supplied to Thereby, each of the output drive circuits 10a to 10a
Each of the loads 9a to 9n can be driven via 0n.

The control device 1 shown in FIG. 1 has two control units 2 and 3 and a control output signal 2a of each of the control units 2 and 3.
When the checking unit 4 confirms that the numbers 9a to 9n match, the load power supply VB is supplied to the loads 9a to 9n to drive the loads 9a to 9n. Highly reliable control can be performed. When the control output signals 2a to 2n and 3a to 3n of the control units 2 and 3 do not match, the supply of the load power supply VB is stopped,
Since the operations of all the loads 9a to 9n are stopped, safety can be improved. Therefore, the control device 1 shown in FIG. 1 is suitable, for example, when importance is placed on the reliability and safety of a control device of a press working machine, an automatic operation control device of a plant or the like, a control device of a vehicle or a distribution device, and the like. is there.

The forced cutoff signal generator 7 generates and outputs a forced cutoff signal 7a while the operation permission signal 4a is being supplied from the checking unit 4. The forced cutoff signal 7a is composed of a short-time L-level pulse signal, and the L-level pulse signal is repeatedly output at a predetermined cycle. A pulse whose L level period is, for example, about 1 ms is output for several hundreds, for example.
It repeats in a cycle of ms to several s. Note that the forced cutoff signal generator 7 is configured to hold the forced cutoff signal 7a at L level when the operation permission signal 4a is not supplied. The forced cutoff signal 7a is supplied to the primary side current cutoff section 8 and each of the control sections 2 and 3.

The primary side current cutoff section 8 includes a power PNP transistor Q1, a base-emitter resistor R1, a base resistor R2, a photocoupler PC1, and a current limiting resistor R
3 is provided. The emitter of the power PNP transistor Q1 is connected to the load power supply VB via the contact 6b of the load power supply relay 6. Power PNP transistor Q
One collector is connected to one end of each of the loads 9a to 9n. The base of power PNP transistor Q1 is connected to the collector of phototransistor PT1 via base resistor R2. The emitter of the phototransistor PT1 is connected to the ground of the load power supply. The cathode of the photodiode PD1 is connected to the ground of the circuit power supply. The forced cutoff signal 7a is supplied to the anode of the photodiode PD1 via the current limiting resistor R3.

When the forced cutoff signal 7a is at the H level, a current flows through the photodiode PD1 via the current limiting resistor R3, and the photodiode PD1 emits light. The light emission of the photodiode PD1 causes the phototransistor P
A conduction state is established between the collector and the emitter of T1. When the collector-emitter state of the phototransistor PT1 becomes conductive, a base current flows through the power PNP transistor Q1 via the base resistor R2, and the emitter-collector state of the power PNP transistor Q1 becomes conductive.
A load power supply VB is supplied to each of the loads 9a to 9n. When the forcible cutoff signal 7a is at the L level, the photocoupler PC1 is turned off, the power PNP transistor Q1 is turned off, and the load power supply V for each of the loads 9a to 9n is turned off.
The supply of B is stopped. As described above, the primary-side current cutoff unit 8 cuts off the supply of the load power supply VB to each of the loads 9a to 9n based on the forced cutoff signal 7a supplied from the forced cutoff signal generation unit 7.

It is to be noted that the relay drive circuit 5 and the load power supply relay 6 are not provided, and the supply and cutoff of the load power supply VB to each of the loads 9a to 9n is performed only by the primary side current cutoff section 8. Good. In the present embodiment, by connecting the contact 6b of the load power supply relay 6 and the primary-side current cutoff unit 8 in series, the reliability of the supply / cutoff operation of the load power supply VB to each of the loads 9a to 9n is improved. Have improved. For example, when a short circuit occurs between the collector and the emitter of the NPN transistor 5a of the relay drive circuit 5, or when the contact 6b of the load power supply relay 6 is welded, the load power supply by the contact 6b of the load power supply relay 6 is used. Even if the VB cannot be cut off, the checking unit 4a
If the operation permission signal 4a output from the
The forced cutoff signal 7a, which is the output of the forced cutoff signal generation unit 7, becomes L level, and the primary current cutoff unit 8 controls each load 9a.
The supply of the load power supply VB to a to 9n can be stopped. Further, even when the power PNP transistor Q1 is kept in a conductive state due to an abnormal operation of the primary current interrupting unit 8, if the operation permission signal 4a output from the checking unit 4a is at L level, When the load power supply relay 6 is in the non-operation state, each of the loads 9a to 9n
Of the load power supply VB can be stopped.

