JPS5939054B2 - Diagnostic method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diagnostic method in a microprogram controlled device.

Conventionally, defect detection of logic elements, logic connections, etc. in each part of the device was
A series of test steps is executed only once according to the microprogram, and the test step number in which a defect is detected is displayed or stored in a display register or equivalent means.

This was done using a diagnostic method. Such diagnostic methods often overlook intermittent failures that occur during diagnosis, or incorrectly identify normally normal areas affected by these intermittent failures as failures. An object of the present invention is to provide a diagnostic method that eliminates the above-mentioned problems and can correctly indicate not only fixed defects but also intermittent defects.

The diagnostic method according to the present invention is characterized by repeatedly performing a series of test steps, during which a test step number corresponding to a previously detected defect is compared with a test step number corresponding to a subsequently detected defect. , the smaller test step number is always displayed on the register that displays the defect to be diagnosed. Next, one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic block diagram showing an example of a diagnostic method according to the present invention.

A microprogram for controlling diagnostic execution is stored in the memory 4, and the microprocessor 5 repeatedly executes a test sequence consisting of a series of test steps in accordance with this microprogram. Connected to the microprocessor 5 are a display register 1, a register or counter 2 that stores the number of executions of a test series (loop number), and a register or counter 3 that indicates the number of the test step being executed. . The microprocessor 5 is also connected to a control target (not shown) via a data bus 7 and a control bus 6. FIG. 2 shows an example of the flow of the diagnostic microprogram, and the operation of the embodiment shown in FIG. 1 will be explained according to this flow.

When the program is started, the loop count m-1 is first set in register 2 (block 101), display register 1 is cleared (block 102), and then test step number n=1 is set in register 3 (block 1).
03).

Execute test step n-1 (block 104)
If no defect is detected, the test step number n is incremented by 1 (block 105), and the updated test step number n is compared with the final step number N (block 106). If there is no match, the test step number is further compared with the content of display register 1, and if the test step number n is smaller, the process jumps to block 104. When a match is found in block 106, the loop count m is incremented by 1 (block 108), and then this updated loop count m is compared with the set count M (block 109).
. When a match is found in this block 109, the diagnosis is stopped. If this coincidence is not achieved, block 103 jumps. When a defect is detected in block 104, a comparison is made to see if the test step number at that time (the test step number where the defect was detected) is 1 (block 110), and if n-1, no further diagnosis is required. Since it is pointless to continue, this test step number n-1 is set in display register 1 (block 111) and the diagnosis is stopped.

If it is determined in block 110 that n=1, the test step number n is set in the display register 114 (block 112), and then the process proceeds to block 108. As is clear from the above description, the execution of the test series is repeated many times, and as a result, the lowest test step number in which a defect is detected is stored in the display register 1. Therefore, it is possible to correctly and with a high probability point out intermittent defects that are likely to be overlooked in one or two executions of the test series. In other words, the test step with the lower number targets the basic functional part of the diagnostic target (equipment), so it can point out the most essential defective part.
It is possible to prevent a peripheral functional unit affected by a defect in a more basic functional unit from being incorrectly pointed out as a defective location. Note that the set number of repetitions M of the test sequence can be arbitrarily determined as long as the above effects can be achieved.

[Brief explanation of drawings]

1 and 2 are a schematic block diagram and a program flow diagram illustrating one embodiment of the diagnostic method according to the present invention. 1...Display register, 4...Memory,
5...Microprocessor.

Claims (1)

[Claims] 1 In a diagnostic method in which a microprocessor sequentially executes a series of test steps according to a microprogram read from memory and indicates the defect to be diagnosed on a display register, the series of test steps is repeatedly executed to The diagnostic method is characterized in that a test step number corresponding to a defect detected in the past is compared with a test step number corresponding to a defect detected subsequently, and the display in the display register is changed to the smaller test step number.