JP2002123301A - Control device - Google Patents

Abstract

(57) [Summary] [Problem] To stop an output signal reliably and without a delay time when any abnormality occurs. A watchdog timer circuit is provided in an IO module. Watchdog timer circuit 3
The controller 8 receives one of the parallel signals from the serial / parallel conversion circuit 33 as the kick signal 37, and determines that some abnormality has occurred in the controller main body 10 when the kick signal 37 is not input, thereby enabling the driver. The signal 39 is output. Therefore, when an abnormality occurs, the output signal 40 can be immediately stopped. Further, even when an abnormality occurs in the CPU 11 itself and the abnormality processing cannot be performed by the software, the output signal 40 can be stopped and the safety is further improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for controlling various control devices such as an industrial robot, and more particularly to a control device for safely stopping an industrial robot when any abnormality occurs. Related to a control device.

[0002]

2. Description of the Related Art Control devices are widely used to control various control devices such as industrial robots. This control device includes a controller main body and an IO module, and controls an industrial robot according to a predetermined procedure.

In such a control device, when any abnormality occurs, it is necessary to detect the abnormality and perform an abnormality process such as stopping the operation of the control device under control.

[0004] For example, when an abnormality occurs in the controller main body when the arc welding equipment is controlled by the control device, the arc welding is continued at the timing when the operation should be stopped, and there is a possibility that the human body or the product is harmed.

FIG. 3 shows a conventional control device having a function of performing an abnormality process when such an abnormality occurs.

[0006] As shown in FIG. 3, this conventional control device includes a controller main body 10 and an IO module 50. The controller main body 10 and the IO module 50 are connected by the serial communication line 20, and the IO module 50 controls the connected control devices by outputting the output signal 40.

The controller body 10 includes a real-time clock circuit (RTC) 12, a CPU 11, a communication chip 15, a watchdog timer circuit (WDT), and the like.
17.

The CPU 11 performs periodic software processing at regular intervals based on the real-time clock generated by the real-time clock circuit 12, generates signals for controlling various control devices, and sends the signals through the communication chip 15. Output to the IO module 50. Further, the CPU 11 generates and outputs a periodic kick signal 16 in a periodic software processing at a constant interval, performs an abnormality processing by software when an abnormality detection signal 18 is input, stops output to the IO module 50, and the like. Is performed.

Watchdog timer circuit (WDT) 17
Does not output the abnormality detection signal 18 while the kick signal 16 is periodically input at regular intervals, and determines that some abnormality has occurred in the CPU 11 when the kick signal 16 is no longer input. Is output.

The IO module 50 includes a communication chip 31, a serial / parallel conversion circuit 33, and a driver 54.

The serial / parallel conversion circuit 33 converts a serial signal received from the controller main body 10 via the communication chip 31 into a parallel signal and outputs the parallel signal.
The driver 54 receives the parallel signal output from the serial / parallel conversion circuit 33, adjusts the voltage level, and outputs the signal as an output signal 40 for driving a control device via the connector 35.

Next, the operation of the conventional control device will be described.

First, the operation in a normal state in which no abnormality has occurred in the controller body 10 and the IO module 50 will be described.

In the controller body 10, the CPU 11 performs periodic software processing at regular intervals based on a real-time clock. By this software processing, an output signal to the IO module 50 is generated, and this output signal is transmitted to the IO module 50 via the serial communication line 20 between the communication chip 15 and the communication chip 31. Serial / parallel conversion circuit 33
Converts the serial signal received by the communication chip 31 into a parallel signal and outputs the signal to the driver 54. The driver 54 receives the parallel signal output from the serial / parallel conversion circuit 33, adjusts the voltage level, and outputs it as an output signal 40 to various control devices via the connector 35. Various control devices output the output signal 40
Is controlled by ON / OFF of the switch, and performs an operation of a predetermined procedure.

Next, the CP in the controller body 10
The operation when some abnormality occurs in U11 will be described.

If any abnormality occurs in the CPU 11,
In the CPU 11, the periodic software processing is not performed, and the kick signal 16 is not output. Then, the watchdog timer circuit 17 outputs the abnormality detection signal 18 to the CPU.
11 is output. Therefore, the CPU 11 performs an abnormal process by software, and the IO module 50
Processing such as stop of output to is performed.

In the conventional control device described above, even when an abnormality occurs in the CPU 11, the abnormality detection signal 18 is output from the watchdog timer circuit 17 to execute the abnormality processing and stop the output to the IO module 50. Can be taken. In some cases, such processing can ensure sufficient safety. However, in this conventional control device, software processing is required while the output to the IO module 50 is stopped after the occurrence of some abnormality is detected. Delay time occurs.

When the software processing itself in the CPU 11 does not normally start, even if the abnormality detection signal 18 is input, the IO module 50
Output is not stopped and safety cannot be ensured.

[0019]

The above-mentioned conventional control device has the following problems. (1) A certain delay time occurs from the occurrence of an abnormality until the output signal is stopped. (2) If the CPU of the controller itself becomes abnormal, the output signal cannot be stopped.

It is an object of the present invention to provide a control device capable of stopping an output signal reliably and without delay when any abnormality occurs.