Each of the loads 9a to 9n is composed of, for example, a plunger having a solenoid coil, a solenoid valve, and the like. Each of the loads 9a to 9n may be an excitation winding of a relay, and may be configured to drive, for example, an electric motor or the like via the relay. Each of the loads 9a to 9n
In the operation state in which the current is being supplied to the load, even if the supply of the current is interrupted for a short time (for example, about 1 ms), the operation state is not restored to the non-operation state. Further, each of the loads 9a to 9n is set to be in an operation state when a current of several tens mA or more flows, and not to be in an operation state even when a current of about several milliamps flows.

In the present embodiment, the control output signals 2a to 2n of the first control unit 2 are supplied to the output drive circuits 10a to 10n, and the control output signals 2a to 2n are supplied to the loads 9a to 9n via the output drive circuits 10a to 10n. Power supply and power supply stop are controlled. Note that the control output signal 3 of the second control unit 3
a to 3n to the output drive circuits 10a to 10n,
Power supply to each of the loads 9a to 9n and power supply stop may be controlled. Further, the control output signals 2a to 2n of the first control unit 2 and the control output signals 3a of the second control unit 3
a to 3n based on a logical product output of the output driving circuits 10
a to 10 n may be configured to be driven.

The output drive circuits 10a to 10n include a photocoupler PC11, a current limiting resistor R11 for limiting a current flowing through the photodiode PD11, a power NPN transistor Q11, a base resistor R12, and a base-emitter resistor R13. Is provided. Phototransistor PT
The collector 11 is connected to the load power supply VB. The emitter of the phototransistor PT11 is connected to a base resistor R12.
To the base of the power NPN transistor Q11. The emitter of the power NPN transistor Q11 is connected to the ground of the load power supply. The collector of power NPN transistor Q11 is connected to the other end of the load.

When the control output signal 2a for the first load of the first control unit 2 is at H level, the photodiode P
A current flows through the series circuit of D11 and the current limiting resistor R11, the photodiode PD11 emits light, and the light emission of the photodiode PD11 is received by the phototransistor PT11. The base current is supplied to the power NPN transistor Q11 via R12, and the collector-emitter of the power NPN transistor Q11 becomes conductive. Power NPN transistor Q
When the switch 11 is turned on, a current corresponding to the load resistance of the load 9a is supplied to the load 9a, and the load 9a is activated. When the control output signal 2a for the first load of the first control unit 2 becomes L level, the photocoupler PC11 is turned off, the power NPN transistor Q11 is turned off (off state), and the load 9a is turned off. Driving is stopped.

Each of the photocoupler circuits 11a to 11n detects the operation state (on / off state) of each output drive circuit 10a to 10n and responds to the operation state (on / off state) of each output drive circuit 10a to 10n. The logic level signal is fed back to the control units 2 and 3.
Each of the photocoupler circuits 11a to 11n includes a photocoupler P
C21 and a current limiting resistor R21 for limiting a current flowing through the photodiode PD21. Current limiting resistor R
A series circuit of the photo diode 21 and the photodiode PD21 is connected in parallel between the collector and the emitter of the power NPN transistor Q11 in the output drive circuit. The emitter of the phototransistor PT21 is connected to the ground of the circuit power supply, and the collector of the phototransistor PT21 is connected to the circuit power supply VC via the pull-up resistor 12a.

Here, the contact 6 of the load power supply relay 6
b is in the closed state, and the PN
When the P-transistor Q1 is in a conductive state and the loads 9a to 9
It is assumed that the load power supply VB is being supplied to one end of 9n. When the power NPN transistor Q11 in the output drive circuits 10a to 10n is off, the load 9a → the current limiting resistor R21 → the photodiode PD2
1 → Photodiode P on ground path for grounding
A current flows through D21, and the photodiode PD21 emits light. The resistance value of the current limiting resistor R21 is set so that the value of the current flowing through the above-described path is several mA.
As a result, the photodiode PD21 emits light to inform the phototransistor PT21 that the power NPN transistor Q11 in the output drive circuit is off, but the load 9a is not operated. The light emitted from the photodiode PD21 is emitted from the phototransistor PT2.
1 and the collector-emitter of the phototransistor PT21 conducts. Thereby, the output drive circuit 1
When the power NPN transistor Q11 in 0a to 10n is in the off state, an L level signal is output to each of the control units 2,
3 is fed back. Output drive circuit 10a-1
When the 0n power NPN transistor Q11 is turned on, the photocoupler PC21 is turned off, and an H-level signal is sent to each control unit 2 by the pull-up resistor 12a.
3 is fed back.

Each of the control units 2 and 3 controls each of the control output signals 2a to 2a.
2n, 3a to 3n output states (whether an H level is output or an L level is output, in other words, a signal for controlling each load to a driving state or a signal for controlling each load to a non-driving state is output. ) And the output signals of the photocoupler circuits 11a to 11n, the operation state of each of the output drive circuits 10a to 10n is monitored. For example, when the L-level control output signal 2a is output to the output drive circuit 10a, and the L-level signal is fed back from the photocoupler circuit 11a, the output drive circuit 1
0a is determined to be operating normally. When the L level control output signal 2a is output to the output drive circuit 10a, the NPN transistor Q in the output drive circuit 10a
11 is turned off, the photocoupler PC21 is turned on, and an L-level signal is fed back.

Each of the control units 2 and 3 includes an output drive circuit 1
When the H-level control output signal 2a is output for 0a, if the H-level signal is fed back from the photocoupler circuit 11a, it is determined that the output drive circuit 10a is operating normally. Output drive circuit 10a
Output an H level control output signal 2a for
NPN transistor Q11 in output drive circuit 10a is turned on to drive load 9a. When the NPN transistor Q11 is turned on, the photodiode PD2
1 is cut off, and the phototransistor PT2
This is because the collector-emitter 1 is turned off, and the H-level signal is fed back by the pull-up resistor 12a.

Further, while the forced cutoff signal 7a is supplied from the forced cutoff signal generation unit 7, the H level signal is fed back from each of the photocoupler circuits 11a to 11n. , It is determined that the photocoupler circuits 11a to 11n are operating normally. When the forced cutoff signal generator 7 is at the L level, the primary side current cutoff 8 causes the load power source VB
Of each of the photocoupler circuits 11a to 11n regardless of the operation state of each of the output drive circuits 10a to 10n.
Is interrupted. In other words, the primary current of each of the photocoupler circuits 11a to 11n is cut off when the forced cutoff signal generator 7 is at the L level. Therefore, the output of each of the photocoupler circuits 11a to 11n becomes H level by each of the pull-up resistors 12a to 12n.

FIG. 2 is a time chart showing the operation of the control device shown in FIG. FIG. 2A shows a forced cutoff signal 7a.
Is shown. Here, the L-level period is tL (for example, 1 ms), and the repetition period is T (for example, 1 s). FIG. 2B shows the state of supply of the load power supply VB to the load. The supply of the load power supply VB is cut off in synchronization with the L level of the forced cutoff signal 7a. FIG. 2 (c)
Indicates a first control output signal 2a of the first control unit 2. FIG. 2D shows the ON / OFF state of the NPN transistor Q11 of the output drive circuit 10a. When the first control output signal 2a is at L level, the NPN transistor Q11 of the output drive circuit 10a is turned off (the load 10a is not driven), and when the first control output signal 2a is at H level, the output drive circuit 10a NPN transistor Q11
Is turned on (the load 10a is driven).

