| 摘要 |
PURPOSE:To obtain a test circuit enabling an inexpensive and highly reliable operation test, by comparing other analogue output on the basis of the analogue output by a comparator. CONSTITUTION:An analogue output generating circuit consists of latches 2X, 2Y and D/A converters 3X, 3Y. The latches 2X, 2Y respectively store the data from a processor 1 to send the same to the D/A converters 3X, 3Y. The D/A converters 3X, 3Y respectively output analogue outputs 10X, 10Y corresponding to the data from the latches 2X, 2Y. These two analogue outputs 10X, 10Y are guided to the comparator provided to a build-in test circuit 12 to be compared with each other and a comparing signal 11 is returned to the processor 1 through a discrete input circuit 7. The output voltage range of the D/A converter 3Y is changed with respect to the output voltage of the D/A converter 3X to perform a test at several points and the presence of abnormality is displayed on a display circuit 8. |
