JPS5679346A - Diagnostic circuit - Google Patents

Abstract

PURPOSE: To shorten the time required for diagnosing an apparatus and simplify the control procedures of the external control device, by adopting a high speed scan-out and the comparison system.

CONSTITUTION: In the memory A1 is stored a data by which the bit corresponding to the scan-out point requiring comparison with the scan-out and the expected value data has been made "1", and in the memory B10 is stored the expected value in this test. In the event of diagnosis, a scan-out data is obtained by making the address register A2 step by "1" under the control of the control circuit 22, reading out the contents of the memory A1, and sending the scan-out address to the apparatus 100 to be diagnosed. It is stored in the shift register 13. After the scan-out has been executed by the prescribed number of times, the memory B10 is read out and is compared with the contents of the register 13. In case when its noncoincidence has occurred, the external control device 101 reads out the contents of the register 13 and the address register B11, and points out the fault position by use of a fault dictionary which has been obtained in advance.

COPYRIGHT: (C)1981,JPO&Japio