JPH02284248A - How to check memory contents - Google Patents

Abstract

PURPOSE:To detect the replacement of memory data even if the memory data was replaced at the time to add plural data by adding them in a state in which each data is weighted with the weight of peculiar information corresponding to its stored position. CONSTITUTION:Addition is executed by using an address counter I 11 for reading sequentially the memory data out of the addresses (n) to n+k of a data area 1, a counter C 12 for generating a peculiar number in order to multiply by the peculiar number different for every stored place of the read-out data, a sum arithmetic register 14 and a sum value arithmetic processing part 13, and the contents of the register 14 is written in a standard added result storage area 2 by a sum value write-in processing part 21. Then, prior to the start of actual sequence arithmetic, processing is executed by the sum arithmetic processing part 13, and the standard added result of a storage area 2 and the contents of the sum arithmetic register 14 are compared by a sum value comparison processing part 22, and sum value coincidence check 23 is executed. Thus, the change of the data stored in the memory and the replacement of the data can be surely checked.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for checking memory contents (data) of an electronic control device such as a programmable controller, and is particularly suitable for correctness checking suitable for detecting data changes due to data replacement. Find out how.

[Conventional technology]

The conventional method for diagnosing the contents of memory in this type of device is as described in Japanese Patent Laid-Open No. 56-68843, in which one byte of contents in the memory is added as an 8-bit binary value in order of address. The result of adding the specified number of bytes is compared with the diagnostic result calculated offline and saved in advance. If the results do not match, it is determined that there has been a change in memory data.

[Problem that the invention seeks to solve]

The above-mentioned prior art has a problem in that when data 1 and data N in FIG. 1 of Japanese Patent Application Laid-Open No. 56-68843 are swapped, the addition result is the same as when they are not swapped, and the swap is not detected.

In a programmable controller, such data may be replaced at the convenience of the user. That is,
There are cases where the input terminal or the output terminal is changed due to the user's convenience, and the data in the memory is replaced accordingly, and the problem is whether the correspondence between the data and the terminal is correct or incorrect.

If a programmable controller is operated after discovering that there has been an error in replacing data, not only will it not operate correctly, but it may also be extremely dangerous depending on the manner in which it malfunctions.

The purpose of the present invention is to solve this problem, even when there is a change in memory contents, especially when memory data with the same sum value (result of addition of memory data) is replaced.
The reason is that it has been made detectable.

[Means for solving problems]

The above object is achieved by, when adding data, processing the data written in each location using unique information that differs depending on the location where memory data is written, and then adding the data.

[Effect]

The unique number, which differs for each location where memory data is written, becomes location information unique to the memory data. Therefore, if certain memory data is moved to the pond location, the location information will naturally change, so the added value will be calculated based on this unique location information and will never be the same, so it will not be written correctly. It becomes possible to detect malfunctions in writing.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

The memory 10 of the programmable controller is I1 assigned to the person output module of the programmable controller.
The 110 allocation for the 0 number is data area 1 for setting information etc. and 11 set in data area 1.
It has an I10 number based on the 0 division in the operand section and consists of a user program area 3 for storing a program of instructions to perform calculations, and a sum storage area 2 for storing the correct sum value of the data area 3 in advance. . 20 is an arithmetic processing unit (CPU), and 30 is a system memory in which a system program for controlling the operations of the CPU 20 and the memory 10 is stored. CPU20
executes sequence operations using the system program and user program.

When writing standard addition results to standard addition result storage area 2, address counter I is used to sequentially read memory data from addresses n to n+ of data area 1 of the memory.
(11), a counter C (12) for generating a unique number for multiplying or combining different unique numbers for each read data storage location, a sum calculation register 14 for performing an addition operation, and The counters (11, 12), the register (14), and the sum value calculation processing unit 13 are used to perform addition according to the processing procedure shown in the flowchart shown in FIG. Write to thumb memory area 2. In FIG. 2, the contents of the address counter ■ are data at each address in the memory 10, and the counter values are l, 2, .・・・・・・
... is an integer value.

The above operation is controlled by the program created in the user program area 3. When comparing the added value for the memory data from addresses n to n+ of the data area 1 with the contents of the memory area 2, the programmable controller is controlled by the program created in the user program area 3. Before starting the actual sequence calculation, the sum calculation processing section 13 performs the processing, and the sum value comparison processing section 22 compares the standard addition result in the storage area 2 with the sum calculation register 14. The contents are compared, a sum value match check (23) is performed, and the result is output to the output section 24.

Next, the effects of the above checking method will be explained using specific examples shown in FIGS. 3 and 4.

Data A (1
FIG. 3 shows a state in which data K (106) is set sequentially from 05) to data K (106). The sum P=nA+ (n+1)B+ (n+2)C+ ·
・・・・・・・・・(n+k)K=n (A+B+C+−・−・−・+IO1B+2C+
......10k K. Next, from the state shown in FIG.
0) is shown in Figure 3, and the sum value Q at this time is
(112) is calculated by the operation procedure shown in Figure 2, and the sum value Q=nA+ (n+1)C+ (n+2)B+・
...+(n+k)K =n (A+B+C+...-...+K)+C+2B+
......10k K.

As a result, since the sum value P (107) and the sum value Q (112) are different, the fact that data has been replaced is surely reflected in the added value.

Further, the condition for P=Q is when B=C according to the above calculation formula. However, if B and C are equal, there is no substantial change even if the data is swapped, so there is no problem even if the sum value does not change.

As described above, when programming the user program area 3 in FIG. 1 based on the data area 1,
In addition, if the standard addition result is set in sum storage area 2 based on the above method, no matter how the contents of data area I are changed afterwards, the sum calculation result of data area 1 and the sum will be stored before the programmable controller calculation. Correct calculations can be performed by performing calculations after confirming that the contents of the storage areas 2 match and that no data has been replaced.

Further, an embodiment will be explained with reference to FIG.

In the above embodiment, the count value of the counter 12 is used as a unique number that differs for each data storage location, but instead of the counter value, the value of the existing P address counter 11] for sequentially reading out data from the memory 1o, i.e. Using the address itself, it is possible to set an addition value in the storage area 2 and add the current data for comparison using the same calculation method as in the previous embodiment. Compared to the previous embodiment, this embodiment does not require a counter C (12) for generating a unique number that differs for each data storage location, and the additional value calculation program is It has the advantage that it is shorter and the sum value calculation processing time can be shortened.

〔Effect of the invention〕

According to the present invention, it is possible to reliably check changes in data stored in memory and replacement of data.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the first embodiment of the present invention, Fig. 2 is a flowchart showing the addition procedure in the embodiment of the present invention, and Figs. 3 and 4 are illustrations of specific examples of the addition method in the embodiment of the present invention. So, Figure 3 is an explanatory diagram before data replacement, Figure 4
The figure is an explanatory diagram after data replacement, and FIG. 5 is a flowchart showing the addition procedure in the second embodiment. 1: Data area, 2: Standard addition result, 3 User program area, lO: Memory, 11: Attle counter, 12: Counter, 13: Sum calculation processing unit, 14: Sum calculation register, n, n+1°・...n+k Near address information, information indicating order. Diagram

Claims (1)

[Claims] 1. In a method for checking the correctness of memory contents by comparing the addition result of a plurality of data stored in a memory with a standard addition result for checking prepared in advance, each A memory content checking method characterized in that data is added with weighting of unique information corresponding to its storage location, and the addition result is compared with the standard addition result for checking prepared in advance. . 2. The memory content checking method according to claim 1, wherein the standard addition result is prepared by adding each data constituting the standard plurality of data weighted with unique information corresponding to its storage position. 3. The memory content checking method according to claim 1 or 2, wherein the unique information is address information of a storage location of each of the data. 4. The memory content checking method according to claim 1 or 2, wherein the unique information is information representing the order of storage positions of each of the data.