JPH01276201A - Control device having backup function - Google Patents

Abstract

PURPOSE:To prevent an output system from being made into an unstable condition due to a hunting by selecting the control signal of a subcontrol part only at the time of the abnormality of a main control part when the hunting frequency of the main control part is below a prescribed value and selecting the control signal of the subcontrol part regardless of the condition of the main control part when the hunting frequency is at the prescribed value or above. CONSTITUTION:When the hunting of a main control part 2M is below the pre scribed value, namely, at the time of the hunting in a range in which the output system is stably operated, an output changeover control part 4 outputs a change over signal to select the control signal of a subcontrol part 2S only at the time of the abnormality of the main control part 2M. When the hunting of the main control part 2M is at the prescribed value or above, namely, at the time of the hunting to exceed the range in which the output system is stably operated, the output changeover part 4 outputs the changeover signal to select the control signal of the subcontrol part 2S. Thus, the control can be executed so as to prevent the output system from being made into the unstable condition due to the hunting of the main control part 2M.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device with a backup function in a control system having a backup function and a return function to normal operation.

BACKGROUND ART FIG. 4 shows the configuration of a conventional control device with a backup function.

In FIG. 4, based on the input signal S1 from the input system 1, the main control section 2M and the sub-control section 2S output control signals S21 and S22 for controlling the output system 6.

In such a control state, if the abnormality detection section 3 checking the main monitoring signal S4 outputted by the main control section 2M determines that the main control section 2M is normal, the abnormality detection section 3 detects that the main control section 2M is normal. A normal output signal (normal signal) Ss is output.

Therefore, the output switching unit 5 selects the control signal S21 output by the main control unit 2M as the output signal S8 based on the output signal S5, and supplies it to the output system 6.

However, when the main control section 2M becomes abnormal, the abnormality detection section 3 detects the abnormality in the main control section 2M and
Output signal indicating that M is abnormal (abnormal signal) Main return signal S that returns Ss and main control unit 2M to normal operation
6, the output switching unit 5 selects the control signal S22 output by the sub-control unit 2S as the output signal S8 based on the output signal S5, and supplies it to the output system 6.

Then, the main control unit 2M is activated by the main return signal S6.
When the main control unit 2M returns to normal operation, the abnormality detection unit 3 detects that the main control unit 2M is normal and outputs a signal (normal signal).
In order to output Ss, the output switching section 5 again selects the control signal 821 outputted by the main control section 2M as the output signal S8, and supplies it to the output system 6.

As described above, by using the output signal S5 of the abnormality detection section 3 as a switching signal for the output switching section 5, control can be switched to the sub-control section 2S when the main control section 2M is abnormal.

However, the sub-control unit 2S must perform only the minimum necessary control to operate the output system 6, and when the main control unit 2M is normal, the output switching unit 5 outputs the control signal S21 output by the main control unit 2M. It is selected as signal S8 and supplied to output system 6.

Problems to be Solved by the Invention However, in the above-mentioned conventional control device with a backup function, the main control section 2M and the sub-control section 2S are directly switched by the output signal S5 outputted by the abnormality detection section 3. When the control unit 2M repeats normal and abnormal states in a short period of time, so-called hunting,
When the control device with a backup function becomes unstable, the operation of the output system 6 also becomes unstable, resulting in a problem that the output system 6 stops operating.

The present invention solves these conventional problems, and aims to provide a control device with a back amplifier function that can control the output system so that it does not fall into an unstable state due to notching of the main control section. This is the purpose.

Means for Solving the Problems In order to achieve the above object, the present invention measures the frequency of repetition of normality and abnormality of the main control section based on the output signal of an abnormality detection section that detects abnormality of the main control section, and If the frequency is less than a predetermined value, the sub-control unit control signal is selected only when the main control unit is abnormal; if the repetition frequency is greater than the predetermined value, the sub-control unit control signal is selected regardless of the state of the main control unit. It is provided with an output switching control section that outputs a switching signal to be selected to an output switching section.

Therefore, according to the present invention, when the hunting in the main control section is less than a predetermined value, that is, within the range in which the output system operates stably, the output switching control section switches on the sub-control section only when the main control section is abnormal. Outputs a switching signal to select a control signal.

If the hunting of the main control section exceeds a predetermined value, that is, the hunting exceeds the range in which the output system operates stably, the output switching control section outputs a switching signal for selecting the control signal of the sub-control section.

Embodiment FIG. 1 is a block diagram showing the configuration of a control device with a backup function according to an embodiment of the present invention.

In FIG. 1, 1 indicates an input system, and 2M indicates a main control section, which outputs a control signal S21 for controlling the output system 6 based on an input signal S1 from the input system 1.

2S indicates a sub-control unit, which receives the input signal Sl from the input system 1.
This outputs a control signal S22 for controlling the output system 6 based on this.

Reference numeral 3 indicates an abnormality detection section, which determines whether the main control section 2M is normal or abnormal by checking the main monitoring signal S4 outputted by the main control section 2M, and outputs a signal S5 indicating whether the main control section 2M is normal or abnormal. and main control section 2M
It outputs a main control signal S6 to return to normal operation when the main control signal S6 becomes abnormal.

Reference numeral 4 indicates an output switching control section, which measures the repetition frequency of normality and abnormality of the main control section 2M based on the output signal (normal signal, abnormal signal) Ss outputted by the abnormality detection section 3, and determines whether the repetition frequency is a predetermined one. In the case of hunting that is less than the specified value, that is, within the range in which the output system 6 operates stably, the control signal S22 of the sub-control unit 2S is selected only when the main control unit 2M is abnormal, and when the repetition frequency is above a predetermined value, that is, the output system 6 In the case of hunting exceeding the stable operation range, a switching signal S7 for selecting the control signal S22 of the sub-control unit 2S is output.

Reference numeral 5 denotes an output switching section, which selects either the control signal 821 outputted by the main control section 2M or the control signal S22 outputted from the sub-control section 2S based on the switching signal S7 outputted by the output switching control section 4, and outputs the output signal S8. That is.

Note that Ss indicates a sub-monitoring signal output from the sub-control unit 2S to the main control unit 2M.

FIG. 2 is a block diagram showing the configuration of the output switching control section 4 shown in FIG. 1.

In FIG. 2, the same parts as those in FIG. This counter measures the hunting frequency (referred to as hunting frequency), and counts the output signal S5 at the rising edge from when it is reset by the reference clock signal S41 outputted by the reference clock generation circuit 41 until it is reset by the next reference clock signal S41. 0 43 indicates a launch circuit, in which the counter 42 is activated by the reference clock signal S41 output from the reference clock generation circuit 41.
Stores the count value.

Reference numeral 44 denotes a register, which stores in advance the hunting frequency at which the output system 6 becomes unstable.

A comparator 45 compares the count value stored in the launch circuit 43 with the hunting frequency stored in the register 44, and outputs a comparison signal S42 that determines whether the output system 6 has reached an unstable state. It is something to do.

46 indicates an OR circuit, which outputs the output signal S5 and the comparison signal S42.
0 is input and outputs a switching signal S7. FIG. 3 is a waveform diagram showing signals of each part of the output switching section 4 shown in FIG. 2.

Next, the operation of the above embodiment will be explained.

In the above embodiment, based on the input signal Sl from the input system 1, the main control section 2M and the sub control section 2S control the output system 6.
A control signal 52ts S22 is output to control the .

In such a control state, if the abnormality detection section 3 checking the main monitoring signal S4 outputted by the main control section 2M determines that the main control section 2M is normal, the abnormality detection section 3 detects that the main control section 2M is normal. If the abnormality detection unit 3 determines that the main control unit 2M is abnormal by outputting a normal output signal (normal signal) Ss, the abnormality detection unit 3 outputs an output signal (abnormal signal) indicating that the main control unit 2M is abnormal. A main return signal S6 for returning Ss and the main control unit 2M to normal operation is output.

Therefore, the counter 42 of the output switching control section 4 outputs an output signal (abnormal signal) Ss(
FIG. 3(a)) is counted as shown in FIG. 3(c), and the count value is determined by the latch circuit 43 by the reference clock signal S41 of the reference clock generating circuit 41 (FIG. 3(b)).
and is immediately reset to zero.

Next, the count value stored in the latch circuit 43 is compared with the hunting frequency at which the output system 6 becomes unstable, stored in advance in the register 44, for example r3J, and if the count value is equal to or higher than the hunting frequency, the comparator 45 goes high A level comparison signal S42 UE3 (Figure (d)) is output.

Then, output signal (abnormal signal) Ss and comparison signal S42
The OR circuit 46 calculates the logical sum with the output signal S7 and outputs the switching signal S7 to the output switching section 5, which selects the control signal S22 of the sub-control section 2S as shown in FIG. 3(e).

The subsequent operations and other operations are similar to those described in the prior art example.

As described above, according to the present invention, the output switching control section 4
Based on the switching signal S7, the output switching unit 5 switches to the control of the sub-control unit 2S, and can control the output system 6 so that it does not fall into an unstable state due to hunting of the main control unit 2M, and also controls the main control unit as much as possible. The output system 6 can be controlled by 2M.

Effects of the Invention As is clear from the embodiments described above, the present invention selects the control signal for the sub-control unit only when the main control unit is abnormal when the hunting frequency of the main control unit is less than a predetermined value. If the value exceeds this value, the control signal for the sub control section is selected regardless of the state of the main control section, so it is possible to control the output system so that it does not fall into an unstable state due to hunting in the main control section. This has the effect that the output system can be controlled by the main control section if possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a control device with a backup function according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of the output switching control section shown in FIG. 1, and FIG. FIG. 4 is a waveform diagram for explaining the operation of the output switching control section shown in the figure, and FIG. 4 is a block diagram showing the configuration of a conventional control device with a backup function. 1... Input system, 2M... Main control section, 2S - Sub control section, 3... Abnormality detection section, 4... Output switching control section, 5... Output switching section, 6 Output system. Name of agent: Patent attorney Toshio Nakao and one other person
-! , 20-no--J) LIJ

Claims (1)

[Claims] A main control section and a sub-control section that output a control signal based on an input signal from an input system, an abnormality detection section that detects an abnormality in the main control section, and a main control section that outputs a control signal based on an output signal of the abnormality detection section. If the frequency of repetition is less than a predetermined value, the control signal for the sub-control section is selected only when the main control section is abnormal; an output switching control section that outputs a switching signal that selects a control signal of the sub-control section regardless of the state of the main control section; and an output switching control section that outputs a switching signal that selects a control signal of the sub-control section regardless of the state of the main control section; A control device with a backup function that includes an output switching section that selects one control signal and supplies it to the output system.