[0021]

In order to achieve the above object, a control device according to the present invention is a control device for driving a control device based on a preset procedure. The control device controls the control device. A serial / parallel conversion circuit for converting a serial signal from the controller main body into a parallel signal, and a signal output from one of the parallel signals from the serial / parallel conversion circuit. A watchdog timer circuit that inputs a kick signal, and when the kick signal is not input, determines that an abnormality has occurred in the controller main body and outputs a driver enable signal; and a parallel signal from the serial / parallel conversion circuit. Generating and outputting an output signal for driving the control device. And IO module having a driver for the output signal in the output stop state and the driver enable signal is output Te, composed.

According to the present invention, the output signal from the driver is stopped almost at the same time that the watchdog timer circuit detects the occurrence of the abnormality and outputs the driver enable signal. It is possible to reduce the delay time until the state becomes as compared with the conventional control device.

Further, according to the present invention, even if an abnormality occurs in the CPU itself in the controller body and the abnormality processing cannot be performed by software, the watchdog timer circuit detects the abnormality and outputs the error to the driver. By outputting the enable signal, the driver stops the output signal, so that the safety can be further improved.

[0024]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a control device according to an embodiment of the present invention. In FIG. 1, the same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

The control device of the present embodiment comprises a controller main body 10 and an IO module 30. The IO module 30 is different from the IO module 50 in the conventional control device shown in FIG.
The watchdog timer circuit 38 is newly added, and the driver 54 is replaced with the driver 34.

The watchdog timer circuit 38 inputs one of the parallel signals from the serial / parallel conversion circuit 33 as a kick signal 37. If the kick signal 37 is not input, some abnormality occurs in the controller body 10. Then, the driver enable signal 39 is output.

The driver 34 has a function of stopping the output signal 40 when a driver enable signal 39 is input from the watchdog timer circuit 38 in addition to the function of the driver 54.

In the control device of the present embodiment, the CPU 11 includes a kick signal to be output to the watchdog timer circuit 38 in the signal output to the IO module 30.

Next, the operation of the control device according to the present embodiment will be described in detail with reference to FIGS. FIG. 2 is a timing chart showing the operation of the control device of the present embodiment.

In the control device according to the present embodiment, the watchdog timer circuit 38 does not output the driver enable signal 39 while the kick signal 37 is periodically output. The output signal 40 is output based on the output.

When some kind of abnormality occurs in the controller body 10 and the kick signal 37 which should be inputted at the time t ₁ is not inputted to the watch dog timer circuit 38, the watch dog timer circuit 38 outputs the driver enable signal 39. Output. Therefore, the driver 34 stops all the output signals 40 and stops the operation of various control devices under control.

Since the driver 34 is constituted by a hardware circuit, the delay time from when the driver enable signal 39 is output to when the output signal 40 is stopped can be considered to be almost zero. Therefore, according to the control device of the present embodiment, the output signal 40 from the driver 34 is stopped almost at the same time when the watchdog timer circuit 38 detects the occurrence of the abnormality and outputs the driver enable signal 39. As a result, the delay time from the occurrence of the abnormality to the stop of the output signal 40 can be reduced as compared with the conventional control device.

Further, according to the control device of the present embodiment, even if the CPU 11 in the controller main body 10 has an abnormality and the software cannot perform the abnormality processing, the watchdog timer circuit 38 is not operated. The occurrence is detected and the driver enable signal 3
By outputting the signal 9, the driver 34 stops the output signal 40. Therefore, according to the control device of the present embodiment, safety can be further improved as compared with the conventional control device.

In this embodiment, an FA (Factory Automation) for controlling various control devices such as an industrial robot is used.
Although the description has been made using the control device, the present invention is not limited to such a case, and is similarly applied to a general control device for controlling a control device other than an industrial robot. Is what you can do.

[0035]

As described above, the present invention has the following effects. (1) The delay time from the occurrence of an abnormality to the stop of the output signal can be shortened as compared with the related art. (2) Even in the case where the CPU itself in the controller body becomes abnormal and it is not possible to perform an abnormal action by software, the output signal can be stopped and the safety can be enhanced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a control device according to an embodiment of the present invention.

FIG. 2 is a timing chart showing an operation of the control device of FIG.

FIG. 3 is a block diagram showing a configuration of a conventional control device.

[Explanation of symbols]

 Reference Signs List 10 Controller main body 11 CPU 12 Real-time clock circuit (RTC) 15 Communication chip 16 Kick signal 17 Watchdog timer circuit 18 Abnormality detection signal 20 Serial communication line 30 IO module 31 Communication chip 33 Serial / parallel conversion circuit (S / P) 34 Driver 35 Connector 37 Kick signal 38 Watchdog timer 39 Driver enable signal 40 Output signal 50 IO module 54 Driver

Claims (1)

[Claims] 1. A control device for driving a control device based on a preset procedure, comprising: a controller main body for generating and outputting a serial signal for controlling the control device; A serial / parallel conversion circuit for converting a signal into a parallel signal, and one of parallel signals from the serial / parallel conversion circuit.
A clock dog circuit that inputs two signals as kick signals, determines that an abnormality has occurred in the controller body when the kick signal is no longer input, and outputs a driver enable signal; and a parallel signal from the serial / parallel conversion circuit. An IO module comprising: a driver that generates and outputs an output signal for driving the control device based on a signal, and outputs the output enable signal when the driver enable signal is output, and the output signal is stopped. Control device consisting of: