FAULT DIAGNOSIS APPARATUS AND FAULT DIAGNOSIS METHOD OF MULTI-CHANNEL ANALOG INPUT/OUTPUT CIRCUIT

摘要

A fault diagnosis apparatus and methodcapable of simultaneously detecting the fault of amultiplexer and the fault of an A/D converter andisolating and identifying causes of these faults, themultiplexer and the A/D converter being used in amulti-channel analog input/output circuit. Test-voltagevalues are inputted from a diagnosis-voltage input unitinto the multiplexer and the A/D converter constitutingan analog-signal conversion unit, the multiplexerhaving plural channels, the A/D converter convertingoutputs from the multiplexer into digital signals, thetest-voltage values being different from each other foreach channel of the multiplexer. Comparisons are madebetween the digital voltage values and the test-voltagevalues inputted, the digital voltage values beingoutputted for each channel of the multiplexer. Fromthis comparison result, it is judged whether themultiplexer is at fault or the A/D converter is atfault.