JPH04321101A - Back-up device for control system - Google Patents

Abstract

PURPOSE:To reduce the power capacity of a back-up device which is needed in addition to a main power supply. CONSTITUTION:An interlocking circuit being a component element of a back-up device consists of a 1st circuit 11 where a manual switch 8 is connected in series to a (b) contact 9 that follows the operation of an object part in accordance with the inhibiting conditions of an interlocking and a 2nd circuit 13 consisting of an (a) contact 12 that follows the operation of the object part in accordance with the forcing conditions of the interlocking connected in parallel to the circuit 11.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is directed to the so-called DDC (Direct
The present invention relates to a backup device for a control system such as a digital control system.

0002

[Prior art] Fig. 2 shows, for example, Utility Model Application No. 58-142703.
1 is a configuration diagram showing a backup device for a conventional DDC system of this kind disclosed in the above publication. In the figure, 1 is a computer (CPU) as an arithmetic control circuit, 2 is an operating end as a controlled unit that operates in response to the output of a command signal generated by the computer 1, and 3 is a connection between the computer 1 and the operating end 2. A backup device provided between the computer 1 and the computer 1 continuously outputs a command signal to the operating end 2 to maintain its operating state when the computer 1 is stopped due to an abnormality or a specific operation. 4 is an analog memory as a storage circuit for storing command signals from the computer 1; 5 is a switching circuit for switching between the signal from the computer 1 and the signal from the analog memory 4; 6 is an interlock circuit which will be detailed later; Reference numeral 7 denotes an operation station as a manual operation section that inputs operation signals for manually controlling the operation end 2 via the analog memory 4 when the computer 1 is stopped.

Next, the overall operation will be explained. During normal automatic operation, the switching circuit 5 selects side a in the figure.
Command signals from the computer 1 are sent to the operating end 2 via the switching circuit 5, and the data is constantly stored in the analog memory 4. Here, if the computer 1 stops for some reason, the switching circuit 5 detects the stoppage of the computer 1 due to, for example, interruption of the strobe signal sent from the computer 1, and immediately switches the selection of the contact to the side b in the figure. As a result, the data stored in the analog memory 4 immediately before this stop is retained as is, and is used as the initial value for subsequent command signals at the operating end 2.
sent to.

Thereafter, manual operation is performed by operating the operating station 7. That is, the state of the operating end 2 is grasped from the feedback signal thereof, and an operating signal is inputted by the manual operating switch 8 of the operating station 7. However, for the equipment plant as a whole, including the control system and the controlled system, various interlocks, specifically prohibitive conditions and forced conditions, are applied to each controlled variable, state variable, etc., depending on the functions of each individual device and plant. exists. Therefore, the operation signal output from the operation station 7 is not directly sent to the operation end 2, but the operation end 2 is controlled based on a determination process based on each of the above-mentioned conditions and the processed signal.

The interlock circuit 6 performs this determination process, and one embodiment thereof is shown in FIG. Specifically, it is composed of a logic circuit that combines AND gates, OR gates, etc. In the figure, "prohibit" is a signal corresponding to a prohibition condition, for example, to prevent an increase operation signal from being output under certain conditions so that the flow rate to be controlled does not exceed a certain value. In addition, "Forced" is a signal corresponding to a forced condition, for example, in order to always ensure that the pressure to be controlled is above a certain value, an increase command signal is output under certain conditions regardless of the presence or absence of an increase operation signal. It is for the purpose of Note that this determination process is necessary even during automatic operation, and although not shown, a logic circuit configuration similar to the interlock circuit 6 is provided in the computer 1.

[0006]

[Problem to be Solved by the Invention] Since the conventional control system backup device is configured as described above,
Even if the computer 1 stops, and therefore the main power supply for control stops, at least the analog memory 4 and interlock circuit 6 of the backup device 3
It is necessary to secure a separate power source to ensure its complete operation. Since the power source for this backup device is generally extremely expensive due to the high reliability required, there is a problem in that the price of the entire device increases. The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a backup device for a control system that can reduce the capacity of an expensive power source.

[0007]

[Means for Solving the Problems] A backup device for a control system according to the present invention connects the interlock circuit in series with a manually operated switch and a b contact that follows the operation of the target section in response to a prohibition condition. The second circuit consists of a first circuit connected to the first circuit, and a second circuit connected in parallel with the first circuit, and a second circuit consisting of an a contact that follows the operation of the target part in accordance with the forced condition.

