JPH07230304A - Dual control method for pc system - Google Patents

Abstract

PURPOSE:To assure the switching synchronism of tasks by producing the interruption signals synchronously with each other through each PC if a communication interruption signal exists when each PC transmits a synchronization command signal and then returns a synchronization end signal for confirmation. CONSTITUTION:The CPU1 and 2 of both PC1 and 2 carry out the program and also output the synchronization command signals 6 and 7 to a synchronization controller 5 with the designated timing. The controller 5 receives the signals 6 and 7 and returns the synchronization end signals 8 and 9 after confirming that both signals 6 and 7 are ready for application. At the same time, the interruption signals 10 and 11 are produced to both PC1 and 2 synchronously with the signals 8 and 9 as long as a common interruption signal 12 exists. As a result, the synchronism is assured for the switching of tasks caused by an interruption. Then the coincidence of internal states is always secured between both PCs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual control method in a PC system using two programmable controllers (hereinafter abbreviated as PC).

[0002]

2. Description of the Related Art A dual system of PCs operates by storing the same program in two PCs and operating the two PCs in parallel, so that even if one PC fails, the other PC runs. It is a PC system that enhances system reliability by continuing. In the parallel operation of the dual system, it is necessary to always match the internal states of the two PCs in order to ensure the continuous operation when one PC fails. Therefore, in the conventional technology,
In general, a method is adopted in which the internal states of two PCs are matched at the start of parallel operation, and the same input data is simultaneously taken into two PCs to execute a program when parallel operation is executed.

[0003]

However, according to the prior art, in a PC that switches a plurality of tasks by an interrupt signal to execute the program of each task, an interrupt due to a subtle difference in CPU clocks between two PCs. Since the task switching synchronism cannot be ensured due to the mismatch of the reception timings, the consistency of the internal states of the two PCs cannot always be ensured. Therefore, the present invention solves such a problem and switches a plurality of tasks by an interrupt signal to execute the program of each task.
Even in C, the purpose is to always ensure the consistency of the internal state.

[0004]

In order to solve the above problems, according to the present invention, in a dual system of a PC that switches a plurality of tasks by an interrupt signal to execute a program of each task, each PC is executed when the program is executed. In accordance with the program, confirms that all the PCs have issued the synchronization command, returns a synchronization completion signal to each of the PCs, and a common interrupt signal to each of the PCs is present. Is to generate an interrupt signal in each of the PCs in synchronization with the synchronization completion signal.

[0005]

According to the above means, the same interrupt can be generated for the two PCs in synchronization with the synchronization command signal from the two PCs and in synchronization with the synchronization completion signal. The synchronization of task switching by is guaranteed. As a result, the consistency of the internal state between the two PCs is always ensured.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration example of a dual system according to the present invention. Reference numerals 1 and 2 denote two PCs constituting the dual system, and 3 and 4 denote CPUs that execute programs stored in the respective PCs. . Each CPU of two PCs
Executes the program and outputs synchronization commands 6 and 7 to the synchronization control device 5 at the timing specified by the program. The synchronization control device 5 receives the synchronization command signals 6 and 7 from the two PCs, confirms that the synchronization command signals 6 and 7 from the two PCs are complete, and returns the synchronization completion signals 8 and 9. At the same time, if the common interrupt signal 12 is present, the same interrupt signals 10 and 11 are generated for the two PCs in synchronization with the synchronization completion signal. FIG. 2 is a timing chart of synchronous control operation of the dual system. As shown by 6 and 7 in FIG. 2, the two PCs output synchronization execution commands at intervals determined by the program and wait for a synchronization completion signal. As shown by 8 and 9 in FIG. 2, the synchronization control device 5 returns the synchronization completion signals 8 and 9 to each PC when both the synchronization commands 6 and 7 from the two PCs are output. At this time, if the common interrupt signal 12 of FIG. 2 exists,
As shown by 10 and 11 in FIG. 2, the interrupt signals 10 and 11 are generated for the two PCs in synchronization with the synchronization completion signals 8 and 9. In this way, since the interrupt signal to the two PCs is generated in synchronization with the synchronization completion signals 8 and 9, the synchronism of task switching by the interrupt is guaranteed, and the two PCs
The consistency of the internal state of is always ensured. It should be noted that each of the C
The PU synchronization command signal can be realized by a read command from the memory or the input port, and the synchronization completion signal can be realized by a read completion signal corresponding to the read command. In a general CPU, the read command is usually prepared as a basic command and can be executed at a high speed, and a simple synchronous control device that responds to the read command can realize a high-speed synchronous operation and a dual overhead having a small overhead. It is possible to realize the system. Further, the interval of the synchronization command signal can be arbitrarily determined in consideration of the interrupt response speed.

[0007]

As described above, according to the present invention, in a dual system of a PC which switches a plurality of tasks by an interrupt signal and executes a program of each task, a simple synchronous control device is used to control each interrupt signal. It is possible to realize a dual PC system capable of high-speed synchronization control that guarantees the synchronization of task switching of the PC.

[Brief description of drawings]

[Fig. 1] Configuration example of dual system

FIG. 2 is a timing chart of synchronous control operation of a dual system.

[Explanation of Codes] 1, 2 Two PCs constituting a dual system 3, CPU for executing programs of 4 PC 5 Synchronous control device 6 No. 1 PC synchronous command signal 7 No. 2 PC synchronous command signal 8, 9 Synchronization completion signal to each PC 10 Interrupt signal to No.1 PC 11 Interrupt signal to No.2 PC 12 Common interrupt signal

Claims (1)

[Claims] 1. In a dual system of a PC that switches a plurality of tasks by an interrupt signal to execute a program of each task, a synchronization command signal is issued from each PC according to the program when the program is executed, and synchronization from all the PCs is performed. After confirming that a command has been issued, a synchronization completion signal is returned to each of the PCs, and if a common interrupt signal to each of the PCs is present, the PCs are interrupted in synchronization with the synchronization completion signal. A dual control method for a PC system, characterized in that a signal is generated.