FIG. 2E shows the current (the primary side current) of the photodiode PD21 of the photocoupler circuit 11a. NPN transistor Q11 of output drive circuit 10a
Is off and the load power supply VB is supplied, the primary current IP is supplied to the photodiode PD21.
D flows. The primary side current IPD flowing through the photodiode PD21 is set to a small current (for example, several mA) such that the load 9a does not operate due to the current limiting resistor R21. Even when the NPN transistor Q11 of the output drive circuit 10a is off, if the supply of the load power supply VB is cut off, the primary current IPD does not flow through the photodiode PD21.

When the NPN transistor Q11 of the output drive circuit 10a is turned on, the series circuit of the current limiting resistor R21 and the photodiode PD21 in the photocoupler circuit 11a is short-circuited by the NPN transistor Q11 which is turned on. The voltage supplied to the series circuit of the resistor R21 and the photodiode PD21 becomes the collector-emitter saturation voltage of the NPN transistor Q11 in the ON state, and is lower than the forward drop voltage of the photodiode PD21).
Does not flow through the primary side current IPD.

FIG. 2E shows an output signal (feedback signal) of the photocoupler circuit 11a. In the present embodiment, the emitter of the phototransistor PT21 is connected to the ground of the circuit power supply,
21 is connected to the circuit power supply VC via the pull-up resistor 12a, the photodiode PD2
In a state where the primary current IPD is flowing through 1, the phototransistor PT21 is conducting (on), an L-level output signal (feedback signal) is output, and the primary current IPD is flowing through the photodiode PD21. In the absence state, the phototransistor PT21 is non-conductive (off)
In this state, an H-level output signal (feedback signal) is output.

Here, when the output drive circuit 10a is in the off state, the output drive circuit 10a goes high in synchronization with the low level of the forced cutoff signal 7a.
Since each of the control units 2 and 3 is configured to supply a level feedback signal, each of the control units 2 and 3 synchronizes with the L level of the forced cutoff signal 7a so that each of the photocoupler circuits 11a to 11a.
It is possible to confirm that each of the photocoupler circuits 11a to 11n operates normally based on the feedback of the H level signal from 11n.

For example, when a failure occurs in the short-circuit mode between the collector and the emitter of the phototransistor PT21,
The conventional diagnostic device cannot detect an abnormality until the load is switched from the non-drive (off) state to the drive state. If the output of the photocoupler circuit remains unchanged at the L level even when the control output signal for driving the load is supplied, whether an abnormality has occurred on the output drive circuit side or on the photocoupler circuit side. It was not possible to tell what was happening. Further, when the control output signal is a signal for activating an alarm device or the like when an abnormality or the like occurs in the operation of the device, and is a signal that does not generate an output for driving a load as long as the device is operating normally. It is difficult to detect that a failure occurs in the short-circuit mode between the collector and the emitter of the phototransistor PT21.

In this embodiment, each of the control output signals 2a to 2n
Is low (control output signal that does not drive the load), if the operation of each of the output drive circuits 10a to 10n is normal, a current flows through the photodiode PD21, the phototransistor PT21 becomes conductive, and the feedback signal ( (L level). Therefore, each control unit 2 and 3 confirms that each feedback signal feeds back a pulse signal synchronized with the forced cutoff signal 7a before generating an H level control output signal to drive each load. By doing so, each output drive circuit 10a
10 to 10 n NPN transistors (load drive transistors) Q11 are not in a failure state in which the conductive state is maintained (a failure state in which the output drive circuit is in the load drive state even when the control output signal is in the load non-drive state). , And
It can be confirmed that the photocoupler circuits 11a to 11n for feeding back the ON / OFF state of each output drive circuit are operating normally.

FIG. 3 is a block diagram showing another specific example of the control device according to the present invention. Control device 3 shown in FIG.
Reference numeral 1 denotes a circuit that cuts off only the primary current (current flowing through the photodiode) of the photocoupler circuit based on the forced cutoff signal 7a and does not cut off the current flowing through the load. Hereinafter, differences from the control device 1 shown in FIG. 1 will be described.

The load power supply VB is supplied to each of the loads 9 a to 9 n via the contact 6 b of the load power supply relay 6 and to the primary-side current interrupting section 32. The configuration of the primary side current interrupting section 32 is the same as that shown in FIG.
The photodiode power supply VP output from the primary-side current cutoff unit 32 is supplied to each of the photocoupler circuits 33a to 33n.

Each of the photocoupler circuits 33a to 33n includes a photocoupler PC33 and a current limiting resistor R for setting the value of the primary current supplied to the photodiode PD33.
33, and a backflow prevention diode D33 for preventing current from being supplied to the photodiode PD33 via the load. One end of the current limiting resistor R33 is supplied with a photodiode power supply VP. Current limiting resistor R
The other end of 33 is connected to the anode of photodiode PD33. The cathode of the photodiode PD33 is connected to the ground of the load power supply. The anode of the backflow prevention diode D33 is connected to the anode of the photodiode PD33. The cathode of the backflow prevention diode D33 is connected to the NPN transistor Q1 in the output drive circuit 10a.
1 collector. Phototransistor PT3
3 is connected to the circuit power supply VC. The emitter of the phototransistor PT33 is connected to the ground of the circuit power supply via the emitter resistor 34a.

If the NPN transistor Q11 in the output drive circuit 10a is non-conductive and the PNP transistor Q1 in the primary side current interrupting section 32 is conductive, the PNP
A current flows through the photodiode D33 through a path from the transistor Q1 → the current limiting resistor R33 → the photodiode D33 → the ground for grounding. Accordingly, the photodiode D33 emits light, and the emission of the photodiode D33 is received by the phototransistor PT33, so that the phototransistor PT33 is turned on. When the phototransistor PT33 is turned on, a power supply voltage of the circuit power supply VC (strictly, a voltage obtained by subtracting the collector-emitter saturation voltage of the phototransistor PT33 from the power supply voltage of the circuit power supply VC) is generated in the emitter resistor 34a. . Thus, when the output drive circuit 10a is in the off state, an H-level signal is fed back to the control units 2 and 3 via the photocoupler circuit 33a. The PNP transistor Q1 in the primary side current cutoff unit 32 is generated by the forced cutoff signal 7a.
Is turned off, the current supply to the photodiode D33 is cut off, the phototransistor PT33 is turned off, and the feedback signal goes low.

When the NPN transistor Q11 in the output drive circuit 10a becomes conductive, the current limiting resistor R33 → backflow prevention diode D33 → NPN transistor Q11
→ Current flows through the ground path for the ground. As a result,
The sum voltage of the collector-emitter saturation voltage of the NPN transistor Q11 and the forward drop voltage of the backflow prevention diode D33 is supplied to the photodiode PD33. Here, the forward voltage drop (threshold voltage) of the photodiode PD33 is, for example, 1.3 volts, NP
Assuming that the saturation voltage between the collector and the emitter of the N transistor Q11 is, for example, 0.2 volt, and the forward drop voltage of the backflow prevention diode D33 is, for example, 0.7 volt.
When the NPN transistor Q11 becomes conductive,
The voltage supplied to the photodiode PD33 is about 0.9
The voltage is lower than the forward voltage drop (threshold voltage) of the photodiode PD33, which is volt. Therefore, the current of the photodiode PD33 cannot flow, the photocoupler PT33 is turned off, and an L level feedback signal is output.

When the NPN transistor Q11 is turned on, the voltage supplied to the photodiode PD33 is substantially equal to or larger than the forward drop voltage (threshold voltage) of the photodiode PD33. In this case, a level shift diode is provided in series with the photodiode PD33 to prevent a current from flowing through the photodiode PD33 when the NPN transistor Q11 is in a conductive state.