[0008]

[Operation] The operation of the interlock circuit when the arithmetic control circuit is stopped will be explained. The b contact provided in response to the prohibition condition is turned off when the target part is operating (the contact relay is energized), and the first circuit cannot operate the manual operation switch due to the off state of this b contact. Regardless, no circuit is formed and no command signal is output. The NO contact provided in accordance with the forced condition is "on" when the target part is in operation, and the second circuit is formed by the ON state of this NO contact. Therefore, the operating condition of the manual operation switch The command signal is output regardless of the

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the main parts of a control system backup device according to an embodiment of the present invention. In this embodiment, an interlock circuit 6 is formed within the operating station 7. however,
In FIG. 1, only the part of the interlock circuit 6 related to "increase PB" among the manual operation switches 8 of the operation station 7 is shown. In FIG. 1, reference numeral 9 indicates a b contact of a relay that follows the operation of the part subject to the prohibition condition. That is, the b contact 9 is a contact that, when the above-mentioned prohibition condition is executed, the relay is energized and turned "off," and when the above-mentioned prohibition condition is not executed, the relay is not energized and is turned "on." be. 10 is a similar b contact corresponding to the protection permissible conditions. The b-contact 9, the b-contact 10, and the manual operation switch 8 are connected in series to form a first circuit 11. Reference numeral 12 denotes an a contact of a relay that follows the operation of the part subject to the forced condition. That is, the a contact 12 is a contact that when the above-mentioned forced condition is executed, the relay is energized and turned “on”, and when the above-mentioned forced condition is not executed, the relay is not energized and turned “off”. . And a contact 1
2 constitutes a second circuit 13. The first circuit 11 and the second circuit 13 are connected in parallel to each other.

Next, the operation will be explained. However, since the operation during normal automatic operation in which the computer 1 operates is the same as the conventional one, the explanation will be omitted, and the operation when the computer 1 is stopped will be explained below. When both the prohibition and protection permission conditions are not executed, the b contacts 9 and 10 are both turned on, and the first circuit 11 is formed in response to the operation of the manual operation switch 8, and the increase command is sent to the analog memory 4. sent to. And this analog memory 4
Now, the stored signal immediately before the computer 1 is stopped is set as an initial value, and from this state, control by an increase command, for example, manual control to increase the flow rate, is continued. When either or both of the prohibition condition and the protection permission condition are executed, b.
Either or both of the contacts 9 and 10 are "off" and the first circuit 1 is turned off regardless of the operation of the manual operation switch 8.
1 is not formed. Therefore, no increase command is output based on the operation of the manual operation switch 8.

Regarding the forced condition, when this is not executed, the a contact 12 is in the "off" state and the second
The circuit 13 is not formed, so the increase command will not be output unless the manual operation switch 8 is operated. When the forced condition is executed, the a contact 12 is turned on, the second circuit 13 is formed, and the increase command is output regardless of the operation of the manual operation switch 8. Of the manual operation switch 8, the part related to "reduced PB" is not shown, but is similar to the part related to "increased PB" described above.

As described above, the interlock circuit achieves the same function as the conventional one. In this embodiment, since the interlock circuit is constructed from the a contact or the b contact of the target section corresponding to each interlock condition, no special power source is required for the interlock circuit itself. Therefore,
The power supply required as a backup device is analog memory 4.
Because of the requirement for high reliability, the required power supply capacity for the backup device, which is generally expensive, can be reduced.

[0013]

Since the present invention is constructed as described above, it is possible to reduce the required power supply capacity of the backup device while maintaining the function of the interlock circuit.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram mainly showing a part of an interlock circuit 6, which is a main part of a backup device for a control system according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a backup device for a conventional control system.

FIG. 3 is a configuration diagram mainly showing a portion of the interlock circuit 6 in FIG. 2;

[Explanation of symbols]

1 Computer as an arithmetic control circuit 2 Operating end 3 as a controlled unit Backup device 4 Analog memory 5 as a storage circuit Switching circuit 6 Interlock circuit 7 Operating station 8 as a manual operating unit Manual operating switch 9 B contact 11 First Circuit 12 A contact 13 Second circuit

Claims (1)

[Claims] 1. An arithmetic control circuit that performs predetermined arithmetic processing and outputs a command signal to a controlled part, a memory circuit that stores the command signal, and a back-up system that serves as a backup when the arithmetic control circuit stops operating. A switching circuit that outputs a signal stored in the storage circuit immediately before the stop to the controlled section in place of a command signal from the circuit, and a switching circuit that outputs the signal stored in the storage circuit immediately before the stop to the controlled part, and the signal stored in the switch circuit at the time of the stop as an initial value. A manual operation section that inputs an operation signal for manually controlling the controlled section, and a manual operation section that is inserted between the manual operation section and the switching circuit, and predetermined prohibition conditions and mandatory conditions regarding the input signal from the manual operation section. In a backup device for a control system equipped with an interlock circuit that performs determination processing based on Consisting of a first circuit connected in series, and a second circuit connected in parallel with the first circuit and consisting of an a contact that follows the operation of the target part in response to the above-mentioned forced conditions. A control system backup device featuring: