JP3832117B2 - Programmable controller backup data protection method and programmable controller - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a backup data protection method for a programmable controller and a programmable controller using the same.
[0002]
[Prior art]
Conventionally, when loading a user program in a programmable controller that does not have a backup battery, or for backing up data in a program / data memory (RAM) that stores data, the minimum operating voltage is received after receiving a power-off notice signal (NMI). The data is saved to the backup EEPROM until the next time, and after the initialization processing operation of the CPU responsible for the arithmetic control processing of the programmable controller is completed at the next power-on, the data is transferred from the EEPROM to the program data memory (RAM). And a method of executing data restoration was used.
[0003]
FIG. 3 shows a system flow of a conventional programmable controller. As shown in FIG. 3 (a), from the time of power-on, the central CPU of the programmable controller is set with a stack pointer, SFR (device memory with built-in CPU < After special function register>) initialization, device memory program / data memory (RAM) initialization, etc., data stored in EEPROM is transferred to program data memory (RAM) by data recovery routine The data is restored, and then the system task, user program execution, and I / O refresh routines are circulated.
[0004]
Here, the power-off notice signal (NMI <non-maskable interrupt>) is on hold from the time the power is turned on until the stack pointer is set, and the power-off notice signal can be accepted from the initialization of the SFR. If there is, the process jumps to the routine of the power-off process in FIG. In this power-off processing routine, as described above, the CPU is reset after executing the data saving to the EEPROM during the period from when the power-off notice signal is received until the minimum operating voltage is reached.
[0005]
[Problems to be solved by the invention]
In the above-described conventional method, if the time from power-on to power-off that causes chattering due to disconnection of the power supply line is several μs, undefined or cleared data is stored in the EEPROM before the data restoration process is completed. May be written. This is because the power-off notice signal is included in NMI (Non-Maskable Interrupt). If the power is turned off immediately after the power is turned on, backup processing (RAM → EEPROM), and indefinite or cleared data is written to the EEPROM.
[0006]
The present invention has been made in view of the above-described points. The object of the present invention is to make data that is unstable or cleared even if the power is turned off immediately after power-on (nonvolatile memory (EEPROM)). It is an object of the present invention to provide a programmable controller data backup data protection method and a programmable controller capable of protecting data without being written to (1).
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a volatile memory from / to which data including a user program is read / written, an electrically rewritable backup non-volatile memory, and a decrease in power supply voltage due to power interruption Sometimes backup processing to store the data in the volatile memory in the backup nonvolatile memory until the power supply voltage reaches the minimum operating voltage, and when the power is turned on, the data stored in the backup nonvolatile memory is read and volatile In a programmable controller having a data protection means for performing restoration processing for writing data to the memory and restoring data, the restoration processing for reading the data stored in the non-volatile memory for backup from the time of power-on and writing to the volatile memory is completed. The backup process is prohibited during .
[0008]
In the invention of claim 2, in the invention of claim 1, when the power is turned on, the data protection means is set after the backup flag indicating "prohibited" and "permitted" of the backup processing of the data protection means is set to "prohibited". The data recovery process is performed by the means, the backup flag is set to “permitted” after the completion of the recovery process, and the data protection means does not perform the backup process while the backup flag is “prohibited”. And
[0009]
According to the third aspect of the present invention, there is provided a program / data memory comprising a RAM from / to which data including a user program is read / written, a backup EEPROM, and a time until the power supply voltage reaches the minimum operating voltage when the power supply voltage is lowered due to power-off Data protection means for performing backup processing for storing data in the program data memory in the EEPROM and for restoring processing for reading data stored in the EEPROM from the EEPROM and writing it into the program data memory when the power is turned on. The data protection means is characterized in that the backup process is prohibited from the time when the power is turned on until the return process from reading the data stored in the EEPROM to writing to the program data memory is completed. To do.
[0010]
According to a fourth aspect of the present invention, in the third aspect of the present invention, the data protection means comprises a CPU that executes a user program, and when the CPU is turned on, the backup flag is set to "prohibited" and then the return is performed. When the power-off notice signal is input from the data protection means that executes the process and sets the backup flag to “permitted” after completion of the restoration process and outputs a power-off notice signal by detecting a drop in the power supply voltage. Before performing the backup processing operation, the backup flag is checked, and if it is “prohibited”, the backup processing is not executed, and if it is “permitted”, it has a function to execute it. .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows the configuration of a programmable controller using an embodiment of the present invention. The programmable controller shown in the figure is a power supply circuit 1, reset ICs 2, 3, a CPU 4, a system memory 5 comprising a ROM, and a non-volatile memory for backup. EEPROM 6, program / data memory 7, which is a volatile memory RAM into which user programs are loaded and data is read / written, input / output I / O 8, interface 9 for connecting external support devices, address / data / I / The reset IC 2 provides a power-off notice signal 11 to the CPU 4, and the reset IC 3 provides a reset signal 12 to the CPU 4.
[0012]
FIG. 2 is a system flowchart of the programmable controller using one embodiment of the present invention. When the power supply circuit 1 is turned on, the CPU 4 sets the stack pointer, sets the backup flag to “prohibited”, and further initializes the SFR. After initializing the program / data memory 7 which is the device memory, the data saved in the EEPROM 6 is transferred to the program / data memory 7 to be restored, and the backup flag is set to “permitted” after the restoration process. After this setting, the system task, user program execution, and I / O refresh routines are moved to a cyclic operation.
[0013]
Here, even after the NMI hold period from when the power is turned on to when the backup flag is set to prohibition ends, and after the transition to the NMI acceptable period, backup is prohibited until the backup flag is set to “permitted”. . When the power-off notice signal 11 is given from the reset IC 2 to the CPU 4 during the NMI acceptance period, the CPU 4 executes the power-off processing routine shown in FIG. 2B. At this time, the CPU 4 sets the backup flag to “permitted”. If the permission is not set, that is, if it is set to “prohibited”, the data saving process, that is, the backup process is not performed, and the reset signal 12 from the reset IC 3 is reset. The When the backup flag is set to “permitted”, the backup process for saving the data in the program data memory 7 to the EEPROM 6 is performed before the reset is reset.
[0014]
As described above, in the programmable controller using the present invention, when the time from turning on the power to turning it off is as short as several μS, as in the case where chattering occurs due to the power supply line being disconnected, the data restoration process is not performed. It is possible to prevent undefined or cleared data from being written to the EEPROM 6 before completion.
[0015]
【The invention's effect】
According to the first aspect of the present invention, a volatile memory in which data including a user program is read and written, an electrically rewritable non-volatile memory for backup, and a power supply voltage at the lowest operating voltage when the power supply voltage is lowered due to power interruption Data stored in the backup nonvolatile memory is read out and written to the volatile memory when the power is turned on, and the data is restored. In a programmable controller having a data protection means for performing recovery processing, backup processing is prohibited from the time the power is turned on until the recovery processing for reading data stored in the non-volatile memory for backup and writing to volatile memory is completed. Therefore, the power line breaks and chattering occurs. If the time from power-on to power-off is extremely short, such as several μs, the indefinite or cleared data is written to the backup non-volatile memory before the data restoration process is completed. There is an effect that data can be protected.
[0016]
In the invention of claim 2, in the invention of claim 1, when the power is turned on, the data protection means is set after the backup flag indicating "prohibition" and "permission" of the backup processing of the data protection means is set to "prohibition". After the restoration process is completed, the backup flag is set to “permitted”, and the data protection means does not perform the backup process while the backup flag is “prohibited”. A configuration capable of obtaining the effect of the first aspect can be realized.
[0017]
According to the third aspect of the present invention, there is provided a program / data memory comprising a RAM from / to which data including a user program is read / written, a backup EEPROM, and a time until the power supply voltage reaches the minimum operating voltage when the power supply voltage is lowered due to power-off Data protection means for performing backup processing for storing data in the program data memory in the EEPROM and for restoring processing for reading data stored in the EEPROM from the EEPROM and writing it into the program data memory when the power is turned on. And the data protection means prohibits the backup process from the time the power is turned on until the data stored in the EEPROM is read and written to the program data memory. Breaks and causes chattering If the time from turning on the power to turning off is extremely short, such as a few μs, the indefinite or cleared data will not be written to the backup non-volatile memory before the data restoration process is completed. There is an effect that a programmable controller capable of protecting data can be realized.
[0018]
According to a fourth aspect of the present invention, in the third aspect of the present invention, the data protection means comprises a CPU that executes a user program, and when the CPU is turned on, the backup flag is set to "prohibited" and then the return is performed. When the power-off notice signal is input from the data protection means that executes the process and sets the backup flag to “permitted” after completion of the restoration process and outputs a power-off notice signal by detecting a drop in the power supply voltage. Before performing the backup processing operation, the backup flag is checked, and if it is “prohibited”, the backup processing is not executed, and if it is “permitted”, it has a function to execute it. This can be realized more easily than the conventional apparatus without adding wear.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram of a programmable controller using an embodiment of the present invention.
FIG. 2 is a flowchart for explaining the operation of the above.
FIG. 3 is a flowchart for explaining a conventional operation.
[Explanation of symbols]
1 Power supply circuit 2, 3 Reset IC
4 CPU
5 System memory 6 EEPROM
7 Program data memory 8 I / O for input / output
9 Support Device Connection Interface 10 Address / Data / I / O Bus 11 Power Off Notice Signal 12 Reset Signal