The control device 31 shown in FIG. 3 is configured to forcibly cut off only the current flowing through the photodiode PD33 based on the forcible cutoff signal 7a.
The current flowing through each of the loads 9a to 9n while the 9n is being driven is not interrupted. Therefore, it is possible to use even a load that requires a short time for operation and recovery (short response time). Further, in the control device 1 shown in FIG. 1, it is necessary to set the forced cutoff time so that the load in the operating state is not restored. However, in the control device 31 shown in FIG. 3, only the current flowing through the photodiode PD33 is forcibly applied. Because of the configuration for shutting off, the forced shutoff time can be set arbitrarily.

In FIG. 3, the photocoupler circuit 33a
By connecting the collector of the phototransistor PT33 in the circuit to the circuit power supply VC and connecting the emitter side of the phototransistor PT33 to the ground of the circuit power supply via the emitter resistor 34a, when the output drive circuit 10a is in the off state. The configuration in which the H-level signal is fed back and the L-level signal is fed back when the output drive circuit 10a is in the ON state has been described. However, the collector of the phototransistor PT33 is connected to a circuit power supply via a pull-up resistor, By connecting the emitter of the phototransistor PT33 to the ground of the circuit power supply and outputting a feedback signal from the collector of the phototransistor PT33, a low-level signal is fed back when the output drive circuit 10a is in the off state, Output drive circuit 10a It may be configured to feed back the H level signal when in the ON state.

FIG. 3 shows a configuration in which the supply of the photodiode power supply VP to the photocoupler circuit 33a is forcibly cut off by the primary side current cutoff unit 32.
One end of the current limiting resistor R33 is connected to the load power supply VB, and a switching element such as a switching transistor is interposed between the cathode of the photodiode PD33 and the ground of the load power supply, thereby forcing this switching element. By controlling to the off state based on the cutoff signal 7a,
The current flowing through the photodiode PD33 (the primary current may be cut off.

FIG. 4 is a block diagram showing a further specific example of the control device according to the present invention. The control device 41 shown in FIG. 4 includes a load power supply VB for each of the loads 9a to 9n.
Is controlled by the PNP transistor Q50 in each of the output drive circuits 50a to 50n. The emitter of PNP transistor Q50 is connected to load power supply VB via contact 6b of load power supply relay 6. The collector of the PNP transistor Q50 is connected to one end of each of the loads 9a to 9n. Each load 9a-9n
Is connected to the ground of the load power supply.

When an H-level first control output signal 2a is supplied from the first control unit 2, a current flows through the photodiode PD50 via the current limiting resistor R50, and the phototransistor PT50 is turned on. When the phototransistor PT50 becomes conductive, a base current flows through the PNP transistor Q50 via the base resistor R52,
The conduction between the emitter and the collector of the PNP transistor Q50 becomes conductive. Thereby, the load can be driven. Note that reference numeral R51 denotes a base-emitter resistance of the PNP transistor Q50. First control output signal 2a
Is at the L level, the photocoupler PC50 is turned off, and the PNP transistor Q50 is turned off.

Each of the photocoupler circuits 60a to 60n includes a photocoupler PC60, a current limiting resistor R60, and a diode D60 for preventing a current from flowing to a load via the photodiode PD60. The photodiode power supply VP, which is the output of the primary-side current interrupting unit 32, is supplied to the anode of the photodiode PD60. The cathode of the photodiode PD60 is a current limiting resistor R60.
To the ground of the load power supply. The anode of diode D60 is connected to the collector of PNP transistor Q50 in output drive circuit 50a. The cathode of diode D60 is connected to the cathode of photodiode PD60. The collector of the phototransistor PT60 is connected to the circuit power supply VC. The emitter of the phototransistor PT60 is connected to the circuit power supply ground via the emitter resistor 34a.

