Method and apparatus for diagnosing a fault of a memory

Abstract

The invention makes it an object to provide a memory fault diagnostic device and a memory fault diagnostic method which can diagnose a memory fault at a minimum time using an interim time after the execution of an application in a predetermined control cycle, and can minimize a fault diagnostic time for the whole memories in a diagnostic object area. An area of a memory has a diagnosis area (41) and a non diagnosis area (42), with the diagnosis area divided into a plurality of Row areas which do not overlap each other, and each of the Row areas is divided into a plurality of Cell areas which do not overlap each other. A memory fault diagnostic method has a diagnostic step in a Row area to diagnose between Cell areas with respect to all the combinations of a set of Cell areas in the Row area, and a diagnostic step between Row areas to diagnose between Row areas with respect to all the combinations of a set of Row areas in the diagnosis area. A Row area size is determined to be a size in which a time of the diagnosis in a Row area becomes equal to a time of the diagnosis between Row areas.

Description

technical field [0001] Embodiments of the present invention relate to a memory fault diagnosis device and a memory fault diagnosis method. Background technique [0002] For example, in a safety instrumentation system such as a plant that requires high safety, it is necessary to perform fault diagnosis on the memory of the control device that controls the system. [0003] Since the safety instrumentation system requires long-term continuous operation without restarting in units of years, it is necessary to perform fault diagnosis of the memory not only when the system is started, but also during operation. [0004] Generally speaking, in the failure of the memory that becomes the target of fault diagnosis, in addition to the read / write (Read / Write) error of one memory cell, there is also a problem that when a certain memory cell is read / written, the values ​​of other memory cells are changed. Varying coupling fails. [0005] The fault diagnosis algorithm for the coupling fa...

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Problems solved by technology

[0007] This method can detect the coupling failure of the entire memory area, but because the number of writes and reads (read / write) of the memory is proportional to the square of the memory size, the fault diagnosis time will increase rapidly when the memory capacity of the diagnostic object becomes larger. big problem

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