Claims (4)

Volatile memory that reads and writes data including user programs, electrically rewritable non-volatile memory for backup, and volatile until the power supply voltage reaches the minimum operating voltage when the power supply voltage drops due to power interruption Programmable with backup processing for storing data on memory in nonvolatile memory and data protection means for reading data stored in nonvolatile memory at power-on and writing to volatile memory to restore data Backup data for a programmable controller that prohibits backup processing from the time the power is turned on until the return processing for reading the data stored in the nonvolatile memory for backup and writing to the volatile memory is completed. Protection method. When the power is turned on, after the backup flag indicating "prohibited" and "permitted" for backup processing of the above data protection means is set to "prohibited", data recovery processing is performed by the data protection means, and after this recovery processing is completed 2. The backup data protection method for a programmable controller according to claim 1, wherein a backup flag is set to "permitted" and the data protection means does not perform backup processing during a period in which the backup flag is "prohibited". Program / data memory consisting of RAM to / from which data including user programs is read and written, EEPROM for backup, and on the program / data memory until the power supply voltage reaches the lowest operating voltage when the power supply voltage drops due to power-off Data protection means for storing data in the EEPROM and data protection means for reading data stored in the EEPROM from the EEPROM when the power is turned on, writing it into the program / data memory, and restoring the data. The programmable controller is characterized in that backup processing is prohibited from the time when power is turned on until the return processing from reading data stored in the EEPROM to writing to the program data memory is completed. The data protection means includes a CPU that executes a user program. When the CPU is turned on, the CPU sets the backup flag to “prohibited” and then executes the return process. After the return process is completed, the backup flag When the power-off notice signal is input from the data protection means that detects the drop in the power supply voltage and outputs the power-off notice signal, the backup flag is set before performing the backup processing operation. 4. The programmable controller according to claim 3, further comprising a function of executing the backup process if the check is "prohibited" and not executing the backup process.

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