JPH0588926A - Automatic switching circuit for monitor and control system - Google Patents

Abstract

PURPOSE:To automatically switch monitor control systems with a simple configuration. CONSTITUTION:An automatic switching circuit 20 is provided with a watchdog timer circuits 21 and 22, which monitor health check signals 34 and 35 periodically generated from monitor and control devices 11 and 12 for the purpose of detecting the abnormality in monitor and control devices 11 and 12 or interface lines between monitor and control devices 11 and 12 and an automatic switching circuit 20 and output alarm signals 36 and 37 at the time of detecting a break of health check signals 34 and 35, and a switching circuit 23 which switches the connection state of interface lines 14, 15, and 16 between a device 13 to be controlled and plural monitor control devices 11 and 12 so that the device 13 to be controlled is connected to the normal monitor control device side in accordance with alarm signals from watchdog timer circuits.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supervisory control system using a computer or the like, which monitors a multiplexed supervisory control system and an interface line between the supervisory control system and a controlled device, The present invention relates to an automatic switching circuit of a supervisory control system that automatically switches.

[0002]

2. Description of the Related Art In a supervisory control system system having a supervisory control system and a controlled device using a computer or the like, the supervisory control system and the interface line are duplicated in order to prepare for an abnormality of the supervisory control system and the interface line. In case of abnormality, a fail-safe function is provided to switch to the other normal state.

Conventionally, as the switching method, the supervisory control system monitors the ready signal from the controlled device,
When the ready signal cannot be detected, it is common to switch to the standby system manually or automatically, and the switching logic was on the supervisory control system (computer) side.

[0004]

However, in the above-mentioned conventional switching system, the computer of the supervisory control system is used to detect disconnection of the interface line and switch the computer of the supervisory control system on the supervisory control system side. The system was constructed by such a method that a function for monitoring the status of the other party between them and a function for switching the control system are provided exclusively for the application program, and a communication line is provided between both computers. Therefore, there are problems that the system becomes complicated and the cost becomes high, and the development cost of the application program becomes high.

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic switching circuit for a supervisory control system, which has a simple structure and can realize automatic switching of the supervisory control system.

[0006]

An automatic switching circuit of a supervisory control system according to the invention of claim 1 is provided corresponding to each of a plurality of supervisory control systems provided for one controlled device, The health check signal that is periodically generated from the supervisory control system is monitored to detect an abnormality in the supervisory control system or the interface line with this supervisory control system, and the interruption of this health check signal is detected. A watchdog timer circuit that outputs an alarm signal is provided between the monitored device and multiple supervisory control systems, and the monitored device is connected to a normal supervisory control system side according to the alarm signal from the watchdog timer circuit. As described above, the switching circuit that switches the connection state between the monitored device and the plurality of monitoring control systems is provided.

In this automatic switching circuit, a watchdog timer circuit provided for each supervisory control system monitors a health check signal periodically generated from each supervisory control system. An alarm signal is output from the watchdog timer circuit.
The switching circuit switches the connection state between the monitored device and the plurality of monitoring control systems so as to connect the monitored device to the normal monitoring control system side in response to the alarm signal.

According to a second aspect of the present invention, there is provided an automatic switching circuit for a supervisory control system, wherein the switching circuit according to the first aspect of the present invention provides an interface line between the switching circuit and a monitored device with the switching circuit and each monitoring circuit. It selectively connects to one of a plurality of interface lines between control systems.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 relate to an embodiment of the present invention.

FIG. 1 is a block diagram showing the configuration of a supervisory control system system including an automatic switching circuit according to this embodiment. As shown in this figure, the supervisory control system includes two supervisory control devices 11 and 12, and a controlled device 13 shared by the supervisory control devices 11 and 12.
An automatic switching circuit 20 is provided between the control target device 13 and the controlled device 13. Each of the monitoring control devices 11 and 12 is composed of a computer or the like, and while performing independent work, the controlled device 13 is shared by both, and when one is abnormal, the other can be backed up.

The automatic switching circuit 20 is provided for each supervisory control device 1.
Watchdog timer circuit 2 provided for each 1 and 12
1, 22 and the watchdog timer circuits 21, 22
In response to the alarm signal from the monitor control device 11, 12
And a switching circuit 23 that switches the system of the interface line between the controlled device 13 and the controlled device 13. The monitoring control devices 11 and 12 and the switching circuit 23 are connected by data interface lines 14 and 15, respectively, and the controlled device 13 and the switching circuit 23 are connected by an interface line 16 respectively.
Connected by. Further, between the supervisory control device 11 and the watchdog timer circuit 21 and the supervisory control device 1
2 and the watchdog timer circuit 22 are connected by health check signal lines 24 and 25, respectively. Further, the watchdog timer circuit 21 and the switching circuit 23 and the watchdog timer circuit 22 and the switching circuit 23 are connected by control lines 26 and 27, respectively.

Each of the monitoring control devices 11 and 12 has a health check signal (contact signal) 3 at an interval of a predetermined cycle T.
4 and 35 are output, and this health check signal 3
The monitoring control device 11,
It is possible to detect an abnormality such as a stop of 12 or an abnormality such as a disconnection of an interface line between the monitoring control devices 11 and 12 and the automatic switching circuit 20.

The supervisory control device 11 and the automatic switching circuit 2
The interface line between 0 and 0 is the data interface line 14 and the health check signal line 24 integrated, and the interface line between the monitoring controller 12 and the automatic switching circuit 20 is the data interface line 15 and The health check signal line 25 is integrated.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 2 is a timing chart for explaining the operation of the automatic switching circuit 20 of this embodiment. Figure 2
As shown in (e), the switching circuit 23 initially includes the interface line 14 on the monitor control device 11 side and the controlled device 1.
It is in a state of being connected to the interface line 16 on the third side.

As shown in FIG. 2A, the supervisory control device 1
Reference numeral 1 is an interval of a cycle T, and outputs a health check signal 34 for detecting an abnormality such as a stop of the monitoring control device 11 or an abnormality such as a disconnection of an interface line. The health check signal 34 is input to the watchdog timer circuit 21 via the health check signal line 24. The watchdog timer circuit 21 monitors the health check signal 34 and checks the health check signal 3 of the previous time.
An alarm signal 36 is output when there is no next health check signal 34 from time 4 onward for a time t _w ( _tw > T). The alarm signal 36 is input to the switching circuit 23 via the control line 26 as a switching control signal.

Similarly, as shown in FIG. 2B, although not synchronized with the health check signal 34, the monitoring controller 12
From the health check signal 35 at the interval of cycle T
Is output and input to the watchdog timer circuit 22 via the health check signal line 25. The watchdog timer circuit 22 monitors the health check signal 35 and outputs an alarm signal 37 when there is no next health check signal 35 from the previous health check signal 35 for a time t _w or more. The alarm signal 37 is input to the switching circuit 23 as a switching control signal via the control line 27.

As shown in FIG. 2A, after the health check signal 34 is output at the time t ₁ , the monitor control device 11
When the health check signal 34 that should be output at time t ₁ ′ of t ₁ + T is cut off due to an abnormality such as a stop of the signal or a disconnection of the interface line, the watchdog timer circuit 21 monitors the time t _w . because doing, as shown in FIG. 2 (c), and outputs an alarm signal 36 at the timing of t ₁ + t _w. When the alarm signal 36 is input to the switching circuit 23, as shown in FIG. _2E , the controlled device 1 is controlled at a timing of t _s1 (= t ₁ + _tw ).
The interface line on the supervisory controller side connected to the interface line 16 on the third side is switched from the interface line 14 on the supervisory controller 11 side to the interface line 15 on the supervisory controller 12 side. In addition, FIG.
As shown in (a), at time t ₂ , the monitoring control device 1
When the health check signal 34 is restored by repairing 1 or the interface line, an alarm signal 36 from the watchdog timer circuit 21 is returned as shown in FIG.
Is reset.