If the PNP transistor Q50 in the output drive circuit 50a is off and the PNP transistor Q1 in the primary side current interrupting section 32 is on, the PNP transistor Q1 → the photodiode PD60 → the current limiting resistor R60 → A current flows through the photodiode PD60 through a ground path for grounding. As a result, the photodiode D60 emits light, and the phototransistor PT60 that has received the emitted light is turned on. When the phototransistor PT60 is turned on, the emitter resistance 34a
The power supply voltage of the circuit power supply VC (strictly speaking, the circuit power supply VC
(A voltage obtained by subtracting the saturation voltage between the collector and the emitter of the phototransistor PT60) from the power supply voltage of the phototransistor PT60. Thereby, when the output drive circuit 50a is in the off state,
An H-level feedback signal is fed back to each of the control units 2 and 3 via the photocoupler circuit 60a. The PN in the primary side current interrupting unit 32 is controlled by the forced interrupting signal 7a.
When the P transistor Q1 is turned off, the current supply to the photodiode D60 is cut off,
T60 is turned off, and the feedback signal goes low.

When the PNP transistor Q50 in the output drive circuit 50a becomes conductive, the load power supply VB
a, and to the current limiting resistor R60 via the diode D60. For this reason, the potential of the current limiting resistor R60 (the cathode side potential of the photodiode PD60) is almost equal to the power supply voltage of the load power supply VB (strictly speaking, the PNP transistor Q5
(A voltage obtained by subtracting the collector-emitter saturation voltage of 0 and the forward voltage drop of the diode D60). Therefore, the potential difference between the anode and the cathode of the photodiode PD60 is lower than the forward drop voltage (threshold voltage) of the photodiode PD60. Therefore, the current of the photodiode PD60 cannot flow, the photocoupler PT60 is turned off, and the L-level feedback signal is output.

When the PNP transistor Q50 is turned on, the potential difference between the anode and the cathode of the photodiode PD60 is substantially equal to or larger than the forward drop voltage (threshold voltage) of the photodiode PD60. Is satisfied, the photodiode PD60
PNP with a level shift diode in series with
It is configured to prevent a current from flowing through the photodiode PD60 when the transistor Q50 is in a conductive state.

The control device 41 shown in FIG. 4 is configured to forcibly cut off only the current flowing through the photodiode PD60 based on the forcible cutoff signal 7a, similarly to the control device 31 shown in FIG. 9n is not interrupted while the loads 9a to 9n are driven. Therefore, it is possible to use even a load that requires a short time for operation and recovery (short response time).
Further, the forced cutoff time can be set arbitrarily.

Each of the control units 1 shown in FIGS.
31 and 41, transistors Q11,
Since the photocoupler circuit is connected between the collector and the emitter of the transistor Q50, the characteristics of the transistors Q11 and Q50 are degraded due to a decrease in the current amplification factor (hfe) of the transistors Q11 and Q50 for driving the load. When the collector-emitter voltage in the ON state of Q11 and Q50 increases and exceeds the forward drop voltage (threshold voltage) of the photodiode, the photocoupler turns on. Therefore, it is possible to detect an increase in the collector-emitter voltage in the ON state of the transistors Q11 and Q50 that drive the load.

Although the present embodiment has been described with reference to the configuration including the forced cut-off signal generation unit 7, the control cut-off signals may be generated and output by the control units 2 and 3 including a CPU or the like. . In the present embodiment, the forced cutoff signal 7a generated by the forced cutoff signal generation unit 7 operating with the circuit power supply VC is supplied to the load power supply VB via a power supply separated signal voltage circuit such as the photocoupler PC1. Although the configuration in which the current flowing through the photodiode of the photocoupler circuit that feeds back the ON / OFF state of the output drive circuit is cut off, the current flowing through the photodiode is controlled by operating the multivibrator circuit or the like on the load power supply VB side. You may make it cut off. Further, each of the control units 2 and 3 has a configuration in which the operation of the photocoupler circuit is determined to be normal based on the synchronization of the forced cutoff signal 7a and the feedback signal. , 3 determine that the photocoupler circuit is operating normally based on the fact that the logic level of the feedback signal from the photocoupler circuit changes at a predetermined cycle without monitoring the output timing of the forced cutoff signal. It is good also as a structure which performs.

[0071]

As described above, the control device according to the present invention forcibly reduces the primary current flowing through the photodiode of the photocoupler circuit for feeding back the ON / OFF operation state of the output drive circuit to the control unit. Since the primary side current interrupting section is provided to cut off the primary current of the photocoupler circuit by the primary side current interrupting section, the output of the photocoupler circuit is turned off. It can be diagnosed that the operation of the photocoupler circuit is normal based on the above. Therefore, it is possible to detect that the phototransistor, the photodiode, and the like on the output side of the photocoupler circuit are in the short-circuit mode failure.

Also, the control device according to the present invention supplies power to a series circuit of a photodiode and a current limiting resistor for limiting a current supplied to the photodiode, thereby reducing the current.
A secondary current is supplied, and a diode is connected between the connection point between the photodiode and the current limiting resistor and the connection point between the output drive circuit and the load, thereby preventing current from being supplied to the photodiode via the load. Since the connection is made in the direction, the output state of the output drive circuit can be detected without receiving the current supply through the load connected in series to the output drive circuit.

Further, by employing a configuration in which only the current flowing through the photodiode is forcibly cut off, the current flowing through each load is not cut off while the load is being driven.
Therefore, it is possible to use even a load that requires a short time for operation and recovery (short response time). When a configuration is used in which current is supplied to the photodiode via a load, the forced cutoff time must be set so that the load in operation does not recover, but only the current flowing through the photodiode is forced. By adopting the configuration of shutting off, the forced shutoff time can be set arbitrarily.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a specific example of a control device according to the present invention.

FIG. 2 is a time chart showing the operation of the control device shown in FIG.

FIG. 3 is a block diagram showing another specific example of the control device according to the present invention.

FIG. 4 is a block diagram showing still another specific example of the control device according to the present invention.

FIG. 5 is a circuit configuration diagram of a conventional failure diagnosis circuit.

FIG. 6 is another circuit configuration diagram of a conventional failure diagnosis circuit.

FIG. 7 is a circuit configuration diagram of another conventional failure diagnosis circuit.

[Explanation of symbols]

1, 31, 41: control device, 2, 3: control unit, 4: check unit, 5: relay drive circuit, 6: load power supply relay,
7: forced cutoff signal generation unit, 8, 32 ... primary side current cutoff unit, 9a-9n ... load, 10a-10n, 50a-50
n: output drive circuit, 11a to 11n, 33a to 33n,
60a to 60n: Photocoupler circuit, D33, D60 ...
Diode, PC11, PC33, PC50: Photocoupler, PD11, PD33, PD50: Photodiode, PT11, PT33, PT50: Phototransistor, R21, R33, R60: Current limiting resistor.

Claims (2)

[Claims] 1. A control output signal generated by a control unit is supplied to an output drive circuit to control a drive / non-drive state of a load, and to control an on / off operation state of the output drive circuit via a photocoupler circuit. Feedback to the control unit,
The operation of the output drive circuit is normal based on a control output signal supplied to the output drive circuit and an on / off operation state of the output drive circuit fed back via the photocoupler circuit. A control device configured to diagnose whether or not the primary current is interrupted, comprising: a primary-side current interrupting unit that forcibly interrupts a primary-side current flowing through a photodiode of the photocoupler circuit; It is determined that the operation of the photocoupler circuit is normal based on the fact that the primary current of the photocoupler circuit is forcibly interrupted by the secondary current interrupter and the output of the photocoupler circuit is turned off. A control device having a configuration for performing diagnosis. 2. A primary current is supplied by supplying power to a series circuit including a current limiting resistor for limiting a current supplied to the photodiode and the photodiode, and the photodiode and the current are supplied. A diode is connected between a connection point of the limiting resistor and a connection point of the output drive circuit and the load in a direction for preventing current from being supplied to the photodiode via the load. The control device according to claim 1.