JPH0728572A - Automatic data preserving device at power interruption - Google Patents

Abstract

PURPOSE:To enable the elimination of a backup power source and an external storage device and to unnecessitate the maintenance required for the device by automatically saving user data in an EEPROM at the time of a power interruption and recovering the data at the time of recovering power. CONSTITUTION:By the power interruption prediction signal from a power source 1, an interruption is made to generate for a CPU 2 and the specified user data is saved in an EEPROM 5 by the interruption processing. Namely, a power source 1 with power interruption prediction signal is used, the power interruption prediction signal monitors an input and the power interruption prediction signal is outputted by an input disconnection, but because a capacitor for smoothing is normally inserted in the power source 1, the output of the power source does not drop instantaneously. Therefore, if the output of the power source is supplied to the CPU 2, the CPU 2 is capable of performing processings till the CUP 2 is stopped due to the drop of power source voltage after the power interruption prediction signal is inputted. In this case, the data amount which can be saved depends on the access time and power consumption of a storage device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer system, which stores specific data in the event of a power failure, and which requires high reliability without maintenance for a long period of time.

[0002]

2. Description of the Related Art As a data protection method in a computer system, various methods have been reported as a method of not destroying a program or data which controls the system itself and a recovery method in the case of being destroyed.

Aside from this, the data storage method used by the user is, for example, a system including an internal storage memory with a backup power source, a CPU, and an input / output device.
Data from the input device is always written in the internal storage memory with a backup power supply, or a system consisting of an external storage device such as a magnetic disk, a CPU, and an input / output device. There is a method of saving it in an external storage device.

However, regarding the method of storing user data, the former method requires maintenance of the device in consideration of the life of the backup power supply. Further, in the latter case, it is impossible to store data frequently considering that the access time of the external storage device is long, and it is less likely that the stored data is the latest data.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a function of surely storing user data that is important and hard to lose even after a long power outage, and has a short change period. The purpose is to provide a computer system for which a storage device can be used for a long period without maintenance.

[0006]

The feature of the present invention resides in that an interruption is generated to the CPU by a power failure prediction signal from a power source, and specific user data is saved in an EEPROM by interruption processing.

The present invention will be described in detail below with reference to FIG. FIG. 1 is a block diagram of a data storage device according to the present invention.

In the figure, 1 is a power supply with a power failure prediction signal. The power failure prediction signal monitors the input and outputs the power failure prediction signal when the input is cut off. Since a smoothing capacitor is usually inserted in the power supply, the power supply output does not drop instantaneously. If this power supply output is supplied to the CPU, the CPU can perform processing from the input of the power failure prediction signal to the stop of the CPU due to the decrease in the power supply voltage. In this case, the amount of data that can be saved depends on the access time and power consumption of the storage device.

Reference numeral 2 is a CPU with an interrupt function. Saves specific data by using the power failure prediction signal as an interrupt activation signal.

Reference numeral 3 is an internal working memory, and reference numeral 5 is a nonvolatile memory EEPROM. The data used in normal processing is stored in the internal work memory. The saving process is to transfer the specific data in the internal working memory to the EEPROM.

[0011]

By the above means, the user's data is automatically saved in the EEPROM at the time of power failure, and the data is restored at the time of power recovery, so that the backup power supply and the external storage device which were conventionally required can be omitted. The maintenance required for is no longer necessary.

[0012]

EXAMPLE Next, an example in which the present invention is applied to a substation control system will be shown. FIG. 2 is a block diagram of the control system. The configuration is the same as in FIG. In the figure, 2 is a CP with an interrupt
U, 3, and 5 are memories. An A / D converter is provided in the input device, and the analog value is loaded into the CPU. The analog values are voltage, current, power, etc. The CPU integrates the amount of electric power from the electric power and outputs it to the output device 4 (setting panel). At this time, the electric energy is an integrated value, so it is saved in the EEPROM to prevent data loss during a power failure.

FIG. 3 shows the characteristics of a power supply device with a power failure prediction signal. The power failure prediction signal is output about 5 ms after the input is cut off. The power output decreases only about 300 ms after the power failure prediction signal is output (C
Until the PU stops due to the power supply voltage drop). During
About 600 words of data can be written to the EEPROM.

FIG. 4 is a flow chart of interrupt processing by the power failure prediction signal. The specific data is saved immediately after the interruption (step 7). After that, a flag for confirming whether or not there is saved data when power is restored is also written in the EEPROM (step 8). After the data saving is completed, the normal processing is not returned to the normal processing so as to prevent the malfunction due to the power supply voltage drop, and the operation shifts to the stop waiting state (step 9).

FIG. 5 is a flow chart of the data restoration process at the time of power restoration. First, the internal work memory 3 is initialized (step 10). In this embodiment, the initial values of the memory are all "0". Next, it is determined whether or not there is saved data (step 11). The presence or absence of the flag written at the time of power failure is determined, and if there is saved data, the data is transferred from the EEPROM to the work memory (step 12). If there is no saved data, nothing is done and the initial value "0" is input to the working memory.

[0016]

The present invention has the following effects. That is, (1) the data storage device at the time of power failure can be maintenance-free.

(2) It is economically advantageous because an external storage device need not be added.

[Brief description of drawings]

FIG. 1 is a block diagram of an automatic data storage device during a power failure.

FIG. 2 is a block diagram of an application example to a substation control system.

FIG. 3 is a characteristic diagram of a DC / DC converter power supply.

FIG. 4 is a flowchart of interrupt processing by a power failure prediction signal.

FIG. 5 is a flowchart of data recovery processing at power recovery (at the time of startup).

[Explanation of symbols]

1 ... Power supply with power failure prediction signal, 2 ... CP with interrupt function
U, 3 ... Internal working memory, 4 ... Output device, 5 ... EEPROM
(Nonvolatile memory), 6 ... Input device.

Claims (4)

[Claims] 1. An automatic data storage device during a power failure in a computer system having a power supply capable of generating a power failure prediction signal and capable of starting an interrupt process using an external signal as an interrupt signal. 2. A computer system having an EEPROM as an internal storage device, wherein specific data is stored in the EEPROM so that the data can be stored even during a power failure. 3. A computer system having an EEPROM as an internal storage device, and having a processing routine for restoring the data stored in the EEPROM to the original area when the power is restored, the automatic data at power failure is provided. Storage device. 4. A computer system having an EEPROM as an internal storage device, capable of selectively storing and restoring specific data used by a user, the automatic data storage device at the time of power failure.