Similarly, as shown in FIG. 2B, time t
After the health check signal 35 is output at _3, the abnormality such as disconnection abnormality or interface line such as stopping of the monitoring control unit 12, the health check signal 35 to be output at time t ₃ 'of the t ₃ + T sectional If a, because the watchdog timer circuit 22 is performing time monitoring of t _w, as shown in FIG. 2 (d), and outputs an alarm signal 37 at the timing of t ₃ + t _w. When the alarm signal 37 is input to the switching circuit 23, as shown in FIG. _2E , the supervisory control connected to the interface line 16 on the controlled device 13 side at the timing of t _s2 (= t ₃ + _tw ). Connect the interface line on the device side to the monitoring control device 1
From the interface line 15 on the second side to the monitoring control device 11
Switch to the interface line 14 on the side. Further, at time t _{4 as} shown in FIG. 2B, when the health check signal 34 is restored due to repair or the like of the supervisory controller 12 or the interface line, as shown in FIG. Alarm signal 3
7 is reset.

As described above, in this embodiment, the supervisory control device 1
While the health check signals 34 and 35 that are asynchronously output from both 1 and 12 are continuously output at the interval T, the monitoring control device 11 and 1 via the switching circuit 23.
2 and the controlled device 13 are fixedly connected, and when any of the health check signals 34 and 35 is interrupted by t _w or more, that is, when an abnormality occurs in the system of any of the monitoring and control devices, Watchdog timer circuit 21, 2
2 and the controlled circuit 1 by the switching circuit 23.
The interface line 16 on the side 3 is automatically switched to another normal system.

As described above, in the present embodiment, among the supervisory control systems that are duplicated so as to share the controlled device while performing independent work, especially the control system that issues a command to the controlled device is mutually backed up. As a result, the controlled device has an automatic switching circuit that automatically switches the interface line between the supervisory control system and the controlled device, and the switching logic is provided not on the supervisory control system side but on the controlled device side. The configuration of the supervisory control system is simplified, the fail-safe function of the supervisory control system can be realized with a simple configuration and at low cost, and the operating rate of the system can be increased.

Further, the controlled device 13 side is provided with only one system of control interface line, and a plurality of supervisory control devices 1 are provided.
It can be designed without being aware of the fact that it is connected to 1 and 12.

Further, the application programs of the computers constituting the supervisory control devices 11 and 12 do not require the mutual supervisory processing related to the switching of the interface line with the controlled device 13, and the software development cost can be reduced, and Reliability is also improved.

[0023]

As described above, according to the first aspect of the present invention, the watchdog timer circuit provided for each supervisory control system monitors the health check signal periodically generated from each supervisory control system. Then, when the health check signal is interrupted, the switching circuit switches the connection state between the monitored device and multiple monitoring control systems so that the monitored device is connected to the normal monitoring control system side. There is an effect that automatic switching of the monitoring control system can be realized with a simple configuration and at low cost.

According to the second aspect of the present invention, in addition to the above effects, the controlled device side has one interface line.
There is an effect that only the system is provided, and the design can be performed without being aware that the system is connected to a plurality of monitoring and control systems.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a supervisory control system system including an automatic switching circuit according to an embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the automatic switching circuit according to the embodiment of the present invention.

[Explanation of symbols]

 11, 12 Supervisory control device 13 Controlled device 20 Automatic switching circuit 21, 22 Watchdog timer circuit 23 Switching circuit

Claims (2)

[Claims] 1. To detect an abnormality of a supervisory control system or an interface line between the supervisory control system and the supervisory control system, which is provided for each of a plurality of supervisory control systems provided for one controlled device. A watchdog timer circuit that monitors the health check signal periodically generated from the monitor control system and outputs an alarm signal when the health check signal is interrupted, the monitored device and multiple monitor control systems. Provided between the two, depending on the alarm signal from the watchdog timer circuit,
An automatic switching circuit for a supervisory control system, comprising a switching circuit for switching a connection state between the monitored device and a plurality of supervisory control systems so that the monitored device is connected to a normal supervisory control system side. .. 2. The switching circuit selectively connects an interface line between the switching circuit and a monitored device to one of a plurality of interface lines between the switching circuit and each monitoring control system. An automatic switching circuit for a supervisory control system according to claim 1, wherein: