JPS60191339A - Redundant digital controller - Google Patents

Abstract

PURPOSE:To attain the redundant digital control with high reliability by adding a function which turns off forcibly an output through a contact output device in case a CPU is faulty and using an OR gate to switch the CPU. CONSTITUTION:Both CPU-A and CPU-B systems 5 and 6 are always performing the self-diagnosis processing and then turn on the CPU-A and CPU-B system fault signals if the faults of both systems are detected. These fault signals are supplied to the input terminals of forcible open signals of contact output devices 17 and 18 respectively. Therefore the output signal of the device 17 is forcibly turned off regardless of the digital output value of the system 5 when a fault of the system 5 is detected. In the same way, the output signal of the device 18 is forcibly turned off when a fault of the system 6 is detected. In such a way, a contact output device turns off forcibly an output in case a falt is detected in the system 5 or 6. Then both devices 17 and 18 are switched by an OR gate 20.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a redundant digital control device that can economize the contact output switching circuit of a digital control device in which central processing units CPUs are multiplexed. be.

[Prior art]

A conventional type of device was the one shown in FIG. In the figure, 1 is a process, and 2 is a redundant digital control device for controlling the process 1 described above. 3 and 4 are A-system and B-system contact input devices that convert contact input signals from the process 1 into digital signals, and 7 and 8 are contact input devices that convert digital signals from central processing units (hereinafter referred to as CPU) 5 and 6. The A-system and B-system contact output devices convert into signals, and 10 is a switch that selectively switches the signals from the contact output devices 7 and 8. Reference numeral 5 denotes a dual CPU (hereinafter referred to as CPU-A system), which reads control input signal values from the contact input device 3 and outputs them to the contact output device 7 after arithmetic processing.

Similarly, 6 is another single-system CPU that is duplicated (hereinafter referred to as
B system) reads the control input value from the contact input device 4, performs arithmetic processing, and outputs it to the contact output device 8. CPU-
The failure detection signals of the A system 5 and the CPU-B system 6 are input to the logic circuit 9. The output of the logic circuit 9 is input to a switch 10 and is used as a signal for selecting the position of the switch 10.

Next, the operation will be explained.

The CPU-A system 5 performs control calculations based on the control input signal value from the process 1 input via the contact input device 3, and outputs the calculation result to the switch 10 via the contact output device 7. Similarly, the CPU-B system 6 also performs control calculations based on the control input signal value from the process 1 inputted via the contact input device 4, and outputs the calculation results to the switch 10 via the contact output device 8. do. Above C
The PU-A system 5°CPU-B system 6 has a similar configuration,
Since the exact same calculations are performed, as long as both CPU systems are normal, the results of the calculations will be exactly the same. Also, C.P.
The UA system 5 always performs self-diagnosis, and if an abnormality is detected as a result of the diagnosis, it turns on the CPU-A thread failure signal.

Similarly, the CPU-B system 6 also constantly performs self-diagnosis, and if an abnormality is detected, the CPU-B system failure signal is turned ON. Next, the logic circuit 9 inputs the above CPU failure signal, determines which CPU output is to be output to the process 1, and outputs the result to the switch 10. The switch 10 is switched according to the output of the logic circuit 9, and C
Select PU output.

For example, if both CPU systems are normal, the logic circuit 9 instructs the switch 10 to maintain the status quo.

Also, if the CPU-A yarn failure signal turns ON, the CPU-A
When the U-B system failure signal turns ON, the switch 10 is instructed to select A, and when both CPU systems fail, the switch 10 is disconnected from both systems and process 1 is maintained as it is. Perform the operation.

Therefore, in a device like the one shown in FIG. 1, the CPU-A system 5. C.P.
If any one of the U-B systems 6 is normal, the plant can be controlled without any trouble, so the reliability of the entire system can be increased.

Since the conventional redundant digital control device is configured as described above, it requires hardware (for example, a logic circuit 9 and a switch 10) to switch the outputs of multiplexed CPUs, which has the disadvantage that the device becomes complicated. there were.

[Summary of the invention]

This invention was made to eliminate the drawbacks of the conventional devices as described above, and by adding a circuit that can forcibly open the output contact from the outside to the contact output device, output switching hardware (e.g. The purpose of this invention is to provide a redundant digital control device that does not require logic circuits 9 and switches 10).

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. First, the configuration will be explained. In FIG. 2, 1 is a process, and 2 is a redundant digital control device for controlling the process 1. 3 and 4 are contact input devices that convert contact input signals from process 1 into digital signals; 17 and 18 are C
This is a contact output device that converts digital signals from the PUs 5 and 6 into relay drive signals to operate or deactivate output contacts.

In addition, 5 is a duplicated single system CPU (CPU-A system)
input the control input signal from the contact input device 3,
After the arithmetic processing, it is output to the contact output device 17. Similarly, 6 is 2
This is the other CPU (CPU-B system) that is duplicated, and reads the control input value from the contact input device 4, performs arithmetic processing, and outputs it to the contact output device 18.

The failure detection signals of the CPU-A system 5 and CPU-B system 6 are connected to the forced input terminals of the contact output devices 17 and 18, respectively.

FIG. 3 shows the configuration of the contact output devices 17 and 18.

However, the contact output device 18 is omitted because it has exactly the same configuration. The contact output devices 17 and 18 are configured so that when the forced input signal is OFF, the relay RY can operate 0N10FF according to the digital output signal from the CPU.
If the forced input signal is ON, relay RY is forced OFF'F regardless of the digital output signal from the CPU.
(inoperable). The above contact output device 1
7. The output of 18 is the OR gate 20 of the block diagram shown in FIG.
is output to process 1 via .

The CPU-A system 5 performs control calculations based on the control input signal value from the process l read through the contact input device 3, and ORs the calculation results through the contact output device 17.
Inform Gate 20. In addition, the CPU-B system 6 is also connected to the above CP.
Similarly to the U-A system 5, control calculations are performed based on the control input signal value from the process 1 read via the contact input device 4, and the calculation results are transmitted to the OR gate 20 via the contact output device 18. Since the CPU-A system 5 and CPU-B system 6 perform exactly the same calculations, the results of their calculations are exactly the same as long as both CPUs are normal.

On the other hand, both the CPU-A system 5 and the CPU-B system 6 constantly perform self-diagnosis processing, and if an abnormality is detected, they output a CPU-A yarn failure signal and a CPU-B yarn failure signal, respectively.
Set it to N. The above fault signals are output from contact output devices 17 and 18 respectively.
Since it is connected to the forced open signal input terminal of
If a failure is detected in the -A system 5, the output signal of the contact output device 17 will be forcibly turned OFF (open) regardless of the digital output value of the CPU-A system 5, and the CPU-B
If a failure is detected in the system, the output signal of the contact output device 18 is forced to K OFF (open).

Therefore, the output state of the OR gate 20 becomes like manure.

i) When CPU-A system 5 and CPU-B system 6 are both normal, CPU-A system 5 and CPU-B system 6 are both normal, and their calculation results are completely equal, so the calculation results of both systems are Output.

ii) When only the CPU-A system 5 is abnormal, the output of the contact output device 17 is turned OFF, so the CPU-B system 6
Only the result of the calculation is output.

1ii) When only the CPU-B system 6 is abnormal, the output of the contact output device 18 is turned off, so only the calculation result of the CPU-A system 5 is output.

iV) When both the CPU-A system 5 and the CPU-B system 6 are abnormal, the outputs of the contact output devices 17 and 18 are both OFF, so the output of the OR gate 20 is also OFF, and the process l is not controlled. Since the output is turned off, the current status is maintained.

Furthermore, in the above embodiment, by configuring the OR gate 20 with a wired OR circuit (see FIG. 4), the 9OR gate 20 can be configured only by tying the signal lines, so there is no need to add new hardware. It is very economical.

Although the above embodiment shows the case where the CPUs 5 and 6 are switched, switching to the manual operation circuit 30 may also be possible, and the configuration of the OR gate 20 can be input from the manual operation circuit 30 as shown in FIG. By providing a gate in the configuration, switching to the manual operation circuit 30 can be easily performed, and the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the CPU is connected to the contact output device.
We added a function to forcibly turn off the output when there is an abnormality, and configured the CPU to switch using an OR gate, making the device inexpensive and highly reliable redundant digital control device. This has the effect that it can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional redundant digital control device, Fig. 2 is a block diagram showing a redundant digital control device according to an embodiment of the present invention, and Fig. 3 is a contact output device of Fig. 2. FIG. 4 is a configuration diagram showing the OR gate portion of FIG. 2; FIG. 5 is a configuration diagram showing a redundant digital control device including a manual operation circuit according to another embodiment of the present invention. It is. l...process, 2...control device, 5, 6...C
P.U. 17.18...Contact output device, 20...OR gate. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Patent applicant Mitsubishi Electric Corporation

Claims (1)

[Claims] In a redundant digital control device in which central processing units are multiplexed, when each central processing unit is normal, it outputs the control output processed by each central processing unit, and when it is abnormal, it outputs the control output 1. A redundant digital control device comprising: a contact output device for disabling output; and an OR gate for supplying a logical sum signal of each of the contact output devices to a process.