MEMORY DIAGNOSTIC METHOD, MEMORY DIAGNOSTIC DEVICE, AND NON-TRANSITORY COMPUTER-READABLE STORAGE MEDIUM

• US 20120324294A1
• Filed: 03/11/2010
• Published: 12/20/2012
• Est. Priority Date: 03/11/2010
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Yamada, Hiroshi, Itano, Yasuharu, Matsuyama, Etsuji
• Granted Patent: US 9,158,618 B2
• Time in Patent Office: Days
• US Class Current: 714/42
• CPC Class Codes: G06F 11/10 Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
• CPC Class Codes: G06F 11/1004 to protect a block of data words, e.g. CRC or checksum G06F11/1076 takes precedence; security arrangements for protecting computers or computer systems against unauthorized activity G06F21/00
• CPC Class Codes: G06F 11/1008 in individual solid state devices G06F11/1004 takes precedence

Abstract

In a memory diagnostic method, a fixed domain stores data that are not changed during process execution. A variable domain stores data that are subject to writing during process execution. A fixed domain diagnostic part adds an error-detecting code to data to be stored in the fixed domain. The fixed domain diagnostic part compares an error-detecting code calculated from data read from the fixed domain with the added error-detecting code to determine whether there is any data error. A variable domain diagnostic part temporarily stores data stored in the variable domain in a memory region different from the memory storing the data, and writes known data in the variable domain where the temporarily stored data were stored. The variable domain diagnostic part reads data from the region where the known data were written and determines whether the data is the same as the written known data.

Claims

1. A memory diagnostic method of diagnosing a memory used by a process during execution of the process, comprising:

a variable domain diagnostic step with the variable domain of the memory storing first data that are possibly subject to writing by the process, comprising storing the first data stored in the variable domain in a withdrawal region different from the memory region storing the first data, writing known data in the variable domain where the first data stored in the withdrawal region were stored, and reading data in the region and determining whether the data is same as the written known data; and

a fixed domain diagnostic step with the fixed domain of the memory storing second data that are not subject to change during execution of the process, comprising adding an error-detecting code to data to be stored and storing it in the fixed domain in advance, and comparing the error-detecting code calculated from the data read from the fixed domain with the added and stored error-detecting code to determine whether there is any data error.

2. The memory diagnostic method according to claim 1, wherein the variable domain diagnostic step or the fixed domain diagnostic step is conducted on all regions of the memory used by the process.

3. The memory diagnostic method according to claim 1, wherein the variable domain diagnostic step or the fixed domain diagnostic step is conducted while all processes but the variable domain diagnostic step and the fixed domain diagnostic step using the memory used by the process are in their wait state.

4. The memory diagnostic method according to claim 1, wherein the variable domain diagnostic step comprises dividing the variable domain into one or two or more parts, storing the first data stored in the variable domain in the withdrawal region on the basis of the divided parts, writing known data in the variable domain where the first data stored in the withdrawal region were stored, and reading data from the region and determine whether the data is same as the written known data.

5. The memory diagnostic method according to claim 1, wherein the variable domain diagnostic step includes a check board test, a walking bit test, a pseudorandom data test, or a fixed pattern data test.

6. The memory diagnostic method according to claim 1, wherein the fixed domain diagnostic step includes error detection using duplication, parity codes, checksums, Hamming codes, cyclic codes, or Hash functions.

7. The memory diagnostic method according to claim 1, wherein:

the process conducts a control procedure for a railcar; and

the variable domain diagnostic step and the fixed domain diagnostic step are conducted while normal operation of the railcar.

8. The memory diagnostic method according to claim 7, wherein the variable domain diagnostic step is conducted while no arithmetic operation of the process is executed.

9. The memory diagnostic method according to claim 8, wherein the variable domain diagnostic step is conducted on one or two or more divided parts of the variable domain in sequence in a given cycle during which no arithmetic operation of the process is executed and, after the variable domain diagnostic step is conducted on all divided parts of the variable domain, the variable domain diagnostic step is conducted again from the first one of the parts of the variable domain.

10. A memory diagnostic device diagnosing a memory used by a process during execution of the process, comprising:

a variable domain diagnostic part that, with the variable domain of the memory storing first data that are possibly subject to writing by the process, stores the first data stored in the variable domain in a withdrawal region different from the memory region storing the first data, writes known data in the variable domain where the first data stored in the withdrawal region were stored, and reads data in the region and determines whether the data is same as the written known data; and

a fixed domain diagnostic part that, with the fixed domain of the memory storing second data that are not subject to change during execution of the process, adds an error-detecting code to data to be stored and stores it in the fixed domain in advance, and compares the error-detecting code calculated from the data read from the fixed domain with the added and stored error-detecting code to determine whether there is any data error.

11. A non-transitory computer-readable storage medium on which is recorded a memory diagnostic program allowing a computer to execute the following steps while the computer executes a process:

a variable domain diagnostic step with the variable domain of the memory storing first data that are possibly subject to writing by the process, comprising storing the first data stored in the variable domain in a withdrawal region different from the memory region storing the first data, writing known data in the variable domain where the first data stored in the withdrawal region were stored, and reading data in the region and determining whether the data is same as the written known data; and

a fixed domain diagnostic step with the fixed domain of the memory storing second data that are not subject to change during execution of the process, comprising adding an error-detecting code to data to be stored and storing it in the fixed domain in advance, and comparing the error-detecting code calculated from the data read from the fixed domain with the added and stored error-detecting code to determine whether there is any data error.