JPS5812601B2 - Duplex control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a redundant control device in which reliability is improved by operating two control devices in parallel.

Conventionally, in order to improve reliability, two control devices are operated in parallel, and if one of them fails, it is separated from the loop and the other control device takes over the operation.

However, in such conventionally known devices,
It is necessary to provide a device between the two control devices to determine the failure of the two control devices, which has the disadvantage of complicating the entire device.

The present invention aims to realize a duplex control device with a simple overall configuration without requiring a special device for duplication between two control devices.

In addition, the present invention allows two control devices to determine whether the device is normal or not under the same conditions over the entire measurement range in which the measurement signal changes.
The aim is to realize a redundant control device that can determine abnormalities.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, 10 is, for example, a measurement signal e from a process.
Input terminals Ch1 and Ch2 to which m is applied are control devices each receiving a measurement signal em, and here, both have the same circuit configuration.

In the control devices Ch1 and Ch2, R1 and R2 are resistors connected in series between the input terminal 10 and the common line, and these constitute voltage dividing means for dividing the voltage of the measurement signal em.

11 and 12 are comparators, respectively, and 20 are comparators 11 and 1, respectively.
For example, a microcomputer is used as a processor that receives signals from 2 as input.

30 is a D/A converter that converts the digital signal from the processor 20 into an analog signal.

The processor 20 has an internal program memory and a data memory, and uses a loop composed of the comparator 11 or 12, the processor 20, and a D/A converter to input data to the input sides of the comparators 11 and 12. Converts the analog signal that is displayed into a digital signal, performs a predetermined calculation on this digital signal, such as a self-check calculation as described later, a PID calculation, or performs a switch 4 as described later.
1 and 51, and performs various tasks in a time-sharing manner.

Reference numeral 4 denotes analog signal holding means, which is composed of a semiconductor switch 41 driven by a signal from the processor 20, a capacitor 42, and an amplifier 43.

A switch 51 is provided on the output side of the analog signal holding means 4 and is driven by a signal from the processor 20.

60 is an output terminal, to which the switches 51 and 52 of the control devices Ch1 and Ch2 are respectively connected in common.

1 is a communication line, and the processors 20 of the control devices Ch1 and Ch2 can communicate with each other via this communication line.

Further, a computer CO is connected to this communication line so that, for example, the contents of the data memory of each processor 20 can be changed as necessary, and data can be exchanged.

The comparator 11 has a measurement signal em given to one input terminal, and a D/D signal given to the other input terminal.
The analog signal ef from the A converter 30 is compared, and the comparison result is used as a human input signal to the processor 20.

The comparator 12 has one input end supplied with a divided voltage signal R2 divided by resistors R1 and R2, and the D/A converter 30 supplied with this divided voltage signal and the other input terminal.
The comparison result is used as a human input signal to the processor 20.

In a device configured in this way, the normal state. , the switch 51 of the control device Ch is conductive and the switch 51 of the control device Ch2 is non-conductive, so that the signal from the processor 20 of the control device Ch1 can be obtained as a control signal at the output terminal 60. There is.

In this state, the control device Ch1 performs a time-sharing operation to self-check whether the following operations are being performed normally.

That is, the processor 20 uses an analog-to-digital conversion loop composed of the comparator 11, the processor 20, and the D/A converter 30 to output data to the comparator 110 according to a signal (program) stored in the program memory section, for example. Convert the given measurement signal em into a digital signal.

Although there are various methods for converting an analog signal into a digital signal, it is simple to use a successive approximation method, for example.

The converted digital signal is written as Em in a part of the data memory, for example.

Next, the processor 20 reads the output signals of the comparators 12, and this time, the processor 20 reads the output signals of the comparators 12, the processor 20, and the D/
The analog-to-digital conversion loop constituted by the A converter 30 converts the partial pressure signal em / n applied to the input terminal of the comparator 12 into a digital signal, which is stored, for example, in a part of the data memory section. ．． /n.

Subsequently, the processor 20 performs a predetermined operation, such as a division operation, using Em and ErrV/n stored in the data memory section in accordance with the self-check program stored in the program memory section, and calculates Em and Em. /
Find the ratio to n.

The procedure used to calculate the ratio depends on the contents of the program, but it is preferable to use various calculation procedures from the standpoint of checking various functions.

As a result of executing the division operation, the answer is n or 1/n, assuming that the analog-to-digital conversion loop and various arithmetic functions are operating normally.

Therefore, the processor 20 determines that the calculation result is n or 1.
/ n, the function of the processor 20 and the comparators 1 1 , 1 2 , D
The entire device, including the /A converter 30, can be self-checked.

Then, the processor 20 determines that the calculation result is n or 1/n.
In this case, the switch 51 of the control device Ch1 is maintained conductive, and the control device Ch
An OK signal indicating that the control device Ch1 is operating normally is sent to the processor 20 of No.2.

On the control device Ch2 side, while receiving this OK signal, the processor 20 makes the switch 51 non-conductive.

It is assumed that in the control device Ch2, the switch 51 is maintained in a non-conductive state, but other operations are performed in exactly the same manner as in the control device Ch1, and the same output is maintained through the communication line.

If the calculation result is n is not yet 1/n, the switch 51 of the control device ch becomes non-conductive, and an indication that the control device Ch1 is abnormal is displayed on the control device Ch2 side via the communication line l. Sends a FAIL signal.

When receiving the FAIL signal from the control device Ch2, the processor 20 turns on the switch 51 and sends the output signal from the control device Ch2 to the output terminal 6 (K).

FIG. 2 is an example of a flowchart of the above-mentioned operation.

With such an operation, even if one control device Ch1 becomes abnormal, it is automatically backed up by the other control device Ch2, and a continuous control signal can be obtained from the output terminal 60.

FIG. 3 is a block diagram showing another embodiment of the present invention.

In this embodiment, in each control device, the measurement signal em and the voltage em/n divided by the resistors R1 and R2 are applied to the A/D converters 13 and 14, respectively, and the converted digital signals Em and Em/n are applied to the A/D converters 13 and 14, respectively. n is given to the processor 20.

In this case, the number of A/D converters may be reduced to one, and a multiplexer may be provided on the input side of this A/D converter, and the selected signal may be applied to the A/D converter. .

As explained above, according to the present invention, since each control device has a function to determine whether its own operation is normal or abnormal, simply by connecting these control devices in parallel,
A duplex control device with a simple overall configuration that can automatically perform backup can be realized.

In addition, each control device commonly inputs the measurement signal em and a voltage-divided signal (em/n), and these values can take arbitrary points depending on the time, and the measurement signal em Even if the ratio is an arbitrary value, if these ratios are calculated, the calculation result will be a constant value. This is used to determine whether the device is normal or abnormal, so for the entire measurement range where the measurement signal changes, Two control devices can always be checked under the same conditions.

Therefore, even if one control device becomes abnormal, it is possible to switch to the other control device without any change in the control output signal.

[Brief explanation of drawings]

FIG. 1 is a configuration block diagram showing one embodiment of the present invention, and FIG.
The figure is a flowchart showing an example of a procedure for determining whether the device is normal or abnormal, and FIG. 3 is a block diagram showing another embodiment of the present invention. 10...Manual terminal, 11,12...
Comparator, 20... Processor, 30...
・D/A converter, 4...Analog signal holding means, 41, 51...Semiconductor switch, l...
...Communication line, Ch1, Ch2... Control device.

Claims (1)

[Claims] 1. A voltage dividing means that divides the pressure of the measurement signal, and converts the measurement signal and the signal divided by the voltage division means into digital signals, and calculates the ratio of the two, and the result is a constant value related to the voltage division ratio of the voltage division means. 2 units including a switch that determines whether the device is normal or abnormal by determining whether the value is normal or not, and a switch that makes the output signal of the device non-conductive if the signal obtained by the switch indicates an abnormal state. It consists of a control device,
Each of the control devices receives the same measurement signal as input, and also receives signals indicating the normal and abnormal states through communication lines, and when one of the control devices becomes abnormal, the output signal of the other control device is A redundant control device that enables the transmission of