JPS62229302A - Digital controller - Google Patents

Abstract

PURPOSE:To enable switching between control systems without using any complicated circuit by comparing the level of each control output with the output of a self-diagnosis part that delivers signals of different levels in response to the normal or abnormal state of each control system and performing the switch between those control systems in terms of a logic circuit. CONSTITUTION:The output of a self-diagnosis part 13 is set at a high level when a control system 10 is normal and therefore a low selector 14 selects the control output given from a D/A converter 12. While the signal of a low level is supplied to a terminal of an AND gate 25 via an inverter 26 and the output of the gate 25 is set at a low level. Thus the signal of a low level is delivered from a low selector 24. While a high selector 30 selects the control output given from the selector 14. When both control systems 20 and 10 are normal and abnormal respectively, the output of the part 13 is set at a low level together with the output of a self-diagnosis part 23 set at a high level respectively. Then the outputs of the selector 14 and the ate 25 are set at high levels. Thus the control output given from a D/A converter 22 is delivered via both selectors 24 and 30.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a digital control device, and particularly to a digital control device that performs online real-time processing and has a backup function.

(b) Conventional technology For digital control equipment that performs online real-time processing, a redundant system is adopted due to its importance and safety. Generally, a duplex method is used for redundancy.

As shown in Figure 2, in this method, in addition to the first control system a used for normal control, an identical second control system is installed on the output side of the analog conversion of the control system. A switch C is provided in the first control system a, and a self-diagnosis section d performs a self-diagnosis in the first control system a, and the output of the second control system tracks the output of the first control system a. When the self-diagnosis section d determines that the first control system a is abnormal, the switch C switches to the second control system.

(c) Problems to be solved by the invention The conventional redundant digital control system described above is provided with a switching device on the analog output side of the control system, and specifically, a relay is used as the switching device. be done.

As a result, the circuit becomes complicated, which increases the cost of the entire device. In addition, there is a problem that the reliability of the relay lowers the evaluation of the system.

In view of the above, an object of the present invention is to provide a digital control device that can switch a control system without complicating the circuit or using a switch such as a relay.

(d) Means for solving the problems The digital control device of the present invention has first and second control systems (
10, 20), and a first control output means (12) that outputs a digitally calculated control signal as an analog signal to the first control system, and a first control output means (12) that determines whether the own system is normal or abnormal, and is a first self-diagnosis means (13) which outputs a signal at a higher level than the analog signal, and outputs a signal at a lower level than the analog signal in the event of an abnormality, and an analog signal from the first control output means. The first low signal selection means (14) receives the signal from the first self-diagnosis means as an input, receives the signal from the first self-diagnosis means, and outputs a lower level signal.

The second control system also includes a second control output means (22) that outputs a digitally calculated control signal as an analog signal, and a second control output means (22) that determines whether the own system is normal or abnormal, and when normal, the signal is higher than the analog signal. a second self-diagnosis means (which outputs a signal at a lower level than the analog signal when an abnormality occurs);
23), receiving an analog signal from the second control output means at one input, and detecting an abnormality in the first self-diagnosis means;
When the second self-diagnosis means outputs a signal indicating normality, a high level signal is received only for the G-snake, and a low level signal is received for the others at the other input, and a second low signal is output that outputs a lower level signal. A selection means (24) is provided.

Furthermore, a high signal selection means (30) is provided which receives the output signals of the first low signal selection means and the second low signal selection means and outputs a higher level signal.

(E) Function In this digital control device, when the first self-diagnosis means determines that the first control system is operating normally, the analog control output from the first control output means is The signal is outputted through a low signal selection means and a high signal selection means.

When an abnormality occurs in the first control system, the first self-diagnosis means determines this and outputs a low level signal, and this low level signal is outputted from the first low signal selection means. In this case, if the second control system is normal, the second self-diagnosis means determines this, and based on the abnormality of the first control system, the second low signal selection means outputs a high level signal. Add signal. Therefore, the analog control output from the second control output means of the second control system is outputted via the second low signal selection means and high signal selection means.

(f) Examples The present invention will now be explained in more detail with reference to Examples.

FIG. 1 is a block diagram of a digital control device showing one embodiment of the present invention. In the figure, the digital control device 1 is composed of a control system 10.20 and a high selector 30.

The control system 10 includes a control calculation unit 11 that performs predetermined digital control calculations, a D/A converter 12 that converts the digital control output from the control calculation unit 11 into an analog signal, and a D/A converter 12 that determines whether the operation of its own system is normal or abnormal. The self-diagnosis section 1 receives control outputs from the self-diagnosis section 13 and the D/A converter 12 at one input.
The low selector 14 receives the signal from 3 at the other input.

When the self-diagnosis unit 13 is operating normally, the self-diagnosis unit 13 outputs a higher level (e.g. 15 V) than the analog signal (e.g. 1 to 5 V).
V) signal, and if the operation is abnormal, it will be low level (
Example: 0 ■) signal is output.

Similarly to the control system 10, the control system 20 includes a control calculation section 21,
D/A converter 22, self-diagnosis section 23 and low selector 2
It is equipped with 4. However, since the control system 20 is provided to bank up the control system 10, a signal indicating whether the self-diagnosis section 23 is normal or abnormal is input to the low selector 24 via the anti-game I.25. ing. A signal from the self-diagnosis section 13 of the control system 10 is applied to the other input terminal of the AND gate 25 via an inverter 26 . That is, a high signal indicating that the self-diagnosis unit 23 is normal is input to the low selector 24 on the condition that the control system 10 is abnormal. Although not shown, the output of the control system 20 tracks the output of the control system IO.

Next, the operation of this embodiment digital control device 1 will be explained.

Normally, the digital control output calculated by the control calculation section 11 of the control system 10 is converted into an analog signal by the D/A converter 12 and input to the low selector 14. If there is no abnormality in the control system 10, a high level signal indicating normality is outputted from the self-diagnosis section 13 and inputted to the low selector 14.

Comparing this high level signal with the analog signal, we find that D/
Since the control output from A converter 12 has a lower level,
This control output is selected and output from the low selector 14. The control system 20 follows this control output, but if the control system 20 is also normal like the control system 10, a high level signal is output from the self-diagnosis section 23 and input to the AND gate 25. However, the high level signal from the self-diagnosis section 13 is inverted by the inverter 26 and applied to the other input terminal of the AND gate 25 at a low level. Therefore, the output of the AND gate 25 becomes low level,
This is input to the low selector 24. Therefore, the low selector 24 selects the low level signal regardless of the control output from the D/A converter 22. therefore,
A control output from the control system 10 from the low selector 14 and a low level signal from the low selector 24 are applied to the high selector 30 . Then, the control output from the higher level control system IO is directly derived.

If an abnormality occurs in the control system 10 while the control system 20 is operating normally, the self-diagnosis section 13 outputs a low level signal indicating the abnormality and applies it to the low selector 14. Therefore, the control output from the D/A converter 12 is not derived from the low selector 14, and the low level signal having a lower level is output.

On the other hand, the low level signal from the self-diagnosis section 13 is inverted by the inverter 26, and a high level signal is input to the AND gate 25. Since the high level signal indicating normality from the self-diagnosis section 2 is applied to the other input terminal of the AND gate 25, a high level signal is derived to the output terminal of the AND gate 25, and this signal is sent to the low selector 24. is applied to one input end of At the other end of the low selector 24,
Since the control output from the D/A converter 22, which is always lower in level than the high level signal, is added, this control
A wholesale output is derived from the low selector 24 and applied to one input terminal of the high selector 30.

Since a low level signal is applied from the control system 10 to the other input terminal of the high selector 30, the high selector 30
From 0, the control Jn output from the control system 10, which has a higher level, is derived.

When an abnormality occurs in the control system 10, the operation is switched from the control system 10 to the control system 20 as described above, and the system is punctured.

(G) Effects of the Invention According to this invention, the first control system and the second control system are each provided with a self-diagnosis section, and high-level diagnostics indicating normality or abnormality are provided.
A low level signal is output, and a level comparison between these and the first and second control outputs is performed using a low signal selection means and a high signal selection means, and switching from the first control system to the second control system is performed. Since this is performed using a logic circuit, the circuit is simple, and since contact means such as relays are not used for switching, reliability can be ensured.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a digital control device showing an embodiment of the present invention, and FIG. 2 is a block diagram for explaining a conventional digital control device. 10/20: Control system, 12/22: D/A converter, Engineering 3/23: Self-diagnosis section, 14/24: Low selector, 30: High selector. Patent applicant: Shimadzu Corporation Agent
Patent Attorney Shigeru Nakamura Figure 2

Claims (1)

[Claims] (1) In a digital control device comprising a first control system and a second control system that backs up the first control system, a digitally calculated control signal is output as an analog signal to the first control system. a first control output means for determining whether the self system is normal or abnormal, and outputting a signal at a higher level than the analog signal when normal and a signal at a lower level than the analog signal when abnormal. a diagnostic means, and the first
a first low signal selection means for receiving an analog signal from the control output means at one input, receiving a signal from the first self-diagnosis means at the other input, and outputting a signal at a lower level; a second control output means for outputting a digitally calculated control signal as an analog signal to the second control system; and a second control output means for determining whether the own system is normal or abnormal, and outputting a signal at a higher level than the analog signal when normal; a second self-diagnosis means that outputs a signal at a lower level than the analog signal when an abnormality occurs;
receives an analog signal from the control output means at one input, and outputs a high level signal only when the first self-diagnosis means outputs a signal indicating abnormality and the second self-diagnosis means normality; receives a low level signal at the other input,
and second low signal selection means for outputting a signal of a lower level, and receiving output signals of the first low signal selection means and the second low signal selection means and outputting a signal of a higher level. A digital control device comprising high signal selection means.